TANG CHEUK HIM v. HOSPITAL AUTHORITY

HCPI 1123/2006

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

PERSONAL INJURIES ACTION NO. 1123 OF 2006

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J U D G M E N T

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I.       INTRODUCTION

1.  Tang Cheuk Him is 9 years old.  On 26 May 1999, shortly before his first birthday, Tang underwent extensive heart surgery at Grantham Hospital.  The purpose was to close a ventrical septal defect (VSD) and ligate a patent ductus arteriosus (PDA).

2.  The Authority runs the hospital and is vicariously liable for the negligence (if any) of its staff.

3.  A team led by Dr. Cheng Lik Cheung (Chief of Service of the Cardiothoracic Surgery Department) operated.  Dr. Cheng was assisted by Dr. Jan W. T. Lee, then senior consultant surgeon specialising in paediatric cardiac surgery. 

4.  The VSD was closed with a piece of Dacron cloth and the PDA ligated with a silk tie.  Tang was then placed on a cardio-pulmonary bypass.

5.  After closing up the surgical incision (a median sternotomy), Dr. Cheng noticed that Tang had no femoral pulses.  Further tests showed that the descending aorta was not pulsating well.

6.  Accordingly, 3 hours later, Tang underwent another operation through the original incision.  In the course of that second surgery, Dr. Cheng cut the PDA ligature.

7.  Upon re-closure of the surgical incision, femoral pulses were found to be palpable.  But, despite a record of Tang’s “limbs” having “spontaneously” moved on day 1 following operation, it was noticed on days 2 and 3 that Tang did not move his feet.  After consultation, Tang was diagnosed as suffering from ischaemic (that is, blood deficiency induced) spinal cord injury.

8.  By his mother as next friend, Tang sued the Hospital Authority for alleged negligence in carrying out the first operation.

9.  Tang’s case is that Dr. Cheng negligently ligated the PDA with the adjoining descending aorta.  This (it is said) cut off the blood flow to Tang’s lower limbs and led to paraplegia.

10.  Tang also complains that the surgical team did not place a lower limb arterial line to monitor blood flow during the first operation.  This (it is said) would have alerted the team to the absence of femoral pulse at a much earlier stage.

11.  Further, Tang contends that his spinal injury ought to have been diagnosed much sooner than day 3 after the second operation.

12.  The application now before me is for an interim payment of up to $1.64 million.  Tang’s legal representatives in effect are submitting that, on the basis of the evidence now before me, Tang will likely succeed in establishing negligence at trial and obtain substantial damages.

II.      BACKGROUND

13.  There are 2 components to normal blood circulation in a person.

14.  There is systemic circulation.  Oxygenated blood flows from the lungs into the left atrium of the heart.  From there, blood is pumped into the aorta and then into the rest of the body other than the lungs.

15.  There is also pulmonary circulation.  Having circulated through the body, blood (now de-oxygenated) flows from the veins into the right atrium of the heart.  The blood then enters the right ventricle from which it is pumped through the pulmonary artery into the left and right lungs.  While in the lungs, the blood is replenished with oxygen.

16.  When a person suffers from VSD and PDA, instead of following the normal systemic circulation route, oxygenated blood shunts back through the VSD and PDA into the right ventricle and pulmonary artery.  This increases the load on the heart due to pulmonary circulation.  Beyond a shunt of a certain magnitude, the load on the heart will be unacceptable and will require correction.

17.  A standard means of correction is to close the VSD with a patch and tie the PDA.  These actions will stem the leakage of blood into the right ventricle and pulmonary artery.

18.  Tang contends that, in performing the first operation, Dr. Cheng must have either ligated the descending portion of the aorta (instead of the PDA) or ligated the descending aorta with the PDA.  Either action would have affected Tang’s systemic circulation by preventing blood from flowing through the aorta into Tang’s lower limbs.

