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morphine and tramadol or non‐opioid analgesics. A small study in children undergoing
adenotonsillectomy for OSA showed a trend to fewer episodes of postoperative desaturation
in children given tramadol compared with morphine, but the difference was only significant
for the second hour after surgery (Hullett et al, 2006 Level II). In patients with a body mass index
of 28 or more and with signs or symptoms suggestive of OSA, there was no difference in the
numbers of respiratory events (obstructive apnoeas, hypopnoeas or central apnoeas) in
patients receiving IV morphine PCA and those receiving an ‘opioid‐sparing’ analgesic regimen
(IV tramadol PCA, parecoxib and ‘rescue‐only’ morphine; however there was a correlation
between more than 15 respiratory events/ hour and total morphine dose (Blake et al, 2009
Level II).
Expert opinion, however, consistently suggests that non‐opioid analgesics and regional
techniques should be considered, either as an alternative to opioids or to help limit the
amount of opioid required (Benumof, 2001; Loadsman & Hillman, 2001; Gross et al, 2006; Chung,
Yuan et al, 2008).
Morbid obesity is strongly associated with OSA (Young et al, 2004) and, using polysomnography,
OSA was identified in 71% of patients presenting for bariatric surgery (Frey & Pilcher, 2003
Level IV). The use of PCA with appropriate bolus doses and monitoring in morbidly obese
patients has been reported to be no less safe than regional or other systemic opioid analgesic
techniques, although the studies lacked power (Kyzer et al, 1995 Level II; Choi et al, 2000 Level IV;
Charghi et al, 2003 Level IV). In a comparison of morbidly obese patients, each of whom had a
preoperative sleep study, with (n = 31) and without (n = 9) OSA undergoing laparoscopic
bariatric surgery, episodes of postoperative hypoxaemia were frequent despite supplemental
oxygen; there was no significant difference between OSA and non‐OSA patients (Ahmad et al,
2008 Level III‐2).
While oxygen therapy alone may not prevent the disruptions of sleep pattern or symptoms
such as daytime somnolence and altered mental function that may occur in patients with OSA,
it can reduce the likelihood of significant hypoxaemia (Phillips et al, 1990; Landsberg et al, 2001).
As patients with OSA are more at risk of hypoxaemia after surgery or if given opioids, the use
of supplemental oxygen would seem appropriate (Gross et al, 2006) despite concerns about
reducing respiratory drive during the apnoeic periods (Lofsky, 2002).
The use of continuous positive airway pressure (CPAP) may help to reduce the postoperative
risks and is recommended in patients with OSA (Benumof, 2001; Loadsman & Hillman, 2001). The
effectiveness of CPAP (used appropriately) in the prevention of OSA in the postoperative
setting is supported by case reports (Reeder et al, 1991; Rennotte et al, 1995; Mehta et al, 2000).
Concerns about the risk of CPAP causing gastric distension and anastomotic leaks after upper
GI surgery appear to be unfounded (Huerta et al, 2002 Level III‐2).
The effective use of CPAP in the setting of acute pain management may require a higher level CHAPTER 11
of supervision than that available in the general surgical ward; most reports of the successful
use of postoperative CPAP utilise extended periods of high‐dependency nursing (Reeder et al,
1991; Rennotte et al, 1995; Mehta et al, 2000).
Advice on the most appropriate environment for the care of OSA patients requiring analgesia
is based on expert opinion only and suggests that the severity of OSA, efficacy of any current
therapy, relevant comorbidities (eg cardiac) and the analgesia required be taken into
consideration (Benumof, 2001; Loadsman & Hillman, 2001; Gross et al, 2006).

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