Obésité en réanimation, définition, épidémiologie, pronostic

An excess of body fat defines obesity. The body mass index (BMI), that is calculated by dividing the weight by the size squared, is currently the most accepted index of obesity and is widely used in clinical and epidemiological studies. The recent increase in obesity prevalence in the general population is accompanied by an increase in the prevalence of obesity among patients admitted to intensive care units (ICU). However, the potential influence of obesity on ICU mortality of these obese patients remains discussed although it has been investigated in several studies. The prospective or retrospective character of these studies, the selected population, the collection methods weight and size vary considerably and may partly explain the apparently contradictory character of the results. Among the studies, which found an increase in mortality in overweight patients, a higher rate of sepsis, nosocomial pneumoniae, ARDS, catheter infections, and heart failure may contribute to a worsened prognosis. On the opposite, other studies conclude that obesity could also contribute to improve ICU outcome: a higher blood level of certain adipokines and of HDL cholesterol in obese patients could indeed explain this. Finally, it is possible that the increase in morbidity due to obesity could be partially counterbalanced by the protective effect of several endogenous factors. Without any doubt future studies will have to be prospective and will need to take into account these biological parameters if one is to explore the reality of the “obesity paradox”.