Hemodynamic outcomes of weaning intraaortic balloon counterpulsation in heart failure

Approximately 100,000 persons per year in the United States require intraaortic balloon counterpulsation (IABC) for the treatment of heart failure. No empirically based protocols exist to guide nurses in the complex process of weaning the heart patient from IABC. Currently, weaning is a complex "trial and error" process and the hemodynamic outcomes of weaning are unknown (Kantrowitz, Cardona & Freed, 1993; Bolooki, 1998). The purpose of this study was to determine the hemodynamic effects of two patterns of weaning IABC in an animal model of heart failure. A repeated measures crossover design was used to test the hypothesis that there were different weaning outcomes for the two weaning patterns in IABC: assist rate reduction (Pattern R) and balloon volume reduction (Pattern V). Thirty dogs age one to three years were used. A standard closed chest model of heart failure using atenolol and halothane was induced prior to the weaning treatment. Subjects were randomly assigned to one of two groups (RV or VR). For Group RV, the assist rate was weaned first (Pattern R) followed by the balloon volume (Pattern V). For Group VR, the balloon volume was weaned first (Pattern V) followed by the assist rate (Pattern R). Seventeen hemodynamic indices reflecting contractility, afterload, and preload were measured during the final one-minute for each stage of the weaning protocol. Descriptive statistics were used to determine the patterns of measurements over the nine stages for each group. To determine main effects and interaction effects, MANOVA and ANOVA with Repeated Measures were used. Two period crossover analyses by t-tests were used to discern carryover effects. Findings revealed that the RV and VR groups were not significantly different at baseline, in degree of heart failure or during full counterpulsation (1:1 assist ratio and maximum balloon volume). During the first weaning period, both groups experienced significant effects on measures of afterload and preload. Rate weaning in the first weaning period resulted in significantly lower continuous cardiac output (CCO, p=0.03) and bolus thermodilution cardiac output (COTD, p=0.02) compared to volume weaning. Groups were not significantly different with regards to weaning responses during the second period of weaning. While tests for carryover were not statistically significant, increasing hemodynamic suppression during the second weaning period suggest possible physiological deterioration of the subjects or regional responses to halothane. Data plots of means and standard error for the dependent measures revealed that rate weaning resulted in greater hemodynamic suppression than volume weaning. Although the differences in responses overall were not statistically significant, results suggest rate weaning results in more negative hemodynamic outcomes particularly for measures of afterload and preload.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Nursing

Grantor dc:publisher

The Ohio State University

Year dc:date

2000

Author dc:creator

• O'Malley, Patricia Anne

Contributors dc:contributor

• Polivka, Barbara

• Nursing
• Medicine

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1363169617

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1363169617