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You are here: BAILII >> Databases >> England and Wales High Court (Queen's Bench Division) Decisions >> Sullivan v Guy's and St Thomas' NHS Foundation Trust [2017] EWHC 602 (QB) (24 March 2017) URL: http://www.bailii.org/ew/cases/EWHC/QB/2017/602.html Cite as: [2017] EWHC 602 (QB)

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IN THE HIGH COURT OF JUSTICE
QUEEN'S BENCH DIVISION

		Royal Courts of Justice Strand, London, WC2A 2LL
		24/03/2017

MR JUSTICE FOSKETT:

Introduction

1. Aiden Sullivan ('Aiden') was born on 10 July 1997 at Farnborough Hospital in Hampshire.
2. Although Aiden was in good condition at birth, the following day he showed signs of respiratory distress, peripheral and central cyanosis and poor feeding which led to his admission to the Special Care Baby Unit. He was transferred from Farnborough to Guy's Hospital in London as an emergency on 11 July.
3. An echocardiogram led to the identification of a severe congenital heart disorder called "pulmonary atresia and intact ventricular septum" (often identified as 'PA+IVS').
4. Physiologically, the pulmonary valve between the right ventricle (which operates as a pump) and the main artery to the lungs had not developed. The consequence was that any blood that entered the right ventricle from the right atrium could not be pumped to the pulmonary artery. Any such blood in fact flowed into the left atrium through the foramen ovale, then into the left ventricle, then into the aorta and finally into the pulmonary artery through the patent ductus arteriosus. This was the only way that blood could get to the lungs. Since the ductus arteriosus normally closes in the first few days of life, urgent steps were required to keep it open and Aiden was given Prostaglandin E for this purpose. This was a temporary measure for a few days.
5. On 14 July 1997 a right modified Blalock Taussig shunt was inserted so that the branch of the aorta was connected to the pulmonary artery. This had the effect of maintaining the blood flow that had previously taken place through the ductus arteriosus. The operation, which was successful, was carried out by Mr (later Professor) David Anderson, Consultant Paediatric Cardiac Surgeon. The Prostaglandin E was withdrawn.
6. The shunt was only ever intended to be (and could only be) a relatively temporary measure since Aiden would effectively outgrow its fixed size when inserted. It was recognised that cardiac catheterisation and further surgery would be necessary the following year. In the meantime, Aiden continued to develop normally.
7. In August 1998 Professor Anderson carried out what is known as a Hemi-Fontan procedure which was the first part of a two-part surgical procedure the purpose of which was to create a route for the venous blood to arrive in the lungs without going through the right side of the heart.
8. Unfortunately, whilst the surgery was itself entirely successful, Aiden failed to recover consciousness in the way ordinarily to be expected after such an operation and it soon became apparent that he was showing signs of having suffered serious brain damage. The issue in these proceedings is whether, as is alleged by the Claimant (Aiden's mother, Mrs Finna Sullivan) the circumstances in which the surgery was carried out should be characterised as negligent by the standards of 1998 and whether that negligence, if it occurred, caused or materially contributed to the damage that Aiden suffered.
9. Sadly, Aiden died on 6 May 2015, shortly before his 18^th birthday and shortly before the case was due for trial in June 2015. The trial was postponed and came on before me in February 2017.
10. Whatever may be the result in this case, this was a tragic outcome both for Aiden and, of course, for his devoted parents and his elder brother.

The essential issue concerning breach of duty

11. The essential issue in this case concerning breach of duty can be formulated quite narrowly. That does not necessarily mean that it is easy to resolve. It relates to the question of whether, in the course of the necessary period of circulatory arrest during the Hemi-Fontan operation carried out by a team led by Professor Anderson (see paragraph 71 below), Aiden's body (particularly his brain) was cooled sufficiently for the operation to be completed safely within the time it took, avoiding the risk of brain damage. It is not (or, at least, by the date of the trial was no longer) in issue that carrying out a Hemi-Fontan operation under circulatory arrest was an acceptable surgical procedure to adopt and that it was not negligent to proceed in this way.
12. As foreshadowed above (see paragraph 7), the aim of the two-part surgical intervention in a case such as this is to establish what is known as a "Fontan" circulation – in other words, a circulation in which all the (deoxygenated) blue blood returning from the body's veins bypasses the heart (where there is no pumping mechanism) and is channelled straight to the lungs. The use of the Hemi-Fontan procedure means that a staged approach is adopted to achieving this objective, the final objective normally being achieved in what is known as a "Fontan completion" procedure. This is a further (relatively straightforward) procedure adopted some years after the Hemi-Fontan. One of the reasons for performing a Hemi-Fontan is to prepare the anatomy of the patient properly for the Fontan completion and it was, I think, common ground that performing a Hemi-Fontan procedure made the final stage easier to achieve surgically than if a bidirectional Glenn was performed initially.
13. Since there is no issue about the intrinsic nature of the surgical intervention carried out in August 1998, there is no need to consider in detail what Professor Anderson did. Suffice it to say that one aspect of what he did was to take steps to enlarge Aiden's left pulmonary artery (which was narrowed) before inserting a bidirectional shunt known as a "Glenn shunt". The effect of the shunt is to connect the superior vena cava ('SVC', the vein that conveys the blue blood back to the heart from the head and neck) directly to the artery to the right lung.
14. Mr Richard Firmin, the Consultant Cardiothoracic Surgeon called on behalf of the Claimant, itemised the component elements of the intracardiac surgery involved as (i) atrial/SVC incision, (ii) atrial septectomy, (iii) pulmonary artery incisions, (iv) SVC to pulmonary artery anastomosis and (v) plastic repair of the right atrium and pulmonary artery anastomosis with a patch (Hemi-Fontan repair). Since these were intracardiac measures (in other words, procedures carried out within the chamber of the heart), it was necessary that they should be carried out under circulatory arrest (see paragraph 16 below) "to prevent air being ejected from the heart into the circulation from the beating heart", according to Mr Firmin. He commented that (iv) was more difficult than usual because there was an additional stenosis of the right pulmonary artery related to the scarring adjacent to the previous Blalock Taussig shunt which had been tied at the start of the procedure. His view was that achieving all these matters "inside 30 minutes would be a challenge for any surgeon" and that the "26 minutes that were necessary to complete this operation suggests a high degree of technical skill." Since, from the surgical point of view, the operation was a total success and this part was completed in 26 minutes, there can be little doubt on this analysis (and indeed on the basis of other evidence) that Professor Anderson is and was a highly skilled surgeon: Mr Firmin also, for example, described the repair of the left pulmonary artery as having been "elegantly done". Professor Wolf (see paragraph 70 below) implied that the "very quick" time taken by Professor Anderson for a Hemi-Fontan procedure suggested that he was an "adept" surgeon.
15. Professor Anderson made it clear in his evidence that it was his "routine practice" to carry out a Hemi-Fontan procedure under a period of circulatory arrest. The period of circulatory arrest takes place within a much longer period when the patient is put on cardiopulmonary bypass ('CPB'). CPB is a technique by virtue of which the work of the heart and lungs is carried out by a machine, often called in popular parlance a "heart-lung machine". Mr Leslie Hamilton, the Consultant Cardiac Surgeon called for the Defendant, described the process as follows:

"The 'blue' blood is drained from the right side of the circulation, passed through a heat exchanger in the machine (so that the patient can be warmed or cooled) and then through an artificial lung where gas exchange (oxygen is put in and carbon dioxide is removed) takes place - the blood is then returned to the arterial circulation."