19.  There is a further element to consider in this case.

20.  In June 1998, shortly after he was born, Tang was diagnosed as having not just VSD and PDA.  Tang was also suspected as having coarctation of the aorta (that is, a congenital narrowing of a section of the aorta).

21.  In July 1998 an echocardiogram showed a VSD of 4.5 mm, a small PDA, and a 28 mm Hg gradient across the aortic arch.  Tubular hypoplasia (incomplete development) of the aortic arch was detected.

22.  But Tang’s doctors decided then that extensive surgery on the aortic arch should be delayed for a few months.  No criticism is made of this decision.

23.  In January 1999, Tang’s doctors assessed the degree of hypoplasia of the aortic arch as not severe.  Accordingly, they decided to close the VSD and PDA first and deal with any coarctation later if necessary.

24.  A competing theory advanced for what happened during the first operation focuses on the possibility of coarctation.

25.  It is suggested that a ridge of tissue (referred to as the posterolateral shelf or ridge) may have jutted out into the lumen of the aorta at the level of the PDA.  This would have narrowed the passage through which blood could flow.

26.  The hypothesis is that ligating the PDA may have further constricted the lumen of the aorta, cutting off blood flow into Tang’s lower limbs.

27.  Dr. Cheng may well have been concerned by the possibility of a complication having occurred in the first operation due to the presence of coarctation.  The thinking appears to have been that the absence of femoral pulse could be attributable to an underestimation of the degree to which coarctation had produced a narrowing of the lumen of the aorta at the level of the PDA.

28.  Therefore, just before operating on Tang for the second time, Dr. Cheng obtained his parents’ permission to explore and (if appropriate) surgically deal with any coarctation.

III.     DISCUSSION

A.      Was the descending aorta ligated by mistake?

29.  Mr. Clough (appearing for Tang) submits that, on the balance of probability, the descending aorta must have been negligently ligated by Dr. Cheng.

30.  In support of his submission, Mr. Clough relies on expert reports prepared by Dr. Mok Che Keung and Dr. Gregory Wai Kee Ho.

31.  Mr. Ashok Sakhrani (appearing for the Authority) challenges the conclusions of Dr. Mok and Dr. Wai.  For this, Mr. Sakhrani relies on a report by Dr. John Leung and an affirmation by Dr. Cheng.

A.1    Dr. Mok’s report

32.  Dr. Mok is a specialist in cardiothoracic surgery.  He was Professor of Cardiothoracic Surgery at Hong Kong University from 1982 to 1992 and is now a consultant at various hospitals (including Grantham Hospital).

33.  Dr. Mok is sceptical of the diagnosis of coarctation.  He suggests that the tests which led to a suspicion of coarctation are inconclusive for one reason or another.

34.  Dr. Mok distinguishes true coarctation which:-

“results from a localized thickening of the aortic media (CoA [coarctation] ledge), which protrudes into the lumen of the vessel and obstructs blood flow, i.e. a short-segment of abrupt narrowing (CoA ledge) of the aorta just proximal or distal to the point of insertion of the ductus arteriosus or ligamentum arteriosum ....”

35.  In Dr. Mok’s view, there is “no evidence of a typical CoA” in Tang’s case.  At best, the relevant angiograms only show “tubular hypoplasia of the aortic arch” or “moderate hypoplasia of aortic isthmus”.

36.  Dr. Mok then continues on the issue of causation:-

“b.     It is well known to paediatric cardiologists and cardiac surgeons that ligation of PDA per se would not compromise blood supply to the lower body.  It only occurs in the rare situation where there is coexisting severe aortic narrowing (CoA) proximal to a usually large PDA and the blood supply to the lower body becomes dependent on shunting of blood from the right heart through the main pulmonary artery and PDA.  In the case of TCH [Tang], the PDA was small and there was no evidence of shunting of blood from the pulmonary artery to the descending thoracic aorta.”

37.  Dr. Mok is critical of the competing theory based on coarctation which I have sketched out in the previous section.  He comments that the explanation is “hypothetical and I have my doubt that it has been reported in the literature”.

