Study inclusion/exclusion criteria. *Exclusion counts nonmutually exclusive, e.g., cases may have multiple exclusion criteria. ARDS = acute respiratory distress syndrome; ASA = American Society of Anesthesiologists; COPD = chronic obstructive pulmonary disease; ETT = endotracheal tube; MET = metabolic equivalent; OSA = obstructive sleep apnea; PPV = pulse pressure variation; SPV = systolic pressure variation.