Predictive value of sleep apnea screenings in cardiac surgery patients.

INTRODUCTION: Obstructive sleep apnea (OSA) is a highly prevalent disorder associated with increased cardiovascular risks. We explored the predictive value of OSA screening instruments in cardiac disease patients awaiting cardiac surgery. METHODS: In this prospective cohort, 107 participants awaiting cardiac surgery from Cleveland Clinic and Johns Hopkins underwent polysomnography after completing Epworth Sleepiness Scale (ESS), Sleep Apnea/Sleep Disorder Questionnaire (SA/SDQ), STOP, STOPBAG2 and Berlin questionnaires. Score comparisons between groups based on apnea-hypopnea index (AHI) ≥15 were performed. Logistic regression with receiver operating characteristic (ROC) analysis was used to investigate optimal threshold. RESULTS: Prevalence of OSA (AHI ≥5) was 71.9% (77/107) and 51 (47.7%) had moderate-to-severe disease (AHI ≥15). Participants were primarily male (57%) and Caucasian (76.6%). Mean age was 67.3 ± 13.3 years and BMI was 26.5 ± 6.6. Of the five screening tools, STOPBAG2 with a cut-point of 0.381 provided 78% sensitivity and 38% specificity (AUC 0.66, 95%CI 0.55-0.77). SA/SDQ yielded a cut-point of 32 for all subjects (AUC: 0.62, 95%CI 0.51-0.73) with sensitivity and specificity of 60% and 62% respectively, while STOP score ≥2 provided sensitivity and specificity of 67% and 52% respectively (AUC: 0.61, 95%CI 0.51-0.72). Among STOP items, "observed apnea" had the strongest correlation with AHI ≥15 (OR 3.67, 95%CI 1.57-8.54, p = 0.003). The ESS and Berlin were not useful in identifying moderate-to-severe OSA. CONCLUSION: Common screening tools had suboptimal performance in cardiac surgery patients. STOPBAG2 was better at predicting the probability of moderate-to-severe OSA in patients undergoing cardiac surgery compared to ESS, SA/SDQ, STOP and Berlin questionnaires.

Meta-analysis of the association between obstructive sleep apnoea and postoperative outcome.

BACKGROUND: Obstructive sleep apnoea (OSA) is often undiagnosed before elective surgery and may predispose patients to perioperative complications. METHODS: A literature search of PubMed-Medline, Web of Science, Scopus, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials up to November 2010 was conducted. Our search was restricted to cohort or case-control studies in adults diagnosed with OSA by screening questionnaire, oximetry, or polysomnography. Studies without controls, involving upper airway surgery, and with OSA diagnosed by ICD-9 codes alone were excluded. The primary postoperative outcomes were desaturation, acute respiratory failure (ARF), reintubation, myocardial infarction/ischaemia, arrhythmias, cardiac arrest, intensive care unit (ICU) transfer, and length of stay. RESULTS: Thirteen studies were included in the final analysis (n=3942). OSA was associated with significantly higher odds of any postoperative cardiac events [45/1195 (3.76%) vs 24/1420 (1.69%); odds ratio (OR) 2.07; 95% confidence interval (CI) 1.23-3.50, P=0.007] and ARF [33/1680 (1.96%) vs 24/3421 (0.70%); OR 2.43, 95% CI 1.34-4.39, P=0.003]. Effects were not heterogeneous for these outcomes (I(2)=0-15%, P>0.3). OSA was also significantly associated with higher odds of desaturation [189/1764 (10.71%) vs 105/1881 (5.58%); OR 2.27, 95% CI 1.20-4.26, P=0.01] and ICU transfer [105/2062 (5.09%) vs 58/3681 (1.57%), respectively; OR 2.81, 95% CI 1.46-5.43, P=0.002]. Both outcomes showed a significant degree of heterogeneity of the effect among studies (I(2)=57-68%, P<0.02). Subgroup analyses had similar conclusions as main analyses. CONCLUSIONS: The incidence of postoperative desaturation, respiratory failure, postoperative cardiac events, and ICU transfers was higher in patients with OSA.

Incremental risk of obstructive sleep apnea on cardiac surgical outcomes.

AIM: Obstructive sleep apnea (OSA) is not generally acknowledged as a perioperative risk factor. High incidence of Sleep disordered breathing has been noticed in patients with cardiovascular disease. The Sleep Heart Health Research Study Group found Apnea-Hypopnea indices (AHI) as modest as 1-10 to be associated with cardiovascular disease manifestations. Given the lack of data we chose to study the incremental risk of OSA in patients undergoing cardiac surgery. METHODS: We looked at 25 587 patients who underwent cardiac surgery at the Cleveland Clinic. Of these, 37 patients were also identified on the Cleveland Clinic Sleep center database as having OSA. Each of these 37 cases were propensity matched for multiple covariates with 5 controls within a distance of 0.001 units. An assumption was made that if the surgery was performed within two years of the diagnosis of OSA, the patient had OSA at the time of the surgery. RESULTS: Higher incidence of encephalopathy (p=0.008), postoperative infection (0.028) and increased ICU length of stay (p=0.031) were noted in the group with OSA after cardiac surgery. The difference in the rates of infection was mostly accounted for by the presence of mediastinitis (8.1% vs 1.6%). Differences in the rates of reintubation, tube time, and overall postoperative morbidity were not statistically significant. CONCLUSIONS: | Increased risk for postoperative complications is suggested in patients with OSA undergoing cardiac surgery. This risk is underestimated on account of lack of awareness about the incidence of OSA in the general population and the cardiovascular population in particular, difficulties in clinical suspicion and diagnosis and limited use of polysomnography.