16. "Circulatory arrest" takes place when the circulation of blood around the body is stopped completely. In other words, the CPB is halted. It follows that all parts of the body, including the brain, are starved of oxygenated blood. This can only be achieved safely (without risk of brain damage) if the body temperature of the patient is lowered so that the metabolic rate falls and the body tissues accordingly require less oxygen. Brain injury can occur if the metabolism in the brain is not reduced to an effective standstill. If it is not so reduced, the brain will continue to require oxygenated blood to sustain the brain cells, but the lack of oxygenated blood during circulatory arrest may lead to ischaemia and cell death within the brain. As already foreshadowed above (see paragraph 11), the principal issue in this case is whether Aiden's body temperature was reduced sufficiently for the period of circulatory arrest concerned to reduce the risk of this occurring. The circulatory arrest involved is known as deep hypothermic circulatory arrest ('DHCA').
17. Whilst, as I have said, it is not alleged that proceeding by way of Hemi-Fontan under circulatory arrest was negligent per se and it is not, therefore, necessary to consider the arguments for and against the procedure, it is worth noting why Professor Anderson adopted the approach because, as he himself acknowledges, the majority of his colleagues would probably have chosen to insert a bi-directional Glenn shunt simply under low flow CPB rather than placing the patient under circulatory arrest. What he said in his witness statement was this:

"17. The reason I prefer the technique of circulatory arrest is that using a heart/lung machine requires placing a tube in the SVC as it nears the heart and right pulmonary artery, thereby often severely restricting the surgical view and space to operate accurately. The presence of these tubes therefore makes reconstruction awkward and on occasions it has been known to compromise the surgical accuracy of the procedure. In addition the defect created in the SVC where the tube was placed can lead to constriction and even thrombosis, which is a major complication.

18. Consequently, the technique I employed with the Claimant, and have continued to use, is one that was taught to me by Dr William Norwood, the surgeon who developed the operation which bears his name and, where the surgical strategy, though for a different condition, is very similar to that which was employed in managing the Claimant's condition.

19. It should be noted that in order to carry out the procedure, a patient is placed on cardiopulmonary bypass in order to reduce whole body temperature. This essentially means that blood is circulated out of the body, cooled, and then re-enters the body to enable the body temperature to be lowered. Once the desired temperature has been achieved, the patient is maintained on cardiopulmonary bypass in order to maintain the desired temperature and at the end of the procedure the blood is slowly re-warmed and re-circulated around the body to warm the patient back to normal temperature. The longer the period of cooling and maintaining the cold temperature, the greater the likelihood that cooling is uniform throughout the body, especially the brain."

18. Prior to the operation on Aiden, Professor Anderson had anticipated that the part of the procedure to be carried out under circulatory arrest would be completed within 25 minutes. His plan was to reduce Aiden's body temperature to 24ºC for that period. In fact the procedure took 26 minutes, but it has not been suggested that the extra minute is material to any issue in the case, whether of breach of duty or causation. The total duration of CPB was approximately 107 minutes and, as indicated, within that period there was a period of circulatory arrest of 26 minutes. It took 60 minutes to cool Aiden on CPB to 24ºC and rewarming on CPB to 37°C took 21 minutes. It should be added that ice was placed around his head to prevent warming of the brain by virtue of the air temperature around.
19. The essential allegation made by the Claimant is that it was negligent not to have reduced the temperature to something less than 24ºC because, it is said, 24ºC was not a safe temperature to choose for a procedure which was planned to take in the order of 25 minutes under circulatory arrest. It was said in the Claimant's Written Opening that the "clear position in 1998 was that [18°C] was the accepted temperature at which the safety of performing the procedure under [circulatory arrest] could be reliably predicted." However, it is also said that it is and was at the material time "the learning that at a temperature of around 18°C the brain can be protected for 30 to 45 minutes, and that at higher temperatures the period of protection decreases." In other words, if a period of circulatory arrest of about 30 minutes is contemplated, the temperature must be reduced to 18°C to ensure that brain damage does not occur. The case advanced against Professor Anderson's method is that it created an unacceptable risk of brain damage which in fact eventuated.

Was there an established practice in 1998 concerning the temperature to which an infant patient should be reduced for the duration of circulatory arrest?

20. The question thus posed is an important factor in determining the outcome of this case. This is not an area where, for example, the National Institute for Health and Care Excellence ('NICE') had produced a set of guidelines following wide consultation or where there was an established written protocol within the hospital (or within the particular speciality) concerned to which it is possible to look for the parameters within which relevant choices for the operative procedures are made. That, of course, is not determinative of the answer to the question: whether there is an established practice can be, and often is, determined by consideration by the court of a wide body of evidence that has not necessarily been subjected to the kind of analysis that NICE or a collective view of relevant expertise can bring to it.
21. If there was an established practice (or an established consensus) in 1998 about the level to which the body temperature of an infant should be reduced for the period of circulatory arrest contemplated during an operative procedure such as that involved in this case and Professor Anderson departed significantly from it, then there would be the makings of a case in negligence against him. Again, it would not necessarily be determinative of the issue, but it would be a start. That is why I will begin by reviewing the evidence relied upon on behalf of the Claimant, to support the assertions summarised in paragraph 19 above. The response on behalf of the Defendant will emerge during that review.
22. These issues, of course, need to be looked at in the context of the approach required by Bolam v Friern Hospital Management Committee [1957] WLR 582 as explained in Bolitho v City and Hackney HA [1998] AC 323.
23. The case against Professor Anderson is supported by Mr Firmin who, in response to a question in one of the agendas for the joint discussion with Mr Hamilton said this in answer to the question identified:

"Do the experts agree that circulatory arrest (including the temperature and duration of) are divisive issues amongst paediatric cardiothoracic surgeons and that the leading textbooks at the time reflected a "remarkable diversity" in views by the different authors?

…

Mr Firmin's answer

Although there were a range of views for specific operations, in 1998 the general view for operations that could reasonably done in alternative ways was that they should be done without circulatory arrest, or with as brief a period of circulatory arrest as possible."

24. In other words, he was saying that by 1998 the "general view" was that circulatory arrest should be avoided where it was reasonably possible to do so, but where it was unavoidable it should be for the shortest period possible. That was his starting-point. That said, as I have already intimated (see paragraphs 11 and 17), he and Mr Hamilton were agreed that it was acceptable practice to carry out the Hemi-Fontan procedure under circulatory arrest in this case so the true issue was the temperature to which the patient should have been cooled for the period in question.
25. So far as the temperature to which the patient should have been cooled was concerned, Mr Firmin expressed the view that it was "not reasonable" for Professor Anderson to choose 24ºC as the temperature and that the temperature should have been 18ºC on the basis of the period of time anticipated for the circulatory arrest. It is, of course, necessary for there to have been an established consensus that this was so at that time (or that choosing some higher temperature could not be justified by the logical scrutiny to which, according to Bolitho, the choice should be subjected). Mr Firmin's interpretation of the data to which further reference will be made below (see paragraph 32-34) is that if at that time a surgeon was contemplating taking 25 minutes for a procedure under circulatory arrest, then it could be done at "something a bit above 18ºC", but that at 24ºC, the limit was "about 20 minutes".
26. The period under scrutiny is 1998. However, it is necessary to trace to some extent the history of the use of circulatory arrest in the context of this type of surgery because it is relevant to the debate in this case. I derive the beginnings of the history from the First edition of 'Cardiac Surgery' (1986) by John W Kirklin and Sir Brian Barratt-Boyes, a book of significance in this area, and other textbooks and literature to which my attention has been drawn.
27. It appears that some research involving dogs by Bigelow and others in Toronto, reported on in 1950, represented the beginnings of the idea that whole-body hypothermia might be useful in cardiac surgery. They demonstrated that dogs cooled to 20°C by surface cooling, followed by total circulatory arrest of 15 minutes' duration, survived. It seems that in the early 1950s there were isolated reports of the successful use of surface cooling in carrying out cardiac surgery, particularly amongst young children. The development of CPB had already begun sometime before and by 1958 there were the first reports of the successful combination of CPB and hypothermia. In due course, CPB was used as the means of cooling and re-warming the patient during profound hypothermia and total circulatory arrest. As time went on, there were further reports from around the world of successful surgery carried out under circulatory arrest and cooling, including a series from the Mayo clinic in Minnesota (where Mr Kirklin had been at the time) and one from the Green Lane Hospital ('GLH') in Auckland, New Zealand were Sir Brian Barratt-Boyes was based.
28. Inevitably, an important focus as the technique developed was upon the concept of what a "safe" period of total circulatory arrest would be. Plainly, it was recognised that body tissues, particularly brain tissues, could be deprived of oxygen for only a limited period before damage would occur (see paragraph 16 above). Subject to the influence of the results of animal experiments, there had, one supposes, to have been some degree of cautious "trial and error" in the early stages because it is impossible to perform ethically an experiment that provides one set of patients with circulatory arrest at a certain temperature for some defined period and another set for some other period and at some different temperature simply to make a comparison between the results.
29. Where issues of temperature are concerned, it is, of course, important that the temperature is measured in the right anatomical place. Where body cooling and warming were carried out by CPB, the received wisdom was that the nasopharyngeal temperature was the best temperature to indicate the temperature of the cerebral cortex. Where a temperature is referred to hereafter, the nasopharyngeal temperature is the temperature recorded unless indicated otherwise.
30. The First edition of Kirklin and Barratt-Boyes continues, after reciting the history I have summarised, with sections entitled "Oxygen consumption during hypothermia" and "Other phenomena during hypothermia and circulatory arrest" before moving to a section entitled "The damaging effects of total circulatory arrest during hypothermia", the preamble to which is as follows:

"It is generally agreed that the brain has the shortest "safe" circulatory arrest time of any organ or region of the body, although occasionally the kidney seems to be damaged by a period of total circulatory arrest when the brain is not. Although the other organs and regions can be severely damaged by long periods of total circulatory arrest, their "safe" circulatory arrest times are generally longer than those of the brain."

