Effect of i.v. Atropine on Cardiac Rhythm, Heart Rate, Blood Pressure and Airway Secretion during Isoflurane Anaesthesia

Atropine, 0.01 mg kg-1, was given i.v. to 30 patients before mask anaesthesia with isoflurane. Controls (n = 28) received a placebo. ECG was recorded on tape throughout anaesthesia and analysed later. There were no ventricular arrhythmias, but six patients in the atropine group and two patients in the placebo group had supraventricular arrhythmias of very short duration. Most cases occurred shortly after atropine, i.e. before anaesthesia. Heart rate increased significantly in both groups, more so after atropine (up to 60%), and remained elevated. In both groups blood pressure fell after the induction of anaesthesia but was close to control during surgery. Suction of airway secretions was necessary in three placebo patients, but excessive secretions were not met. The frequency of airway reflexes was similar in the two groups. It is concluded that due to the pronounced tachycardia the routine use of i.v. atropine can hardly be recommended before mask anaesthesia with isoflurane.