38.  Instead of the competing theory, Dr. Mok believes that the descending aorta was probably ligated either on its own or together with the PDA.  He states:-

“d.     In my opinion, a probable mechanism whereby PDA ligation leads to compromise descending thoracic aortic blood flow would be inadvertent inclusion of the descending thoracic aorta in the PDA ligature or actual ligation of the descending thoracic aorta instead of the PDA...  This is a genuine potential hazard at PDA ligation via the median sternotomy incision especially in neonates/ infants.  If the surgeon were critical of this rare potential complication and had taken precautionary measures (e.g. palpation of the femoral pulses immediately following PDA ligation; monitoring the lower limb BP [blood pressure] with an additional arterial line; or monitoring the pulsatility of descending thoracic aorta with TEE [[trans-oesophageal echo], this would not have happened.

e.       Dr. Cheng and his colleagues never mentioned the possibility of inadvertent ligation of the descending aorta could have happened to TCH.  In the Operation Record Dr. Cheng stated, ‘The descending aorta was small about 4.5 mm in size and very close to the PDA.  The PDA ligature was cut so as to prevent the ligature further compromised the descending aorta’.  If Dr. Cheng had a clear view of the descending aorta and the PDA ligature before it was cut, then he would know for sure whether the descending aorta was or was not ligated or included in the PDA ligature inadvertently.  On the other hand, since he was suspicious that the compromised blood flow to the lower half of the child’s body was PDA ligation related, it would be reasonable to assume that immediately following re-sternotomy, Dr. Cheng would be totally focusing on cutting the PDA ligature as soon as possible, and that he only saw the descending aorta only after removal of the ligature.  Hence, he would have no knowledge whether the ligature had included the descending aorta or not.  In any case, when ligating a PDA via the median sternotomy incision, a surgeon usually only isolates and ligates the pulmonary end of the PDA.  Dissecting the aortic end of the PDA and descending aorta are usually avoided because the left recurrent laryngeal nerve (a nerve supplying the voice box) is lying there.  Hence, the descending thoracic aorta is usually not well seen.  If the descending aorta were clearly visible, it suggested that dissection in its vicinity had been carried out.  On the available information, it is likely that the inadvertent ligation of the descending aorta was the cause of the paraplegic condition of TCH...”

A.2    Dr. Wai’s report

39.  Dr. Wai is the Medical Director of the Hong Kong Children Heart Fund.  He is a consultant paediatric cardiologist.

40.  Dr. Wai examined Tang on 26 August 2003.  An echocardiogram showed a small residual opening of 3 mm in the VSD and a PDA of 4 mm.  An MRI revealed no gradient across the descending aorta (diameter 11 mm) and no coarctation of the aorta.

41.  Dr. Wai advances 3 possibilities as the cause of Tang’s paraplegia.  They are:-

“(1)   ligation of the PDA causing distortion and interruption fo the blood supply to the aorta distal to the PDA with the presence of narrowing of the distal aorta at that point, namely coarctation of the aorta;

(2)     ligation of the PDA causing distortion of the aorta distal to the PDA in the absence of any narrowing or coarctation of aorta;

(3)     the aorta distal to the PDA was inadvertently ligated during surgery instead of the PDA.”

42.  Dr. Wai dismisses Possibility 1 as a cause.  This is because he does not find sufficient evidence of coarctation.  In this connection, he notes:-

(1)     Coarctation is clinically diagnosed from discrepant blood pressure readings in the upper and lower limbs.  There was (Dr. Wai says) no evidence of this in pre-operation assessments.

(2)     Patients having VSD, PDA and coarctation do not usually respond well to medical treatment.  In contrast, Tang responded well to anti-heart failure treatment before surgery.

(3)     Echocardiograms taken before surgery show the presence of VSD but not coarctation.

(4)     Following the cutting of the PDA ligature, blood pressure returned to Tang’s lower limbs.  Later, blood pressure in the upper and lower limbs remained normal with no discrepancy.