31. The authors refer to the experimental studies with animals and then to the "studies in humans". They indicate that the "functional state of the human brain during and very early after profound hypothermia and total circulatory arrest has been studied only by electroencephalographic evidence of brain function." They refer to other studies including tests on the intellectual and psychological development of children who have been subjected to circulatory arrest and their conclusion was as follows:

"In summary, the data from patients are somewhat conflicting. There is considerable agreement that arrest times of longer than 60 minutes at 18-20°C are not safe, and some of the data suggest the probability that arrest periods of longer than 45 minutes may not be safe. It must be remembered that at present there are no data on late intellectual development following the use in infancy of profound hypothermia with continuous full-flow or low-flow perfusion rather than circulatory arrest."

32. Having considered material relating to kidney and liver function in the context of circulatory arrest, the authors then go on to express their conclusions on what constitutes a "safe" duration of total circulatory arrest and the passage, to which a good deal of reference was made in the evidence, is worth quoting:

"The preceding information does not allow the formulation of a table or a rigorously derived equation relating "safe" duration of total circulatory arrest to various temperatures based on rigorously derived rules. Knowledge of biological systems in general indicates that, were adequate information available, the relationships should be expressed as the probability of no functional or structural damage (i.e. the probability of "safe" circulatory arrest) at a given temperature, rather than as an absolute value.

In addition to the data already presented, a few additional comments are indicated. Our initial experience at the Mayo Clinic suggested that 45 minutes was the maximum "safe" duration even when the nasopharyngeal temperature was reduced to 20ºC. At GLH … we calculated the oxygen debt from measurements of O2 consumption in 10 infants after a mean of 55 minutes of circulatory arrest at 23ºC and concluded that the total energy stores had probably been drawn upon during that interval.

As a guide to the use of total circulatory arrest, Figure 2-8 shows three curves relating to the probability of "safe" total circulatory arrest to the arrest time at three temperatures: 37, 28 and 18ºC. These estimates are based on currently available information and, because of the lack of data, have not been rigorously derived. To emphasise that each curve would have a degree of uncertainty even were considerable data available, the 70% confidence limits around the continuous point estimate of 18ºC, suggested by the little information that is available, are shown in Figure 2-8b. The preceding pages indicate that histologic changes in the central nervous system, without functional abnormalities, are the most sensitive indicators of lack of complete safety of the arrest period used. The portrayal at 18ºC of essentially complete safety of 30 minutes of circulatory arrest is consistent with all available information. The portrayal of essentially complete safety of arrest for at least 70% of subjects at 45 minutes is also consistent with the facts, and the damage produced within this time period is likely to be structural and without functional sequelae. Most patient will have some evidence of structural damage from 60 minutes of arrest, but only 10% of these patients will have evident functional damage and in many of these the manifestations will be transient.

Other support systems, such as continuous CPB at normothermia or with moderate or profound hypothermia with or without very low perfusion flow rates, have their own potential for damage, particularly in infants. A large body of rigorously derived information about these is also lacking. Further, the heart disease being treated itself has great potential for producing damage. An inaccurate repair can produce damage and inaccuracies are more likely to result when surgical exposure is poor. The surgical team weighs the relevant risks and imponderables of these and other factors in deciding in an individual patient whether total circulatory arrest should be used and, if it is to be used, its duration and patient temperature during it …."

33. The figures to which reference was made in the preceding passages appear below:

34. A footnote describes the two graphs as follows:


"Figure 2-8

(a) Nomogram of an estimate (not rigorously derived) of the probability of "safe" total circulatory arrest absence of structural or functional damage) according to the arrest time, at nasopharyngeal temperatures of 37, 28 and 18°C.

(b) Nomogram of an estimate with 70% confidence limits (dashed line) at 18°C nasopharyngeal temperature at 40 minutes of circulatory arrest are estimated at 20 as a basis for calculating these confidence limits. Note that at 30 minutes "safe" arrest is highly likely and that at 45 minutes it is probable. Other data suggest that at 45 minutes the damage will probably be only structural and without evident functional sequelae …."

35. It is right to note, as Mr Stephen Miller QC, for the Defendant, seeks to emphasise, that precisely the same passage appears in the Second edition in 1993 which was the extant edition at the time Professor Anderson was conducting the Hemi-Fontan procedure on Aiden. His short point is that there is nothing that could be read or construed as a warning against cooling to temperatures of around 24ºC for the purposes of circulatory arrest and draws attention to the concluding sentence which reads as follows:

"The surgical team weighs the relevant risks and imponderables of these and other factors in deciding in an individual patient whether total circulatory arrest should be used and, if it is to be used, its duration and patient temperature during it."

36. It is undoubtedly correct that there is nothing specifically to warn against using 24ºC although it is equally right to say that there is no clear indication of the length of the "safe" period for a cooling merely to that temperature - although it might be thought possible to make an estimate using an appropriate intermediate point between the 28ºC and the 18ºC lines. Mr Hamilton attempted this, unsuccessfully as he was forced to acknowledge.
37. Professor Anderson was confronted by Mr Philip Havers QC, for the Claimant, with the text set out in paragraph 32 above and by footnote (b) to Figure 2-8 and accepted that what Kirklin and Barrett-Boyes were saying was that, according to all the available information, 30 minutes of total circulatory arrest at 18ºC either was essentially completely safe or was highly likely to be safe. However, Professor Anderson said that it did not address specifically cooling to 24ºC, but that it was plain from the oxygen debt measurements in the 10 infants referred to "after a mean of 55 minutes of circulatory arrest at 23ºC" (see the second paragraph quoted in paragraph 32 above) that there was a practice at GLH of reducing merely to that temperature (only one degree less than his practice at the time) for in the region of 55 minutes.
38. Professor Anderson was not challenged further in relation to that assertion or asked about the paper upon which the passage was based, but when Mr Firmin gave evidence the following day he was taken to both and the supporting paper was produced. The paper, which was published in the British Journal of Anaesthesia in 1971, was entitled "Metabolic effects of deep hypothermia and circulatory arrest in infants during cardiac surgery".
39. The paper, to which Mr Barratt-Boyes (as he then was) was a contributor, reviewed the position of 21 infants who underwent surgical repair of severe cardiac abnormalities during deep hypothermia and circulatory arrest. Three out of the 21 did not survive, but the sentence in the text of the textbook appears to have been based upon the position of ten "survivors" for whom there was what the authors of the article described as "complete" data. What the summary of the whole paper (as written by the authors) said was as follows:

"Measurement of oxygen uptake and calculation of lactacid oxygen debt suggested that 55 minutes of circulatory arrest was near to the maximal safe interval at 23°C."

