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  • Author or Editor: Guilherme M. Mendes x
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Abstract

Objective—To determine the cardiorespiratory effects of an IV infusion of propofol alone or in association with fentanyl, alfentanil, or sufentanil in cats and, for each combination, the minimal infusion rate of propofol that would inhibit a response to noxious stimuli.

Design—Randomized crossover study.

Animals—6 cats.

Procedure—Cats were anesthetized 4 times in random order. After IV administration of fentanyl, alfentanil, sufentanil, or saline (0.9% NaCl) solution, anesthesia was induced with propofol (7 mg/kg [3.2 mg/lb], IV) and maintained for 90 minutes with a continuous infusion of propofol in conjunction with fentanyl (0.1 µg/kg/min [0.045 µg/lb/min]), alfentanil (0.5 µg/kg/min [0.23 µg/lb/min]), sufentanil (0.01 µg/kg/min [0.004 µg/lb/min]), or saline solution (0.08 mL/kg/min [0.036 mL/lb/min]).

Results—Minimal infusion rate of propofol required to prevent a response to a noxious stimulus was higher when cats received saline solution. After 70 minutes, minimal infusion rate of propofol was significantly higher with fentanyl than with sufentanil. Decreases in heart rate, systolic blood pressure, rectal temperature, and respiratory rate were detected with all treatments. Oxygen saturation did not change significantly, but end-tidal partial pressure of carbon dioxide increased with all treatments. There were no significant differences in recovery times or sedation and recovery scores among treatments.

Conclusions and Clinical Relevance—Results suggest that infusion of propofol in combination with fentanyl, alfentanil, or sufentanil results in satisfactory anesthesia in cats. (J Am Vet Med Assoc 2003;223:1608–1613)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine sedative and cardiorespiratory effects of dexmedetomidine alone and in combination with butorphanol or ketamine in cats.

Design—Randomized crossover study.

Animals—6 healthy adult cats.

Procedures—Cats were given dexmedetomidine alone (10 μg/kg [4.5 mg/lb], IM), a combination of dexmedetomidine (10 μg/kg, IM) and butorphanol (0.2 mg/kg [0.09 mg/lb], IM), or a combination of dexmedetomidine (10 μg/kg, IM) and ketamine (5 mg/kg [2.3 mg/lb], IM). Treatments were administered in random order, with ≥ 1 week between treatments. Physiologic variables were assessed before and after drug administration. Time to lateral recumbency, duration of lateral recumbency, time to sternal recumbency, time to recovery from sedation, and subjective evaluation of sedation, muscle relaxation, and auditory response were assessed.

Results—Each treatment resulted in adequate sedation; time to lateral recumbency, duration of lateral recumbency, and time to recovery from sedation were similar among treatments. Time to sternal recumbency was significantly greater after administration of dexmedetomidine-ketamine. Heart rate decreased significantly after each treatment; however, the decrease was more pronounced after administration of dexmedetomidine-butorphanol, compared with that following the other treatments. Systolic and diastolic blood pressure measurements decreased significantly from baseline with all treatments; 50 minutes after drug administration, mean blood pressure differed significantly from baseline only when cats received dexmedetomidine and butorphanol.

Conclusions and Clinical Relevance—Results suggested that in cats, administration of dexmedetomidine combined with butorphanol or ketamine resulted in more adequate sedation, without clinically important cardiovascular effects, than was achieved with dexmedetomidine alone. (J Am Vet Med Assoc 2003;222:37–41)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the effects of 2 remifentanil infusion regimens on cardiovascular function and responses to nociceptive stimulation in propofol-anesthetized cats.

Animals—8 adult cats.

Procedures—On 2 occasions, cats received acepromazine followed by propofol (6 mg/kg then 0.3 mg/kg/min, IV) and a constant rate infusion (CRI) of remifentanil (0.2 or 0.3 μg/kg/ min, IV) for 90 minutes and underwent mechanical ventilation (phase I). After recording physiologic variables, an electrical stimulus (50 V; 50 Hz; 10 milliseconds) was applied to a forelimb to assess motor responses to nociceptive stimulation. After an interval (≥ 10 days), the same cats were anesthetized via administration of acepromazine and a similar infusion regimen of propofol; the remifentanil infusion rate adjustments that were required to inhibit cardiovascular responses to ovariohysterectomy were recorded (phase II).

Results—In phase I, heart rate and arterial pressure did not differ between remifentanil- treated groups. From 30 to 90 minutes, cats receiving 0.3 μg of remifentanil/kg/min had no response to noxious stimulation. Purposeful movement was detected more frequently in cats receiving 0.2 μg of remifentanil/kg/min. In phase II, the highest dosage (mean ± SEM) of remifentanil that prevented cardiovascular responses was 0.23 ± 0.01 μg/kg/min. For all experiments, mean time from infusion cessation until standing ranged from 115 to 140 minutes.

Conclusions and Clinical Relevance—Although the lower infusion rate of remifentanil allowed ovariohysterectomy to be performed, a CRI of 0.3 μg/kg/min was necessary to prevent motor response to electrical stimulation in propofol-anesthetized cats. Recovery from anesthesia was prolonged with this technique.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine sedative and cardiorespiratory effects of romifidine alone and romifidine in combination with butorphanol and effects of preemptive atropine administration in cats sedated with romifidine-butorphanol.

Design—Randomized crossover study.

Animals—6 healthy adult cats.

Procedures—Cats were given saline (0.9% NaCl) solution followed by romifidine alone (100 µg/kg [45.4 µg/lb], IM), saline solution followed by a combination of romifidine (40 µg/kg [18.1 µg/lb], IM) and butorphanol (0.2 mg/kg [0.09 mg/lb], IM), or atropine (0.04 mg/kg [0.02 mg/lb], SC) followed by romifidine (40 µg/kg, IM) and butorphanol (0.2 mg/kg, IM). Treatments were administered in random order, with ≥ 1 week between treatments. Physiologic variables were determined before and after drug administration. Time to recumbency, duration of recumbency, time to recover from sedation, and subjective evaluation of sedation, muscle relaxation, and analgesia were assessed.

Results—Bradycardia developed in all cats that received saline solution and romifidine-butorphanol or romifidine alone. Preemptive administration of atropine prevented bradycardia for 50 minutes in cats given romifidine-butorphanol. Oxyhemoglobin saturation was significantly decreased 10 minutes after romifidine-butorphanol administration in atropinetreated cats.

Conclusions and Clinical Relevance—Results suggested that administration of romifidine alone or romifidine-butorphanol causes a significant decrease in heart rate and that preemptive administration of atropine in cats sedated with romifidine-butorphanol effectively prevents bradycardia for 50 minutes. (J Am Vet Med Assoc 2002;221: 506–510)

Full access
in Journal of the American Veterinary Medical Association