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CLINICAL REVIEW: Cindy den Herder, Joachim Schmeck, Dick J K Appelboom, and Nico de Vries Risks of general anaesthesia in people with obstructive sleep apnoea BMJ 2004; 329: 955-959 [Full text]

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Obstructive sleep apnoea (OSA)

M Thirumaran   (24 October 2004)

Obstructive Sleep Apnoea, Anaesthesia and Operations

Peter KK Au-Yeung   (25 October 2004)

UK help for the difficult airway

Keith C Judkins   (25 October 2004)

Need for post operative intensive care for sleep apnoea?

Adam K Woo, Paul Dodd   (27 October 2004)

Evidence based anaesthesia?

Michael Foley   (27 October 2004)

An opportunity missed.

Donald Mackie, John Loadsman.   (30 October 2004)

Obstructive sleep apnoea and floppy eyelid syndrome

Raman Malhotra, Ioannis Mavrikakis, and Raman Malhotra   (31 October 2004)

The compelling incentive to eradicate mutant anaesthetic memes and meme complexes.

Richard G Fiddian-Green   (31 October 2004)

A Misleading Title

Andrew P Syndercombe, Ian Harper   (16 November 2004)

Looking for a guideline

Bradley A Stone   (17 December 2004)

Caution with sedatives in OSA patients

Ian Forsyth   (29 March 2005)

