England and Wales Court of Appeal (Civil Division) Decisions

Case No: A2/1999/0928

1. Obstructive sleep apnoea ("OSA") is a known medical condition. An obstruction occurs in the respiratory tract whilst the patient is asleep. The cause is physical, either excess bodily tissue in the neck or incompetent ie relaxed muscle tone. The pharynx becomes blocked, causing a cessation of breathing ("apnoea") which lasts, according to the usual standard of measurement, for 10 seconds or more. When there is a partial obstruction, and breathing is restricted but not stopped, the incident is known as hypopnoea.

2. The incident may cause the sleeper to awake. The deprivation of air and therefore of oxygen to the lungs and heart may cause disturbing symptoms, such as an increased rate of heart-beat. There may be a significant reduction in the oxygen level in the blood (desaturation) and with it the risk of damage to the heart and brain.

3. Modern research has established that the same harmful effects can occur even though the sleeper does not awake. The brain is aroused by the physical response to the obstruction and it remains active at a subliminal level, but the sleeper is not conscious that this is happening. He may sleep the night through but when he awakes he does not feel refreshed, because the activity in his brain has prevented him from reaching the deeper levels of sleep, upon which refreshment depends. This is called "sleep fragmentation" to distinguish it from "sleep deprivation" where the sleeper spends much of the night awake.

4. During the following day, unsurprisingly, the person suffering from sleep fragmentation will exhibit all the symptoms of one who has not had a good night's sleep, because in fact he has not done so. Listlessness, lack of judgment, indecisiveness and inability to think clearly are the common experience, in addition to simple tiredness, or daytime somnolence as it is called for diagnostic purposes.

5. It follows from this that a person who exhibits these symptoms during the day despite having had what he believes was a good night's sleep immediately identifies himself as a possible sufferer from OSA. The processes of brain arousal can be measured by modern electronic means and the diagnosis may be confirmed in this way. The equipment measures the number of apnoea/hypopnoea incidents, and the results may point to repeated obstructions due to this physical cause, even though the precise nature of the obstruction cannot be measured or identified.

6. Other symptoms are important: whether the person has a pre-disposition to snoring and whether he is overweight or unfit and therefore more liable to have excessive body tissue or reduced muscle tone in the respiratory tract. (Use of the masculine is justified by the fact that the majority of sufferers are males.)

7. It is important to bear in mind that the most straightforward case occurs when the obstruction causes the sleeper to awake. He senses that he is choking and clears the restricted airway, voluntarily or involuntary. The reversal of air pressures may cause him to regurgitate part of the contents of his stomach, though this is not a typical result of the obstruction. In such a case, it is unnecessary to resort to sophisticated means of determining whether or not an obstruction has occurred, and if the sleep deprivation is sufficient the natural consequences follow. The reasons for daytime somnolence then are apparent; the patient did not have a good night's sleep, nor does he believe that he had done so.

8. A recognised treatment for sufferers from OSA is the breathing equipment known as CPAP (continuous positive airways pressure). The patient wears a face mask throughout the night and a bedside pump supplies air at a steady pre-determined pressure which is sufficient to prevent obstructions forming in the airway.

Parties

9. The claimant in these proceedings and the respondent to the appeal is Dr Satish Khanna. He was born on 17 June 1947 and was a doctor of medicine from July 1969 until 14 December 1994 when he retired. He did so on the ground of ill-health.

10. The appellants are four insurance companies who on various dates agreed to insure the claimant against the risk of his becoming disabled or incapacitated from carrying on his occupation by reason of ill-health. Nothing turns on the detailed wording of the policies. The judge, Mr Justice Eady, said that:--

"In each case, however, the claim depends on his demonstrating that he is permanently prevented through sickness from carrying on his practice as a doctor (and, in some cases, that he is also unable to carry out any other employment for which he might be thought reasonable suitable" (page 1),

and the appeal was argued on this basis.

The claimant's history

11. Having qualified in India in 1969, the claimant came to this country in 1972 and spent some years working as a junior hospital doctor specialising in orthopaedics. He decided to go into general practice and from November 1985 he was a trainee with a practice near Crawley in West Sussex, obtaining his vocational training certificate one year later. Due to the tragic family consequences of a road accident in which he too suffered personal injury, it was not until 13 June 1989 that he commenced practice from an address at Langley Green, Crawley, with a relatively small number of patients who came mostly from the local Asian community.

