RESUMEN
OBJECTIVE: To compare the speed and quality of induction of general anaesthesia using three different inhalant agents and one intravenous agent, in healthy dogs undergoing desexing surgery. MATERIALS AND METHODS: Less excitable dogs were not premedicated; others were premedicated with intramuscular acepromazine and morphine. Anaesthesia induction protocol was randomly assigned, with halothane, isoflurane or sevoflurane delivered by mask, or propofol delivered intravenously. Maximum vaporiser settings were used for inhalant inductions. Induction of anaesthesia was considered complete at the time of endotracheal intubation. Quality of induction was scored by the administering veterinarian. RESULTS: Seventy-one dogs were enrolled. Twenty-four received no premedication and 47 received premedication. Isoflurane inductions were significantly faster than halothane inductions (2.86 +/- 0.25 vs 3.71 +/- 0.22 min; mean +/- SE, P = 0.013). Sevoflurane inductions (3.29 +/- 0.24 min) were not significantly different from either halothane (3.71 +/- 0.22 min, P = 0.202) or isoflurane inductions (2.86 +/- 0.25 min, P = 0.217). Induction with propofol (1.43 +/- 0.13 min) was significantly faster than inhalant induction (P < 0.001 in each case). Premedication decreased the dose requirement and time to induction for dogs induced with propofol, but did not significantly change the time to intubation for inhalant inductions. Dogs administered propofol and/or premedication were significantly more likely to have an excellent quality of induction, but there was no difference between inhalant agents in terms of induction quality. CONCLUSION: Sevoflurane possesses chemical properties that should produce a more rapid induction of anaesthesia in comparison to halothane or isoflurane. However, in clinical practice patient related factors outweigh this improvement.
Asunto(s)
Anestesia por Inhalación/veterinaria , Anestesia Intravenosa/veterinaria , Anestésicos por Inhalación/administración & dosificación , Anestésicos Intravenosos/administración & dosificación , Perros/fisiología , Propofol/administración & dosificación , Animales , Perros/cirugía , Femenino , Halotano/administración & dosificación , Intubación Intratraqueal/veterinaria , Isoflurano/administración & dosificación , Masculino , Éteres Metílicos/administración & dosificación , Sevoflurano , Factores de Tiempo , Resultado del TratamientoRESUMEN
OBJECTIVE: To discern the effects of anaesthesia protocols and decreasing core body temperature on time to recovery from general anaesthesia. MATERIALS AND METHODS: Healthy adult dogs undergoing desexing surgery were enrolled. More excitable dogs were premedicated with intramuscular acepromazine and morphine; calmer dogs were not premedicated. Anaesthesia was induced using halothane, isoflurane or sevoflurane delivered by mask, or by intravenous propofol, and maintained in standard fashion using one of the three inhalant agents. Thermostat controlled heat mats were used during surgical preparation and surgery. Oesophageal temperature was recorded throughout surgery. The time from cessation of anaesthetic administration until the dog successfully raised itself to sternal recumbency was considered the time of recovery. RESULTS: Sixty-nine dogs completed the study, 42 males anaesthetised for 60.4 +/- 20.5 min, and 27 females anaesthetised for 85.4 +/- 33.2 min. Oesophageal temperature at the end of surgery was 36.8 +/- 0.80 degrees C. Oesophageal temperature had a significant effect on recovery time, with lower temperatures contributing to slower recoveries. Premedication significantly lengthened recovery times. The choice of induction or maintenance anaesthetic agent had no effect on recovery time. DISCUSSION: Hypothermia is a common complication of general anaesthesia and surgery. Amongst other deleterious effects, it is associated with slower recovery from anaesthesia, likely due to a number of different mechanisms.