A 5-year-old male-castrated Cocker Spaniel presented to the Veterinary Teaching Hospital of the University of Georgia for a total ear canal ablation. Premedication was with carprofen 2.2？mg/kg SQ, hydromorphone 0.1？mg/kg IM, diazepam 0.2？mg/kg IM, and glycopyrrolate 0.01？mg/kg IM. The patient was induced with lidocaine 2？mg/kg IV and etomidate 1？mg/kg IV and maintained with sevoflurane and a constant rate infusion consisting of lidocaine 0.05？mg/kg/min. Before surgery start, the patient’s systolic arterial blood pressure was 110？mmHg, heart rate (HR) was 85 beats/min, respiratory rate was 8 breaths/min, end-tidal sevoflurane concentration was 3.2%, and end-tidal CO2 (ETCO2) was 23？mmHg. As a scrub was being performed, the patient’s HR abruptly dropped to 20 beats/min over the course of 2 minutes. His ETCO2 simultaneously decreased to 16？mmHg. At this time, cardiopulmonary arrest was diagnosed. After two minutes of resuscitation, a spontaneous heart beat was obtained and the patient was successfully recovered and discharged without further incident. The cardiac arrest in this case is most likely attributable to an overdose of inhalant anesthesia, which was diagnosed by an anesthetic inhalant concentration monitor. A gas analyzer may be a helpful contribution to the small animal practitioner, particularly those performing more lengthy or complex procedures. 1. Introduction Anesthesia in pet dogs can be associated with intraoperative fatality due to the anesthesia. In people, the incidence of anesthetic-related arrest is approximately 1 in 40,000 patients [1]. In small animals, this value has been estimated at 2 in 1,000 [2], which represents a significantly greater risk than in people. In dogs undergoing anesthesia, successful return of spontaneous circulation occurs in approximately 50% of patients, indicating an anesthetic-related mortality rate of 1 in 1,000 [2]. The incidence of anesthetic arrest in small animals in general practice is unknown, but the incidence of peri-operative fatality in dogs has been estimated at 2 in 100, which reflects a marked increase compared to a university setting [2, 3]. It is possible that this difference is due to increased expertise at an institution, increased vigilance, or greater monitoring technology and interventional capabilities. A gas analyzer is a device that is equipped to measure end-tidal concentrations of various gasses and vapors, notably CO2 and halogenated inhalant anesthetics [4]. A number of technologies can be used to determine this information, with the most simple being infra-red, whereby infra-red
References
[1]
C. C. P. Eagle and N. J. Davis, “Report of the anaesthetic mortality committee of Western Australia 1990–1995,” Anaesthesia and Intensive Care, vol. 25, no. 1, pp. 51–59, 1997.
[2]
E. H. Hofmeister, B. M. Brainard, C. M. Egger, and S. Kang, “Prognostic indicators for dogs and cats with cardiopulmonary arrest treated by cardiopulmonary cerebral resuscitation at a university teaching hospital,” Journal of the American Veterinary Medical Association, vol. 235, no. 1, pp. 50–57, 2009.
[3]
D. C. Brodbelt, K. J. Blissitt, R. A. Hammond et al., “The risk of death: the confidential enquiry into perioperative small animal fatalities,” Veterinary Anaesthesia and Analgesia, vol. 35, no. 5, pp. 365–373, 2008.
[4]
J. A. Dorsch and S. E. Dorsch, “Gas monitoring,” in Understanding Anesthesia Equipment, J. A. Dorsch and S. E. Dorsch, Eds., pp. 679–750, Williams & Wilkins, Philadelphia, Pa, USA, 4th edition, 1999.
[5]
J. Weaver, “The latest ASA mandate: CO2 monitoring for moderate and deep sedation,” Anesthesia Progress, vol. 58, no. 3, pp. 111–112, 2011.
[6]
A. K. J. Parviainen and C. M. Trim, “Complications associated with anaesthesia for ocular surgery: a retrospective study 1989–1996,” Equine Veterinary Journal, vol. 32, no. 6, pp. 555–559, 2000.
[7]
J. P. Fast, M. G. Perkins, R. A. Pearce, and S. Mecozzi, “Fluoropolymer-based emulsions for the intravenous delivery of sevoflurane,” Anesthesiology, vol. 109, no. 4, pp. 651–656, 2008.
[8]
J.-X. Zhou, N.-F. Luo, X.-M. Liang, and J. Liu, “The efficacy and safety of intravenous emulsified isoflurane in rats,” Anesthesia and Analgesia, vol. 102, no. 1, pp. 129–134, 2006.
[9]
E. H. Hofmeister, B. M. Brainard, L. M. Sams, D. A. Allman, and A. M. Cruse, “Evaluation of induction characteristics and hypnotic potency of isoflurane and sevoflurane in healthy dogs,” American Journal of Veterinary Research, vol. 69, no. 4, pp. 451–456, 2008.
[10]
R. H. de Jong and E. I. Eger II, “MAC expanded. AD50 and AD50 values of common inhalation anesthetics in man,” Anesthesiology, vol. 42, no. 4, pp. 384–389, 1975.
[11]
J. Wilson, T. J. Doherty, C. M. Egger, A. Fidler, S. Cox, and B. Rohrbach, “Effects of intravenous lidocaine, ketamine, and the combination on the minimum alveolar concentration of sevoflurane in dogs,” Veterinary Anaesthesia and Analgesia, vol. 35, no. 4, pp. 289–296, 2008.
[12]
W. W. Muir III, A. J. Wiese, and P. A. March, “Effects of morphine, lidocaine, ketamine, and morphine-lidocaine-ketamine drug combination on minimum alveolar concentration in dogs anesthetized with isoflurane,” American Journal of Veterinary Research, vol. 64, no. 9, pp. 1155–1160, 2003.