12. In addition to his general practice, he obtained a number of local appointments as a police surgeon, for the Crawley area in January 1990, then for Gatwick and Reigate, and then for the Mid-Sussex police area. He was also appointed as a medical examiner by the DSS and as doctor/surgeon for HM Customs and Excise at Gatwick Airport and as a doctor on call at local airport hotels.

13. These appointments together with the demands of his general practice meant that he was on call for 24 hours each day. It appears that he was unable to obtain any significant help or cover for night calls, which were frequent. According to his wife's witness statement, whom he married in 1971:--

"My husband was full of energy and determination. He was always an extremely hard worker. Ever since I have known him, I have known him to be a workaholic. He was always very upbeat and when at home he was always attentive to me and the children."

They have two daughters, born in 1972 and 1975. Their third child, a son, was tragically killed in the motor accident in 1986 when he was aged nearly seven.

14. The judge said this about the respondent's work until August 1993:--

"[The] evidence suggests that Dr Khanna was a competent and dedicated general practitioner from 1989 when he began his sole practice in Crawley, until August 1993. There is nothing pointing to incompetence or decision-making errors prior to that time." (pages 9 - 10).

However, the appellants challenge this finding and the assumptions made by the judge. They assert (Skeleton Argument page 25) that no evidence was led regarding his competence as a GP. "His competence as a GP was not an issue in the case; it was therefore not investigated by the defendants; and the Judge should not have constructed his decision round it."

15. Apart from questions which this raises as to the burden of proof and of adducing evidence, there was unchallenged evidence from the claimant's wife and daughters that matters did change in August 1993. She noticed that his snoring became louder than usual and that he started choking during the night. "It was, however, the sudden occurrence of repeated choking that really caused alarm ... I grew quite worried indeed" (page 139). She found him regurgitating fluids from his mouth and nose whilst sleeping. She continued:--

"I noticed him sleeping less and taking on more work and my daughters and I did start to check up on him on a rota basis although we did not need a rota as such since we were all quite worried and would often be awake anyway."

Financial Problems

16. By that date, August 1993, the claimant had severe financial problems. The judgment makes only a passing reference to them:--

"He had worrying financial difficulties worsened by negative equity and rising interest rates." (page 9).

17. The evidence is set out in detail in the appellants' Skeleton Argument paragraphs 5 - 10, 24 and 32 - 37. The claimant commenced practice with the aid of a business loan of £130,000 from Lloyd's Bank in Crawley. The business plan was based on a projected capitation figure of 2000 patients after two years. Even by 1994 the figure did not exceed 835. In May 1993 he asked the bank to accept "hiccups in the overdraft facilities" and in July 1993 he was told that he was spending £800 per month more than his income allowed and was refused an increased overdraft. Between then and April 1994 he borrowed from other sources at higher rates of interest, and when he retired in November 1994 he had a deficiency of assets against his liabilities of £193,000.

August 1993 to November 1994

18. It is effectively common ground that during this period the claimant slept poorly, worked increasingly longer hours and deteriorated both in his general health and in his ability to work competently as a doctor. He became worried that he would make a serious mistake if he continued, and so on 14 November 1994 he was permitted to retire on grounds of ill-health.

19. The appellants say that the poor sleep and general deterioration was caused by worry over his financial problems and by his own decision to work all the hours he could, thereby reducing even further the hours that he could sleep. His "sleep hygiene" was poor.

20. The claimant's case is that he was disabled or incapacitated by OSA which his doctors diagnosed at the time. These doctors included his general practitioner, Dr Truter, and a consultant, Dr Simonds, both of whom gave evidence at the trial.

21. The respondents called two expert witnesses who said that the diagnosis was wrong. Professor Douglas is a leading authority on sleep medicine, who was consulted in September 1998. He never examined Dr Khanna. His conclusion was that at that date Dr Khanna "does not have the sleep apnoea/hypopnoea syndrome and should not be regarded as unable to work on those grounds" (page 209). Dr Cayton's view was expressed rather differently:--

"The symptoms described by Dr Khanna in 1993/4 and the investigations and treatment he describes as being prescribed by Dr Wright and Dr Simonds are compatible with the diagnosis of the SAHS.

