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  • Author or Editor: Peter W. Hellyer x
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Summary

Effects of endotoxemia on left ventricular contractility and systemic hemodynamics were determined in pentobarbital-anesthetized swine. A multielectrode conductance (volume) catheter and a high-fidelity pressure transducer catheter were passed retrograde into the left ventricle to continuously measure pressure and volume. End-systolic pressure-volume relationships were determined during transient (8 to 10 s) caudal vena caval balloon occlusion. Lactated Ringer's solution was administered at a rate sufficient to maintain left ventricular end-diastolic pressure ≥ 6 mm of Hg. Following baseline measurements, Escherichia coli endotoxin (055-B5) was infused iv at 2.5 μg/kg of body weight/h for 3 hours. Left ventricular end-systolic elastance (Ees), the slope of the end-systolic pressure-volume relationship; end-systolic elastance normalized for left ventricular end-diastolic volume (Ees norm); the rate of increase of left ventricular pressure (dP/dtmax); and preload recruitable stroke work (prsw, stroke work-to-end-diastolic volume relationship) did not change in endotoxemic swine, compared with baseline measurements or with values from control (physiologic saline solution-treated) swine. Left ventricular pressures and volumes had marked pig-to-pig variability in the control and endotoxin-treated groups. Determination of Ees, Ees norm, and prsw was further confounded by development of frequent premature ventricular contractions during caudal vena caval balloon occlusion. Endotoxin significantly (P < 0.05) decreased left ventricular end-diastolic pressure, compared with that in control swine, and significantly (P < 0.01) decreased left ventricular end-diastolic volume, compared with baseline. Endotoxin decreased cardiac index and arterial blood pressure, whereas heart rate, central venous pressure, and mean pulmonary arterial pressure increased. Endotoxin did not decrease myocardial contractility, as measured by Ees, Ees norm dP/dtmax, or prsw in anesthetized swine.

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in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Summary

We investigated the influence of parasympathetic tone on the arrhythmogenic dose of dobutamine in horses premedicated with xylazine, anesthetized with guaifenesin and thiamylal, and maintained on halothane in oxygen. Six horses were used in 12 randomized trials. In each trial, after end-tidal halothane concentration was stabilized at 1.1% (1.25 times minimum alveolar concentration [mac]) in oxygen, either saline solution (0.02 ml/kg of body weight) or atropine (0.04 mg/kg) was administered iv. Five minutes later, dobutamine infusion was started at dosage of 2.5 μg/kg/min, iv. The dobutamine infusion was continued for 10 minutes, or until 4 or more premature ventricular complexes occurred within 15 seconds, or sustained narrow-complex tachyarrhythmia clearly not sinus in nature occurred. If the criteria for termination were not met, dobutamine infusion was increased by 2.5 μg/kg/min, after the hemodynamic variables had returned to baseline. The horses were allowed to recover, and were rested for at least 1 week before the second trial. The arrhythmogenic dose of dobutamine was calculated by multiplying the infusion rate by the elapsed time into infusion when arrhythmia occurred. There was significant difference between the arrhythmogenic dose of dobutamine (add) in saline-treated horses (mean ± sem, add = 105.6 ± 16.3 μg/kg) and atropimzed horses (add = 36.2 ± 8.7 μg/kg). There were no differences in the prearrhythmia or immediate postarrhythmia ventricular heart rate (hr) or systolic (sap), diastolic (dap), or mean (map) arterial pressures between treated and control groups. The change in hemodynamic variables from prearrhythmia to immediate postarrhythmia formation was not different between the 2 groups. Ventricular beats were clearly evident in 8 of the 12 arrhythmias meeting the criteria for establishing the add. These results indicate that atropine may lower the arrhythmogenic threshold for dobutamine in halothane-anesthetized horses.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether infusion of xylazine and ketamine or xylazine and propofol after sevoflurane administration in horses would improve the quality of recovery from anesthesia.

Animals—6 healthy adult horses.

Procedures—For each horse, anesthesia was induced by administration of xylazine, diazepam, and ketamine and maintained with sevoflurane for approximately 90 minutes (of which the last 60 minutes were under steady-state conditions) 3 times at 1-week intervals. For 1 anesthetic episode, each horse was allowed to recover from sevoflurane anesthesia; for the other 2 episodes, xylazine and ketamine or xylazine and propofol were infused for 30 or 15 minutes, respectively, after termination of sevoflurane administration. Selected cardiopulmonary variables were measured during anesthesia and recovery. Recovery events were monitored and subjectively scored.

Results—Cardiopulmonary variables differed minimally among treatments, although the xylazine-propofol infusion was associated with greater respiratory depression than was the xylazine-ketamine infusion. Interval from discontinuation of sevoflurane or infusion administration to standing did not differ significantly among treatments, but the number of attempts required to stand successfully was significantly lower after xylazine-propofol infusion, compared with the number of attempts after sevoflurane alone. Scores for recovery from anesthesia were significantly lower (ie, better recovery) after either infusion, compared with scores for sevoflurane administration alone.