Obstructive sleep apnoea (OSA) 24 October 2004
M Thirumaran, Specialist Registrar,Respiratory medicine Leeds General Infirmary,Leeds,LS1 3EX Send response to journal: Re: Obstructive sleep apnoea (OSA)	This is an excellent review covering the preoperative and postoperative complications the anaesthetists and intensivists face. Obstructive sleep apnoea(OSA) is one among the sleep disordered breathing which could be potentially treatable medically. The prevalence of OSA in middle age women is yet to be properly studied. The author is certainly right in highlighting that OSA is an under recognised condition. The prevalence is similar, if not more than some medical conditions like Type 1 diabetes and Asthma. Excluding other causes of sleepiness like sleep deprivation, depression, narcolepsy, hypothyroidism or drugs is very important. Epworth sleepiness scale(ESS) is a validated tool in assessing patients with OSA. Although the correlation between ESS and OSA severity is weak it’s the best available tool to the clinicians in initial screening. I think getting the physician interested in sleep at an early stage is very important. A multidisciplinary approach is very important as these patients are at risk of variety of complications including hypertension, cerebrovascular disease and heart disease. Competing interests: None declared
Obstructive Sleep Apnoea, Anaesthesia and Operations 25 October 2004
Peter KK Au-Yeung, Specialist Anaesthetist Hong Kong Send response to journal: Re: Obstructive Sleep Apnoea, Anaesthesia and Operations	The problem with using the Epworth Sleepiness Scale (ESS) as a screen for Obstructive Sleep Apnoea (OSA) is that ESS only measures the impact of the frequent desaturations on daytime arousal. As sleepiness is also dependant on the ability of any individual to tolerate sleep disruption and/or sleep deprivation, this is another independant factor which comes between frequency of desaturations and degree of sleepiness. Tolerance of sleep disruption can vary with age. Of course the same degree of sleep disruption can occur without apnoea, hypopnoea or desaturation in the upper airways resistance syndrome (UARS) but the large intrathoracic pressure swings can still lead to cardiopulmonary sequelae. Oxygen therapy for OSA is controversial as some studies have shown that arousal with consequent cessation of apnoea occurs at the same level of oxygen saturation regardless of whether or not oxygen was given. The frequency of arousal per unit time falls at the expense of lengthening apnoea when oxygen is given. That would then lead to hypercarbia and elevated intracranial pressures. Continuous positive airways pressure (CPAP) on the other hand splints the airways and prevents obstruction. Oxygen can always be added to CPAP in the post-operative period. It is also worth bearing in mind that OSA is a dynamic obstruction and as such, even the humble Guedel oropharyngeal airway can provide a route for breathing when the anaesthetised patient starts to experience airway obstruction from OSA. Finally, anyone involved in the care of patients who have undergone operations should bear in mind that post-operative sleep disturbances start from pre-operative events. These can occur regardless of anaesthetic technique (regional versus general) and even no anaesthetic! The poor quality of sleep from the first night effect of the pre-operative admission and the discomfort of the first few post-operative days lead to alterations of sleep architecture which results in rebound phenomena in the third to fifth post-opertive night. Both slow wave sleep and rapid eye movement (REM) sleep rebound and unfortunately they are often associated with sleep disordered breathing. This may explain some of the deaths and myocardial infarctions occurring in this period. Competing interests: None declared
UK help for the difficult airway 25 October 2004
Keith C Judkins, Consultant Anaesthetist Mid Yorkshire Hospitals NHS Trust, Wakefield, WF1 4EE Send response to journal: Re: UK help for the difficult airway	I enjoyed reading this well-written if somewhat basic article. I was however greatly surprised that the BMJ - a British journal - had apparently failed to ask the Dutch authors whether there are any helpful UK websites as well as the two American ones mentioned. There are, of course. As well as the Association of Anaesthetists of GB and Ireland (www.aagbi.org) and the Royal College of Anaesthetists (www.rcoa.ac.uk), there is the Difficult Airway Society (www.das.uk.com) which has several helpful documents, including an algorithm, which can be found at www.das.uk.com/guidelines. The Scottish Intercollegiate Guidelines Network (SIGN) have produced an excellent guideline on the management of OSA which can be found at www.sign.ac.uk/pdf/sign73.pdf. The British Sleep Society is at http://www.sleeping.org.uk. Surely a British journal should make sure to promote the excellent material available in the UK? Competing interests: Ordinary member, Difficult Airway Society
Need for post operative intensive care for sleep apnoea? 27 October 2004
