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bypass time [min] 99 [90, 119] 94 [83, 106] .009 Time intubated [min] 344 [301, 382] 298 [259, 338] < .001 Ventricular fibrillation after releasing crossclamp [%] 28.6 11.7 .003 Total amount of CCP [mL/kg] 37 [30, 48

Open access
in American Journal of Veterinary Research

management of IC seems justified, especially given that serious complications such as hemorrhage and the development of ventricular fibrillation can result. 3 , 12 The primary aim of this study was to evaluate whether screening for CPP could obviate the

Full access
in Journal of the American Veterinary Medical Association

quick and aggressive treatment. As well as this, the potential of this arrhythmia to progress to ventricular fibrillation is of grave concern, as the option to attempt to externally defibrillate horses back to normal sinus rhythm does not exist. This

Free access
in Journal of the American Veterinary Medical Association

after presentation, the dog suddenly developed ventricular tachycardia that progressed to ventricular fibrillation evident on ECG, then vocalized and collapsed in CPA. Cardiopulmonary resuscitation and intubation were immediately initiated. Epinephrine

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

Although the cardiovascular and respiratory effects of halothane and isoflurane have been documented in a variety of common mammalian laboratory animals, they have not been investigated in birds. In this study, the effects of halothane and isoflurane anesthesia on respiratory rate, heart rate, heart rhythm, and mean arterial pressure in adult Pekin ducks were evaluated. Both anesthetics significantly increased heart rate and depressed blood pressure and respiration. Halothane induced a more profound alteration in heart rate and respiratory rate. With the ducks under halothane anesthesia, abnormal cardiac rhythms included ventricular fibrillation, ventricular bigeminy, and multifocal ventricular rhythms. Other than cardiac tachycardia, isoflurane induced no changes in cardiac rhythm.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether QT interval is prolonged or sudden death is caused by ventricular fibrillation resulting from torsades de pointes and to identify hemodynamic effects of ontazolast.

Animals—28 Beagles.

Procedure—Physiologic variables were measured for 2 hours in conscious dogs given ontazolast (0, 1, or 3 mg/kg of body weight, IV) and for 1 hour in anesthetized dogs given cumulative doses of ontazolast (0, 1, 3, 6, or 8 mg/kg, IV).

Results—Ontazolast prolonged QT interval and QT interval corrected for heart rate (QTc) at doses of 6 mg/kg in anesthetized dogs. At 8 mg/kg, both variables remained prolonged but tended to decrease. In conscious dogs, ontazolast increased QT interval and QTc 15 minutes after administration, but both variables returned to reference ranges by 60 minutes. In conscious dogs, ontazolast increased maximum rate of increase of left ventricular pressure and maximal velocity of fiber shortening, indicators of inotropy, and increased tau, indicating a decreased rate of relaxation. One conscious dog receiving 3 mg/kg developed nonfatal torsades de pointes, but another conscious dog developed ventricular fibrillation. Two anesthetized dogs receiving 6 mg/kg developed early afterdepolarizations, and all dogs developed secondary components in their T waves.

Conclusion and Clinical Relevance—Ontazolast possesses potent class-III antiarrhythmic properties and induces prolongation of QTc in a dose-dependent fashion. Because there was a clear dosedependent prolongation of QT interval in all instances, ontazolast may serve as a positive-control compound for studying other compounds that are believed to prolong the QT interval. (Am J Vet Res 2000;61:1364–1368)

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in American Journal of Veterinary Research

Summary

Surgical treatment of 201 dogs with patent ductus arteriosus at the College of Veterinary Medicine, The Ohio State University was evaluated retrospectively to determine risk factors for development of surgical complications. During surgery, 15 dogs (7%) died because of hemorrhage associated with ductus dissection (n = 8), pulmonary edema (n = 4), ventricular fibrillation (n = 1), hemorrhage not associated with ductus dissection (n = 1), and cardiac arrest immediately after ductus ligation (n = 1). An additional 8 dogs (4%) died <1 month after surgery (total mortality before, during, and immediately after surgery, 11%). Nineteen dogs (9.5%) developed hemorrhage during surgery. Sixteen dogs developed complications other than hemorrhage (pulmonary edema [n = 4], cardiac arrest [n = 4], iatrogenic lung trauma [n = 3], ventricular fibrillation [n = 2], septicemia [n = 2], and recanalized ductus [n = 2]). Correlation was not found between age, sex, body weight, surgical technique (Jackson method vs standard method of dissection), or surgeon level of training and development of hemorrhage during surgery, other complications, or survival <5 days. Positive correlation (P < 0.05) was found between hemorrhage and death within 5 days after surgery. Positive correlation (P < 0.05) was also found between other complications and death within 5 days after surgery. Nineteen dogs survived surgery, but later died of unrelated causes (mean life span, 57 months); 63 of the dogs were still alive and doing well as of January 1990 (mean life span, 47 months after surgery).

