Anaesthetic and electrocardiograpic profiles in prolonged inhalation anaesthesia in Nigerian indigenous dogs

Abstract

Electrocardiograph during anaesthesia provides information on cardiac electrical activity which may affect cardiac function. This study was carried out to evaluate the effect of prolonged volatile anaesthesia using halothane and isoflurane on the electrographic and anaesthetic profiles in Nigerian dogs. They were prepared for anaesthesia and connected to a 5-lead patient monitor (GMI®). Venous access was secured and lactated ringer's solution administered at a maintenance flow rate of 5mlkghr-1.Tracheae were intubated following induction with thiopentone and anaesthesia maintained with 0.5% halothane (group A) and 2.0% isoflurane (group B) in 2liters/minute oxygen respectively with the animals breathing spontaneously. The readings were taken, prior to induction of anaesthesia (control) and every 30 minutes thereafter for six hours during anaesthesia. Data were presented as mean and standard deviation.Differences were considered significant at p≤0.05. The values of ST segment (sec) and P-waves (sec) were both low, 0.068 ± 0.013 and 0.064 ± 0.017 and 0.020 ± 0.001 and 0.020 ± 0.001 respectively for isoflurane and halothane. However the values of P-waves (mV) and P-R intervals (sec) were significantly higher in group A, (0.193 ±0.136 and 0.046 ±0.01) compared to group B, 0.193 ± 0.98 and 0.039 ± 0.01 respectively. Isoflurane produced prolongation of Q-T intervals (sec) and QRS complex (sec), 0.123 ± 0.018 and 0.023 ± 0.008 compared to halothane, 0.121 ± 0.023 and 0.021 ± 0.005. The ECG parameters measured revealed no adverse effect of halothane or isoflurane on the heart in Nigerian local dogs.There was prolonged QT interval in group B. In conclusion, halothane appears a better drug of choice in prolonged anaesthesia in Nigerian dogs.