178
IFPMA code
on
advertising
SiR,—Three years ago The Lancet reported on the promotion of benzydamine (’Benzitrat’; Searle) to a paediatricians’ congress in Brazil. The doctors were offered prizes of rally bicycles, surfboards, and skateboards (gifts requiring balance, presumably like the balanced product) in the "Benzicard" lottery. A month before the congress Health Action International protested to the International Federation of Pharmaceutical Manufacturers Association (IFPMA) about this promotion. Seven months after it, IFPMA replied. It did not consider that the promotion violated the IFPMA voluntary code of advertising, but the company had taken note of the criticism and the campaign had been withdrawn.2 Perhaps the company was mindful of skating too close to the clause in the Association of the British Pharmaceutical Industry code of practice which states that "gifts may be distributed to members of the medical and allied professions provided the gift is inexpensive and relevant to the practice of medicine or pharmacy". In November, 1990, Roche, through its agents in Sri Lanka, promoted ceftriazone (’Rocephin’) at the annual sessions of the Ceylon College of Physicians with a darts competition. Those hitting the bull’s eye in one shot were awarded the prize of an umbrella. The competition and the prize emphasise that the drug is administered only once a day-a one-shot drug to provide 24 hour cover. When this promotion was brought to the notice of the manufacturers, the regional manager of Roche Pharmaceuticals and Chemicals, Hong Kong, Mr S. Hoffmann, replied that the company was absolutely not in breach of the IFPMA code. However, he added that Roche would refrain from using the darts game in future. Roche felt that the umbrellas were of negligible commercial value. The umbrella costs the equivalent of a day’s wages for a labourer in Sri Lanka-and a vial of rocephin costs four
day’s wages. On the other hand, Roche may be correct in their interpretation. This promotion represents honesty in advertising, in a way. Darts is rarely played in developing countries, and these countries rarely have the microbiological resources required for the rational use of powerful antibiotics such as ceftriaxone. So at least in developing countries when rocephin is used, the chances of success could be as remote as that of a novice in darts. Department of Pharmacology, Faculty of Medicine, Colombo 8, Sri Lanka
rather than contamination counts. If the isolated suite system has no effect on infection the costs of such designs-the extra money to build them and to maintain them, the costs of theatre wear and overshoes worn by those not entering the theatres themselves, and the inconvenience to staff who would not otherwise have to change clothing-need to be discussed. If the isolated theatre suite is of no proven benefit-Iask as a theatre user not as an expert in infection control-is it just a cosmetic exercise that should be abandoned? Department of Anaesthesia, Ealing Hospital,
CHRISTOPHER HENEGHAN
Southall UB1 3HW, UK
Occupational infection
among anaesthetists
SIR,-Your editorial (Nov 3, p 1103) and subsequent correspondence (Dec 8, p 1456) show a surprising lack of concern for personal occupational safety by some anaesthetists. Crossinfection control can also be poor in general medical practice as shown by the infrequent use of autoclaves and protective gloves, inadequate knowledge of sterilisation, and poor uptake of hepatitis vaccination.1,2 Most UK clinical dental staff have, in contrast, been shown to have been immunised against hepatitis B virus,3 and to use gloves and other infection control measures.’ These practices will become more widespread, since UK clinical dental students are nearly always immunised against hepatitis B virus5 and are made aware of this occupational hazard at a very early stage in their careers. Therefore, it would seem important to immunise medical students against hepatitis B and to emphasise the need for regular booster immunisation and appropriate control of cross-infection in all clinical specialties. Centre for the
Study of Oral Disease, University Department of Oral Medicine, Surgery, and Pathology, Bristol Dental School and Hospital, Bristol BS1 2LY, UK
CRISPIAN SCULLY STEPHEN PORTER
Morgan DR, Lamont TJ, Dawson JD, Booth C. Decontamination of instruments and control of cross infection in general practice Br Med J 1990, 300: 1379-80. 2 Kinnerstey P. Attitudes of general practitioners towards their vaccination against hepatitis B Br Med J 1990; 300: 238. 3. Samaranayake LP, Scully C, Dowell TB, et al. New data on the acceptance of the hepatitis B vaccine by dental personnel in the United Kingdom Br Dent J 1988, 1.