Adam K Woo, Specialist Registrar Anaesthesia King George Hospital, Barley Lane, Ilford, Essex IG3 8YB, Paul Dodd Send response to journal: Re: Need for post operative intensive care for sleep apnoea?	Editor- Herder et al (BMJ 2004; 329: 955-959) advocate post operative surveillance in an intensive care unit for patients with obstructive sleep apnoea post operatively. However Department of Health guidelines suggest that high dependency unit care will meet the clinical surveillance and treatment requirements identified by the authors(1). It may therefore be inappropriate to suggest intensive care provision in this instance, at least in the UK. Clinical reviews published in major peer reviewed journals are likely to inform later evidence based guidelines. It is incumbent on all health care professionals to ensure responsible guidance for the use of limited intensive care resources in this country(2). Dr Adam Woo, Specialist Registrar in Anaesthetics, King George Hospital Essex Dr Paul Dodd, Consultant in Anaesthesia and Intensive Care, King George Hospital, Essex (1) Department of Health. Guidelines on admission to and discharge from Intensive Care and High Dependency Units. March 1996 (2) The Intensive Care Society. Evolution of Intensive Care in the UK, 2003 Competing interests: None declared
Evidence based anaesthesia? 27 October 2004
Michael Foley, Consultant anaesthetist James Cook University Hospital, Middlesbrough, UK TS4 3BW Send response to journal: Re: Evidence based anaesthesia?	The authors of this review make an unequivocal recommendation that all patients with difficult airways should be given methylprednisolone 250mg to prevent peri-operative swelling of the airway. The only reference cited to support this is of a study in which rat skin was burned with a CO2 laser; those rats pre-treated with steroids developed less tissue swelling than untreated controls. By what leap of logic do the authors use this observation to support their recommendation? Maybe it doesn't matter, but the editor of the BMJ chose this review as the cover story and I would expect the content to be to a higher standard. Competing interests: None declared
An opportunity missed. 30 October 2004
Donald Mackie, Consultant anaesthetist Lower Hutt, New Zealand. 6009, John Loadsman. Send response to journal: Re: An opportunity missed.	Although the title suggests a review of the risks {Cindy den Herder, Joachim Schmeck, Dick J K Appelboom, and Nico de Vries Risks of general anaesthesia in people with obstructive sleep apnoea BMJ 2004; 329: 955- 959} the paper offers little quantification of such risks. For example, we read that obstruction and apnoeas occur "often" directly after extubation quoting Loadsman and Hillman who state no such thing {Loadsman JA, Hillman DR. Anaesthesia and sleep apnoea. Br J Anaesth 2001;86: 254-66.) and that opiates make this worse. Some comorbidities are mentioned with no detail of prevalence. Surprisingly, there is no mention of right heart failure and cor pulmonale. The paper meanders through an incomplete list of tips on perioperative management. The pros and cons of premedication with benzodiazepines are mentioned but no conclusion is drawn. We wonder how their anticonvulsive activity contributes to upper airway obstruction as suggested? What evidence is there that a preoperative anxiolytic reduces any complications that might result from general anaesthesia? The McCoy laryngoscope and Fastrack are useful aids to airway management, but why are they singled out over others? Fibreoptic scopes are barely touched upon. Their use in emergencies is completely dismissed - a brave call. In the next paragraph Table 2 contains a version of the [American Society of Anesthesiologists] Difficult Airway Algorithm that has been simplified to the point of uselessness. It is not clear whether this advice is for perioperative management of upper airway surgery or any surgery. There is a recommendation for the administration of methylprednisolone to avoid airway swelling but the only reference given for this relates to CO2 laser surgery in the oropharynx. Should we give this dose of steroids to patients with Obstructive Sleep Apnoea presenting for, say, knee surgery? Elsewhere, there is reference to delayed apnoea after intravenous opioids. The reference cited deals with *epidural* administration of opioids, an unusual choice of analgesia for upper airway surgery. What evidence is there that the sedation caused by clonidine results in any less airway compromise than any other sedative agent, particularly when added to the effects of other perioperative drugs? The cautionary statement regarding oxygen administration and "hypoxic drive" is questionable. There are other specific problems with this paper. The definitions of apnoeas and hypopnoeas are incorrect. The data and references supplied regarding prevalence of OSA are outdated. The discussion regarding slow wave sleep (stages 3 and 4) is nonsensical. Slow wave sleep is the sleep stage *least* associated with upper airway obstruction. Similarly, the oft -repeated speculation regarding REM rebound and its potential consequences is inaccurately and inadequately discussed. The challenge of perioperative management of the patient with sleep apnoea is familiar to many anaesthetists. The general comments on the prevalence of sleep apnoea and the need for awareness are reasonably sound. The rest of this article, sadly, misses an opportunity to add much else. Whether the failure lies with the authors or the editors we must decide for ourselves. Competing interests: None declared