Conclusions and Clinical Relevance—Xylazine-ketamine or xylazine-propofol infusion significantly improved quality of recovery from sevoflurane anesthesia in horses. Xylazine-ketamine or xylazine-propofol infusions may be of benefit during recovery from sevoflurane anesthesia in horses for which a smooth recovery is particularly critical. However, oxygenation and ventilation should be monitored carefully.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To assess the prevalence of medical errors (specifically, near misses [NMs] and adverse events [AEs]) and their personal and professional impact on veterinarians.

DESIGN Cross-sectional study.

SAMPLE Members of the Veterinary Information Network (n = 46,481).

PROCEDURES An electronic survey regarding veterinarians' experiences with NMs and AEs was distributed via email to an online veterinary community between September 24 and October 21, 2015. Responses were summarized and compared between genders by means of the χ2 test.

RESULTS 606 veterinarians completed the survey (1.3% response rate). Overall, 447 (73.8%) respondents reported involvement in ≥ 1 NM (n = 389 [64.2%]) or AE (179 [29.5%]). The NMs had a short-term (≤ 1 week) adverse impact on professional life for 68.0% (261/384) of respondents and longer-term negative impact for 36.4% (140/385). The impact on respondents' personal lives was similar (63.6% [245/385] and 33.5% [129/385], respectively). For AEs, these numbers were 84.1% (148/176), 56.2% (99/177), 77.8% (137/176), and 50.6% (89/175), respectively. Both NMs and AEs were more likely to negatively impact female veterinarians than male veterinarians.

CONCLUSIONS AND CLINICAL RELEVANCE These findings suggested that many veterinarians experience emotional distress after a medical error. Support should be provided to mitigate this adverse impact on the wellbeing of veterinarians and, potentially, their future patients.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To estimate the proportion of veterinarians working with feline patients in private practices who do or do not perform onychectomy and assess attitudes regarding and practices related to onychectomy in a large population of veterinary practitioners.

DESIGN Anonymous online survey.

SAMPLE 3,441 veterinarians.

PROCEDURES An online survey was provided to members of the Veterinary Information Network from June 18, 2014, through July 9, 2014. Descriptive statistics and frequency distributions for applicable response types were calculated, and Mann-Whitney U tests were conducted to compare responses to onychectomy-related opinion questions between respondents who indicated they did or did not perform the procedure. Not all respondents answered every question.

RESULTS 2,503 of 3,441 (72.7%) survey respondents reported performing onychectomy, and 827 (24.0%) indicated they did not; 1,534 of 2,498 (61.4%) performing the procedure reported a frequency of < 1 onychectomy/month. Most (2,256/3,023 [74.6%]) respondents who performed onychectomy indicated that they recommended nonsurgical alternatives. Surgical techniques and approaches to analgesia varied, with use of a scalpel only (1,046/1,722 [60.7%]) and perioperative administration of injectable opioids (1,933/2,482 [77.9%]) most commonly reported. Responses to opinion questions in regard to the degree of pain associated with onychectomy and recovery; whether declawing is a form of mutilation, is necessary in some cats for behavioral reasons, or is a necessary alternative to euthanasia in some cats; and whether state organizations should support a legislative ban on onychectomy differed significantly between respondents who did and did not perform the procedure.

CONCLUSIONS AND CLINICAL RELEVANCE Onychectomy is a controversial topic, and this was reflected in survey results. In this sample, most veterinarians performing the procedure reported that they did so infrequently, and most offered nonsurgical alternatives to the procedure.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To measure cardiac output in healthy female anesthetized dogs by use of lithium dilution cardiac output and determine whether changes in mean arterial pressure were caused by changes in cardiac output or systemic vascular resistance.

Design—Prospective clinical study.

Animals—20 healthy female dogs.

Procedure—Dogs were anesthetized for ovariohysterectomy. Ten dogs breathed spontaneously throughout anesthesia, and 10 dogs received intermittent positive-pressure ventilation. Cardiovascular and respiratory measurements, including lithium dilution cardiac output, were performed during anesthesia and surgery.

Results—Mean arterial pressure and systemic vascular resistance index were low after induction of anesthesia and just prior to surgery and increased significantly after surgery began. Cardiac index (cardiac output indexed to body surface area) did not change significantly throughout anesthesia and surgery.

Conclusions and Clinical Relevance—Results provide baseline data for cardiac output and cardiac index measurements during clinical anesthesia and surgery in dogs. Changes in mean arterial pressure do not necessarily reflect corresponding changes in cardiac index. (J Am Vet Med Assoc 2005;227:1419–1423)

Full access
in Journal of the American Veterinary Medical Association