Pathophysiology of obesity. Impact on laparoscopy.

Obesity is a pandemic disease affecting a large group of the population and activating other diseases like diabetes, hypertension and even cancer. An obese patient is an challenge for anesthesia due to its different physiology. A better understanding of the pathophysiology is important for anesthesia as 1 on 4 of our patients today are suffering from obesity. This number is increasing every year even with the explosive demand for bariatric surgery. The simplest method to measure obesity is the body mass index (BMI = total body weight in kg divided by the quadrate of length in cm). A BMI between 25 and 30 means overweight, between 30 and 40 obese, between 40 and 50 morbid obese, between 50 and 60 super obese and above 60 super super obese. Physiologic changes are due to the weight effect like knee arthrosis, due to the volume effect, like the increased intra abdominal resting pressure, due to the increased organ size like the rise in metabolic activity, due to the increased cardiovascular perfusion needs like the higher cardiac output, due to the hormonal changes like the higher incidence of diabetes or due to the adaptation of organ functions like ventricular hypertrophy. Adipose tissue increases peripheral everywhere in the body or only central in the abdomen. The peripheral distribution is more frequent in woman (gynoid shape) while central abdominal fat is found more in man (android shape). The waist-tohip ratio (1). measures this peripheral versus central fat distribution. The co-occurrence of any three of the following abnormalities, dyslipidemia, elevated blood pressure, impaired glucose tolerance, and central (android) obesity is identified now as metabolic syndrome, also called syndrome X, insulin resistance syndrome or Reaven‘s syndrome. A report from the National Cholesterol Education Program – Adult Treatment Panel (NCEP–ATP III) identified metabolic syndrome as an independent risk factor for cardiovascular disease and considered it an indication for intensive treatment. Soon, metabolic syndrome will overtake cigarette smoking as the number one risk factor for heart disease (2). The metabolic syndrome is associated with a proinflammatory/prothrombotic state that may include elevated levels of C-reactive protein, endothelial dysfunction, hyperfibrinogenemia, increased platelet aggregation, increased levels of plasminogen activator inhibitor 1. The etiology of the metabolic syndrome has not been established definitively. One hypothesis presumes that the primary cause is insulin resistance and this correlates with visceral fat. The link between insulin resistance and cardiovascular disease probably is mediated by oxidative stress, which produces endothelial cell dysfunction, promoting vascular damage and atheroma formation. The second hypothesis blames hormonal changes for the development of abdominal (android) obesity, insulin resistance, and lipid abnormalities, linking psychosocial problems with acute myocardial infarction. The primary goal for the management of metabolic syndrome is to reduce the risk of cardiovascular disease and diabetes (3). Bariatric surgery today is the most successful treatment for metabolic syndrome The mortality and morbidity is now very low in experienced centers (4) and therefore the name of bariatric surgery has changed to metabolic surgery in treating the metabolic syndrome.