164: 74-77.
KRISANTHA WEERASURIYA
1. Anon. Paediatricians get their skates on. Lancet 1987; ii: 735. 2. Chetley A. A healthy business?: world health and the pharmaceutical London: Zed Books, 1990: 60.
industry.
RW, Scully C, Dowell TB. Attitudes and practices regarding control of cross-infection in general dental practice. Health Trends 1989, 21: 10-12 5. Scully C, Matthews RW. Uptake of hepatitis B immunisation amongst United Kingdom dental students Health Trends 1990; 22: 92.
4. Matthews
Occupational hazards and protection of Why isolate theatre suites? SIR,-For 20 years or more new operating-theatres have been built to a plan which allows or requires all personnel to change their clothes and shoes before entering the theatre suite. Access to the areas in the theatre suite but outside the operating-theatres is usually denied to anyone who has not changed completely. The logic, presumably, is that infection associated with surgery is at least in part due to exogenous bacterial contamination and that outdoor clothes are more likely to carry bacteria while clean theatre wear (or other materials) can be contaminated by contact with outdoor clothes and shoes. However, a bacterial challenge must reach a certain level before infection occurs, and contamination is very unlikely to reach that point if floors and walls are kept clean. Furthermore changing clothes can increase shedding of bacteria. Despite these criticisms nearly all new suites are built to this isolation design. However, not all hospitals use them in this way for in areas outside the theatres themselves there is mingling of staff in outdoor clothes and those in theatre wear, and it is still possible to walk up to the door of a theatre to confer with colleagues inside. There are also still operating theatres of the pre-isolated design where access up to the theatre door is available to all. Open access makes life easier for theatre personnel and saves time. It could not be allowed if the price is a higher infection rate. But is it? I know of no hard evidence that the isolated suite system makes any difference to outcome, as measured by infection rates
the fetus
SIR,-Contrary to the implication of the title of your Nov 24 (p 1289), it is not the woman but the fetus who is the primary focus of protection against such agents in occupational editorial
settings. Your comments, moreover, combine the action of "teratogens" and "mutagens" by implying that agents affecting spermatozoa and ova exert a teratogenic effect, giving the impression that since agents that act before conception can affect both sexes it is of as much importance to protect the male parent as the female parent. The fact that mutagens and other reproductive toxms can affect paternally derived gametes does not negate the much greater potential effect on the fetus of maternal exposure to hazards during pregnancy. Your remarks imply that there is no more reason to protect the female than the male parent, suggesting implicitly that the courts take the view that actions targeted to the woman during pregnancy are discriminatory. But it is nature that has discriminated: it is the woman who carries the fetus and it is through her that teratogens reach the fetus. No one has yet documented any association of paternal alcoholism or alcohol ingestion independent of maternal behaviour with fetal alcohol syndrome, nor of paternal thalidomide ingestion independent of maternal exposure with limb reduction defects. This is not to deny the possible role of the male parent in the transmission of hazardous substances to the pregnant woman, through, for example, bringing
179
home toxins on workclothes or by smoking. But in this role the man is simply one part of the larger environment in which women too-sisters, mothers, friends--could be vectors of reproductive hazards. Certainly we should attempt to diminish exposures of both sexes to toxins. But this should not mask the special role of the pregnant woman in the transmission of possible teratogens to the fetus. School of Public Health, University of California, Berkeley, California 94720, USA
E. B. HOOK
