BACKGROUND: Bilateral interruption of the upper thoracic sympathetic chain at T2 level represents a selective cure for essential hyperhidrosis. Following the surgical sympathectomy, significant changes in pulmonary function has been observed. Our hypothesis was that thoracic sympathectomy may increase airway resistance during mechanical ventilation and which may be attenuated by the anticholinergics. METHODS: 21 patients with essential hyperhidrosis in ASA physical status class 1 under going thoracoscopic sympathectomy, they were randomizely divided into two groups: glycopyrrolate premedication group (n=13) and non-premedication, control group (n=9). Glycopyrrolate 0.2 mg was administered 30 minutes before the induction of anesthesia. Blood pressure, heart rate, peak airway pressure, plateau pressure were measured at before and immediate after sympathectomy. Respiratory compliance and resistance were calculated. RESULTS: After thoracoscopic sympathectomy, there was significant increase in mean peak airway pressure (15 +/- 3 vs 18 +/- 3 cmH2O, P<0.05) and decrease in respiratory compliance (52 +/- 12 vs 45 +/- 10 ml/cmH2O, P<0.05) compared to baseline. However there was no significant difference between glycopyrolate premedication group and non-premedication group. Conclusion: Thoracoscopic upper dorsal sympathectomy in patients with essential hyperhidrosis causes increase peak airway pressure and decrease the compliance of respiratory system during mechanical ventilation.