40. Mr Firmin accepted that reference to the Table set out in the paper showed that at the time with which the paper was concerned (1969-71) there were significant periods of circulatory arrest at 23°C. Reference to the Table itself does demonstrate in relation to the 18 survivors a spread of temperatures from 22°C to 25.7°C (with many at or around 23°C) and the spread of periods of circulatory arrest from 31 minutes to 67 minutes. Mr Firmin said that the authors were looking at "total oxygen debt for the whole body" and not for the brain specifically and that the technology available in 1998 was "completely different" from that available at the earlier time. He did, however, recognise that the two (very distinguished) authors continued to include the same sentence in the text concerning this series of patients in the edition published in 1993.
41. I have not received any evidence about how critically an informed reader of a medical textbook such as this is to be expected to approach a sentence such as that which appeared in this book and to question whether it is still up-to-date. I should have thought that it was ordinarily not necessary to go beyond the sentence in the text itself, the reader being entitled to assume that the authors still considered it to be of relevance. Interestingly, in the 3rd edition of the book, published in 2003, the reference to the paper and this series of patients was deleted by the new authors of the book, but that, of course, was ten years later than the second edition.
42. I will return to the implications of all this later, but Kirklin and Barratt-Boyes was not the only textbook available during the relevant period and I should turn now to deal with other sources of learning on this general issue.
43. In 1983 came the 1st edition of "Surgery for Congenital Heart Defects" by Stark and de Leval, both of Great Ormond Street. When dealing with the suggested "safe" period for total circulatory arrest they said this:

"During hypothermia we accept … total circulatory arrest periods indicated by Kirklin et al (1973) and which are summarised in ...Table 8.2. When the intracardiac repair is performed employing the technique of cardiopulmonary bypass, profound hypothermia and total circulatory arrest, the nasopharyngeal temperature is lowered to 19ºC. At that temperature we have arrested the circulation for periods up to 60 minutes. In view of the possible alterations in various systems, such long periods of circulatory arrest should be avoided …."

44. Table 8.2 is as follows:

Table 8.2

Estimated safe duration of total circulatory arrest

_________________________________________

Temperature	Duration
(nasopharyngeal)	(minutes)
28ºC	20
26ºC	30
22ºC	45
19ºC	60

45. The expression "we accept" (and indeed other expressions such as "we maintain" and "we have arrested") makes it clear that the two authors are referring to their clinical practice, albeit it would seem that it was, at least in part, derived from the original work of Kirklin and others published in 1973.
46. Taking that Table as it stands, it would be difficult to see how it could be said to be outside acceptable practice to take a temperature of 24ºC for a planned period of circulatory arrest of 25 minutes.
47. However, by the time of the 2^nd edition, published in 1994, the relevant text had changed. Although Stark and de Leval remained the principal authors, other contributors dealt with aspects of the text. The Chapter on 'Perfusion Techniques' was written on this occasion by Mr (later Professor) Martin Elliott.
48. The first paragraph of this Chapter contains the following passage:

"Since the early 1960s, there has been a dramatic improvement in the quality of results of surgery for congenital heart disease. This has been attributable at least in part to an improvement in cardiopulmonary bypass techniques. This in turn is the consequence of an improvement in the quality of the components of the circuit and an improved understanding of the pathophysiology of cardiopulmonary bypass. Despite these advances, however, reviews (Elliott et al. 1993; Hill et al., 1993) have exposed wide variation between units in bypass methodology in both Europe and North America …."

49. The relevant section under the sub-heading 'Circulatory arrest' reads as follows:

"If circulatory arrest is decided upon, single venous cannulation is usually employed, a low haematocrit predetermined, and the temperature of the prime adjusted according to the criteria defined earlier. Bypass is established at full flow (2.4 litres/m²/minute) and continued until the nasopharyngeal or tympanic membrane temperature has reached a predetermined level. But what should that level be? There is remarkable variability in reported practice; temperatures employed for circulatory arrest ranged from 12°C to 22°C in Elliott et al's (1993) survey. However, there are convincing data (Kern et al., 1993) suggesting a relationship between temperature and cerebral protection, which should enable a more sensible choice of bypass temperature.

In my practice, the nasopharyngeal temperature is lowered to 17°C. If the operation is expected to last for longer than 45 minutes, the temperature is reduced to approximately 15°C. Bypass should be continued for at least 20 minutes (according to the most recent data) before the circulation is arrested. This results in even distribution of blood flow to the brain and good cerebral protection. Vasodilating agents (phenoxybenzamine or phentolamine mesylate [Regitine]) also facilitate even cooling. There is no evidence at present that barbiturates or steroids impose any significant additional protection to the brain during circulatory arrest, although results of some work suggest that N-methyl-D-aspartate (NMDA) receptor antagonists may have a role in cerebral protection (Kern et al., 1993). The use of such cerebral protective regimens is not yet defined but is the subject of research in many institutions.

There is considerable debate about whether circulatory arrest is really necessary at all for most of the operations performed in the neo-natal period. A large prospective randomised trial is being conducted in Boston Children's Hospital to determine whether low flow or no flow is preferable in performing the arterial switch operation. These data are not yet available to us. Our own policy has been more pragmatic: to employ cardiopulmonary bypass with either full or reduced flow for the majority of all procedures and to use circulatory arrest only when access is otherwise impossible or as required if venous return is excessive."

50. Before dealing with the reliance placed on this passage on behalf of the Claimant, it is, I think, worth pausing to refer to the survey carried out by Professor Elliott and colleagues from Great Ormond Street published in 'Perfusion' (1993). It was one of the surveys referred to in the opening paragraph of this Chapter and the survey referred to in the first paragraph quoted in paragraph 48 above.
51. Letters containing a questionnaire were sent to all the centres known, or thought, to be carrying out surgery for congenital heart disease in the UK and Eire. The answers were largely given by telephone. The review suggests that the results reflect the practices adopted in June 1992 (see paragraph 52 below). The institutions canvassed included Guys where Professor Anderson was working.
52. One of the conclusions of the review was that the temperature at which CPB was undertaken was an instance where "the variations were greatest." Thirteen of the sixteen institutions did utilise total circulatory arrest during arterial switch and total anomalous pulmonary venous connection procedures for neonates weighing 2.5 – 3 kilograms. The authors explained that the results indicate that "the lowest temperature used on CPB in neonates (thus reflecting the practice during circulatory arrest) also varied from 12°C to 20°C." I should say that that does indeed appear to be the conclusion to be drawn from the material in the review article. The textbook refers to a range, the upper end of which is 22°C (not 20ºC), suggesting that there may have been a transcription error from the original article. At all events, it does appear that temperatures exceeding 18ºC were used, although there does not seem to be a clear reference to 24ºC in the relevant types of operation. However, there are two points that do need to be considered in this context: first, the period of time during which there was in any situation total circulatory arrest was not given (indeed the question was not asked) and, secondly, that at the time the procedure was carried out on Aiden he was no longer a neonate, but an infant (weighing 8.69 kgs), the consensus (though not based on any firm scientific evidence) being that neonates are better protected against circulatory arrest and hypoxia than infants. Nonetheless, Professor Elliott was undoubtedly justified in saying that practices at that time varied. There is a rather engaging passage towards the beginning of the article (to which no specific reference was made during the trial) which highlights the way in which practices were justified at that time:

"The techniques employed in the practice of CPB for the surgery of congenital heart disease may derive from a number of sources. They may be historical to the institution (we've always done it this way), utterly dependant on the surgeon (this is the way I want it done), gleaned from text books (this is the way the Kirklin says it should be done), modified by recent publications (have you seen the latest paper in Perfusion?), or meetings (I've just come back from the AATS and I think we should do this), or by word of mouth from other perfusionists, specialists, or sales representatives (have you heard what they're doing in Neasden?). Usually, the practice of an individual institution is derived from a mixture of all these sources. We hope that this survey will put the information available into context.

In the course of the data collection for this paper it became clear that few units had any real idea of what was going on (in terms of detailed practice) elsewhere in the UK. Each centre seemed fascinated by the prospect of finding out, and we hope that the survey reported here will both satisfy that curiosity and help identify inappropriate or outdated practices. It certainly reflects the current practice in June of 1992."

