For a study, researchers sought to assess how fluid bolus delivery affected the incidence of severe hypotension, cardiac arrest, and mortality.

Between February 1, 2019, and May 24, 2021, 1,067 critically sick patients had tracheal intubation with sedation and positive pressure ventilation at 11 intensive care units in the United States. The last follow-up was scheduled for June 21, 2021. Patients were randomized at random to receive a 500-mL intravenous fluid bolus (n=538) or no fluid bolus (n=527). The primary outcome was cardiovascular collapse (defined as new or increased vasopressor administration or systolic blood pressure of <65 mm Hg between anesthesia induction and 2 minutes after tracheal intubation, or cardiac arrest or death between anesthesia induction and 1 hour after tracheal intubation). The incidence of mortality before day 28, which was censored at hospital release, was the secondary outcome.

In the study, 1,065 (99.8%) of the 1,067 participants randomized completed the experiment and were included in the main analysis (median age, 62 years [IQR, 51-70 years]; 42.1% were women). The cardiovascular collapse occurred in 113 (21.0%) of the fluid bolus group and 96 (18.2%) of the no fluid bolus group (absolute difference, 2.8% [95% CI, -2.2% to 7.7%]; P=.25). Vasopressors were given to 20.6% of patients in the fluid bolus group compared to 17.6% of patients in the no fluid bolus group, systolic blood pressure was less than 65 mm Hg in 3.9% vs. 4.2%, cardiac arrest occurred in 1.7% vs. 1.5%, and death occurred in 0.7% vs. 0.6%. Death occurred prior to day 28 occurred in 218 patients (40.5%) in the fluid bolus group against 223 patients (42.3%) in the no fluid bolus group (absolute difference, -1.8% [95% CI, -7.9% to 4.3%]; P=.55).

Administration of an intravenous fluid bolus vs. no fluid bolus did not substantially reduce the incidence of cardiovascular collapse among critically sick patients undergoing tracheal intubation.