Long-stay or short-stay and discharge from mental handicap hospitals SIR,-As part of the strategy for the discharge of patients from mental handicap hospitals money is available for distribution to the regional health authority for every long-stay patient who is discharged from hospital. On the surface this seems commendable on the grounds that the hospital will need less money to provide facilities for its remaining patients and that the lot of patients transferred to community facilities will be improved. Money is only transferred for patients who have been resident in hospital for many years. If a patient is admitted to a mental handicap hospital because of illness or behavioural disturbance at home and there is no suitable placement in the community he remains in hospital. Since the patient is no longer being supervised by the community services there is less urgency to find a suitable home for him, and many individuals remain in hospital for some time. Although both regional and national policy proscribes long-term admissions to mental handicap hospitals there is a curious advantage in labelling such patients long-stay. When I organise case conferences for such individuals I am always asked whether the patient is a long-stay or a short-stay patient. If the patient can be designated long-stay a community placement is sought eagerly because discharge will then be accompanied by an agreed sum of money. The wheels are set in motion and within a month or two visits have been arranged to both the residential establishment and the training centre and the patient is often soon discharged. If the patient is short-stay these initiatives are not undertaken and the patient languishes in hospital. "When I use a word it means just what I choose it to mean", said Humpty Dumpty in Lewis Carroll’s Through the Looking Glass. He would appreciate how long means short and short means long. Prudhoe
Hospital,
Prudhoe, Northumberland, NE42 5NT, UK
S. P. TYRER
Doctors’ hours SIR,-Your Dec 22/29 editorial makes many criticisms, most of them justified, of the excessive hours worked by doctors in the National Health Service. It also criticises the heads of agreement issued by the Ministerial Working Group as not addressing all the issues. Unfortunately your editorial is grossly inaccurate in certain respects, which will dilute the impact of some of the well-directed criticisms. The sentence "Newly appointed consultants will have a greater involvement in patient care when on call", far from "revealing the seniority of the group" is not in the agreement at all. This error prejudices most of the discussion in the subsequent paragraph on the need for consultant expansion. The agreement states in para 4.4 that it reaffirms a commitment to the Achieving a Balance document’s objective of "maintaining existing rates of consultant expansion. Over and above this, additional career grade staff, especially consultants, will be required in particular places and specialties". The agreement goes on to detail some of the ways in which additional consultants can help in the reduction of junior doctors’ hours. Para 4.6 states that consultants should not be required to be compulsorily resident when on call. There are many ways in which additional consultants can help without being resident. For example, in emergency work a lot of unecessary surgery is done at night which could be handled with benefit by a fresh team led by an (additional) consultant the following day. This would enable hard-pressed junior staff to take part in shift systems or have time off
after a night on call. This could well be of benefit to patients, if safer surgery is done with less risk of complications. Additional consultants could also do the service workload, replacing a junior who may at present be doing an outpatient clinic or operating-list after a night on call. I agree that the sums on offer are inadequate when set beside the money spent on implementing the latest NHS reforms. Far greater numbers of consultants are required, with the full funding of additional secretarial and other staff, to help reduce junior doctors’ hours. The position in Scotland is even more difficult because the present rate of consultant expansion is 0-5%, a sixth of that in England and Wales. With the crisis management being used to balance books before April 1 in areas such as Lothian already threatening cuts in consultant numbers, it is clear that adequate targeted funding is the prime requirement if a reduction in junior doctors’ hours is to be achieved.
ARTHUR McG. MORRIS, 41 Constitution Street, Dundee DD3 6JH, UK
Chairman, Scottish Committee for Hospital Medical Services
*)*The passage in question was removed from a draft of the agreement at a very late stage indeed, as was a sentence about younger consultants being asked to do more emergency work than older ones. Perhaps it is not just financial commitment that needs to be questioned in this discussion.-ED. L.
