Small hemodynamic effect of typical rapid volume infusions in critically ill patients

Objectives: To determine what volumes are commonly used for rapid volume infusions in critically ill patients admitted to the intensive care unit (ICU) for >12 hrs; and to determine the effective ness of a typical rapid volume infusion in producing hemodynamic change and increasing left ventricular end-diastolic volume. Design: A prospective survey of clinical practice (part I)and a prospective clinical investigation (part 2). Setting: Two hospital ICUs (11 and six beds) of which one is university affiliated. Patients: Critically ill patients admitted to the ICU for >12 hrs. Interventions: Infusion of 500 mL of normal saline over 5 to 10 mins. Measurements and Main Results: For 1 month, we recorded the volume and composition of all volume infusions given as a rapid bolus in patients admitted to the ICU for >12 hrs. We then measured the effect of the median rapid volume infusion in a subset of 13 patients by measuring hemodynamics (using arterial and pulmonary artery flotation catheters) and left ventricular end-diastolic area (using transgastric short-axis views from transesophageal echocardiograms). During 470 patient days, 159 rapid volume infusions were administered. The average rapid volume infusion administered was 390 +/- 160 mL (median 500; interquartile range 250 to 500). Crystalloid solutions were used for two thirds of the rapid volume infusions and colloid solutions were used for one third of the rapid volume infusions. The rapid volume infusion of 500 mt of saline did not significantly increase mean arterial pressure (78.0 +/- 11.9 to 79.3 +/- 14.6 mm Hg), cardiac index (4.3 +/- 1.7 to 4.6 +/- 1.8 L/min/m(2)), right atrial pressure (11.1 +/- 3.8 to 12.4 +/- 3.3 mm Hg), left ventricular end diastolic area (8.6 +/- 1.7 to 9.1 +/- 1.8 cm(2)/m(2)), or left ventricular end-systolic area (3.5 +/- 1.5 to 3.6 +/- 1.5 cm(2)/m(2)). Pulmonary artery occlusion pressure increased slightly but significantly from 12.9 +/- 3.4 to 14.7 +/- 3.3 mm Hg (p < .05). Conclusions: After patients are admitted to the ICU for >12 hrs, rapid volume infusions are common therapeutic interventions but the rapid volume infusions are typically small. The effect of a typical rapid volume infusion on hemodynamics and left ventricular areas in these patients is surprisingly small.