Obesity and survival in critically ill patients with acute respiratory distress syndrome: a paradox within the paradox

Excerpt

The incidence of obesity is steadily increasing, and its prevalence, defined as a body mass index (BMI) above 30 kg/m², is 13% in the world adult population, and rises to up to 40% in high-income countries [1]. As a consequence, around 20% of the patients admitted to the intensive care unit (ICU) are obese [2]. Obesity and overweight are associated with an increased risk of death in the general population [3], but in specific disease conditions a decrease in mortality has been reported: this is the case of patients with septic shock [4] and acute respiratory distress syndrome (ARDS), and is referred to as the obesity paradox. The association between higher BMI and lower mortality is difficult to interpret and potentially influenced by several confounding factors. In patients with ARDS, this paradox is particularly surprising, as obese patients have peculiar alterations of the respiratory function, such as increased chest wall elastance and lower total respiratory system compliance, posing specific challenges for the clinician when mechanical ventilation is required [5, 6]. …