Exercise induced asthma: the protective role of CO2 during swimming SiR,—Reggiani et all found less asthma associated with the lower maximum minute ventilation (VE) in competitive swimming than in running or cycling. It is well known that swimming causes less exercise-induced asthma (EIA) than do other forms of exercise—indeed in some cases no EIA is seen. No explanation for this has been forthcoming, although it has been postulated that the humid air breathed during swimming is protective. I suggest that the protective effect of swimming might result from hypoventilation and hypercapnia due to constrained breathing patterns. During swimming VE is much less than during either running or cycling. 1,3 ’ The constrained breathing patterns necessitated by all the competitive swimming strokes, apart from backstroke, are probably responsible for the lower VE seen with this form of exercise. This, in turn, results in some "retention" of CO2 as well as enhanced oxygen extractionThe increased alveolar CO2 tension (P A CO2) might prevent EIA from swimming, either because it causes bronchodilatation or, owing to its vasodilatory properties, because it preserves the bronchial bloodflow despite airway cooling. Preservation of bloodflow may prevent both excessive airway drying6 and/or post-exercise reactive hyperaemia.7 A high anaerobic tolerance has been regarded as important for competitive swimmers. A common training programme incorporates controlled frequency breathing where swimmers restrict breathing frequencies from a normal breath every two arm strokes to every four, six, or eight strokes; this causes a decrease in VE, and P, CO2 values can be as high as 6-95 KPa (52 mm Hg) when breathing once every six armstrokes.5 The asthmatic swimmers studied by Reggiani et all were trained competitive swimmers; all were afforded complete protection from EIA and even recorded a mild brochodilatation after swimming, but after cycling or running they had a striking reduction in FEV1. To establish if humidity of the inspired air was important Bar Yishay et aP standardised heart rate, oxygen consumption, VE, tidal volume, and degree of humidity in their studies on untrained asthmatic children. When comparing running and swimming, under the same conditions of respiratory heat and water loss, they found a 13% fall in FEV after swimming and a 20% fall in FEV, while running. In their attempt to standardise the VE of swimming to running, they might have removed some of the protection against EIA afforded by the biomechanics of swimming (ie, hypoventilation). In most land-based forms of exercise, patterns of breathing are not constrained, VE increases proportionately throughout exercise, and end-tidal CO2 tensions are either normal or low.8 Therefore
IFPMA code
on
advertising
SiR,—Three years ago The Lancet reported on the promotion of benzydamine (’Benzitrat’; Searle) to a paediatricians’ congress in Brazil. The doctors were offered prizes of rally bicycles, surfboards, and skateboards (gifts requiring balance, presumably like the balanced product) in the "Benzicard" lottery. A month before the congress Health Action International protested to the International Federation of Pharmaceutical Manufacturers Association (IFPMA) about this promotion. Seven months after it, IFPMA replied. It did not consider that the promotion violated the IFPMA voluntary code of advertising, but the company had taken note of the criticism and the campaign had been withdrawn.2 Perhaps the company was mindful of skating too close to the clause in the Association of the British Pharmaceutical Industry code of practice which states that "gifts may be distributed to members of the medical and allied professions provided the gift is inexpensive and relevant to the practice of medicine or pharmacy". In November, 1990, Roche, through its agents in Sri Lanka, promoted ceftriazone (’Rocephin’) at the annual sessions of the Ceylon College of Physicians with a darts competition. Those