CJA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text (PDF)
Right arrow Submit a scholarly reply
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Neumeister, M. W.
Right arrow Articles by Hall, R. I.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Neumeister, M. W.
Right arrow Articles by Hall, R. I.

Canadian Journal of Anesthesia, Vol 44, 1120-1126, Copyright © 1997 by Canadian Anesthesiologists' Society

ARTICLES

Factors influencing MAC reduction after cardiopulmonary bypass in dogs

MW Neumeister, G Li, G Williams, G Doak, JA Sullivan and RI Hall
Department of Anaesthesia, Dalhousie University, Halifax, Nova Scotia, Canada.

BACKGROUND: Anaesthetic requirements may be reduced following surgery employing cardiopulmonary bypass (CPB). This study, in dogs, determined the role of a) volatile agents (enflurane [E] vs isoflurane [I]), b) oxygenator (bubble [B] vs membrane [M]), and c) presence [FL] vs absence [NoFL] of an in-line arterial filter in the bypass circuit in altering anaesthetic requirements following CPB. METHODS: Male mongrel dogs were anaesthetized with either enflurane (n = 24) or isoflurane (n = 24). They were randomly assigned to one of eight groups (n = 6 per group); Group 1 (E/B/FL), Group 2 (E/M/FL), Group 3 (E/M/NoFL), Group 4 (E/B/NoFL), Group 5 (I/M/FL), Group 6 (I/B/FL), Group 7 (I/M/NoFL) or Group 8 (I/B/NoFL). MAC was determined using the tail-clamp method at hourly intervals, twice before and three times after a one hour normothermic perfusion using aortoatrial cannulation and CPB. RESULTS: Prior to CPB, MAC was reproducible (enflurane: MAC1 2.17 +/- 0.29 vs MAC2 2.14 +/- 0.28%; isoflurane: MAC1 1.42 +/- 0.31 vs MAC2 1.41 +/- 0.33%) and differed among groups only for the volatile agent employed. Following CPB, MAC was reduced in all groups (P < 0.05 vs pre-CPB measurements) except Group 1 (E/B/FL). The degree of MAC reduction in other groups ranged from 39-64% and was not different based on type of agent employed, use of a membrane or bubble oxygenator, or presence or absence of an in-line arterial filter. CONCLUSION: In dogs, MAC reduction following CPB was variable, not related to type of volatile agent employed, use of a membrane or bubble oxygenator, or presence or absence of an in-line arterial filter. The explanation for reductions in anaesthetic requirements following CPB in this model remains speculative.




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1997 by the Canadian Anesthesiologists' Society.