ABSTRACT
Obesity is classified according to body mass index. Obesity affects every body system and is a contributory factor to many other diseases. It can cause particular difficulties for the anaesthetist. Obese patients have an increased basal metabolic rate, which when combined with a lower functional residual capacity means that their oxygen saturations drop very quickly. Obstructive sleep apnoea (OSA) is common in obese patients and relatively underdiagnosed. Careful preoperative enquiry is important, as patients with OSA are often very sensitive to opiates and they should be administered with caution. Routine preoperative assessment with particular attention to: airway assessment, symptoms of OSA, gastrointestinal reflux, concomitant disease, exercise tolerance and ensure adequate thromboprophylaxis. As higher airway pressures are often required during positive pressure ventilation it is sometimes difficult to have adequate seal around the laryngeal mask for the effective ventilation.