53. This mirrors to a large extent what Professor Anderson said about the way that practices emerged (see paragraph 64 below), though his position is that the practice he was adopting by the time of Aiden's operation had been developed through a process of evolution designed to secure the best overall outcome (see paragraphs 61-68 below).
54. Professor Elliott's concern was to encourage a more co-ordinated approach throughout the country so that best practice could be achieved. There is, so far as I am aware, no evidence that this was pursued in a way that resulted in any such recognised practice, certainly not by 1998. It seems to be common ground that Professor Elliott was not an enthusiast of total circulatory arrest. Mr Hamilton, who was part of the Great Ormond Street team in 1988/89-1993 said that he "was not a proponent of circulatory arrest, unlike Professor de Leval who was his senior and did use it more." I have no reason to doubt that and one can discern his cautious approach in relation to circulatory arrest in the third paragraph of the passage referred to in paragraph 49 above.
55. At about the time of this survey Professor Anderson was still using 18ºC, but his practice changed in the following few years (see paragraph 61). I will revert to this and the case advanced against him later (see paragraph 61 et seq), but there were two further textbooks in existence at or about the relevant time to which I should make reference. The first was the 2^nd edition (June 1994) of the book entitled 'Pediatric Cardiac Surgery' by Professor Mavroudis of the Children's Memorial Hospital of Chicago. The chapter on CPB, deep hypothermia and circulatory arrest was written by David McGiffin and James Kirklin (who I understand to be the son of John Kirklin). In short summary, this largely repeated what was in the 2^nd edition of Kirklin and Barratt-Boyes. The second was a book first published in 1998 called 'Mastery of Cardiac Surgery' by Professor Kaiser and others (of the Children's Hospital of Philadelphia), the chapter on CPB being written by Nolan and Zacour. It describes the perfusion techniques involved when hypothermia is induced in the following way:

"The perfusionist can begin cooling the perfusate to induce hypothermia once full flow and adequate decompression are established. The primary advantage of hypothermic cardiopulmonary bypass is the reduced metabolic rate and oxygen consumption; although not linear, this approximates 5% to 7% per degree Celsius. In addition, hypothermia sustains intracellular reservoirs of high-energy phosphates (essential for cellular integrity), and preserves high intracellular pH and electrochemical neutrality (a constant OH¯/H+ ratio). As a result of these associated interactions, hypothermic patients can survive periods of circulatory arrest of up to 1 hour without suffering from the effects of anoxia (Table 29-6)." (Emphasis added.)

56. Table 29-6 was as follows:

Table 29-6 Definition of Levels

of Hypothermia and Approximate

"Safe" Circulatory Arrest Times.

______________________________________

Hypothermia	Patient Temperature (ºC)-	Circulatory Arrest
Level		Times (mins)
Mild	37 – 32	5 – 10
Moderate	32 – 38	10 – 15
Deep	28 – 18	15 – 60
Profound	>18	60 – 90

57. Mr Hamilton, who referred to this book, said that it was "very much practically orientated" and would have been heavily relied upon by trainees. He drew attention to Table 29-6 which gave a definition of "safe" circulatory arrest times. Taking the Table at face value, it would be difficult to see why a reader would not be entitled to conclude that a 25 or 26-minute period of circulatory arrest could not take place "safely" at 24ºC.
58. Another paper that was published in the 'Annals of Thoracic Surgery' (June 1988), to which reference was made during the trial, was by Coselli and others entitled 'Determination of Brain Temperatures for Safe Circulatory Arrest during Cardiovascular Operation'. It was referred to in the 2^nd edition of Kirklin and Barratt-Boyes, but does not appear to have been taken into account in the 2^nd edition of Stark and de Leval because it is not one of the papers cited in the references to the Chapter written by Professor Elliott. Professor Anderson did not suggest that he was aware of it at the time. Nonetheless, its potential relevance can be detected from the abstract:

"Profound hypothermia protects cerebral function during circulatory arrest in the surgical treatment of a variety of cardiac and aortic abnormalities. Despite its importance, techniques to determine the appropriate level of hypothermia vary; studies of temperatures recorded from multiple peripheral body sites show inconsistent findings. The purpose of this study is to establish objective criteria to consistently identify intraoperatively the safe level of hypothermia. Our studies are based on experimental evidence showing a correlation between brain temperature and development of electrocerebral silence (ECS) on the electroencephalogram (EEG), and the recognition that the EEG, as an objective measure of brain function, can easily be recorded intraoperatively. We studied 56 patients who required circulatory arrest during operation for replacement of the ascending aorta or aortic arch (N=55) or aortic valve replacement (N=1). Peripheral body temperatures from the nasopharynx, [oesophagus], and rectum and the EEG were continuously recorded during body cooling. Circulatory arrest time ranged from 14 to 109 minutes. No peripheral body temperature from a single site or from a combination of sites consistently predicted ECS. There was a wide variation in temperature among body sites when ECS occurred: nasopharyngeal, 10.1° to 24.1°C; [oesophageal], 7.2° to 23.1°C; rectal, 12.8° to 28.6°C. Fifty-one (91%) of the 56 patients survived. Three had neurological deficits, none clearly related to hypothermia. Two patients (3.6%) required re-exploration for postoperative bleeding. We conclude that monitoring the EEG to identify ECS is a safe, consistent, and objective method of determining the appropriate level of hypothermia."

59. Having listened to Mr Firmin's analysis of this paper and that of Mr Hamilton, and having re-read the transcript of their views and the paper itself, it does seem to me that Mr Hamilton's analysis is the more accurate. The patients were adults, but neither Mr Firmin nor Mr Hamilton suggested that this made the study irrelevant. The authors were, said Mr Hamilton, simply trying to see when ECS (the physiological state when "no electrical activity of cerebral origin can be detected") occurred in each individual patient about to undergo cardiac surgery and to see whether that state could reliably be related to the temperatures taken at the three locations identified. It did not involve any pre-planning of the time to be spent under circulatory arrest: the surgery required to the carried out under circulatory arrest did not commence until the state of ECS was demonstrated on the EEG. The study suggested there was no reliable connection. In the section of the paper entitled 'Comment' the authors said this:

"There has been general acceptance of the concept that peripheral temperature reflects core temperature and, in turn, brain temperature, which for obvious practical considerations is not measured directly in cardiovascular procedures. If this were indeed the case, a close relationship would be expected between one or more peripheral temperature measurements and the temperature at which ECS develops on the EEG. Woodhall and co-workers … observed this to consistently occur at a brain temperature of 20° to 22°C.

However, we found no relationship between temperatures recorded at any of the three peripheral sites and the development of ECS. The variability of measured peripheral temperatures suggest that monitoring of temperature at these sites may not be a reliable indicator of cerebral temperature or metabolic activity. In addition, the poor correlation between various peripheral temperature sites suggests that combining data from multiple recording sites would also not reliably predict the development of ECS."

The reference to "Woodhall and co-workers" was to a series of three papers published in 1958, 1959 and 1960.

60. It follows from the results in this (prospective) series of patients that the temperatures (as measured in the nasopharynx) at which ECS occurred were between 10.1°C and 24.1°C. The conclusion of the authors was that the most reliable way of ensuring that ECS is established before circulatory arrest is commenced is by intraoperative use of the EEG. I have not received any direct evidence about whether intraoperative EEG became a recognised part of procedures involving circulatory arrest thereafter and it has not been raised as an issue as such in this case, but it is interesting to note that the paper by Hirsch and others (see paragraphs 80-84 below) shows, on the basis of the review of the literature carried out during a period after the Coselli paper was published, that the use of routine "EEG monitoring cannot be recommended." However, the collateral findings of relevance from the Coselli study are (i) that the precise temperature at which ECS is achieved in an individual patient is variable and (ii) that even (adult) patients made the subject of circulatory arrest for lengthy periods did not suffer neurological sequelae as a result of the hypothermia.
61. The conclusions to be drawn from that series of patients does not appear to have been influential in the analysis of the textbook writers at the time and it is by reference to the textbooks that the Claimant primarily seeks to criticise Professor Anderson. As I have indicated, in the period from about 1996 to 1998 he gradually changed his practice such that he cooled infants undergoing this kind of surgery to 24°C if he was contemplating a circulatory arrest of about 25 minutes (see paragraph 65 below). By the time of the operation on Aiden, Professor Anderson said that he had embarked on the process of utilising a higher temperature than 18°C and there had been no adverse consequences in any patient.
62. Mr Havers challenged the wisdom of doing so, largely on the basis that (1) there was nothing in Kirklin and Barratt-Boyes, 2nd edition, to support 24°C as a safe temperature for as long as 25 minutes, (2) it should have been apparent from the 2nd edition of Stark and de Leval that Professor Elliott was of the view that his practice was "safe", that practice being to take 17°C as the usual temperature for circulatory arrest, but that where "the operation" was expected to last for more than 45 minutes, the temperature should be reduced to 15°C and (3) that Professor Anderson's own series of patients prior to operating on Aiden was an inadequate basis for making the change. Mr Havers suggested that Professor Anderson was "taking a leap in the dark" in adopting the practice he did given that there was nothing in the literature to show that 26 minutes of circulatory arrest at 24°C was or would be safe.
63. Professor Anderson's response in summary was that none of the guidelines offered in the textbooks was based on solid science, as Kirklin and Barratt-Boyes acknowledged expressly, that there was nothing in any of the passages quoted to suggest that arrest for 25 or 26 minutes at 24°C was unsafe and that he was confident that his own clinical experience justified his gradual move to 24°C for this procedure (a decision that he says has been confirmed since the operation on Aiden).
64. Looking back 20 years, he said he could not say specifically whether he had read the relevant passage in the 2^nd edition of Stark and de Leval, but said it was likely that he was aware of Professor Elliott's practice at the time. The reason, he said, was as follows:

