Why is the morbidly obese patient at high risk of anesthetic complications?

Obesity is often associated with obstructive sleep apnea (OSA), which increases the risk of intraoperative and postoperative complications. The role of preoperative screening of OSA is crucial, with adequate management based on continuous positive pressure before, during and after surgery. The obese patient is at risk of postoperative complications: difficult airway management, acute respiratory failure following extubation due to atelectasis and airway obstruction, added to morphine overdosing. Optimal management of difficult mask ventilation and intubation, protective ventilation, combined to the reduction of sedatives and analgesics and the sitting position as soon as possible with a postoperative monitoring should decrease the occurrence of complications. Cardiovascular risk is also increased in the obese patient. Preoperative screening of cardiovascular complications with appropriate therapy, combined to per- and postoperative hemodynamic optimization with a close monitoring allow to limit the cardiovascular risk. Drug dosing titration is fundamental due to unknown pharmacokinetic and pharmacodynamics properties in obese patients. Neuromuscular monitoring should always be used whenever neuromuscular blocking drugs are used, as depth of anaesthesia monitoring, especially when total intravenous anaesthesia is used in conjunction with neuromuscular blocking drugs. Appropriate prophylaxis against venous thromboembolism (VTE) after assessment of risk benefit ratio and early mobilisation are recommended since the incidence of venous thromboembolism is increased in the obese.