Obstructive sleep apnoea in patients undergoing cardiac surgery: Screening, postoperative outcomes and perioperative care

Abstract

Obstructive sleep apnoea (OSA) is common and high prevalence has been described amongst patients undergoing cardiac revascularisation surgery. An excess of postoperative complications has been reported in patients with untreated Obstructive Sleep Apnoea (OSA) following surgical procedures, including those undergoing cardiac surgery. This has led some clinicians towards pre-operative screening for OSA though the best screening methodology has not yet been established. Moreover, the effect of screening and of treatment for OSA on surgical outcomes remains unknown. Does current evidence justify screening and treating patients before they present for surgery? Is this leading to potential delay in surgery whilst awaiting sleep diagnostics and commencing the treatment? This review article will examine the available evidence base and endeavour to answer these questions and identify implications for future research. OSA and cardiovascular diseaseSleep Disordered Breathing is a term used to cover a range of breathing events encountered during sleep and includes obstructive sleep apnoea (OSA), central sleep apnoea, Cheyne-Stokes respiration and respiratory effort related arousals. OSA is the most common form of sleep disordered breathing. OSA is common 1 and the reported prevalence has increased in the last two decades 1 with the new data reported mainly in European population of adults 40-85 years old showing that at least mild OSA (apnoea-hypopnoea index ≥5) was present in 84% of men and 61% of women and at least moderate disease (apnoea-hypopnoea index ≥15) was present in 50% of men and 23 % of women 2 . OSA and cardiac disease share some common risk factors and in patients undergoing coronary artery bypass graft (CABG) procedures reported prevalence is high, ranging between 41 and 87% 3-5 .High proportions of patients may present for surgery without a previous diagnosis of OSA 6,7 and may be at risk of worse postoperative outcomes 8 . In patients with moderate to severe OSA syndrome Continuous Positive Airway Pressure (CPAP) is the conventional treatment with established clinical and cost effectiveness 9 but its effect on cardiovascular outcomes has not been confirmed. A recent, large, randomised controlled trial of adults with moderate to severe OSA and pre-existing cardiovascular disease showed that the use of CPAP had no significant effect on the prevention of recurrent serious cardiovascular events 10 . It is possible that patients with compliance exceeding 4h/night may