However, my studies have not confirmed the presence of sleep apnoea at the present time. If he does have sleep apnoea initially undetected because of a first night effect [note: this refers to the tests carried out under Dr Cayton's supervision over two nights - 31 October/1 November 1997], the evidence from the second night shows that the condition is responsive to treatment with appropriate treatment with nasal CPAP [continuous positive airway pressure].

Therefore it is my opinion, that at the present time, Dr Khanna does not have sleep apnoea, which is unresponsive to appropriate treatment." (page 164).

This difference was identified by the Judge:--

"On the other hand, the defendants contend that he does not actually qualify as having OSA at all, alternatively, if he does, then it is manageable with the assistance of ... CPAP." (pages 4 - 5).

22. The equipment known as CPAP consists of a mask with leather straps and the bedside pump which I have described. The patient has to get used to the noise of the pump as well as the discomfort of wearing the mask.

The Judge's conclusion

23. The judge addressed the fundamental issue which Mr Livesey QC for the defendants (present appellants) submitted should be formulated as follows:--

"He suggested that the test should be whether the claimant has been truly prevented from working by a medical condition, at the material times, to which it has been shown that OSA has at least made `a material contribution'." (page 4).

Mr Day QC for the claimant did not dissent.

The judge added:--

"It is the validity of his original claims under the policies, made shortly after he ceased working, that is in issue before me." (page 4)

24. He found the expert witness for both parties "objective and helpful in their evidence" (page 5) and he said later that both Professor Douglas and Dr Cayton were "cogent and vigorous" (page 17) in the reasons they gave for disagreeing with Dr Simonds.

25. He concluded:--

"I must recall, however, in this context that I am not concerned with whether Dr Khanna has demonstrated that his inability to function as a GP was solely attributable to OSA. I am concerned with whether he has demonstrated, on a balance of probabilities, that it made a `material contribution'. I have come, although not without some hesitation, to the ultimate conclusion that it did." (page 17)

"I can accept that OSA has to be assessed in the light of the personal characteristics of this patient and that Dr Khanna was particularly vulnerable to its impact (as Dr Simonds suggests). I have come to the conclusion, applying the civil standard of proof, that there is no other more likely explanation for the continuing cluster of symptoms displayed by him than the one proffered by Dr Simonds. As she herself observed on 5 June 1997, at the stage when steroids were proving to be a damaging and complicating feature, `... he has been investigated by so many parties in the past that it seems unlikely something new will turn up'. Even now, that gap has yet to be convincingly filled.

Our state of knowledge about OSA and the nature of sleep generally is not such that a definitive answer can be given. Some elements of the claimant's symptoms remain somewhat puzzling, but civil litigation does not require definitive answers. It requires only that the court should, in the light of the evidence available, come to a conclusion on the balance of probabilities. Applying that test, I hold that Dr Khanna was indeed obliged to retire in 1994, and that he has remained unfit to carry out any relevant work subsequently, because of an underlying chronic condition. I regard OSA as the only realistic candidate, in the light of Dr Simonds' diagnosis." (page 18).

"The defendants' suggestion is that Dr Khanna does not have a condition that can be classified as OSA. That I reject. I accept the expert evidence of Dr Simonds. They also say that, if he did have such a condition, it being only a mild form of the disorder, it would have been sufficiently manageable with CPAP as to enable Dr Khanna to function within normal limits. The fact is, however, that it alleviates. It does not enable him to function as a GP. He still had sleep that left him unrefreshed. Crucially, he has continued to suffer from cognitive impairment." (page 19).

And finally:--

"Despite the powerful evidence of Dr Cayton and Professor Douglas, this [Dr Simonds' evidence] seems to provide the most coherent and consistent account of a strange history that cannot, on any view, be fully explained." (page 19).

The "material time"

26. The principal issue is whether the claimant was suffering from OSA in November 1994, when he retired, and if so, whether that condition made a material contribution to his disablement or incapacity which caused him to retire. If those questions are answered in the claimant's favour, then the appellants as I understand them do not contend that his condition has improved since 1994, but they say that the symptoms are or can be sufficiently treated by CPAP to mean that he has not remained disabled or incapacitated since that date. The Judge was concerned with the period from 1994 to the date of trial in July 1999, and so are we. Mr Livesey told us that the judgment in this case does not relate to any date after the trial, and Mr Day, I think, did not disagree. I merely record that no reference was made during the hearing of the appeal to any date or period later than that which is covered by the evidence.