Obstructive sleep apnoea and floppy eyelid syndrome 31 October 2004
Raman Malhotra, Consultant Ophthalmologist and Oculoplastic Surgeon Corneo Plastic Unit, Queen Victoria Hospital, Holtye Road, East Grinstead, West Sussex, RH19 3DZ, Ioannis Mavrikakis, and Raman Malhotra Send response to journal: Re: Obstructive sleep apnoea and floppy eyelid syndrome	Editor Den Herder et al(1) highlight the risks of anaesthesia and sedation in patients with obstructive sleep apnoea and point out useful symptoms and signs to help identify this under-recognised disorder. With the aim of providing further clues to identifying patients with obstructive sleep apnoea we write to remind the readers of the association between obstructive sleep apnoea and floppy eyelid syndrome, a condition that is well-documented in the ophthalmic literature.(2-4) Patients with symptoms related to floppy eyelid syndrome commonly present to the Ophthalmologist or Oculoplastic Surgeon complaining of non-specific ocular irritation, redness, or a foreign body sensation. Due to these vague symptoms, it too may be misdiagnosed, however the most distinctive feature of floppy eyelid syndrome is a pliant upper eyelid tarsus that is easily stretched and everted without any excess manipulation. In fact, on direct questioning patients often report that their upper eyelids spontaneous evert during sleep. As a result of such laxity, patients may also have upper eyelid ptosis or lower eyelid ectropion. The ophthalmic management of floppy eyelid syndrome often requires surgery in the form of horizontal eyelid shortening, however it has been reported that treatment of obstructive sleep apnoea itself may reverse the changes of floppy eyelid syndrome.(3) We would therefore suggest that in addition to the recommendations by den Herder et al(1), if obstructive sleep apnoea is suspected then attention should also be directed to the presence of symptoms of non-specific ocular irritation, redness, or a foreign body sensation and to signs of significant horizontal eyelid laxity with easily everted upper eyelids. References 1. den Herder C, Schmeck J, Appelboom DJ, de Vries N. Risks of general anaesthesia in people with obstructive sleep apnoea. Bmj 2004;329(7472):955-9. 2. McNab AA. Floppy eyelid syndrome and obstructive sleep apnea. Ophthal Plast Reconstr Surg 1997;13(2):98-114. 3. McNab AA. Reversal of floppy eyelid syndrome with treatment of obstructive sleep apnoea. Clin Experiment Ophthalmol 2000;28(2):125-6. 4. Bilenchi R, Poggiali S, Pisani C, De Aloe G, Motolese PA, Motolese E, et al. Floppy eyelid syndrome associated with obstructive sleep apnoea. Br J Dermatol 2004;151(3):706. Competing interests: None declared
The compelling incentive to eradicate mutant anaesthetic memes and meme complexes. 31 October 2004
Richard G Fiddian-Green, FRCS, FACS c.o Sanders, Iemple Gdns, Moor Park Send response to journal: Re: The compelling incentive to eradicate mutant anaesthetic memes and meme complexes.	"In this review we discuss the various anaesthetic aspects of obstructive sleep apnoea, including preoperative, perioperative, and postoperative points of special interest"(1). The statement suggests that anaesthetists in the NHS might have assumed clinical rsponsibilities that are no longer limited to the operating room. That is tacit acknowledgement that outcomes from anaesthesia need to be measured not only in terms of morbidity and 30-day mortality but also in terms of disability-adjusted-life-years and longevity. In which case should they not be held partly if not wholly responsible for the high mortality in cardiac surgry in Bristol? Anaesthesia, one of the miracles of modern medicine, has evolved by trial and error. Their medical memes (2)include maintaining an airway, arterial oxygenation, blood pressure and urine flow. Maintaining tissue perfusion (3)rather than tissue oxygenation (4) is the pathophysiological objective of their meme complexes. In cardiac surgery that meme complex has included, "perioperative plasma volume expansion with colloid..., guided by esophageal Doppler measurement of cardiac stroke volume" the efficacy of which was assessed with measrements of gastric intramucosal pH. In reality the pathophysiological objective of their meme complexes should have been to preserve tissue energetics, a completely different kettle of fish (5). The present study has shown that, "Patients with obstructive sleep apnoea are at high risk of developing complications when having surgery or other invasive interventions under general anaesthesia, whether or not the surgery is related to obstructive sleep apnoea"(6). This is but one of numerous risk factors, including sepsis and emergency surgery, in which adverse outcomes are more common than those associated with anaesthesia for elective procedures performed on otherwise healthy patients. In