(5)     Dr. Wai’s examination in 2003 showed no coarctation.

43.  Dr. Wai’s report does not discuss Possibility 2 in any detail.  Instead, having rejected Possibility 1, Dr. Wai simply continues as follows (emphasis supplied):-

“(B)   The hypothesis/ possibility of inadvertent ligation of the aorta distal to the PDA

This indeed could cause interruption of blood supply to the aorta distal to the ligation and cause a spinal cord injury. Surgical expert opinion stated that in neonate/ infant PDA ligation by a median sternotomy incision, inadvertent ligation of the aorta distal to the PDA is a possible devastating complication. Judging from the report on the second part of the operation, when the operating surgeon had removed the ligature, the blood supply to the lower limbs returned immediately and no attempt for correction of possible coarctation of aorta was carried out in the second part of the operation.

Conclusion

Since no coarctation of aorta was found and that the thick silk ligation causing distorted aortic arch/ regional anatomy is an extremely unusual situation, inadvertent ligation of the distal arch instead of the PDA is the only logical possibility.

Summary

The lower limb paralysis is definitely related to the surgical procedure on the 26th May of 1999 at the Grantham Hospital.

The only logical and probable cause of the paralysis of the lower limb is the inadvertent ligation of the aorta distal to the PDA.”

44.  As far as I can see, that brief part of the 1st sentence of Dr. Wai’s “Conclusion” section which I have underscored, is the only place where Dr. Wai considers Possibility 2.  However, it is unclear to me why, simply because something is unusual, it can logically be ruled out.

A.3    Dr. Leung’s report

45.  Dr. Leung is a specialist in cardiothoracic surgery.  He was in charge of the cardiothoracic unit at Grantham Hospital from 1969 to 1977.  He does not hold himself out as a specialist in paediatric cardiac surgery.

46.  Dr. Leung believes that it is unlikely that Dr. Cheng ligated the descending aorta.  He raises a number of points in support of this belief.

47.  First, Dr. Leung observes that the PDA was ligated after the pericardium (sac around the heart) had been opened. 

48.  Given the ligation was done within the pericardial sac, a surgeon “would be much less likely to encroach on the aorta, or ligate the wrong structure such as the descending aorta”.  This is because the descending aorta lies outside the pericardial sac.

49.  Second, Dr. Leung notes that the perfusion pressure was initially dropped to 30 mm Hg. 

50.  This (Dr. Leung believes) is consistent with normal practice and must have been done to decongest the pulmonary artery and enable the surgeon to check the position of the ligature loop.  The surgeon should then have been able to tie the ligature “without too much retraction of the pulmonary artery”.

51.  Had something other than the PDA been ligated at this stage, “so much blood would have been pouring down the pulmonary artery [via the PDA] that it would be very difficult to do the next step [of the bypass procedure]”.

52.  Third, Dr. Leung comments that, if the PDA and the adjacent aorta been tied together, “the left laryngeal nerve would be damaged and severe hoarseness and choking would become obvious”.  On the evidence, neither hoarseness nor choking happened.

53.  Dr. Leung concludes as follows:-

“No one can be sure what did happen but I raise the following:-

a.       If the ligature was put around the descending aorta below the PDA, a lot of blood would flow through the PDA during the bypass, making further surgical process virtually impossible.

b.      If the ligature was put around the aorta above the PDA, there would still be retrograde blood flow from the descending aorta through the PDA, making further surgical process very difficult.  But the records’ timing shows that this was not the case.

c.       If the ligature was put around the PDA and the adjacent aorta all wrapped up in one bundle, then the left recurrent laryngeal nerve would have been damaged and the patient would have sever hoarseness -- but this was not the case.

d.      If the ligature was put around the PDA and the descending aorta, then because the surgeon had lubricated the silk with wax, it would slip into the aorta above the PDA as it was being tied.  The result would be as in (b).

e.       If the ligature was put around the PDA and the proximal aorta, then the lubricated silk would slip into the descending aorta as it was being tied.  The result would be as in (a).”