"… I would have been aware of the variability of practice because it's a small community of cardiac surgeons specialising in paediatrics and we meet and, of course, we discuss our own varying techniques. And some people might have raised an eyebrow about something that you did, … but we all accept that there are many ways of achieving the same outcome and what works in one centre and in the hands of a particular surgeon may not in the hands of another. And the worst possible thing is to … be changing your practice on a whim … because [it] can lead to complete chaos. You really have to try and get a technique, refine it and establish it and stick with it unless there is a really good evidence base that says you should do differently."

65. Professor Anderson's further response to the criticism that he moved from a temperature of 18ºC to 24ºC without justification was expressed briefly in these terms:

"The decision to go to 24 degrees was not some sort of mad venture of my own. It was a carefully considered decision in the context of my own practice, looking at the outcomes, trying to reduce the morbidity associated with deep hypothermic circulatory arrest, which influences clotting, and … the systemic resistance. So seeking to get a package of practice in the operating theatre for this kind of case that produced optimum outcome for all cases. And I believe that my practice since and the results achieved have supported that, which is why I have not changed and I still use 24 as the preferred temperature."

66. That represented a summary of a much lengthier explanation given in his witness statement and evidence in chief.
67. As I have already indicated, he said that his own practice developed through an evolutionary process. As indicated in his witness statement (see paragraph 17 above), he learned the Hemi-Fontan surgical procedure from Dr William Norwood. He accepted that Dr Norwood cooled to 18ºC. However, he said that as he (Professor Anderson) became more proficient and confident with the procedure, he realised that he could accomplish it within a period of circulatory arrest which he felt was likely to be safe and which, in his judgment, "counterbalanced" other potentially undesirable consequences of a prolonged CPB. I will return to those consequences below (see paragraphs 72-77).
68. The evolutionary process referred to by Professor Anderson involved initially, he said, dealing with a few (probably less than 10 in total) procedures at 20-22ºC and then moving to 24ºC. He produced data from 15 operative procedures in infants of varying ages (between one month and 63 months) between March 1996 and August 1998 (just before the operation on Aiden) in which the patient's temperature was reduced to 24°C. Not all were on circulatory arrest for as long as 25/26 minutes, but 8 certainly were, 4 were in the region of 15-20 minutes and the other 3 were cases where the circulatory arrest was not continuous, but overall each had comparable total periods as in the other cases. In none of those 15 cases was there any evidence of neurological injury in the immediate aftermath of the surgery and in those who were followed up in later life no late neurological injury had emerged.
69. Mr Havers sought to place a different gloss on this series by suggesting that where patients had been lost to long term follow up, they should be excluded, as should the one case where there was a "question mark" over whether the temperature was 18°C or 24°C, but Aiden's case should be added to the list. This would result, he suggested, in the conclusion that the "risk" of serious neurological injury by taking 24ºC is the temperature was 6 – 6.5%, a risk which was said to be unacceptable. With respect, I have no doubt that this represents a flawed approach, whether statistically or otherwise. Until Aiden's case, Professor Anderson will have seen each of the procedures at 24°C to which I have referred in paragraph 68 as having been entirely successful, in none of which were there any immediately obvious neurological consequences of the acute kind that occurred in Aiden's case.
70. In my judgment, it is not a fair criticism of Professor Anderson to say that his own series of cases until Aiden's operation gave him an insufficient basis for choosing 24°C as an appropriate temperature, particularly when the underlying evidence base for the "recommended" practice of others "does not allow the formulation of a table or a rigorously derived equation relating "safe" duration of total circulatory arrest to various temperatures based on rigorously derived rules" (see paragraph 32 above). It is, of course, correct to acknowledge, as Dr Jonathan Smith and Professor Andrew Wolf, the Consultant Paediatric Anaesthetists called for the Claimant and Defendant respectively, agreed, that this series does not prove the safety of choosing 24ºC for a 25-minute period of circulatory arrest, but, as Professor Wolf said, it does show that what Professor Anderson did was within his usual practice and that the series demonstrated "acceptable outcomes". That is a view it is impossible to reject.
71. I have observed already (see paragraph 14) that the evidence suggests that Professor Anderson is and was a very skilled surgeon. Mr Firmin acknowledged that to be so and it is, perhaps, also right to note that neither Mr Firmin nor Mr Hamilton has ever carried out this procedure, certainly when the patient is under circulatory arrest. On the basis of his own knowledge of how long it took him to conduct such a procedure it does not appear to me to be intrinsically unreasonable for Professor Anderson to have "taken a view" on the temperature to which the infant was cooled during the anticipated period of circulatory arrest provided, of course, that there was no established learning that the temperature he chose was not sufficiently low for the purpose or that there was other evidence available to him (perhaps in the context of his own clinical experience) that suggested the temperature he chose was too risky. Mr Firmin and Mr Hamilton acknowledged that Professor Anderson was entitled to take into account his own experience. I have already indicated how he arrived where he did in relation to this issue, but it is not without some significance to note that, albeit the lead physician in undertaking the procedure, there will be at least an anaesthetist present, together with other members of the surgical team. Whilst I have not heard from any other member of the team, there is no evidence in the records that any one of them, particularly the anaesthetist, expressed any concerns about what was proposed – nor, incidentally, that anything untoward or unexpected happened during the operation on Aiden. Professor Wolf was of the view that Professor Anderson's choice of 24ºC for a period of 25 minutes' circulatory arrest "was within allowable limits" and would not have triggered an expression of concern by the anaesthetist. Again, that is not a view that I can reject.
72. As indicated in what Professor Anderson said as recorded in paragraph 65 above, the approach he adopted from 1996 onwards had involved weighing the various risks that, in his experience, arose from the use of CPB and deep hypothermia. That involved weighing the risk of neurological damage from circulatory arrest as part of a balancing exercise when taking into account other risks. In short, he was concerned that if the patient was cooled too much and for too long there were risks arising from systemic vascular resistance, potential renal failure and coagulation difficulties.
73. Mr Havers cross-examined him about these issues, the essential suggestion being that they could be accommodated perfectly satisfactorily and safely by means other than merely reducing the patient's temperature to 24°C. This was on the basis that Dr Smith had expressed the view that systemic vascular resistance (which, it is accepted, can arise) can be avoided by proper re-warming, the administration of vasodilators and the administration of inotropes. In relation to the risk of renal failure, he suggested that diuretics could be used and, as an effective last resort, dialysis. In relation to possible blood coagulation difficulties, Dr Smith said that extra clotting factors, including platelets, can be administered, with the possible need for one or two extra days in intensive care.
74. Professor Anderson recognised that these facilities existed, but each, in his view, had its disadvantages. For example, so far as the administration of platelets was concerned, he said that platelets can be very vasoactive and he had seen patients arrest on the administration of platelets. Renal failure was something that it was highly desirable to avoid because of its morbidity risk.
75. Professor Wolf had recognised in the joint statement with Dr Smith that the benefits from a warmer temperature would be "better cardiac performance post circulatory arrest, improved coagulation, reduced constriction in the systemic blood vessels (aiding improved cardiac output and organ perfusion)", but appeared to suggest that the benefits were "marginal". Not unnaturally, Mr Havers alighted upon the word "marginal" to suggest that the supposed benefits of going to the higher temperature were minimal compared with the increased risk of neurological damage.
76. Professor Wolf explained that he used the word "marginal" in the context of the fine margins that applied to modifications made from time to time in the management of paediatric cardiac surgical cases which was, he asserted, a "high risk area".
77. As I listened to this debate (and having reviewed it for the purposes of composing this judgment), it has seemed to me to be plain that this was an area where views (and indeed experience) may quite reasonably vary (and differ) without it being said that one or other is right or wrong (or better). I do not see how the court could resolve the differences thrown up by the competing views about the weight to be given to these various factors in deciding how best to proceed with the Hemi-Fontan procedure. At the end of the day, Professor Anderson was obviously an experienced and talented surgeon and his own judgment on these issues has to be accorded respect. Some of his colleagues might disagree with him, others might agree, but merely because some might disagree with this aspect of his personal balancing exercise does not make his approach a negligent approach.
78. If one was to describe the whole process by which Professor Anderson (with, at the very least, the tacit agreement of the rest of his team) reached the decision by the time of Aiden's operation that 25 minutes at 24°C was safe, it would surely be the process referred to in Kirklin and Barratt-Boyes highlighted in paragraph 35 above.
79. Logically, the question of whether there was an established consensus about what constituted safe practice in this context in 1998 must be determined by reference to the knowledge and learning reasonably available until that time. Indeed, the focus of the foregoing analysis has been on material and learning that preceded the operation on Aiden. The three additional areas of learning to which I am about to refer post-date the operation, but they add some comfort that the conclusion to which I have come, namely, that there was no established consensus concerning safe practice, is correct.
80. The first is the survey carried out by Hirsch and others. The authors, representing many of the best and most highly respected centres for paediatric cardiology in the USA, conducted a systematic review of the literature relating to neuromonitoring and neuroprotection strategies during CPB in infants of age 1 year or less between 1 January 1990 and 30 July 2010. Of the 527 potentially relevant manuscripts, 162 fulfilled the relevant selection criteria and were subjected to analysis. The results were published as 'Protecting the Infant Brain During Cardiac Surgery: A Systematic Review' in 'The Annals of Thoracic Surgery' (2012). Before referring to one or two aspects of the paper, it is worth noting the following passage towards the beginning of the paper:

