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Abstract

OBJECTIVE

To determine the cardiopulmonary effects of IV administration of fentanyl to cats anesthetized with isoflurane and during anesthetic recovery with concurrent administration of acepromazine or dexmedetomidine.

ANIMALS

6 healthy adult cats.

PROCEDURES

Cats received an IV bolus (5 μg/kg) followed by an IV infusion (5 μg/kg/h) of fentanyl for 120 minutes during isoflurane anesthesia and for 30 minutes after discontinuing isoflurane. Cats were randomly assigned in a crossover study to receive acepromazine (0.05 mg/kg) or dexmedetomidine (2.5 μg/kg), IV, when isoflurane was discontinued. Cardiopulmonary data were obtained during anesthesia and for 30 minutes during the anesthetic recovery period.

RESULTS

The administration of fentanyl during isoflurane anesthesia resulted in a transient increase in arterial blood pressure, mean pulmonary artery pressure, and oxygen delivery. Compared with values during isoflurane anesthesia, administration of dexmedetomidine during anesthetic recovery resulted in significant decreases in cardiac index, stroke index, and oxygen delivery and significant increases in arterial, central venous, and mean pulmonary artery pressures; systemic vascular resistance index; and oxygen extraction ratio. Administration of acepromazine resulted in increases in heart rate, cardiac index, oxygen uptake, and oxygen extraction ratio. Oxygen extraction ratio did not differ between acepromazine and dexmedetomidine.

CONCLUSIONS AND CLINICAL RELEVANCE

Fentanyl transiently improved indices of cardiopulmonary performance when administered to healthy cats anesthetized with isoflurane. The cardiovascular effects of acepromazine and dexmedetomidine in healthy cats receiving fentanyl during recovery from isoflurane anesthesia differed, but measured cardiopulmonary parameters remained within acceptable limits.

Full access
in American Journal of Veterinary Research

OBJECTIVE

To determine factors associated with change in rectal temperature (RT) of dogs undergoing anesthesia.

ANIMALS

507 dogs.

PROCEDURES

In a prospective observational study, the RT of dogs undergoing anesthesia at 5 veterinary hospitals was recorded at the time of induction of anesthesia and at the time of recovery from anesthesia (ie, at the time of extubation). Demographic data, body condition score, American Society of Anesthesiologists (ASA) physical status classification, types of procedure performed and medications administered, duration of anesthesia, and use of heat support were also recorded. Multiple regression analysis was performed to determine factors that were significantly associated with a decrease or an increase (or no change) in RT. Odds ratios were calculated for factors significantly associated with a decrease in RT.

RESULTS

Among the 507 dogs undergoing anesthesia, RT decreased in 89% (median decrease, −1.2°C [-2.2°F]; range, −0.1°C to −5.7°C [–0.2°F to −10.3°F]), increased in 9% (median increase, 0.65°C [1.2°F]; range, 0.1°C to 2.1°C [3.8°F]), and did not change in 2%. Factors that significantly predicted and increased the odds of a decrease in RT included lower weight, ASA classification > 2, surgery for orthopedic or neurologic disease, MRI procedures, use of an α2-adrenergic or μ-opioid receptor agonist, longer duration of anesthesia, and higher heat loss rate. Lack of μ-opioid receptor agonist use, shorter duration of anesthesia, and lower heat loss rate were significantly associated with an increase in RT.

CONCLUSIONS AND CLINICAL RELEVANCE

Multiple factors that were associated with a decrease in RT in dogs undergoing anesthesia were identified. Knowledge of these factors may help identify dogs at greater risk of developing inadvertent perianesthetic hypothermia.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the cardiopulmonary effects of IV fentanyl administration in dogs during isoflurane anesthesia and during anesthetic recovery with or without dexmedetomidine or acepromazine.

Animals—7 sexually intact male purpose-bred hound-type dogs aged 11 to 12 months.

Procedures—Dogs received a loading dose of fentanyl (5 μg/kg, IV) followed by an IV infusion (5 μg/kg/h) for 120 minutes while anesthetized with isoflurane and for an additional 60 minutes after anesthesia was discontinued. Dogs were randomly assigned in a crossover design to receive dexmedetomidine (2.5 μg/kg), acepromazine (0.05 mg/kg), or saline (0.9% NaCl) solution (1 mL) IV after anesthesia ceased. Cardiopulmonary data were obtained during anesthesia and for 90 minutes after treatment administration during anesthetic recovery.

Results—Concurrent administration of fentanyl and isoflurane resulted in significant decreases in mean arterial blood pressure, heart rate, and cardiac index and a significant increase in Paco2. All but Paco2 returned to pretreatment values before isoflurane anesthesia was discontinued. During recovery, dexmedetomidine administration resulted in significant decreases in heart rate, cardiac index, and mixed venous oxygen tension and a significant increase in arterial blood pressure, compared with values for saline solution and acepromazine treatments. Acepromazine administration resulted in significantly lower blood pressure and higher cardiac index and Po2 in mixed venous blood than did the other treatments. Dexmedetomidine treatment resulted in significantly lower values for Pao2 and arterial pH and higher Paco2 values than both other treatments.

