Anesthesia for bariatric surgery.

Obesity has become one of the most important public health problems confronting industrialized nations. In 1997 the prevalence of obesity in Europe was 15%-20%. The situation in the USA was even worse. The concept of ideal body weight (IBW) originates from life insurance studies which describe the weight associated with the lowest mortality rate for a given height and gender. IBW can be estimated from the formula IBW (kg) = height (cm) – x, where x is 100 for adult males and 105 for adult females. Obesity can be defined as more than 20% above IBW and morbid obesity as more than twice IBW. The body mass index (BMI) is a more robust measure of the relationship between height and weight and is widely used in clinical and epidemiological studies : BMI = body weight (kg)/height (m). A BMI < 25 kg/m is considered normal, a person with a BMI of 25-30 kg/m is considered overweight but at low risk of serious medical complications while those with a BMI > 30, > 35 and > 55 kg/m are considered obese, morbidly obese and super-morbidly obese respectively. Morbidity and mortality rise sharply when the BMI is > 30 kg/m. Obesity is associated with many chronic health problems such as cardiovascular disease, diabetes mellitus, arthritis and cancer. Given recent reports that bariatric surgery offers sustained reductions in body weight, it is certain that anesthesiologists are going to care for an increasing number of obese patients in the foreseeable future. These patients may present a considerable challenge because of the pathophysiology and complications associated with obesity. Bariatric operations can be broadly categorized by their mechanism of either restricting food intake or inducing maldigestion/malabsorption. The most frequently performed procedures are the laparoscopic adjustable gastric band and the Rouxen-y gastric bypass. The laparoscopic adjustable gastric band (LAGB) consists of two components, a silicone band with an inner inflatable cuff and a reservoir connected by tubing. The band is placed around the gastric cardia to create a small proximal gastric pouch with an adjustable restrictive outlet that limits the amount of food that can be consumed. Advantages of this technique are the very low operative morbidity and mortality. Disadvantages are its apparent inferior outcomes regarding weight loss and the substantial intermediate and long-term complications with reports of band slippage, gastric perforation, band erosion and malfunction requiring reoperation in up to 20% of patients. (Acta Anaesth. Belg., 2006, 57, 387-393)