Contrary to previous reports, age, body weight, and surgical technique did not affect results. Surgical complications were uncommon, but frequently resulted in death. Long-term survival was likely if surgical complications did not develop.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate sevoflurane as an inhalation anesthetic for thoracotomy in horses.

Animals—18 horses between 2 and 15 years old.

Procedure—4 horses were used to develop surgical techniques and were euthanatized at the end of the procedure. The remaining 14 horses were selected, because they had an episode of bleeding from their lungs during strenuous exercise. General anesthesia was induced with xylazine (1.0 mg/kg of body weight, IV) followed by ketamine (2.0 mg/kg, IV). Anesthesia was maintained with sevoflurane in oxygen delivered via a circle anesthetic breathing circuit. Ventilation was controlled to maintain PaCO2 at approximately 45 mm Hg. Neuromuscular blocking drugs (succinylcholine or atracurium) were administered to eliminate spontaneous breathing efforts and to facilitate surgery. Cardiovascular performance was monitored and supported as indicated.

Results—2 of the 14 horses not euthanatized died as a result of ventricular fibrillation. Mean (± SD) duration of anesthesia was 304.9 ± 64.1 minutes for horses that survived and 216.7 ± 85.5 minutes for horses that were euthanatized or died. Our subjective opinion was that sevoflurane afforded good control of anesthetic depth during induction, maintenance, and recovery.

Conclusions and Clinical Relevance—Administration of sevoflurane together with neuromuscular blocking drugs provides stable and easily controllable anesthetic management of horses for elective thoracotomy and cardiac manipulation. (Am J Vet Res 2000;61:1430–1437)

Full access
in American Journal of Veterinary Research

Summary

The effect of xylazine on the arrhythmogenic dose of epinephrine (ade) was studied in 9 horses. Anesthesia was induced by administration of guaifenesin (50 mg/kg of body weight, iv) followed by thiamylal (4 to 6 mg/kg, iv) and was maintained at 1 minimal alveolar concentration (mac) of halothane (0.89%). Base apex ecg and facial artery pressure were recorded. Epinephrine was infused in a sequence of arithmetically spaced increasing rates (initial rate 0.25 µg/kg/min) for a maximum of 10 minutes. The ade was defined as the lowest epinephrine infusion rate to the nearest 0.25 µg/kg/min at which at least 4 premature ventricular depolarizations occurred in a 15- second period. Xylazine (1.1 mg/kg, iv) was administered after the control ade was determined. Xylazine did not significantly alter the ade (control, 1.12 ± 0.38 µg/kg/ min; xylazine, 1.21 ± 0.46 µg/kg/min). Blood pressure increased transiently for 8 minutes after xylazine administration. Baseline systolic and diastolic arterial pressures and heart rate were not significantly different from control baseline pressures and heart rate 15 minutes after xylazine administration. Blood pressure and heart rate increased significantly during control and xylazine ade determinations. Significant differences in pH, Pao2 , Paco2 , or base excess were not observed between baseline and ade in the control or xylazine groups. One horse developed atrial fibrillation, and 2 horses developed ventricular fibrillation during ade determinations.

Free access
in American Journal of Veterinary Research

Summary

The relative myocardial irritant properties of halothane, isoflurane, and pentobarbital were evaluated in chickens. Sixteen adult male broiler chickens were randomly assigned to 1 of 3 groups: group-1 chickens were anesthetized with pentobarbital (30 mg/kg, iv), group-2 chickens were anesthetized with halothane (end tidal halothane 1.2%), and group-3 chickens were anesthetized with isoflurane (end tidal isoflurane 2.1%). Birds in any 2 of the 3 treatment groups were tested on any 1 day. Local anesthesia was induced, and blood pressure, heart rate, ecg, and blood gas variables were measured before general anesthesia was induced. Positive-pressure ventilation with an inspired O2 fraction > 0.95 was adjusted to result in an end tidal CO2 concentration that reflected a PaCO2 similar to that obtained prior to anesthesia and ventilation. All measurements were repeated. The threshold for ventricular fibrillation in response to electrical stimulation of the heart was then determined for all birds. Effects of anesthesia on hemodynamic and blood gas variables were similar in all 3 groups. Compared with halothane or pentobarbital, isoflurane anesthesia resulted in a significantly (P < 0.05) lower threshold for electrical fibrillation of the heart.

Free access
in American Journal of Veterinary Research