The Effects of Intravenous Injection of Atropine on Airway Pressure, Respiratory Compliance and Resistance in Normal Subjects during General Anesthesia / 대한마취과학회지

ABSTRACT

Atropine, an anticholinergic agent, has bronchodilating effects, so it had been used to treat bronchospasm. But, bronchodilating effects in normal man is controversial. In this study, after anesthetizing patients who did not have any respiratory disease, intravenous injection of atropine to the subjects was done, and then we monitored airway pressures to see the changes in respiratory mechanics indirectly. ASA physical status class 1 or 2 patients were studied. Without premedication, intravenous injection of fentanyl 3 mcg/kg, midazolam 0.1 mg/kg, thiopental 3 mg/kg and vecuronium 0.15 mg/kg was done consecutively. Ventilation was controlled by face mask with O2-N2O(50%)-isoflurane( < 0.5 vo1.%) for 5 minutes with closed circuit anesthetic machine(Physio-Flex) and then intubation was done. After intubation anesthesia was maintained with O2-N2O(50%)-isoflurane( < 0.5 voL%) and ventilation was controlled with tidal volume 9 ml/kg, respiratory rate 11/min and inspiratory tlow rate was maintained constantly for each subject. When airway pressure was stabilized, atropine 0.015 mg/kg was injected intravenously. Thereafter, for 20 minutes peak airway pressure(P), plateau pressure(P(peak)), mean airway pressure(P(plateau)), mean arterial pressure and heart rate were monitored every minute interval. And we calculated dynamic compliance, static compliance and resistance of total respiratory system. Atropine produced significant decrease in P(peak) and increase in dynamic compliance but did not produce significant changes in P(plateau) P(mean) , and static compliance and resistance. In CONCLUSION, atropine has bronchodilating effect in normal subjects anesthetized with isoflurane of low concentration.