Incidence, Predictors, and Outcome of Difficult Mask Ventilation Combined With Difficult Laryngoscopy

Abstract

C ontinuous positive airway pressure (CPAP) is the most widely used treatment for obstructive sleep apnea (OSA), which is common in patients undergoing surgery. Obstructive sleep apnea is a comorbid condition associated with hypertension, stroke, cardiovascular disease, heart failure, and arrhythmias. Recent studies have reported conflicting findings on the effectiveness of titrated CPAP for treatment of OSA. This review looks at the effect of CPAP in patients with OSA undergoing surgery in terms of reducing the length of stay (LOS), risk of postoperative adverse events, and perioperative apnea-hypopnea index (AHI).A search of PubMed-MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Health Technology Assessment was used to find studies including adult surgical patients, using either preoperative and/or postoperative CPAP or no-CPAP, with available information on OSA and available information on postoperative adverse events as well as AHI and LOS. To analyze the occurrence of perioperative adverse events in patients receiving CPAP compared with those who did not, risk reduction was calculated. The number of patients needed to be treated to benefit was calculated.Six studies, with information on 904 patients, were included in the meta-analysis. Those included 3 observational studies, 2 randomized controlled trials, and 1 case series. In 4 of the studies, CPAP was used preoperatively and postoperatively, whereas 1 used CPAP only preoperatively; 1 used CPAP only postoperatively. Of the 904 patients, 471 received CPAP, and 433 did not. The CPAP group saw 134 postoperative adverse events, and the no-CPAP group saw 133 (P = 0.19), and the difference was not statistically significant. Risk reduction was calculated as 12%, whereas the risk ratio was 0.88 (95% confidence interval, 0.73-1.06; P = 0.19). The number of patients needed to be treated to benefit was 45. Two studies reported on AHI, with 100 patients receiving preoperative CPAP and 51 patients continuing CPAP postoperatively. With postoperative CPAP, the preoperative AHI baseline without CPAP was reduced substantially (mean preoperative ± SD AHI vs postoperative AHI, 37 ± 19 vs 12 ± 16 events per hour; P < 0.001). Five of 6 studies reported LOS, with 278 patients in the CPAP group and 300 in the no-CPAP group.A LOS trend toward statistical significance was shown for the CPAP group compared with the no-CPAP group (4.0 ± 4.0 vs 4.4 ± 8.2 days; mean difference, −0.79; 95% confidence interval, −1.59 to 0.01; asymptotic P = 0.05).The authors concluded that although CPAP can reduce postoperative AHI, and the meta-analysis showed a trend toward shorter hospital stay, there was no difference in the occurrence of adverse events between CPAP and no-CPAP patients. This may be owing to low compliance in the preoperative and postoperative periods. COMMENTAlthough the prevalence of OSA in the general population is said to range from 9% to 25%, the prevalence is considerably higher in the surgical population. Indeed, i...