Figure 2. Effect of Fluid Bolus Administration on Cardiovascular Collapse.

^aScores on the Acute Physiology and Chronic Health Evaluation (APACHE) II can range from 0 to 71; higher scores indicate a greater severity of illness.²⁰ Patients were dichotomized at the median APACHE II score of the cohort, which was 19.

^bRefers to patients who received vasopressors or inotropes within the hour prior to enrollment.

^cPredicted probability of cardiovascular collapse²¹ was calculated from age, systolic blood pressure at induction of anesthesia, APACHE II score, use of vasopressors, presence of cirrhosis, oxygen saturation at induction of anesthesia, presence or absence of a procedural indication for tracheal intubation, the anesthetic agent used, the neuromuscular blocking agent used, indication for tracheal intubation, presence of chronic kidney disease, and sex (additional details appear in eFigure 6 in Supplement 2).