"There are few subjects debated among pediatric cardiac surgeons that are more contentious than the neuromonitoring and neuroprotective strategies used during cardiac surgery in neonates and infants. Any discussion of the use of deep hypothermic circulatory arrest (DHCA) or near-infrared spectroscopy (NIRS) will elicit multiple, very strongly held opinions. Each potential neuroprotective or monitoring strategy has advocates who promote their viewpoint with great fervor along with individuals who hold the counterpoint with equal intensity. Unfortunately, the body of evidence that supports one strategy or viewpoint over another is often limited and inconclusive. In order to determine the role of any intervention or monitoring in the clinical setting, it is incumbent upon us to understand that everything we do is associated with potential clinical gains, limitations, and potential harm with intervention, as well as increased cost."

81. This appears to reflect what Mr Hamilton, in particular, said about the general position obtaining in 1998 which, the paper would appear to indicate, continued to be the position thereafter. His answer to the question referred to in paragraph 23 above was as follows:

"Yes … even now there is a vigorous ongoing debate about the use and time of circulatory arrest, with strongly held views on both sides."

82. The general conclusion of the Hirsch review is revealed in the following paragraph:

"Many innovative approaches to the conduct of CPB and to monitoring the functional status of the brain and its blood supply have been introduced into clinical practice. Perfusion strategies for infant heart surgery have evolved considerably over the last 2 decades. Many practitioners have adopted practices that allow them to avoid or minimize the use of DHCA, as there was a presumption that neurodevelopmental morbidity was largely related to this technique. In addition, numerous modalities have been introduced for purposes of perioperative and intraoperative monitoring of the brain and its blood supply, metabolism, and electrophysiologic status. While some of these strategies and practices have been widely adopted, and even promoted by their proponents as best practices or "standard of care," the strength of evidence supporting the use of these practices has not been previously assessed in a systematic fashion. Unfortunately, the body of evidence that supports one strategy or viewpoint over another is often limited and not conclusive."

83. The following passage is of particular relevance in the present context:

"With respect to blood gas management, cooling strategy, and perfusion strategy (continuous bypass, DHCA, regional cerebral perfusion), there are no data to demonstrate superiority or to recommend any specific practice relative to others."

84. Although the paper did not appear until 2012, it did embrace the surgical practices adopted for a period of over 20 years starting at the beginning of 1990. It covered, therefore, the period of 8 years leading up to the operation on Aiden, but also the period of 12 years thereafter. Accordingly, it lends support to the conclusion that there was no established consensus about the standard of care to be expected at the time - and indeed that none has truly emerged since.
85. Another paper, to which Dr Smith drew attention, by Neufeld and others entitled 'Five-year neurocognitive and health outcomes after the neonatal arterial switch operation', was published in the Journal of Thoracic and Cardiovascular Surgery in December 2008. Its purpose was to assess the 5-year neurocognition and health of a cohort of Canadian neonates who underwent the arterial switch operation for transposition of the great arteries. The cohort consisted of 69 consecutive neonates who had operations from 1996-2003 with full-flow cardiopulmonary bypass and selective DHCA. Whilst the paper was concerned with neurological outcome, it demonstrates that DHCA was used in 33 out of 69 cases with a mean time of circulatory arrest of between 15 and 37 minutes, depending on the complexity of the surgical procedure, with the lowest temperature to which the patient was cooled being 21ºC and the highest such temperature being 23ºC. Of the four cases categorised as "complex" (which would be applicable to Aiden's case), the mean time for circulatory arrest was 37 minutes with a standard deviation of 24 and a lowest temperature just before DHCA of 22ºC with a standard deviation of 3. This suggests a wide band for circulatory arrest times with a relatively narrow band of temperatures around 22ºC.
86. What this does support is the proposition that cooling to 24ºC for 25 minutes in a complex operation was not out of the ordinary during this period.
87. Finally, there is the series of patients operated on by Professor Anderson after the operation on Aiden. He has said, and I accept, that he had never had a consequence such as that which occurred in Aiden's case prior to the operation on Aiden. However, he also said that he did not change his practice thereafter and conducted a significant number of similar operations at 24°C over the next 12 years or so, in many of which the period of circulatory arrest was in the region of 25 – 30 minutes, and, in one or two cases, slightly longer. In none of those cases, he said, was there neurological injury of any significance, certainly not of the catastrophic nature as occurred in Aiden's case. There is no basis upon which I can reject that evidence and it adds support, albeit to some extent ex post facto support, to the proposition that, at least in Professor Anderson's hands, a procedure of the nature undertaken in Aiden's case could, and usually was, carried out without significant neurological sequelae if carried out at 24°C during a period of circulatory arrest lasting 25 – 30 minutes. That other surgeons may adopt a different approach does not alter the position.
88. Before parting with this aspect of the case, I would observe that, whilst not always said explicitly, it is likely that all the papers to which my attention has been drawn during the case would proceed on the basis of a desire to see evidence that satisfies to the scientific standard the proof that a particular procedure is to be preferred or that a particular practice is to be avoided. The court's approach requires a lesser standard of proof. Nonetheless, it has not been suggested that I should do other than to accept these various papers at face value and to try to determine their impact accordingly.
89. As will be apparent, it is, in my view, quite clear that, certainly in 1998, there was no clearly established pattern of practice concerning the temperature to which an infant should be cooled for a particular period of circulatory arrest other than the general proposition that the longer the period of circulatory arrest, the lower the temperature should be. Everyone knew that there were risks of neurodevelopmental damage through circulatory arrest, but practices developed, much along the lines of the sentence in Kirklin and Barratt-Boyes quoted above (see paragraph 35), which either proved satisfactory or required changes.
90. As previously indicated, my primary task is to decide whether the Claimant has established that there was in 1998 an established consensus within the paediatric cardiac surgery community that merely reducing the patient's temperature to 24°C for a procedure intended to take 25 minutes under circulatory arrest was something that carried too high a risk of significant neurological damage for it to be undertaken. The short answer is that it has not been so demonstrated. It may well be that many surgeons would not have done what Professor Anderson did, but that has never been the test in this context. If what Professor Anderson did was logically defensible on the basis of the existing knowledge and could be supported by a body of responsible opinion, that would result in what he did escaping the epithet 'negligent'. For the reasons I have given, I believe that what he did meets those tests and, accordingly, I do not consider that his approach was negligent.
91. Since that is my conclusion, this case must fail on the basis that breach of duty has not been established. It follows that, strictly speaking, the issue of causation does not need to be addressed. I will, however, indicate my conclusion on the issue, albeit somewhat more briefly than might otherwise have been the case.

