Study objective: To investigate the effect of small dose of intravenous (IV) prostaglandin E(1) (PGE(1)) on blood volume (BV) and cardiac output (CO) by pulse dye-densitometry (PDD) in patients administered isoflurane anesthesia.
Design: Prospective, randomized study.
Setting: University hospital.
Patients: 14 ASA physical status I and II adult patients undergoing elective neurosurgery.
Interventions: Patients were randomly assigned to either the PGE(1) group (n = 7) or the control group (n = 7). Anesthesia was induced with thiamylal, fentanyl, and vecuronium, and maintained with isoflurane and nitrous oxide. When the cardiovascular system stabilized after craniotomy and incision of the dura mater, we administered a small dose of PGE(1) at a rate of 0.02 microg/kg/min (PGE(1) group) or saline at a rate of 2 mL/min (control group).
Measurements and main results: Blood volume, CO, and mean transit time (MTT) were measured by PDD before and 60 minutes after the start of administration. At the same timing, mean arterial pressure (MAP), heart rate (HR), and central venous pressure (CVP) were measured, and systemic vascular resistance (SVR), cardiac index (CI), and CO/BV were computed. As for MAP, there was no significant difference within a group and between groups. In the PGE(1) group, significant increases were noted in CI from 2.54 +/- 0.46 to 3.24 +/- 0.83 (mean +/- SD) L/min/m(2) (p < 0.05), in CO/BV from 0.90 +/- 0.24 to 1.19 +/- 0.33 (p < 0.05), and in HR from 65.7 +/- 10.1 to 74.9 +/- 12.1 bpm (p < 0.05), and a significant decrease was observed in MTT from 22.3 +/- 6.5 to 18.2 +/- 5.1 seconds (p < 0.05 ). Cardiac index and CO/BV in the PGE(1) group increased higher than in the control group, while BV, CVP and SVR remained consistent in both groups.
Conclusions: A small dose of PGE(1), low enough not to provoke hypotension, increased CO without alterations in BV. The increase in CO seemed to be mainly due to an increase in HR.