theoretical physics the validity of an equation, such as those derived by Einstein thoeries of special and general relativity or the string theorists, drived in the evolution of the elusive "theory of everything" is assessed from the accuracy of its predictions of increasingly extraneois physical phenomena such as COBE ripples and gravitational waves. The same should apply to anaesthesia. The validity of the memes and meme complexes that dictate their management should be assessed by their ability to avoid adverse outcomes in increasingly risky circumstances such as obsructive sleep apnoea and ruptured aneurysms. That adverse events still occur is, therefore, indicative of deficiencis in thier existing memes and meme complexes. This concluson assumes that all adverse events in elective and emergency surgery are potentially avoidable which I believe they are. The authors of the present study conclude, "Surgeons of all specialties, and especially anaesthetists, should be aware that undiagnosed obstructive sleep apnoea is common...They should be alert to patients who are at risk of having obstructive sleep apnoea and be aware of the potential preoperative and postoperative complications in such patients"(1). I submit that they miss the major point, the deficiencis lie not in the presence or absence of obstructive sleep apnoea per se but in mutated anaesthetic memes and meme complexes. What is needed to eliminate the risks of surgery in obstructive sleep apnoea and ruptured aneurysms is the erradication of the mutated memes and meme complexes rsponsible for the deficiencies and the evolution of new memes and meme complexes such as those I have considered elsewhere in addition to a earlier contribution to The British Journal of Anaesthesia (4). The continued complacency with the status quo is unacceptable for there are realistic opportunities for huge improvements in outcome in high risk patients in the short term. The major beneficiaries of any improvemtns are likely to be the increasingly small percentage of patients that continues to develop complications unpredictably and die after major elective surgery such as that for obstructive sleep apnoea and especially cardiovascular operations. In 1999 97,137 elective cardiac operations were performed in New York state alone with a mortality of 2.75% and 9847 elective aortic operations with a mortality of 5.5%(7). The magnitude of the problem is hidden in the small percentages. If this residual mortality were to be eliminated in al elective crdiovasculr operations hundreds of lives could be saved each year in New York state alone. The number of lives that could be saved in the whole or the US and espcialy the world is prportionately large. What of emergency operations? The number of lives that might be saved each year if perioperative risks were to be eliminated must be collossal. Surgeons and anaesthtists have a compelling reason to define and eliminate mutant medical memes and meme complexes dictating current perioperative management and replace them with more effective ones. 1. Cindy den Herder, Joachim Schmeck, Dick J K Appelboom, and Nico de Vries Risks of general anaesthesia in people with obstructive sleep apnoea BMJ, Oct 2004; 329: 955 - 959. 2. Defining existing medical memes, meme complexes, eradicating mutations and evolving new ones. Richard G Fiddian-Green (29 October 2004) eLetter re: John Gabbay and Andrée le May Evidence based guidelines or collectively constructed "mindlines?" Ethnographic study of knowledge management in primary care BMJ 2004; 329: 1013-0 3. Mythen MG, Webb AR. Perioperative plasma volume expansion reduces the incidence of gut mucosal hypoperfusion during cardiac surgery. Arch Surg. 1995 Apr;130(4):423-9. 4. Fiddian-Green RG. Gastric intramucosal pH, tissue oxygenation and acid-base balance. Br J Anaesth. 1995 May;74(5):591-606. 5. Defining existing medical memes, meme complexes, eradicating mutations and evolving new ones. Richard G Fiddian-Green (29 October 2004) eLetter re: John Gabbay and Andrée le May Evidence based guidelines or collectively constructed "mindlines?" Ethnographic study of knowledge management in primary care BMJ 2004; 329: 1013-0 6. Cindy den Herder, Joachim Schmeck, Dick J K Appelboom, and Nico de Vries Risks of general anaesthesia in people with obstructive sleep apnoea BMJ 2004; 329: 955-959 7. Josephine A. Sollano, MPH, Annetine C. Gelijns, PhD, Alan J. Moskowitz, MD, Daniel F. Heitjan, PhD, Suzanne Cullinane, BS, Ted Saha, BS, Jonathan M. Chen, MD, Patrick J. Roohan, MS, Keith Reemtsma, MD, Eileen P. Shields, BA Volume-Outcome Relationships In Cardiovascular Operations: New York State, 1990-1995 J Thorac Cardiovasc Surg 1999;117:419-430 Competing interests: None declared
A Misleading Title 16 November 2004
