Fractional change in blood volume following normal saline infusion in high-risk patients before noncardiac surgery

Patients with multiple-system disease were considered to be at high-risk to develop cardiac complications when undergoing an elective noncardiac surgical procedure. Their operative risk was prospectively assessed by a protocol that included recording the presence of established clinical risk factors and measuring the hemodynamic response to an intravenous infusion of up to 2 L of normal saline given over a two-hour period. The day prior to their operations, 126 patients were admitted to the Surgical Intensive Care Unit, where pulmonary artery catheters were inserted without serious complications. One hundred and elven patients tolerated the entire 2-L infusion. The hemoglobin concentration of blood was measured before and after the infusion. The fractional change in blood volume (BV after/BV before) calculated with the hemoglobin data was 1.06 ± 0.06 (mean ± SD). A multivarient discriminant analysis showed that the fractional change in blood volume was a covariant with a higher correlation rank than the hemodynamic data in identifying patients at risk for an adverse outcome.