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Abstract

Objective—To determine whether end-tidal partial pressure of carbon dioxide (PETCO2) correlated with PaCO2 in isoflurane-anesthetized African grey parrots receiving intermittent positive pressure ventilation (IPPV).

Design—Prospective study.

Animals—14 healthy mature African grey parrots (Psittacus erithacus timnus).

Procedure—Each bird was anesthetized via mask with isoflurane, intubated, and connected to a pressure-limited intermittent-flow ventilator. Respiratory rate was altered while holding peak inspiratory pressure constant (5 cm H2O) to achieve a PETCO2 in 1 of 3 ranges: < 30 mm Hg, 30 to 40 mm Hg, and > 40 mm Hg. Blood was collected from the superficial ulnar artery of each bird at least once during each of the 3 ranges. Arterial blood samples were collected for blood gas analysis while PETCO2 was recorded simultaneously.

Results—A strong correlation between PETCO2 and PaCO2 was detected over a wide range of partial pressures, although PETCO2 consistently overestimated PaCO2 by approximately 5 mm Hg. End-tidal partial pressure of CO2 and PaCO2 also correlated well with arterial blood pH, and the acute response of the bicarbonate buffer system to changes in ventilation was similar to that of mammals.

Conclusions and Clinical Relevance—Results indicated that PETCO2 reliably estimates PaCO2 in isofluraneanesthetized African grey parrots receiving IPPV and suggest that IPPV combined with capnography is a viable option for anesthetic maintenance in avian anesthesia. (J Am Vet Med Assoc 2001;219:1714–1718)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine safety and efficacy of an anesthetic protocol incorporating medetomidine, ketamine, and sevoflurane for anesthesia of injured loggerhead sea turtles.

Design—Retrospective study.

Animals—13 loggerhead sea turtles.

Procedure—Anesthesia was induced with medetomidine (50 µg/kg [22.7 µg/lb], IV) and ketamine (5 mg/kg [2.3 mg/lb], IV) and maintained with sevoflurane (0.5 to 2.5%) in oxygen. Sevoflurane was delivered with a pressure-limited intermittent-flow ventilator. Heart rate and rhythm, end-tidal partial pressure of CO2, and cloacal temperature were monitored continuously; venous blood gas analyses were performed intermittently. Administration of sevoflurane was discontinued 30 to 60 minutes prior to the end of the surgical procedure. Atipamezole (0.25 mg/kg [0.11 mg/lb], IV) was administered at the end of surgery.

Results—Median induction time was 11 minutes (range, 2 to 40 minutes; n = 11). Median delivered sevoflurane concentrations 15, 30, 60, and 120 minutes after intubation were 2.5 (n = 12), 1.5 (12), 1.25 (12), and 0.5% (8), respectively. Heart rate decreased during surgery to a median value of 15 beats/min (n = 11). End-tidal partial pressure of CO2 ranged from 2 to 16 mm Hg (n = 8); median blood gas values were within reference limits. Median time from atipamezole administration to extubation was 14 minutes (range, 2 to 84 minutes; n = 7).

Conclusions and Clinical Relevance—Results suggest that a combination of medetomidine and ketamine for induction and sevoflurane for maintenance provides safe, effective, controllable anesthesia in injured loggerhead sea turtles. (J Am Vet Med Assoc 2002;221:1019–1025)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the cardiopulmonary effects of immobilizing doses of xylazine-ketamine (XK), medetomidine-ketamine (MK), medetomidine-ketamine- acepromazine (MKA), and medetomidine-butorphanol- ketamine (MBK) in captive red wolves.

Design—Prospective study.

Animals—32 adult captive red wolves.

Procedure—Wolves were randomly assigned to 1 of 4 treatment groups: XK, MK, MKA, or MBK. Physiologic variables measured included heart rate, blood pressure, respiratory rate, tidal volume, oxygen-hemoglobin saturation (SpO2), end-tidal CO2, arterial blood gases, and rectal temperature. Induction time, muscle relaxation, and quality of recovery were assessed.

Results—Heart rates were lower in wolves in the MBK group than for the other groups. All 4 drug combinations induced considerable hypertension, with diastolic pressures exceeding 116 mm Hg. Blood pressure was lowest in wolves receiving the MBK combination. Respiratory rate was significantly higher in wolves receiving XK, MK, and MKA. Tidal volumes were similar for all groups. Wolves receiving XK, MK, and MKA were well-oxygenated throughout the procedure (SpO2 > 93%), whereas those receiving MBK were moderately hypoxemic (87% < SpO2 < 93%) during the first 20 minutes of the procedure. Hyperthermia was detected initially following induction in all groups.

Conclusions and Clinical Relevance—The α2- adrenoceptor agonist-ketamine combinations provide rapid reversible anesthesia for red wolves but cause severe sustained hypertension. Such an adverse effect puts animals at risk for development of cerebral encephalopathy, retinal hemorrhage, pulmonary edema, and myocardial failure. Although the MBK combination offers some advantages over the others, it is advised that further protocol refinements be made to minimize risks associated with acute hypertension. (J Am Vet Med Assoc 2000;217:1366–1371)

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in Journal of the American Veterinary Medical Association