Anaesthetic considerations with the metabolic syndrome

The rising incidence of obesity has led to increased prevalence of a distinct, obesity-related metabolic syndrome. This syndrome is characterized by truncal obesity, insulin resistance, altered lipid levels, and hypertension. Definition of the metabolic syndrome rests on a set of clinical criteria instead of a single diagnostic test. It carries a different risk profile than obesity alone, and poses special challenges for the anaesthesiologist. These include preoperative risk stratification for common comorbidities, identifying reasonable thresholds for implementing preoperative risk reduction, overcoming obesity-related issues in intraoperative management, and delivering safe postoperative care. The metabolic syndrome predisposes to coronary artery disease, congestive heart failure, obstructive sleep apnoea, pulmonary dysfunction, and deep venous thrombosis. Because its different presentations can have different risk profiles, anaesthesiologists should assess the cumulative risk of each component of the metabolic syndrome separately, which significantly complicates preoperative management. Since obesity itself is difficult to treat, preoperative risk reduction can be difficult. Few data exist to inform best practice as to the anaesthetic care of patients with metabolic syndrome. This review evaluates and synthesizes current evidence regarding perioperative care for patients with the metabolic syndrome, including indications for preoperative testing; use of aspirin, beta-blockers, statins, heparin, and angiotensin-converting enzyme inhibitors; anaesthetic strategies including regional anaesthesia; and postoperative management including continuous positive pressure ventilation by mask, prevention of pulmonary embolism, and indications for advanced respiratory monitoring.