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The young lamb can increase cardiovascular performance during isoflurane anesthesia
C M Brett1, D F Teitel, M A Heymann
1Department of Anesthesia, University of California, San Francisco 94143-0648.
Anesthesiology
|November 1, 1989
Summary
Young lambs under isoflurane anesthesia show reduced cardiac output. Hypoxemia during anesthesia improved cardiac performance, indicating lambs can increase oxygen delivery when needed.
Area of Science:
- Anesthesiology
- Pediatric Cardiology
- Veterinary Physiology
Background:
- Isoflurane anesthesia significantly reduces cardiac output and myocardial blood flow in young lambs.
- Concerns exist regarding the cardiovascular adaptability of young lambs during anesthesia, especially when oxygen delivery is compromised.
Purpose of the Study:
- To investigate the capacity of young lambs to enhance oxygen delivery during isoflurane anesthesia.
- To assess the response of myocardial performance to hypoxemia in awake, 1-week-old lambs.
Main Methods:
- Measurements included mean systemic arterial pressure, heart rate, cardiac output, and regional blood flow distribution.
- Calculations involved stroke volume, oxygen consumption (total body and myocardial), and fractional oxygen extraction.
- Three states were compared: awake, 1.0 MAC isoflurane with FIO2 1.0, and 1.0 MAC isoflurane with FIO2 0.09.
Main Results:
- Isoflurane anesthesia significantly decreased mean systemic arterial pressure, heart rate, and cardiac output.
- Hypoxemia normalized heart rate and increased stroke volume beyond control and anesthetic levels.
- Cardiac output under hypoxemia surpassed levels observed during isoflurane anesthesia alone.
Conclusions:
- Young lambs demonstrate an ability to increase cardiac output and stroke volume in response to hypoxemia, even under isoflurane anesthesia.
- This compensatory mechanism suggests a potential for increased oxygen delivery when challenged during anesthetic states.