الفهرس 
General introduction to BMIOnly 14 pages are availabe for public view
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Abstract
The epidemic of obesity is already having major effects on population health. Obesity develops in an individual when energy intake exceeds energy expenditure over a long period. The biological processes regulating energy balance are very tightly regulated. However, these mechanisms of appetite control can easily be overwhelmed by a willingness to eat when not hungry if attractive food is provided in inductive settings. Control pathways include short-term signalling of hunger and satiety with hormones derived from the gastrointestinal tract to the central nervous system, long-term signalling of energy stores via leptin and insulin to the brain, and control of metabolism. Rare genetic syndromes that present in early childhood with severe obesity (such as leptin deficiency and mutations in the pro-opiomelanocortin gene) demonstrate that these pathways are biologically important in humans. Most obesity develops as a result of modern lifestyles in genetically susceptible individuals. These changes include increased consumption of high-energy food at the same time as physical activity levels have declined dramatically; in many societies less affluent people seem to be most at risk. Other causes of obesity that should be considered include drugs that increase appetite and structural damage to areas of the central nervous system involved in appetite control, such as the hypothalamus
Generally, recent data indicates a positive effect on outcome of obese compared to non obese patients presenting at the ICU
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irrespective of respiratory management in terms of thirty day and one year survival . When mechanical ventilation is required in obese patients, physiological differences in pulmonary function have to be taken into account.
Generally, large multi- centered studies on respiratory management of obese patients in the ICU are still needed . Concerning patient positioning, there is data supporting that a sitting posture or PP in patients with ARDS may reduce the pressure applied onto the chest by adipose tissue leading to an increase in compliance and FRC (functional residual capacity ) . Adjusting the body position may aid to avoid the need for high ventilatory pressures and thus, ventilator associated lung injury may be reduced. Another possible maneuver to increase pulmonary compliance and facilitate mechanical ventilation is a reduction or cessation of general anesthesia and early tracheotomy.
The association of obesity with sepsis mortality revealed mixed results. Three studies reported no significant association between obesity and mortality, 1 study observed increased mortality among obese patients with bacteremia whereas 3 studies found decreased mortality among obese patients. Clinicians are facedwith a number of challengeswhilemanaging obese patients with sepsis and should be mindful of the impact of obesity on antibiotics administration, fluid resuscitation, and ventilator management .
Also increasing BMI seems to be strongly associated with increased rates of HIT in intensive care unit patients
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The management of the morbidly obese critically ill patient is a challenging and formidable task. A better understanding of the pathophysiologic changes that occur with obesity and the complications unique to this group of patients may improve their outcome .