hitting the bull’s eye in one shot were awarded the prize of an umbrella. The competition and the prize emphasise that the drug is administered only once a day-a one-shot drug to provide 24 hour cover. When this promotion was brought to the notice of the manufacturers, the regional manager of Roche Pharmaceuticals and Chemicals, Hong Kong, Mr S. Hoffmann, replied that the company was absolutely not in breach of the IFPMA code. However, he added that Roche would refrain from using the darts game in future. Roche felt that the umbrellas were of negligible commercial value. The umbrella costs the equivalent of a day’s wages for a labourer in Sri Lanka-and a vial of rocephin costs four
day’s wages. On the other hand, Roche may be correct in their interpretation. This promotion represents honesty in advertising, in a way. Darts is rarely played in developing countries, and these countries rarely have the microbiological resources required for the rational use of powerful antibiotics such as ceftriaxone. So at least in developing countries when rocephin is used, the chances of success could be as remote as that of a novice in darts. Department of Pharmacology, Faculty of Medicine, Colombo 8, Sri Lanka
rather than contamination counts. If the isolated suite system has no effect on infection the costs of such designs-the extra money to build them and to maintain them, the costs of theatre wear and overshoes worn by those not entering the theatres themselves, and the inconvenience to staff who would not otherwise have to change clothing-need to be discussed. If the isolated theatre suite is of no proven benefit-Iask as a theatre user not as an expert in infection control-is it just a cosmetic exercise that should be abandoned? Department of Anaesthesia, Ealing Hospital,
CHRISTOPHER HENEGHAN
Southall UB1 3HW, UK
Occupational infection
among anaesthetists
SIR,-Your editorial (Nov 3, p 1103) and subsequent correspondence (Dec 8, p 1456) show a surprising lack of concern for personal occupational safety by some anaesthetists. Crossinfection control can also be poor in general medical practice as shown by the infrequent use of autoclaves and protective gloves, inadequate knowledge of sterilisation, and poor uptake of hepatitis vaccination.1,2 Most UK clinical dental staff have, in contrast, been shown to have been immunised against hepatitis B virus,3 and to use gloves and other infection control measures.’ These practices will become more widespread, since UK clinical dental students are nearly always immunised against hepatitis B virus5 and are made aware of this occupational hazard at a very early stage in their careers. Therefore, it would seem important to immunise medical students against hepatitis B and to emphasise the need for regular booster immunisation and appropriate control of cross-infection in all clinical specialties. Centre for the
Study of Oral Disease, University Department of Oral Medicine, Surgery, and Pathology, Bristol Dental School and Hospital, Bristol BS1 2LY, UK
CRISPIAN SCULLY STEPHEN PORTER
Morgan DR, Lamont TJ, Dawson JD, Booth C. Decontamination of instruments and control of cross infection in general practice Br Med J 1990, 300: 1379-80. 2 Kinnerstey P. Attitudes of general practitioners towards their vaccination against hepatitis B Br Med J 1990; 300: 238. 3. Samaranayake LP, Scully C, Dowell TB, et al. New data on the acceptance of the hepatitis B vaccine by dental personnel in the United Kingdom Br Dent J 1988, 1.
164: 74-77.
KRISANTHA WEERASURIYA
1. Anon. Paediatricians get their skates on. Lancet 1987; ii: 735. 2. Chetley A. A healthy business?: world health and the pharmaceutical London: Zed Books, 1990: 60.
industry.
RW, Scully C, Dowell TB. Attitudes and practices regarding control of cross-infection in general dental practice. Health Trends 1989, 21: 10-12 5. Scully C, Matthews RW. Uptake of hepatitis B immunisation amongst United Kingdom dental students Health Trends 1990; 22: 92.
