Document Detail

Determination of the minimum alveolar concentration of isoflurane in llamas.
MedLine Citation:
PMID:  10100767     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To determine the minimum alveolar concentration (MAC) of isoflurane (ISO) in llamas.
STUDY DESIGN: Prospective study.
ANIMALS: Eight adult neutered male llamas (9 +/- 1 years [x +/- SD], 177 +/- 29 kg).
METHODS: Anesthesia was induced and maintained in otherwise unmedicated llamas with a mixture of ISO in oxygen administered through a standard small-animal, semi-closed circle system using an out-of-circle, agent-specific vaporizer. The time from mask placement to intubation was recorded. Inspired and end-tidal (ET) ISO was sampled continuously. At each anesthetic concentration, a constant ET ISO was maintained for at least 20 minutes before application of a noxious electrical stimulus (50 volts, 5 Hz, 10 ms for up to 1 minute). A positive or negative response to the stimulus was recorded, and ET ISO then increased (if positive response) or decreased (if negative response) by 10% to 20%. Individual MAC was the average of multiple determinations. Body temperature was maintained at 37 +/- 1 degrees C. Selected cardiopulmonary variables (heart rate [HR], respiratory rate [RR], arterial blood pressure [ABP]) and ET ISO were recorded at hourly intervals from first ISO. Arterial blood was collected for pH, PCO2, PO2 analysis and measurement of packed cell volume (PCV) and total protein (TP) at 2 hour intervals. Following MAC determination, the anesthetic was discontinued and llamas were allowed to recover. Duration and quality of recovery were noted.
RESULTS: The time from start of induction by mask to completion of intubation took 19.1 +/- 4.8 minutes. The MAC of ISO corrected to one atmosphere at sea level (barometric pressure 760 mm Hg) in these llamas was 1.05 +/- 0.17%. Mean ABP increased from 70 +/- 26 mm Hg at the end of the first hour of anesthesia to 102 +/- 7 mm Hg measured at the end of the sixth hour of anesthesia. ET ISO decreased from 2.06 +/- 0.10% to 1.27 +/- 0.07% over the same time period, but MAC did not change with time. The duration from first ISO to discontinuation of ISO averaged 6.19 +/- 0.9 hours. Animals were able to support their heads in a sternal posture at 23 +/- 10 minutes, and stood 62 +/- 26 minutes following discontinuation of the anesthetic.
CONCLUSION: The MAC for ISO is similar to, but slightly lower than, values reported for other species.
CLINICAL RELEVANCE: Knowledge of MAC may facilitate appropriate clinical use and provide the basis for future investigation of ISO in llamas.
K R Mama; A E Wagner; D A Parker; P W Hellyer; J S Gaynor
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Veterinary surgery : VS     Volume:  28     ISSN:  0161-3499     ISO Abbreviation:  Vet Surg     Publication Date:    1999 Mar-Apr
Date Detail:
Created Date:  1999-06-01     Completed Date:  1999-06-01     Revised Date:  2011-04-25    
Medline Journal Info:
Nlm Unique ID:  8113214     Medline TA:  Vet Surg     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  121-5     Citation Subset:  IM    
Department of Clinical Sciences, Colorado State University, Fort Collins 80523, USA.
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MeSH Terms
Anesthetics, Inhalation / blood*
Camelids, New World / metabolism*
Isoflurane / blood*
Prospective Studies
Reg. No./Substance:
0/Anesthetics, Inhalation; 26675-46-7/Isoflurane

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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