Andrew P Syndercombe, SpR Anaesthesia Wansbeck General Hospital NE63 9JJ, Ian Harper Send response to journal: Re: A Misleading Title	Editor – The review by den Herder et al is disappointing in several respects. The title misleads as it purports to discuss, in broad terms, the problems associated with the administration of general anaesthesia to patients with obstructive sleep apnoea syndrome (OSAS). The emphasis, however, lies with anaesthesia for surgical procedures directed at the treatment of this condition. Furthermore, we would seriously question some suggestions made relating to peri-operative management strategies, especially the use of sedative agents pre- and post-operatively. These may well be safe in a specialist unit dealing with many such patients on a regular basis, but may represent extreme danger to the majority of patients with OSAS and requiring general anaesthesia or sedation. The description of the difficult airway algorithm lacks clarity. In the discussion the use of the fibre-optic bronchoscope is dismissed in “acute emergencies” whereas the use of a rigid bronchoscope (beyond the capabilities of the vast majority of anaesthetists in this country) features as a potentially useful aid. The diagrammatic algorithm employed is over simplistic, and conforms neither with those of the American Society of Anaesthesiologists nor with that produced by the Difficult Airway Society. The patho-physiological consequences of OSAS are grossly neglected (there is no mention of pulmonary hypertension and right ventricular strain/hypertrophy/failure). An understanding or recognition of these features is central to appreciating the problems associated with surgery and anaesthesia in these patients. A review of this nature in the British Medical Journal should aim for the broadest possible appeal and should convey vital educational material. It should not be forgotten that many other clinicians in addition to anaesthetists employ potent sedative agents to achieve various “non- invasive” procedures, often in inappropriate settings (Scoping our practice – NCEPOD[1]). In this regard the review fails. 1. http://62.73.160.132/2004report/index.htm - NCEPOD Scoping Our Practice – The 2004 Report of the National Confidential Enquiry into Patient Outcome and Death. Abbreviations: NCEPOD - National Confidential Enquiry into Patient Outcome and Death Competing interests: None declared
Looking for a guideline 17 December 2004
Bradley A Stone, Anesthesiologist, Medical Director Asheville Surgery Center, 5 Medical Park Drive, Asheville, NC, 28803-2493, USA Send response to journal: Re: Looking for a guideline	I enjoyed the article, but find insufficient recommendations to construct a protocol for assessment and management of surgical patients at risk of sleep apnea. 1. How to initially screen patients for risk of having sleep apnea? This article suggests we look for symptoms such as heavy snoring, sudden awakening, observed apneas, and daytime sleepiness, and signs such as obesity and large neck circumference. Would one alone be sufficient to suggest further testing? 2. How to confirm and assess severity of sleep apnea? Polysomnography is the "gold standard" but is expensive and difficult to schedule without postponing most surgeries. The Epworth Sleepiness Scale lacks optimal sensitivity and specificity. Home testing devices (such as the Sleep Strip) look interesting if further studies demonstrate adequate sensitivity and specificity. 3. How to identify patients with sleep apnea at risk of postoperative respiratory complications? General anesthesia and postoperative opioids are suggested to increase postoperative risks. In what surgeries would use of regional anesthesia eliminate increased risk? 4. What level of postoperative operative monitoring is required? The article suggests intensive care, but is pulse oximetry with telemetry adequate? How long would more intensive monitoring be required? 5. Does use of nasal continuous airway pressure obviate the need for more than routine levels of postoperative monitoring? I look forward to more evidence and consensus opinions that generate guidelines for cost-effective and efficient screening and safe management of patients with sleep apnea undergoing surgery. Brad Stone MD Competing interests: None declared
Caution with sedatives in OSA patients 29 March 2005
Ian Forsyth, Consultant Anaesthetist Princess Margret Hospital Send response to journal: Re: Caution with sedatives in OSA patients	I read with interest a review article published in October 2004; “Risks of general anaesthesia in people with obstructive sleep apnoea “. The review makes the very valid point that OSA (obstructive sleep apnoea is commonly associated with obesity, difficulty in intubation, mask ventilation and maintaining an unobstructed airway post operatively. I am concerned about the article's seeming suggestion that a benzodiazipine premed should be considered, and further that the long acting sedative drug clonidine be used towards the end of anaesthesia for cardiovascular stability. It needs to be stressed that this is certainly not accepted ‘routine practise‘ in all hospitals . To be honest I would suggest that all sedative drugs should be minimised in these patients. I would argue that preparative cardiovascular stability would much more safely achieved using selective beta-blocker that does not have sedative properties. I would be interested in further comment from the anaesthetic community. Ian Forsyth Staff Anaesthetist Princess Margaret Hospital, Perth WA Competing interests: None declared