Conclusions and Clinical Relevance—Fentanyl resulted in transient pronounced cardiorespiratory effects when administered during isoflurane anesthesia. During anesthetic recovery, when administered concurrently with an IV fentanyl infusion, dexmedetomidine resulted in evidence of cardiopulmonary compromise and acepromazine transiently improved cardiopulmonary performance.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE: To determine the intracoelemic (ICe) dose of alfaxalone required to induce loss of righting reflex (LRR) in garter snakes (Thamnophis sirtalis) and to evaluate the tactile stimulus response in unanesthetized and alfaxalone-anesthetized snakes.

ANIMALS: 8 healthy mature garter snakes.

PROCEDURES: During the first of 3 phases, snakes received each of 3 doses (10, 20, and 30 mg/kg) of alfaxalone, ICe, with a 2-week washout period between treatments. Times to LRR and return of righting reflex were determined after each dose. During phase 2, unanesthetized snakes underwent tactile stimulation testing with Semmes-Weinstein monofilaments once daily for 3 consecutive days to determine the baseline tactile pressure required to elicit purposeful movement. During phase 3, snakes were anesthetized with alfaxalone (30 mg/kg, ICe), and the tactile pressure required to induce purposeful movement was assessed at predetermined times after LRR.

RESULTS: Intracoelomic administration of alfaxalone at doses of 10, 20, and 30 mg/kg induced LRR in 0, 5, and 8 snakes, respectively. For snakes with LRR, median time to LRR following the 30-mg/kg dose (3.8 minutes) was significantly shorter than that following the 20-mg/kg dose (8.3 minutes); median time to return of righting reflex did not differ between the 2 doses. Mean ± SD tactile pressure that resulted in purposeful movement in unanesthetized snakes was 16.9 ± 14.3 g. When snakes were anesthetized, the mean tactile pressure that resulted in purposeful movement was significantly increased from baseline at 10, 20, and 30 minutes after LRR.

CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested ICe administration of alfaxalone might be effective for anesthetizing garter snakes.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate the repeatability and accuracy of fingertip pulse oximeters (FPO) for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate (PR) in anesthetized dogs breathing 100% O2.

ANIMALS

29 healthy client-owned anesthetized dogs undergoing various surgical procedures.

PROCEDURES

In randomized order, each of 7 FPOs or a reference pulse oximeter (PO) was applied to the tongue of each intubated anesthetized dog breathing 100% O2. Duplicate measurements of oxygen saturation (Spo 2) and PR were obtained within 60 seconds of applying an FPO or PO. A nonparametric version of Bland-Altman analysis was used. Coefficient of repeatability was the interval between the 5th and 95th percentiles of the differences between duplicate measurements. Bias was the median difference, and the limits of agreement were the 5th and 95th percentiles of the differences between each FPO and the PO. Acceptable values for the coefficient of repeatability of Spo 2 were ≤ 6%. Agreements were accepted if the limits of agreement had an absolute difference of ≤ ± 3% in Spo 2 and relative difference of ≤ ± 10% in PR.

RESULTS

Coefficient of repeatability for Spo 2 was acceptable for 5 FPOs, but the limits of agreement for Spo 2 were unacceptable for all FPOs. The limits of agreement for PR were acceptable for 2 FPOs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that some FPOs may be suitable for accurately monitoring PRs of healthy anesthetized dogs breathing 100% O2, but mild underestimation of Spo 2 was common.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate agreement among diplomates of the American College of Veterinary Anesthesia and Analgesia for scores determined by use of a simple descriptive scale (SDS) or a composite grading scale (CGS) for quality of recovery of horses from anesthesia and to investigate use of 3-axis accelerometry (3AA) for objective evaluation of recovery.

ANIMALS 12 healthy adult horses.

PROCEDURES Horses were fitted with a 3AA device and then were anesthetized. Eight diplomates evaluated recovery by use of an SDS, and 7 other diplomates evaluated recovery by use of a CGS. Agreement was tested with κ and AC1 statistics for the SDS and an ANOVA for the CGS. A library of mathematical models was used to map 3AA data against CGS scores.

RESULTS Agreement among diplomates using the SDS was slight (κ = 0.19; AC1 = 0.22). The CGS scores differed significantly among diplomates. Best fit of 3AA data against CGS scores yielded the following equation: RS = 9.998 × SG0.633 × ∑UG0.174, where RS is a horse's recovery score determined with 3AA, SG is acceleration of the successful attempt to stand, and ∑UG is the sum of accelerations of unsuccessful attempts to stand.

CONCLUSIONS AND CLINICAL RELEVANCE Subjective scoring of recovery of horses from anesthesia resulted in poor agreement among diplomates. Subjective scoring may lead to differences in conclusions about recovery quality; thus, there is a need for an objective scoring method. The 3AA system removed subjective bias in evaluations of recovery of horses and warrants further study.

Full access
in American Journal of Veterinary Research