4. Matthews
Occupational hazards and protection of Why isolate theatre suites? SIR,-For 20 years or more new operating-theatres have been built to a plan which allows or requires all personnel to change their clothes and shoes before entering the theatre suite. Access to the areas in the theatre suite but outside the operating-theatres is usually denied to anyone who has not changed completely. The logic, presumably, is that infection associated with surgery is at least in part due to exogenous bacterial contamination and that outdoor clothes are more likely to carry bacteria while clean theatre wear (or other materials) can be contaminated by contact with outdoor clothes and shoes. However, a bacterial challenge must reach a certain level before infection occurs, and contamination is very unlikely to reach that point if floors and walls are kept clean. Furthermore changing clothes can increase shedding of bacteria. Despite these criticisms nearly all new suites are built to this isolation design. However, not all hospitals use them in this way for in areas outside the theatres themselves there is mingling of staff in outdoor clothes and those in theatre wear, and it is still possible to walk up to the door of a theatre to confer with colleagues inside. There are also still operating theatres of the pre-isolated design where access up to the theatre door is available to all. Open access makes life easier for theatre personnel and saves time. It could not be allowed if the price is a higher infection rate. But is it? I know of no hard evidence that the isolated suite system makes any difference to outcome, as measured by infection rates
the fetus
SIR,-Contrary to the implication of the title of your Nov 24 (p 1289), it is not the woman but the fetus who is the primary focus of protection against such agents in occupational editorial
settings. Your comments, moreover, combine the action of "teratogens" and "mutagens" by implying that agents affecting spermatozoa and ova exert a teratogenic effect, giving the impression that since agents that act before conception can affect both sexes it is of as much importance to protect the male parent as the female parent. The fact that mutagens and other reproductive toxms can affect paternally derived gametes does not negate the much greater potential effect on the fetus of maternal exposure to hazards during pregnancy. Your remarks imply that there is no more reason to protect the female than the male parent, suggesting implicitly that the courts take the view that actions targeted to the woman during pregnancy are discriminatory. But it is nature that has discriminated: it is the woman who carries the fetus and it is through her that teratogens reach the fetus. No one has yet documented any association of paternal alcoholism or alcohol ingestion independent of maternal behaviour with fetal alcohol syndrome, nor of paternal thalidomide ingestion independent of maternal exposure with limb reduction defects. This is not to deny the possible role of the male parent in the transmission of hazardous substances to the pregnant woman, through, for example, bringing
179
home toxins on workclothes or by smoking. But in this role the man is simply one part of the larger environment in which women too-sisters, mothers, friends--could be vectors of reproductive hazards. Certainly we should attempt to diminish exposures of both sexes to toxins. But this should not mask the special role of the pregnant woman in the transmission of possible teratogens to the fetus. School of Public Health, University of California, Berkeley, California 94720, USA
E. B. HOOK
Long-stay or short-stay and discharge from mental handicap hospitals SIR,-As part of the strategy for the discharge of patients from mental handicap hospitals money is available for distribution to the regional health authority for every long-stay patient who is discharged from hospital. On the surface this seems commendable on the grounds that the hospital will need less money to provide facilities for its remaining patients and that the lot of patients transferred to community facilities will be improved. Money is only transferred for patients who have been resident in hospital for many years. If a patient is admitted to a mental handicap hospital because of illness or behavioural disturbance at home and there is no suitable placement in the community he remains in hospital. Since the patient is no longer being supervised by the community services there is less urgency to find a suitable home for him, and many individuals remain in hospital for some time. Although both regional and national policy proscribes long-term admissions to mental handicap hospitals there is a curious advantage in labelling such patients long-stay. When I organise case conferences for such individuals I am always asked whether the patient is a long-stay or a short-stay patient. If the patient can be designated long-stay a community placement is sought eagerly because discharge will then be accompanied by an agreed sum of money. The wheels are set in motion and within a month or two visits have been arranged to both the residential establishment and the training centre and the patient is often soon discharged. If the patient is short-stay these initiatives are not undertaken and the patient languishes in hospital. "When I use a word it means just what I choose it to mean", said Humpty Dumpty in Lewis Carroll’s Through the Looking Glass. He would appreciate how long means short and short means long. Prudhoe
Hospital,
Prudhoe, Northumberland, NE42 5NT, UK
S. P. TYRER
