The availability of circulating blood volume values alters fluid management in critically ill surgical patients.

BACKGROUND: This study evaluated whether commercially available blood volume measurements in critically ill surgical patients altered fluid management. METHODS: Patients admitted to the surgical intensive care unit of a tertiary care teaching hospital were prospectively evaluated. The frequency of changes in fluid management when results of blood volume measurements were available was determined. RESULTS: In a pilot study, the frequency of instances when measurement of blood volume would have altered fluid management was statistically significant (P = .0003). In 40 subsequent patients, treatment change occurred in 36% of instances when blood volume results were obtained (P < .001). In the majority, no immediate qualitative change in clinical status occurred, with a desirable clinical response in 39% and no negative treatment responses (P < .001). CONCLUSIONS: Blood volume measurements may assist in the management of critically ill surgical patients by providing a direct measure of intravascular volume. Further studies are warranted to determine its effect on outcome.

Circulating blood volume measurements correlate poorly with pulmonary artery catheter measurements.

BACKGROUND: Determination of the intravascular volume status of a critically ill surgical patient is paramount for appropriate fluid and cardiovascular management. Many clinical parameters have been utilized to estimate intravascular volume but none are precise indicators of circulating blood volume. The purpose of this observational pilot study was to compare measured blood volume with hemodynamic parameters obtained from the pulmonary artery catheter and to determine if incorporation of these measurements altered treatment decisions in critically ill surgical patients. METHODS: Blood volume measurements were prospectively obtained in twenty surgical intensive care unit patients with a pulmonary artery catheter when intravascular volume status was deemed uncertain by traditional clinical parameters. RESULTS: There was a statistically significant, but weak, correlation between blood volume results and pulmonary artery occlusion pressure, but no correlation with central venous pressure, cardiac index, and stroke volume index. Blood volume information altered treatment in 21% of instances, and 5 of these 6 patients demonstrated a favorable clinical response. CONCLUSIONS: Circulating blood volume measurements may be useful in critically ill surgical patients when clinical appraisal of intravascular volume is uncertain. This remains to be validated in a larger, prospective randomized trial.