Obstructive sleep apnoea – debunking the myths : THE RECOVERY ROOM AND BEYOND
I Banks
Royal Adelaide Hospital, Adelaide SA
There is little evidence to guide safe practice when caring for patients with obstructive sleep apnoea (OSA) post-operatively. In most cases, the studies simply have not been done. Further compounding the confusion is the fact that there are probably many patients who have undiagnosed OSA, but have an uneventful post-operative recovery.
The “myths” that need to be addressed are:
- Opioid analgesia is not safe in OSA patients
- OSA patients need high dependency (HDU) care post-operatively
- Only the first post-operative night is a problem
- Oxygen supplementation is dangerous in OSA patients
Opioid therapy
To say that opioids should be avoided in post-operative analgesia is too simplistic: there may be no alternative. There have been a number of case reports of post-operative fatalities that have been attributed to the use of opioids, via the intramuscular, PCA or epidural route [1,2,3]. However, these cases involved the use of background infusions of opioids, the co-administration of other sedative agents, and the lack of oxygen saturation monitoring. Macintyre [4] has pointed out that sedation for patients using PCA is slow in onset, and precedes respiratory depression, so that if sedation scoring is used, the safety of opioid use is much enhanced, even in patients with OSA. Opioid analgesia, when properly monitored, is acceptable.
There have been no studies done to establish whether there is any difference in the safety profiles of the different opioid drugs.
High dependency care
HDU care, other than that provided in the Recovery Room, is not always readily available because of pressure on bed occupancy. Is HDU care necessary for all OSA patients post-operatively? A study on OSA patients having upper airway surgery [5] concluded that any significant complications occurred in the first two hours post-operatively, i.e. in Recovery, and therefore gave a guide as to which patients needed more intensive post-operative care. Helfaer [6] and colleagues noted that children with mild OSA, with no craniofacial abnormalities, who underwent adenotonsillectomy had improved polysomnography on the night of surgery. However, as Benumof [7] notes, there are patients who clearly need HDU care, those who clearly do not, and “a large grey area in between the two extremes”. He suggests that the factors that needed to be assessed included: the body mass index of the patient; the severity of the OSA; the degree of associated cardiopulmonary disease and the post-operative opioid requirement. The type of the surgical procedure also needs to be taken into account. Hillman et al. [8] noted how the supine position exacerbates airway obstruction. As some patients (e.g. total hip arthroplasty patients) need to nursed in this position, this too needs to be considered in the decision to admit to a high dependency area.
Tung and Rock [9], in their review, raised concerns about REM-rebound, when there is a decrease in the amount of REM sleep in the first two post-operative nights, but a dramatic increase in REM sleep on the third night. The degree of REM-rebound seems to be related to the type of surgery. As airway obstruction is more pronounced in REM sleep, this rebound may leave the patient more prone to airway obstruction. This too is unproven, but raises the issue whether more prolonged intensive monitoring is indicated in some patients.
Oxygen supplementation
There are many reasons why patients need additional oxygen post-operatively. People have expressed concerns that the additional oxygen will prolong apnoeic spells, and worsen hypercapnia. Although oxygen therapy does not prevent obstructive episodes, it will help reduce the hypoxaemia associated with obstruction, as well as the hypoxaemia associated with anaesthesia, analgesia and surgery. However, the outcome benefit of supplemental oxygen has not been formally established [9]. For those OSA patients with chronic hypercapnia, such as those with COPD need special attention.
Time of Presentation
Saturday 13 May 2006 - 1530-1700
References
1. Sleep apnea and narcotic postoperative pain medication: a morbidity and mortality risk. A.Lofsky, www.apsf.org/resource_center/newsletter/2002/summer/04sleepapnea.htm
2. Respiratory depression associated with patient-controlled analgesia; a review of eight cases. Etches RC: Can J Anaesth; 1994, 41:2, 125-32
3. Three sudden postoperative respiratory arrests associated with epidural opioids in patients with sleep apnea; Ostermeier AM, Roizen MF, Hautkappe M, Klock, PA, Klafta JM. Anesth Analg: 1997; 85: 452-60
4. Intravenous patient-controlled analgesia: one size does not fit all. Macintyre PE. Anesthesiology Clin N Am: 23 (2005) 109-123
5. Conservation of resources; indications for intensive care monitoring after upper airway surgery on patients with obstructive sleep apnea. Terris DJ, Fincher EF, Hanasono MM, Fee WE, Adachi K. Laryngoscope: 108(6); June 1998, 784-788
6. Polysomnography after adenotonsillectomy in mild pediatric obstructive sleep apnea. Helfaer MA, McColley SA, Pyzik PL, Tunkel DE, Nichols DG, Baroody FM, April MM, Maxwell LG, Loughlin G. Crit Care Medicine. 24(8), August 1996, 1323-1327
7. Obstructive sleep apnea in the adult obese patient: implications for airway management. Benumof JL. Journal of Clinical Anesthesia: 2001:13, 144-156
8. Obstructive sleep apnoea and anaesthesia. Hillman DR, Loadsman JA, Platt PR, Eastwood PR. Sleep Med Rev: Dec 2004; 8(6); 459-71
9. Perioperative concerns in sleep apnea. Tung A, Rock P. Current Opinion in Anaesthesiology. 2001, 14; 671-67
