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Left ventricular, systemic arterial, and baroreflex responses to ketamine and TEE in chronically instrumented monkeysEffects of prescribed doses of ketamine five minutes after application and influences of transesophageal echocardiography (TEE) on left ventricular, systemic arterial, and baroreflex responses were investigated to test the hypothesis that ketamine and/or TEE probe insertion alter cardiovascular function. Seven rhesus monkeys were tested under each of four randomly selected experimental conditions: (1) intravenous bolus dose of ketamine (0.5 ml), (2) continuous infusion of ketamine (500 mg/kg/min), (3) continuous infusion of ketamine (500 mg/kg/min) with TEE, and (4) control (no ketamine or TEE). Monkeys were chronically instrumented with a high fidelity, dual-sensor micromanometer to measure left ventricular and aortic pressure and a transit-time ultrasound probe to measure aortic flow. These measures were used to calculate left ventricular function. A 4-element Windkessel lumped-parameter model was used to estimate total peripheral resistance and systemic arterial compliance. Baroreflex response was calculated as the change in R-R interval divided by the change in mean aortic pressure measured during administration of graded concentrations of nitroprusside. The results indicated that five minutes after ketamine application heart rate and left ventricular diastolic compliance decreased while TEE increased aortic systolic and diastolic pressure. We conclude that ketamine may be administered as either a bolus or continuous infusion without affecting cardiovascular function 5 minutes after application while the insertion of a TEE probe will increase aortic pressure. The results for both ketamine and TEE illustrate the classic "Hawthorne Effect," where the observed values are partly a function of the measurement process. Measures of aortic pressure, heart rate, and left ventricular diastolic pressure should be viewed as relative, as opposed to absolute, when organisms are sedated with ketamine or instrumented with a TEE probe.
Document ID
20040088393
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Koenig, S. C.
(Jewish Hospital Heart and Lung Institute, University of Louisville Kentucky 40202, United States)
Ludwig, D. A.
Reister, C.
Fanton, J. W.
Ewert, D.
Convertino, V. A.
Date Acquired
August 21, 2013
Publication Date
December 1, 2001
Publication Information
Publication: Comparative medicine
Volume: 51
Issue: 6
ISSN: 1532-0820
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Cardiopulmonary

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