Doctors’ hours SIR,-Your Dec 22/29 editorial makes many criticisms, most of them justified, of the excessive hours worked by doctors in the National Health Service. It also criticises the heads of agreement issued by the Ministerial Working Group as not addressing all the issues. Unfortunately your editorial is grossly inaccurate in certain respects, which will dilute the impact of some of the well-directed criticisms. The sentence "Newly appointed consultants will have a greater involvement in patient care when on call", far from "revealing the seniority of the group" is not in the agreement at all. This error prejudices most of the discussion in the subsequent paragraph on the need for consultant expansion. The agreement states in para 4.4 that it reaffirms a commitment to the Achieving a Balance document’s objective of "maintaining existing rates of consultant expansion. Over and above this, additional career grade staff, especially consultants, will be required in particular places and specialties". The agreement goes on to detail some of the ways in which additional consultants can help in the reduction of junior doctors’ hours. Para 4.6 states that consultants should not be required to be compulsorily resident when on call. There are many ways in which additional consultants can help without being resident. For example, in emergency work a lot of unecessary surgery is done at night which could be handled with benefit by a fresh team led by an (additional) consultant the following day. This would enable hard-pressed junior staff to take part in shift systems or have time off
after a night on call. This could well be of benefit to patients, if safer surgery is done with less risk of complications. Additional consultants could also do the service workload, replacing a junior who may at present be doing an outpatient clinic or operating-list after a night on call. I agree that the sums on offer are inadequate when set beside the money spent on implementing the latest NHS reforms. Far greater numbers of consultants are required, with the full funding of additional secretarial and other staff, to help reduce junior doctors’ hours. The position in Scotland is even more difficult because the present rate of consultant expansion is 0-5%, a sixth of that in England and Wales. With the crisis management being used to balance books before April 1 in areas such as Lothian already threatening cuts in consultant numbers, it is clear that adequate targeted funding is the prime requirement if a reduction in junior doctors’ hours is to be achieved.
ARTHUR McG. MORRIS, 41 Constitution Street, Dundee DD3 6JH, UK
Chairman, Scottish Committee for Hospital Medical Services
*)*The passage in question was removed from a draft of the agreement at a very late stage indeed, as was a sentence about younger consultants being asked to do more emergency work than older ones. Perhaps it is not just financial commitment that needs to be questioned in this discussion.-ED. L.
Exercise induced asthma: the protective role of CO2 during swimming SiR,—Reggiani et all found less asthma associated with the lower maximum minute ventilation (VE) in competitive swimming than in running or cycling. It is well known that swimming causes less exercise-induced asthma (EIA) than do other forms of exercise—indeed in some cases no EIA is seen. No explanation for this has been forthcoming, although it has been postulated that the humid air breathed during swimming is protective. I suggest that the protective effect of swimming might result from hypoventilation and hypercapnia due to constrained breathing patterns. During swimming VE is much less than during either running or cycling. 1,3 ’ The constrained breathing patterns necessitated by all the competitive swimming strokes, apart from backstroke, are probably responsible for the lower VE seen with this form of exercise. This, in turn, results in some "retention" of CO2 as well as enhanced oxygen extractionThe increased alveolar CO2 tension (P A CO2) might prevent EIA from swimming, either because it causes bronchodilatation or, owing to its vasodilatory properties, because it preserves the bronchial bloodflow despite airway cooling. Preservation of bloodflow may prevent both excessive airway drying6 and/or post-exercise reactive hyperaemia.7 A high anaerobic tolerance has been regarded as important for competitive swimmers. A common training programme incorporates controlled frequency breathing where swimmers restrict breathing frequencies from a normal breath every two arm strokes to every four, six, or eight strokes; this causes a decrease in VE, and P, CO2 values can be as high as 6-95 KPa (52 mm Hg) when breathing once every six armstrokes.5 The asthmatic swimmers studied by Reggiani et all were trained competitive swimmers; all were afforded complete protection from EIA and even recorded a mild brochodilatation after swimming, but after cycling or running they had a striking reduction in FEV1. To establish if humidity of the inspired air was important Bar Yishay et aP standardised heart rate, oxygen consumption, VE, tidal volume, and degree of humidity in their studies on untrained asthmatic children. When comparing running and swimming, under the same conditions of respiratory heat and water loss, they found a 13% fall in FEV after swimming and a 20% fall in FEV, while running. In their attempt to standardise the VE of swimming to running, they might have removed some of the protection against EIA afforded by the biomechanics of swimming (ie, hypoventilation). In most land-based forms of exercise, patterns of breathing are not constrained, VE increases proportionately throughout exercise, and end-tidal CO2 tensions are either normal or low.8 Therefore