Medical history August 1993 to November 1994

27. When the claimant suffered the alarming choking symptoms described by his wife, and even more graphically by his daughters, he first referred himself to Dr Martin Smith, a consultant physician at Guildford. He complained also of severe muscle pains on waking, a condition known as myalgia which, it is agreed, is entirely separate from and unconnected with OSA. Because of the regurgitation problem, the claimant thought that there might be some gastric illness, but Dr Smith carried out barium studies which showed no abnormality. Dr Smith thought that sleep apnoea might be the diagnosis and referred the claimant to an ENT surgeon, Dr David Wright, who confirmed a severe problem of nocturnal hypoxic episodes and nocturnal gastric reflex. He advised surgery to the palate and back of the throat. This was carried out (uvulopalatoplasty) in December 1993 with some benefit for two months but by March 1994 the same symptoms had returned (Dr Truter's Report, page 147). On 11 March Dr Truter referred him again to Dr Wright. On 17 May 1994, Sleep Study tests were carried out and "significant episodes of airway obstruction and hypopnoeas ... accompanied by significant desaturation" were reported (page 311), but at the trial the expert witnesses though that no conclusions could be drawn from this. Dr Truter's witness statement continues:--

"In the summer of 1994 Dr Khanna was still suffering from poor sleep, acid reflex and severe muscle pain on waking. In order to minimise the problems he tried to keep busy at night. He was self-medicating. ... .His sleep pattern was poor and the unremitting nature of his symptoms led him to consult Dr A A R Gossage, Consultant Physician. He was advised to be referred to Dr A K Simonds at the Brompton Hospital."

28. Dr Khanna's own account of the summer of 1994 included (page 107) "I was fully aware that I was still suffering from poor sleep and acid reflex, further that there was severe muscle pain upon waking ... . I tried to keep myself as busy as possible ... ." His wife said "After a few months, however, the choking came back. This time it was worse. The frequent choking had now become a daily event. Additionally, he was falling asleep during the day which was incredibly unusual for him." (Page 140). He complained of being in severe pain all the time, and she noticed that he has become uncharacteristically forgetful.

29. Dr Truter's referral letter to Dr Simonds reads in part (page 313):--

"He is in trouble with sleep apnoea and episodes of hypopnoea which have rendered him irritable, forgetful and suffering with myalgia and headaches on waking. It has made his life extremely difficult as he is often up at night working as a police surgeon."

30. Dr Simonds arranged for a sleep study to be carried out and recommended the use of CPAP. Her conclusion began "Obstructive sleep apnoea is confirmed" (Page 322). The "Sleep Study Admissive" dated 12 August 1994 is a questionnaire which Dr Khanna completed on entry. We were referred to various of his answers, including "Sleep quality: v poor", "No refreshing sleep. In fact felt more refreshed if he deliberately stays awake all night", "Nocturnal choking [yes]" and "Dreads going to sleep".

31. The use of CPAP which Dr Simonds prescribed improved the episodes of hypopnoea but not the quality of sleep or muscle pains (Dr Truter, page 147) and on 31 October Dr Simonds arranged another Sleep Study Admissive at the Brompton Hospital. She reported to Dr Truter on the following day:--

"He and his wife have noted a marked reduction in his snoring and he no longer has choking episodes at night. Sleepiness has improved somewhat, but he still feels hypersomnolent during the day." (page 325).

Meanwhile, also on 31 October, Dr Khanna visited Dr Truter at his surgery for an "unscheduled consultation" (page 147). Dr Truter's statement reads:--

"[He] said that he felt very unwell and in spite of the treatment could not concentrate properly, was making simple errors, was irritable with his patients and recognised that he was not functioning properly" (page 147).

Dr Truter concluded that Dr Khanna was not fit to practise on the grounds of ill-health and on the basis of "a proved medial diagnosis (sleep apnoea)" (Page 147). He set in train the events which led to Dr Khanna's treatment with the approval of the Health Authority and others. Dr Simonds agreed:--

"At present his sleep quality, though improved, remains poor and accompanied by daytime somnolence.

