Effects of phenylephrine on cardiac output and venous return depend on the position of the heart on the Frank-Starling relationship.

doi:10.1152/japplphysiol.00126.2012

Paper

Effects of phenylephrine on cardiac output and venous return depend on the position of the heart on the Frank-Starling relationship.

Published Jul 15, 2012 · M. Cannesson, Zhongping Jian, Guo Chen

Journal of applied physiology

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103

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7

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Abstract

INTRODUCTION phenylephrine is used daily during anesthesia for treating hypotension. However, the effects of phenylephrine on cardiac output (CO) are not clear. We hypothesized that the impact of phenylephrine on cardiac output is related to preload dependency. METHODS eight pigs were studied at a preload independent stage (after CO augmentation) and at a preload dependent stage (after a 21 ml/kg hemorrhage). At each stage, phenylephrine boluses (0.5, 1.0, 2.0, and 4.0 μg/kg) were given randomly while mean arterial pressure (MAP), CO, inferior vena cava flow (IVCf) (both measured using ultrasonic flow probes), and pulse pressure variation were measured. RESULTS at the preload independent stage, phenylephrine boluses induced significant increases in MAP (from 72 ± 6 to 100 ± 6 mmHg; P < 0.05) and decreases in CO and IVCf (from 7.0 ± 0.8 to 6.0 ± 1.1 l/min and from 4.6 ± 0.5 to 3.8 ± 0.6 l/min, respectively). At the preload-dependent stage, phenylephrine boluses induced significant increases in MAP (from 40 ± 7 to 65 ± 9 mmHg), CO (from 4.1 ± 0.6 to 4.9 ± 0.7 l/min), and IVCf (from 3.0 ± 0.4 to 3.5 ± 0.6 l/min; all data presented are for 4 μg/kg). Incremental doses of phenylephrine induced incremental changes in cardiac output. A pulse pressure variation >16.4% before phenylephrine predicted an increase in stroke volume with a 93% sensitivity and a 100% specificity. CONCLUSION impact of phenylephrine on cardiac output is related to preload dependency. When the heart is preload independent, phenylephrine boluses induce on average a decrease in cardiac output. When the heart is preload dependent, phenylephrine boluses induce on average an increase in cardiac output.

Non-RCT

Animal Study

Highly Cited

Study Snapshot

Phenylephrine boluses decrease cardiac output when the heart is preload independent, and increase it when the heart is preload dependent.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

Effects of phenylephrine on cardiac output and venous return depend on the position of the heart on the Frank-Starling relationship.

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