Causation

92. It is not disputed that prior to the operation, Aiden had no neurological deficits, but that soon thereafter those deficits first manifested themselves. As previously indicated (see paragraph 71 above), there was no record of anything occurring during the surgical procedure to indicate that something untoward had happened.
93. Subsequent CT and MRI scans demonstrated the damage that has caused those neurological deficits. Dr Marcus Likeman, the Consultant Neuroradiologist instructed by the Defendant, described the areas of change demonstrated as follows:

"The imaging series is in keeping with a global insult to cerebral grey matter and the globus pallidus bilaterally. Appearances are most likely due to an hypoxic-ischaemic injury. The presence of swelling in the first CT study with resolution on the second indicates injury was acute and likely occurred in the days before the first CT study. It is not possible to determine when injury occurred more precisely from the imaging, and I defer to clinical opinion. Aiden's widespread clinical deficits are due to the global injury resulting from hypoxia ischaemia."

94. Dr Norman McConachie, the Consultant Neuroradiologist instructed on behalf of the Claimant (in succession to the late Dr Brian Kendall), said that he broadly agreed with Dr Likeman's findings. He said that the relevant radiological evidence was of (i) some brain swelling on 22 August 1998 which had settled by 27 August, with generalised atrophy having developed by 9 October, (ii) bilateral deep grey matter injury, mainly affecting the lentiform nuclei and (iii) bilateral subinsular and capsular white matter oedema on the CT scans.
95. They were both agreed that the damage in Aiden's case occurred in areas of the brain where there is high metabolism, areas that are at the greatest risk of damage being caused by a short period of circulatory arrest. Dr McConachie was prepared to say that it was more likely than not that the damage occurred during the 26-minute period of circulatory arrest and "assuming the insult was the same throughout the 26 minutes, the damage probably accrued towards the end of that period". Dr Likeman, on the other hand, was unprepared to accept that such a conclusion could be drawn because there was no evidence in the literature (or indeed in Professor Anderson's series of patients) that this kind of damage can occur during circulatory arrest. Dr Likeman felt that a neuroradiologist could not answer the question of precisely when the damage occurred and that it was a matter for those with expertise in cellular metabolism. That seemed to me to be clear.
96. On that basis, it is necessary to turn to what the Consultant Paediatric Neurologists say on the issue. Dr Diane Smyth prepared a report for the Claimant and Dr Lewis Rosenbloom for the Defendant. Both are highly experienced in their field, but I sensed that neither felt able to throw much informed light on the difficult question of when the irreversible damage occurred in this case. Dr Rosenbloom was only prepared to accept that it was possible that it occurred during the intra-operative period (in other words, from the time that anaesthesia was induced to leaving the recovery room), but that the absence of any recorded adverse intra-operative episodes made it equally possible that it occurred at some other time. Dr Smyth considered that there was no period other than the period of circulatory arrest when the damage could have occurred, but significantly she said the following in the joint statement with Dr Rosenbloom:

"It is not possible to determine when the damage occurred during the 26 minutes of cardiac arrest. All that can be said is that it is probable the damage occurred during the total and continuous period of arrest."

97. She repeated this in the following form at a later stage in the joint statement:

"All that can be said is that events relating to the continuous period of arrest at 24ºC were what caused Aiden's brain damage but it is impossible to say scientifically at what point during the 26-minute period of arrest that the irreversible brain damage occurred."

98. When she gave her oral evidence she modified this somewhat by accepting the proposition that the "earlier minutes" of the circulatory arrest would have been non-damaging and, whilst it is "very difficult to say exactly when" the damage occurred "but on first principles and of [her] understanding that the period of 20 minutes at a temperature of 24ºC for this sort of surgery that it is probably more likely that the damage occurred towards the end of the period", but she repeated that "overall [she had] to say it has certainly been in the period of the total and continuous period of arrest."
99. The 20-minute "safe period" was derived from what Mr Firmin had said. He said that, in his view, the limit for circulatory arrest at 24ºC was "about 20 minutes" (see paragraph 25 above). Assuming for present purposes that the damage did occur during the period of circulatory arrest, this is the point at which the wheel has turned full circle. The evidential basis for saying that 20 minutes at 24ºC is "safe" and that any period thereafter is potentially "unsafe" is too slender (for the reasons considered during the analysis of breach of duty) for there to be a conclusion to that effect, even on the balance of probabilities. There are many possibilities, but no probabilities.
100. Mr Miller has submitted that it is too simplistic to conclude from the fact that Aiden appeared completely normal before the operation, but damaged immediately afterwards, and that there does not appear to have been any problem with the anaesthesia nor with the perfusion during bypass and re-warming, that the damage must have been caused during the 26-minute period of circulatory arrest. He cautions against transposing the familiar model used in perinatal asphyxia cases (namely, that a healthy foetus can withstand 10 minutes of total hypoxia before brain damage starts occurring) to the current scenario which is what he suggests that the Claimant's experts are doing. He contends that the evidence suggests that the organs of the body, including the brain, behave differently during and after a sustained period of cooling which, of course, is not the position during the birth process of a baby. He asks rhetorically "Why has similar injury, or anything like it not occurred in Professor Anderson's other cases?"
101. These are formidable arguments, but if I had to reach a conclusion, based on all the strands of evidence in this case, factual, expert and radiological, I would conclude, on the balance of probabilities, that the brain damage was caused during the 26-minute period of circulatory arrest. However, I consider that Dr Smyth was right to say that it is simply not possible to say when within that period the damage became irreversible. There is a temptation to apply by analogy the perinatal learning, but that is not valid and appears to be accepted not to be valid. There is some evidence in the literature (see paragraph 60) that individuals may vary in the temperature at which circulatory arrest brings the brain metabolism to a halt. It may simply be that exceptionally in Aiden's case it was necessary to go lower than 24ºC to achieve it whereas in everyone else whose case has been reported it was not – nor has it been Professor Anderson's experience in any of the many other cases he has dealt with. It may simply be that there is no explanation of the damage in his case. That would be deeply unsatisfactory to anyone involved in considering the case, but as Professor Wolf said, it does happen from time to time.
102. At all events, had it been necessary to go on to consider the question of causation, I would have been obliged to say that, whilst satisfied that it was caused during the 26-minute period, I could not be satisfied that it was caused during any negligently extended part of that period.

Conclusion

103. The outcome will doubtless come as a disappointment to Aiden's parents. Anyone would have immense sympathy for them and I regret not being able to give them the satisfaction of knowing the true reason for the brain damage he suffered. I suspect that was more important to them than any compensation. However, the evidence has not enabled me to do so and the claim must be dismissed.
104. I am sure that Professor Anderson looks back on the operation with regret at the outcome and wonders what went wrong. That would be understandable, but the evidence has not satisfied me that whatever did go wrong was because of his negligence by the standards of 1998. I do not know the extent to which DHCA continues to be used for procedures of the nature undertaken in Aiden's case and whether, if it is, the debate as to what constitutes safe practice in the sense of the temperature to which the brain must be cooled for a defined period has been resolved. Unless there is now greater precision than what was revealed in the paper by Hirsch and others (see paragraphs 80-84 above), it would appear that the debate may well continue.
105. I am grateful to Mr Havers, Mr Thomas and Mr Miller for their considerable assistance