I feel that these problems are sufficiently severe to advice Dr Khanna to cut down substantially on the work load, in particular I think that retirement from his busy and stressful general practice commitments would be advisable" (24 November 1994) (Page 327).

32. His retirement from general practice would have left him free to continue his employment as a police surgeon, etc. But in the result he retired completely. At one stage it was thought that his inability to work might be caused by stress or by depression, but a psychiatrist who examined him reported that there was no form of mental ill-health.

Financial problems - August to November 1994

33. The time which Dr Khanna had off work for his operation (late 1993) and subsequent convalescence increased his already serious financial problems, because he had to employ other doctors to do his work, or some of it. From 1994 he had the additional burden of paying high rates of interest eg on his credit card at 26% APR. He saw the bank manager Mr R Sinclair on 3 November and pleaded unsuccessfully for an increase in his overdraft limit. (Page 442). He agreed in evidence that his financial position was hopeless (Appellants' Skeleton paragraphs 37, 39). On 16 November Lloyd's dishonoured two of his cheques.

Medical history - retirement to trial

34. Some reference was made to post-retirement medical reports though mainly because they included descriptions of Dr Khanna's pre-retirement condition and symptoms. On 31 October 1997 when he was examined by Dr Cayton, who was instructed by the appellants, a two-night Sleep Study was carried out, the first night without CPAP, the second with. Her conclusion has been quoted above. The test results showed that on the first night, without CPAP, there was an overall "sleep efficiency" figure of 44.2%, an "Arousal index" (recording every instance of arousal, from whatever cause, including eg outside disturbances) of 14.1 per hour of sleep, and an Apnoea-Hypopnoea index of 5.4 per hour of sleep. On the second night, with CPAP, the figures were sleep efficiency 83.6%, Arousal index 14.1 per hour (the same) and an Apnoea-Hypopnoea index of 0.9 per hour. The appellants rely on these figures as showing that in October/November 1997 the incidence of apnoea/hypopnoea even without CPAP was below the normal diagnostic limit and that with CPAP they effectively disappeared. These tests were carried out at Birmingham and they are referred to as "the Birmingham polysomnography".

The appeal

35. The trial judge gave permission to appeal, noting that "the outcome depended upon a fine appraisal of the evidence" and that it was not possible to conclude that the appeal would have no prospect of success. The Notice of Appeal runs to 13 pages and includes detailed criticisms of the Judge's approach and of his findings. The appellants' contentions were summarised in Mr Livesey's Skeleton Argument, as follows:--

"(i) Above all, that the reasoning of the Judge as set out ... above, was flawed.

(ii) Secondly, that the resolution of the dispute between the parties required the application of a traditional Judicial approach in which the accuracy, authority and credibility of the witness was evaluated. So that ... .

(iii) Where, as here, there was a head-on conflict of expert evidence between Dr Simonds on the one hand and Professor Douglas and Dr Cayton on the other hand, the Judge should have decided which expert witness he intrinsically preferred and explained why;

(iv) Where, as here, the defendants contended that the results of the Birmingham polysomnography disproved the claimant's contentions, the Judge should have ruled whether they did or not and why;

(v) Had he approached the matter as he should, the Judge would have

* rejected Dr Simonds original diagnosis;

* rejected Dr Simonds evidence;

* concluded that OSA was not the cause of Dr Khanna's inability to work."

36. These contentions were further refined at the conclusion of the hearing before us in four paragraphs which helpfully set out the appellants' main points:--

1. The Judge misdirected himself in that his reasoning was flawed;

2. The judgment therefore cannot be sustained on the ground that there was evidence which supported the Judge's findings;

3. The judgment should have set out the Judge's reasons for resolving a number of disputed issues as he did; and

4. On the evidence, the Judge should have decided the case in the appellants' favour: "the evidence pointed in our direction".

37. The principal ground, that the Judge's reasoning was flawed, centres upon a paragraph at page 17 which because of its importance I should quote in full:--

"It is said for the defendants that there has been a consistent pattern of poor sleep hygiene; and unhealthy life-style and lack of exercise. Yet his wife and daughters have described how, over the last year or so, Dr Khanna has been even more forgetful and difficult to communicate with. That is consistent with an underlying chronic and deteriorating condition of some kind. In the absence of any other convincing medical opinion from someone who has examined him and considered the whole case in depth, I find that to be the probability. The only diagnosis that I have which corresponds to that picture is the one given originally by Dr Simonds in 1994, and reinforced through her developing acquaintance with the claimant and his symptoms over the intervening years. Every one agrees that OSA is a chronic condition that can deteriorate."