A.4    Dr. Cheng’s affirmation

54.  Dr. Cheng categorically affirms that he “looped a silk suture around the PDA and ligated it within the pericardium sac”.

55.  He confirms that he “had no difficulty in the visual identification of the relevant cardiovascular structures and their anatomical relationship in performing this [first] operation”.

56.  Of the second operation, Dr. Cheng deposes:-

“At re-exploration, I removed the ligature around the PDA.  I did not ligate the descending aorta.  If I had done so, there would have been excessive blood flow from the descending aorta through the PDA when I repaired the VSD via the pulmonary arteriotomy [during the first operation].  There was no such excessive blood flow.  If I had ligated the PDA and adjacent aorta together, the left recurrent laryngeal nerve would have been damaged and TCH would have severe hoarseness.  This is also not the case.  In any event, if the ligature had included the descending aorta, I would have noticed it and stated it in the operation record.  The wound was then closed. After closure of wound, femoral pulses were noticed to be palpable.  A femoral arterial line was then inserted. The pressure difference between the upper and lower limbs was about 25 mm Hg.  After careful consideration, the Surgical and the Paediatric Cardiac team decided t give TCH a chance for growth and not to proceed with the CoA repair.  This decision was explained to and accepted by the parents of TCH.  On 31st May 1999, Dr. Chiu Shui Wah [then Chief of Service of the Cardiothoracic Department] and Professor M. P. Leung [then Chief of Service of the Paediatric Cardiac Unit] explained in detail to the parents again and the explanation was accepted by the parents.”

A.5    Dr. Mok’s reply report

57.  By letter dated 1 September 2007 Dr. Mok responded to Dr. Leung’s views.

58.  First, Dr. Mok suggests that Dr. Cheng would have had to perform some dissection around the PDA before he could loop a silk suture around it.  This looping of a silk suture would have been performed in “a very limited and deep space especially in an infant”.  Dr. Mok therefore thinks that, “[i]n the case of TCH, there was no doubt that the surgeon had done some dissection of the pericardium”.

59.  Dr. Mok then reasons as follows:-

“(iii)   In fact, the surgeon did dissect through the back of the pericardium and expose the descending aorta.  Dr. Leung noted that the surgeon could see the descending aorta when the pericardial opening was re-opened at exploration, i.e., a structure outside the opaque pericardial sac could be seen from inside the sac because it was cut open.  Operative Procedure paragraph 4 line 3 -- ‘The descending aorta was small about 4.5 mm in size and was very close to the PDA’  This was not mentioned in the paragraphs on Operative findings i.e. at the 1st operation. It was only described in the 2nd operation (i.e. re-exploration). Since the 2nd operation only involved re-opening the median sternotomy and pericardial wounds, as well as removal of the ‘PDA ligature’, it did not involve any dissection.  The dissection through the posterior wall of the pericardium and exposing the descending aorta must therefore be done at the first operation before application and removal of the ligature.  Thus, Dr. Leung’s comment that since the ligature was done within the pericardial sac, the surgeon was much less likely to have enclosed the aorta is clearly wrong.”

60.  Second, Dr. Mok accepts that a drop followed by a rise in profusion pressure would indicate that the PDA and not another structure had been ligated.

61.  But (Dr. Mok says) “the same changes in blood pressure -- an initial drop followed by a rise in perfusion pressure -- would also occur if the PDA and descending aorta were ligated together”.

62.  Further, if the PDA and descending aorta had been tied together, then (according to Dr. Mok) “there would be no blood coming down from the pulmonary artery when it was opened”.

63.  Third, Dr. Mok argues that the tying up the descending aorta with the PDA would not necessarily damage the left recurrent laryngeal nerve as Dr. Leung suggests.  This is because that nerve “would be lying between the entry and exit points of a ligature suture”.  The tissues surrounding the nerve would “wrap around the nerve and the suture/ ligature would not have any direct contact or inflict any injury to the nerve”.

