Safe and successful treatment of the morbidly obese patient requires a level of organizational commitment, protocols, expertise and staff training. Patients with morbid obesity should be identified by the surgeons and referred to the anesthetists at an earlier stage for pre-operative assessment. Morbidly obese patients have a greater risk of pulmonary hypertension due to obstructive sleep apnea and CO2 retention. Obesity is strongly correlated with obstructive sleep apnea syndrome (OSA). Large double lumen tubes (DLT) is used to minimize airway resistance in morbidly obese patients undergoing one-lung ventilation (OLV). Direct airway measurement is an accurate way of selecting a DLT rather than tube selection based solely on patient gender, height and weight. Morbidly obese patients have a higher proportion of adipose tissue and lower proportions of tissue water and lean body mass. These can cause differing patterns of drug distributions.