38. This paragraph is followed by the conclusion which I have already quoted above, beginning with "I can agree ...". Mr Livesey submits that the Judge was wrong to attach weight as he did to evidence of the claimant's condition "over the last year or so", that this formed a vital link in his chain of reasoning, and that his conclusions therefore cannot be supported for the reasons he gave for them. Thus he says "The third paragraph on page 17 of the Judgment is absolutely central to the Judge's reasoning" (Skeleton Argument paragraph 53(b)).

39. There was also some ambivalence, Mr Livesey submits, in the course of the trial as to whether evidence of the claimant's up-to-date medical condition was relevant, and therefore admissible, or not. The judgment refers to this obliquely at page 4. The Judge accepted that the claimant's only allegation was that he suffered from OSA and that he continued to suffer from it, subject to the benefits obtained from treatment by CPAP. Any evidence directed towards other health problems therefore was irrelevant "unless they are connected with OSA". It appears from this that up-to-date medical evidence was correctly treated as relevant to the claim, but only to that limited extent. There is no basis in my judgment for holding that the Judge misdirected himself with regard to it.

40. I would agree with Mr Livesey that the up-to-date evidence standing alone did not justify a finding by the Judge that symptoms established "over the last year or so" were caused by, or even were materially contributed to by, OSA as the claimant alleged. But that is not what the Judge did find. He said merely that the evidence was consistent with the diagnosis of OSA that was made by Dr Simonds in 1994. He then proceeded to make his finding as to whether that diagnosis was or was not correct. In the next paragraph "I return however, ..." to the condition of the central issue, whether Dr Simonds' diagnosis was correct and whether OSA "materially contributed" to the disability and incapacity suffered by Dr Khanna in November 1994. Therefore, I cannot agree Mr Livesey's submission that the "third paragraph" was a crucial step in the Judge's reasoning which led to his conclusion on the central issue.

41. Next, Mr Livesey submits that the Judge's conclusion was wrong. The evidence did not establish that Dr Simonds was correct in her 1994 diagnosis of OSA. It has to be noted, first, that Dr Simonds was not given an opportunity in cross-examination to respond to the criticisms that were made of her in Mr Livesey's submissions to us. They were unsupported by any evidence and so we are entitled to reject them, in my judgment, on that ground alone. But I should add, secondly, that the diagnosis was supported by Dr Truter, who was Dr Khanna's general practitioner throughout the relevant period, by the consultant physician Dr Smith, who excluded the possibility of gastric problems, and by the ENT surgeon Dr Wright who operated on Dr Khanna in the belief that the diagnosis was correct, with a measure of at least temporary success. The possibility of a psychiatric cause was excluded subsequently. Dr Cayton went no further that to say, in November 1997, that the symptoms of OSA, if it existed, were controlled by CPAP. It is against this background that the Judge had to consider and evaluate the expert evidence of Professor Douglas, who never examined Dr Khanna.

42. Mr Livesey's submission on the medical issue, whether Dr Simonds correctly diagnosed OSA in 1994, rested on the ground that the diagnosis should not be made unless there was no other realistic explanation for the cluster of symptoms displayed by the individual patient. This guidance was given by Professor Douglas and was noted by the Judge. Dr Simonds agreed with it. By August 1994 it was submitted, there were symptoms for which OSA cannot be held responsible, in particular the myalgia of which Dr Khanna complained throughout. The regurgitation problem is not symptomatic of OSA, though it may be experienced by a minority of sufferers, and Dr Smith's opinion that there was no gastric disorder may have been wrong. The symptoms of irritability etc which are well-documented were due to the fact that Dr Khanna was deliberately denying himself of sleep; his "sleep hygiene" was poor. There is little evidence of daytime somnolence, and this of itself, Mr Livesey submits, contradicts the diagnosis of OSA, because the diagnosis is only permitted when no other realistic explanation can be given. Here the explanation is obvious: Dr Khanna was sleeping poorly, partly no doubt as the result of worry caused by his mounting financial problems and partly because he drove himself to work all hours of the day and night. His myalgia may have been another, separate, cause.