64.  Fourth, Dr. Mok disagrees that there could have been any slipping of the ligature upwards or downwards the aorta if the PDA and descending aorta had been tied together.  That is because “[t]o loop a ligature around any ... structure involve[s] dissection around it, i.e. the ligature is confined in a very limited tunnel crated by the dissection”.

65.  Fifth, Dr. Leung believes that “the old practice of lubricating the silk [tie] ha[s] long been abandoned” at Grantham Hospital.

A.6    Analysis

66.  I am unable to conclude from the various reports just summarised that on the balance of probability Dr. Cheng and his team will be held at trial to have been negligent.

67.  The expert evidence shows that there is a considerable debate among reputable cardiothoracic surgeons as to whether Dr. Cheng must have ligated the descending aorta during the first operation.

68.  The reports of Dr. Mok and Dr. Wai rely to a significant extent on surmise.  They may be right.  But the correctness of their inferences is something which I cannot evaluate now in the absence of cross-examination.

69.  Let me give some examples (which are not meant to be exhaustive).

70.  First, there may or may not have been coarctation.  I cannot summarily rule out the possibility of coarctation and a complication in the first operation arising therefrom at this stage.

71.  This is especially so when a Paediatric Cardiac Catheterization Report dated 19 January 1999 records Tang as showing “Moderate, severe” signs of “Hypoplasia of isthmus and coarctation of aorta”.

72.  The same Report states the results of an angiogram thus: “There is coarctation around 2 cm beyond the left subclarian artery and post-stenotic dilatation of the descending aorta.”  A coarctation measurement of 4.91 mm is then given.

73.  Second, I do not think that Dr. Mok has fully answered Dr. Leung’s point that, if the descending aorta had been ligated (either on its own or together with the PDA), there would have been so much blood flowing through the pulmonary artery as to have rendered it impossible to proceed with the first operation. 

74.  Dr. Mok suggests that there would not be much blood if both the PDA and descending aorta had been tied together.  But in that case where would the blood which is restricted from circulating through the descending aorta have gone? 

75.  Would the binding together of the descending aorta and the PDA not have caused some other complication which would have become immediately manifest or obvious during the first operation?  There may be a simple medical answer to my question. But I do not find it in the current evidence.

76.  Third, Dr. Cheng states that he ligated the suture within the pericardial sac.  In rebuttal, Dr. Mok surmises that Dr. Cheng must have dissected part of the sac.  This (Dr. Mok thinks) would have left an opening in the pericardium through which the descending aorta might have been seen and confused with part of the PDA.

77.  Dr. Mok arrives at his conclusion following an elaborate chain of reasoning based on his reading of Dr. Cheng’s affirmation evidence.  This conclusion is nonetheless at variance with what Dr. Cheng has unequivocally affirmed. 

78.  I am unable to say now, in the absence of cross-examination, that on the balance of probability Dr. Cheng is wrong and Dr. Mok’s reading must be right.

79.  Fourth, Dr. Mok doubts that what he calls “the old practice” of lubricating the silk tie was followed at Grantham Hospital. 

80.  But there is no evidence one way or the other as to whether the silk tie actually used in Tang’s case was or was not waxed. 

81.  I do not think that I can discount Dr. Leung’s evidence then on the basis of Dr. Mok’s understanding of what current practice at the hospital may be.

82.  In my judgment, it is simply not possible in the absence of a trial to say that there is a plain case of liability on the balance of probability in respect of the key issue of ligation.

B.      Should a lower limb arterial line have been used to monitor Tang’s blood flow during the first operation?

83.  On this issue, both counsel also rely heavily on their experts’ views.

84.  Dr. Mok states that, if an arterial line had been inserted, the surgical team would have instantly diagnosed a blockage in the distal arch and prevented neurological damage.

