
Cardiopulmonary bypass reduces the minimum alveolar concentration for isoflurane.
OBJECTIVE: The purpose of this investigation was to determine the influence of cardiopulmonary bypass (CPB) on the minimum alveolar concentration (MAC) of isoflurane in a rat model of CPB. DESIGN: Prospective. SETTING: University research laboratory. PARTICIPANTS: Sprague-Dawley rats. INTERVENTIONS: Using tail-clamp methodology, the pre- and post-CPB MAC for isoflurane was studied. METHODS AND MAIN RESULTS: Rats were anesthetized with isoflurane, intubated, ventilated, and surgically prepared for CPB, after which they were randomized to either Sham-operated or CPB groups. The CPB group (n = 10) underwent 90 minutes of normothermic nonpulsatile CPB. The Sham group (n = 13) were cannulated but did not undergo CPB. Pre- and post-CPB MAC determinations were compared within groups using a paired Student t test. The CPB group had a pre-CPB baseline isoflurane MAC of 1.09% +/- 0.11% versus 1.09% +/- 0.08% in the Sham group (p = 0.90). Twenty minutes after CPB, the CPB group exhibited a decrease in MAC to 0.98% +/- 0.14% (p = 0.0026, compared with baseline). The MAC in the Sham group was unchanged (p = 0.5852, compared with baseline). Two hours after CPB, the MAC in the CPB group remained lower compared with baseline at 0.99% +/- 0.14% (p = 0.0032). CONCLUSIONS: CPB resulted in a small (10%) but significant reduction in the MAC for isoflurane. The mechanism behind this reduction in MAC is not clear but may be related to CPB-induced cerebral injury.
Duke Scholars
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Related Subject Headings
- Time Factors
- Rats, Sprague-Dawley
- Rats
- Pulmonary Alveoli
- Models, Animal
- Male
- Isoflurane
- Intubation, Intratracheal
- Hemodynamics
- Cardiopulmonary Bypass
Citation

Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Time Factors
- Rats, Sprague-Dawley
- Rats
- Pulmonary Alveoli
- Models, Animal
- Male
- Isoflurane
- Intubation, Intratracheal
- Hemodynamics
- Cardiopulmonary Bypass