43. In my judgment, there is a logical flaw in this submission, predicated as it is on the proposition that OSA cannot be disproved unless there are symptoms of irritability etc and of daytime somnolence for which no other realistic explanation can be given. That may be true if the sleeper is not woken by the episodes of apnoea and hypopnoea, but is nevertheless deprived of deep sleep as explained in the opening paragraphs of this judgment. If he is woken by them, then the reason why he is being deprived of sleep is apparent. It is simply not a case where the sufferer believes that he has slept through the night and daytime somnolence has to be explained.

44. The evidence in the present case goes further. Not only was Dr Khanna woken, he found that he was choking, and he got to the stage where he dreaded going to sleep. He and his family were concerned that the choking is symptomatic of OSA, and there is no evidence of any other cause for it, apart from the possibility of gastric upset which Dr Smith excluded in 1993 and which has not been identified or even suggested since.

45. Another difficulty in the way of Mr Livesey's submission, that Dr Simonds' diagnosis was wrong and was not proved to be correct, is that on the evidence the CPAP treatment which she prescribed was beneficial in reducing if not entirely relieving the symptoms. The fact that it was successful is consistent with the existence of an obstruction which was prevented by continuous moderate air pressure. That is the quintessential feature of OSA. No other condition has been suggested which could be ameliorated by CPAP.

46. This leads to the appellants' alternative contention, that if OSA was correctly diagnosed then it was sufficiently treatable by CPAP to mean that Dr Khanna was not disabled or incapacitated by it, as he claims that he was. Here the Birmingham polysomnography is directly relevant. An article by Dr Simonds published in 1994 (British Medical Journal volume 309 page 35) states that "for diagnostic purposes the occurrence of 15 or more episodes of apnoea or hypopnoea per hour (apnoea/hypopnoea index) is usually considered abnormal". The index figure for Dr Khanna, even without CPAP, was below 6. The degree of desaturation and other factors may be crucial: Dr Khanna suffered none. Dr Simonds acknowledged this in cross-examination, but she maintained her view that here might be a lower incidence and that her diagnosis was correct. A related factor is that an Arousal Index of below 30 would not be regarded as pathological: Dr Khanna's as recorded at Birmingham was only 14.

47. There was also evidence that during the year after his retirement Dr Khanna did indeed suffer from daytime somnolence. He became torpid and inactive, and Mr Livesey may have exaggerated only slightly when he said that Dr Khanna during this period did little more than watch TV. Since he was benefiting from CPAP, the submission continued, he was not suffering from incidents of apnoea/hypopnoea, and therefore his somnolence cannot have been due to OSA.

48. This is the converse of the contention that Dr Khanna did not suffer from OSA before his treatment because the evidence shows that he was hyperactive and not showing signs of daytime somnolence at that time. In this context, it is relied upon as evidence that the cause of his condition was not OSA.

49. It is unnecessary in my judgment to go further into this submission or to quote from the evidence given by Dr Simonds, Professor Douglas and Dr Cayton, with whom most though not all of these matters were raised.

50. In my judgment, there was ample evidence to support the Judge's conclusion, that OSA was proved to have made a material contribution to Dr Khanna's disability and incapacity, both at the time of his treatment and subsequently. I am also satisfied that on the evidence his findings were correct. OSA was the condition diagnosed at the time. I can see no reason to doubt it now.

51. The third and final ground of appeal is that the Judge failed to give reasons for preferring the evidence of Dr Simonds to that of the appellants' expert witnesses and for deciding certain issues as he appears to have done in favour of the claimant. The appellants rely on the recent judgment of this Court in Flannery v Halifax Estate Agencies Ltd [2000] 1 WLR 377. There, the principle was upheld that judges today owe a general duty to give reasons for their decisions. The Court continued:--

"It is not a useful task to attempt to make absolute rules as to the requirement for the judge to give reasons" (Page 381C)

Among its comments, the Court included:--

"(3) The extent of the duty, or rather the reach of what is required to fulfil it, depends on the subject matter ... where the dispute involves something in the nature of an intellectual exchange, with reasons and analysis advanced on either side, the judge must enter into the issues concerned before him and explain why he prefers one case over the other" (page 382A).