85.  Dr. Leung acknowledges that a line could have been inserted.

86.  But Dr. Leung also says that:-

“[t]his is not done routinely in many established centres.  Each additional arterial line carries additional risks of detachment, bleeding and infection.  A femoral line has advantages and disadvantages.  It does not necessarily reflect the status of the spinal cord circulation.  I have seen cases with little or no femoral pulsation for considerable periods without spinal cord damage.  I have also seen cases where the arterial line was accidentally disconnected leading to substantial bleeding.  In the case of an infant all covered up with sterile operating towels, a disconnected femoral line would go unrecognized for a long time with substantial blood loss...”

87.  Dr. Mok responds:-

“a.     In the presence of a lower limb arterial line, any compromise in blood flow to the lower body would be known immediately.  It will reflect the status of blood supply to the spinal cord and not the spinal cord per sec.  In recent years, all connectors to in-situ needles or tubings have safety locks to prevent inadvertent dislodgment.  Furthermore, it is now a routine practice in aortic surgery to insert a lower limb arterial line in order to minimize ischaemic spinal cord injury; the blood pressure of the lower limb is routinely monitored continuously to ensure that the lower limb blood pressure is kept over 50 mm Hg.

b.      I understand from the Nursing Officer-in-charge of OT of the Grantham Hospital that since the case of TCH, a lower limb arterial line is routinely inserted to patients during corrective surgery of similar problems.”

88.  Dr. Cheng states:-

“I confirm that there was no indication for placing femoral arterial line for the monitoring of blood flow during the [first] Operation.”

89.  Again, given the divergence in reputable expert opinion, I cannot summarily conclude that at trial Dr. Cheng will be found to have been negligent in failing to insert an arterial line.

90.  At the time of the operation in 1999, the use of such a line may have reasonably been regarded as a surgical team’s judgment call.  I cannot say at this stage that Dr. Cheng’s exercise of such judgment was flawed in the circumstances.

91.  Mr. Clough fairly acknowledged that he was not pressing this issue for the purposes of this interim payment application.

C.      Should Tang’s paraplegia have been diagnosed earlier?

92.  On the evidence, I am bothered by a question of causation.

93.  It is unclear what damage stems from the failure to detect the paraplegia until day 3 (as opposed to day 1).

94.  Nor is it apparent from Tang’s expert reports how soon after the second operation it is claimed that Tang’s paralysis ought to have been discovered. 

95.  I am unsure precisely what difference an earlier detection (on day 1 or 2 as opposed to day 3) would have made to Tang’s condition.

96.  Therefore, I do not think that I can order an interim payment on the basis of this issue.  Again, Mr. Clough fairly said that he was not pressing this issue for the purposes of this interim payment application.

IV.     CONCLUSION

97.  I have every sympathy with Tang’s condition.  Nonetheless, I am also acutely aware that professional reputations are at stake here.

98.  Mr. Clough stressed the restoration of blood flow to the lower limbs after the silk ligature was cut.  This (Mr. Clough said) was a strong pointer that the descending aorta must have been tied up.  I am unable to accept that submission without further evidence (including cross-examination at trial).  It seems to me that a restoration of circulation to the lower limbs following a cutting of a PDA tie would be equally consistent with the competing theory of a complication due to coarctation.

99.  The evidence presently strikes me as finely balanced.  Liability is far from a foregone conclusion.  In that circumstance, I am unable to accede to the application for an interim payment.

100.  Let me say a brief word about quantum.

101.  Mr. Sakhrani queried the amount of payment sought.  But, if I had found in Tang’s favour on the issue of liability, I would have had no hesitation in accepting the interim payment of $1.64 million as reasonable and appropriate.

102.  Paraplegia due to negligence typically gives rise to damages in the order of at least $10 million.  Seen in that context, an interim award of $1.64 million appears to be wholly proportionate and modest.

103.  The application for interim payment is dismissed.  There will be an Order Nisi that costs be in the Defendant’s cause, such costs to be taxed if not agreed in any event.