Comparison of cardiopulmonary effects of propofol, ketamine-propofol and isoflurane anesthesia in the domestic chicken (Gallus gallus domesticus).

OBJECTIVE

To compare the effects of propofol, ketamine-propofol and isoflurane, at similar anesthetic depth, on cardiopulmonary variables in unpremedictated chickens.

STUDY DESIGN

Prospective, randomized, crossover experimental trial.

ANIMALS

A total of 10 male Leghorn domestic chickens, aged 3 months and body mass 1.4-2.0 kg.

METHODS

Birds were randomly assigned to each of three anesthetic protocols, 7 days apart: intravenous propofol, intravenous ketamine-propofol or isoflurane. Anesthesia was induced (indicated by loss of righting reflex and tracheal intubation) and maintained with propofol (10 mg kg minute, then 1.1 mg kg minute), ketamine-propofol (5 mg mL ketamine and 5 mg mL propofol combined; 10 mg kg minute, then 1.1 mg kg minute) or isoflurane [5% vaporizer setting initially, then end-tidal concentration (Fe'Iso) of 2%] for 65 minutes. Anesthesia was maintained at a similar anesthetic depth based upon positive or negative responses to toe pinch. Heart rate (HR), respiratory rate (f), noninvasive arterial blood pressure and arterial blood gases were measured during anesthesia. Propofol or ketamine-propofol infusion rates and Fe'Iso required to prevent movement in response to a noxious stimulus and recovery times were recorded.

RESULTS

Anesthesia induction dose was 9.0 ± 0.8 (mean ± SD) and 12.2 ± 0.3 mg kg for propofol and ketamine-propofol, respectively. Propofol and ketamine-propofol infusion rates and Fe'Iso required to prevent movement in response to the noxious stimulus were 0.88 ± 0.14 mg kg minute, 0.92 ± 0.14 mg kg minute and 1.45 ± 0.28%, respectively. Cardiopulmonary variables remained clinically acceptable, but ketamine-propofol was associated with a significantly higher HR (p = 0.0001) and lower f (p = 0.0001). Time to extubation did not differ among treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

Cardiovascular and respiratory variables were maintained within normal ranges in all treatments. Coadministration of ketamine with propofol significantly reduced the induction and maintenance dose of propofol.