In that case, the judge limited himself to "a bare summary of the expert evidence given on behalf of each party" (page 379G), referred to the fact that he had the benefit of seeing and hearing the witnesses, and concluded:--

"Having done so, I prefer the expert evidence that was given for the defendants to that which was given for the plaintiffs,"

followed by a few additional comments (page 380B). The appeal was allowed on the ground that these reasons were insufficient.

52. Mr Livesey submits that the Judge fell into the same error in the present case. This makes necessary a summary of the references to the conflict of expert evidence in the judgment. These concluded in the penultimate paragraph (page 19, quoted above) with "I accept the expert evidence of Dr Simonds", and in the final paragraph, where he dealt with a particular point made against Dr Simonds by the defendants, he said:--

"Again I do not feel that I can reject that evidence. Despite the powerful evidence of Dr Cayton and Professor Douglas, this seems to provide the most coherent and consistent account of a strange history that cannot on any view be fully explained".

But those were conclusions only. In the course of his judgment, the Judge addressed first "The fundamental issues", indicating that these were concerned with OSA only, then proceeded to consider the conflict of expert evidence (pages 5 - 9), including in this a brief, general account of the nature of OSA (page 5). He then assessed this conflict against the factual background, and in the course of doing so made further reference to the medical issues and to the expert evidence (pages 9 - 15). He came to his conclusions at pages 17 - 19 and he stated them as such, making it clear that he addressed the correct question, namely, what was the cause of the claimant's "cluster of symptoms" in 1994, all of which were described in the judgment, and whether OSA made a material contribution towards them. The claimant succeeded on the balance of probabilities -- a correct statement of the burden of proof.

53. Mr Livesey's submission in my view is impossible for him to maintain to its full extent. He contends that the judgment is comparable with that given in Flannery. Clearly, it is not. The Judge did give his reasons, and it is perhaps ironic that Mr Livesey's primary submission depends upon a close analysis and critique of the chain of reasoning which led the Judge to the conclusion he reached.

54. There is, however, some force in my judgment in the criticism which was developed in the course of the hearing that the Judge should have given more detailed reasons than he did with regard to some specific issues that were raised in connection with the medical evidence. He referred to the apnoea/hypopnoea index (AHI - see page 8 of the judgment) but not to the level regarded as pathological in the published literature or to the figures recorded for the claimant at different times. He made no reference to the number of Arousals, though I for my part do not understand why the total number of Arousals, including those due to noise or other external causes, is directly relevant to the diagnosis of OSA. He did not make detailed findings as to the extent to which CPAP improved Dr Khanna's condition, nor as to the evidence of daytime somnolence at different times. In these particular respects, in my view, the judgment might rightly be regarded as deficient.

55. On the other hand, I would expressly reject the submission that the Judge made insufficient reference to the symptoms experienced by Dr Khanna or to his choking in particular (pages 13 - 14 "He nevertheless remained wary of a recurrence of the choking problem", despite using CPAP).

56. But in my judgment also, the defects I have identified above do not come near to providing a valid ground of appeal in the present case. Essentially, there are two reasons, one general, one specific. In general, the trial judge must always try not to lose sight of the wood for the trees. The more that individual trees are pointed out to him, the more important it becomes that he must stand back to survey the whole picture before reaching his final decision. It is understandable that individual trees may then not be accounted for in his reasons.

57. Secondly, and specifically, the expert evidence in this case gave rise to an issue as to whether OSA should properly be diagnosed by reference to measurable and measured events alone. Dr Simonds was firmly of the view that the proper approach is to make an assessment for each individual patient. The Judge referred expressly to this issue -- see for example at page 6:--

"[Dr Simonds] also emphasised that the diagnosis and significance of OSA for the individual cannot be limited to the enumeration of apnoea/hypopnoea events per hour ...".

58. The Judge accepted this evidence, as he was entitled to do. In my judgment, his decision should not be criticised in the circumstances of this case for failing to deal in greater detail with certain matters which, in the light of the evidence which he accepted, were not material to his decision.

59. For these reasons, I would dismiss this appeal.

BUXTON LJ:

60. I agree.

PILL LJ:

61. I also agree.