Intraoperative stroke volume optimization using stroke volume, arterial pressure, and heart rate: closed-loop (learning intravenous resuscitator) versus anesthesiologists.
OBJECTIVE
The authors compared the performance of a group of anesthesia providers to closed-loop (Learning Intravenous Resuscitator [LIR]) management in a simulated hemorrhage scenario using cardiac output monitoring.


METHODS
A prospective cohort study.


METHODS
In silico simulation.


METHODS
University hospital anesthesiologists and the LIR closed-loop fluid administration system.


METHODS
Using a patient simulator, a 90-minute simulated hemorrhage protocol was run, which included a 1,200-mL blood loss over 30 minutes. Twenty practicing anesthesiology providers were asked to manage this scenario by providing fluids and vasopressor medication at their discretion. The simulation program was also run 20 times with the LIR closed-loop algorithm managing fluids and an additional 20 times with no intervention.


RESULTS
Simulated patient weight, height, heart rate, mean arterial pressure, and cardiac output (CO) were similar at baseline. The mean stroke volume, the mean arterial pressure, CO, and the final CO were higher in the closed-loop group than in the practitioners group, and the coefficient of variance was lower. The closed-loop group received slightly more fluid (2.1 v 1.9 L, p < 0.05) than the anesthesiologist group.


CONCLUSIONS
Despite the roughly similar volumes of fluid given, the closed-loop maintained more stable hemodynamics than the practitioners primarily because the fluid was given earlier in the protocol and CO optimized before the hemorrhage began, whereas practitioners tended to resuscitate well but only after significant hemodynamic change indicated the need. Overall, these data support the potential usefulness of this closed-loop algorithm in clinical settings in which dynamic predictors are not available or applicable.
Department of Anesthesiology & Perioperative Care, University of California Irvine, Orange, CA 92868, USA. jrinehar@uci.edu
Joseph
J
Rinehart
Elena
E
Chung
Cecilia
C
Canales
Maxime
M
Cannesson
D000764:Anesthesia, Closed-Circuit / Q000379:methods* / Q000592:standards; D000776:Anesthesiology / Q000379:methods* / Q000592:standards; D062186:Arterial Pressure / Q000502:physiology*; D015331:Cohort Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007430:Intraoperative Care / Q000379:methods* / Q000592:standards; D007431:Intraoperative Complications / Q000517:prevention & control; D010820:Physicians; D019106:Postoperative Hemorrhage / Q000517:prevention & control; D011446:Prospective Studies; D013318:Stroke Volume / Q000502:physiology*