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  • Body mass index (BMI) is easy to measure, but should be considered a rough guide because it may not correspond to the same degree of obesity in different individuals.

  • High levels of BMI are related to several noncommunicable diseases, such as respiratory and cardiovascular diseases, musculoskeletal disorders, and even some types of cancers.

  • BMI trends in children and adolescents are of particular concern for the prediction of how the burden of obesity might affect the population in the near future.

  • One well-known effect of obesity is the reduction in lung volumes that results from increased abdominal volume, total intrathoracic fat, and, when present, chronic heart disease leading to cardiac enlargement.

  • Both ventilation and perfusion are altered in obese patients. Functional residual capacity is reduced; due to low expiratory reserve volume, ventilation is preferentially distributed to the poorly perfused upper lung zones.

  • The association between obesity and hypertension, diabetes mellitus, dyslipidemias, and the obstructive sleep apnea syndrome has also been shown to increase the incidence of cardiovascular disorders.

  • Eccentric left ventricular hypertrophy is commonly observed in obese patients (BMI >40 kg/m2) and is usually associated with left ventricular dysfunction.

  • During obesity, adipose cells can accumulate in peripheral skeletal muscles, reducing their function and possibly changing their metabolic pattern.

  • Allied to increased neural drive, the anatomical radius of maximum curvature of the diaphragm is altered in obesity, changing proportionally with BMI.

  • Acute changes in the adipose tissue microenvironment, such as alterations in oxygen supply and consumption, redox imbalance, and neutrophil recruitment into adipose tissue, lead to adipocyte hypertrophy and hyperplasia. This is associated with a shift in adipokine production from adiponectin to leptin, as well as resistin, visfatin, tumor necrosis factor-α, among others.

  • Although obesity and overweight are associated with an increased risk of death in the general population, in certain specific disease conditions a decrease in mortality has been reported, including septic shock and the acute respiratory distress syndrome (ARDS); this is referred to as the obesity paradox.

  • Obesity increases the risk of mortality and intensive care unit admission in people infected with the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2).

  • The obesity paradox observed prior to the COVID-19 pandemic does not protect obese patients with SARS-CoV-2 during intensive care unit stay, possibly due to the pathological mechanisms of COVID-19.

  • In obese patients with healthy lungs, the optimal tidal volume is within the range of 6 to 8 mL/kg of predicted body weight.

  • No major differences in postoperative pulmonary complications have been shown when comparing positive end-expiratory pressure (PEEP) = 12 cmH2O with alveolar recruitment maneuvers versus PEEP = 4 cmH2O.

  • Recruitment maneuvers done by Ambu-bag inflation are associated with postoperative pulmonary complications in obese patients undergoing elective surgeries.

  • Tidal volume within the range of 4 to 6 mL/kg of predicted body weight is protective in obese patients with ARDS.

  • For obese patients with ARDS who exhibit severe reduction of resting lung volumes, ...

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