PULMONARY-FUNCTION CHANGES DURING EPIDURAL-ANESTHESIA FOR CESAREAN DELIVERY

Although changes in pulmonary function in parturients are documented, little is known about effects of regional anesthesia on these changes. This study was undertaken to determine if two local anesthetics, ofte n used for epidural anesthesia for cesarean delivery, have different e ffects on pulmonary function testing. Nineteen ASA physical status I p arturients undergoing elective cesarean delivery with epidural anesthe sia were randomly assigned in double-blind fashion to receive either 0 .5% bupivacaine or 2% lidocaine with epinephrine (1/200,000). Pulmonar y function tests were measured using a calibrated spirometer with comp uter-recorded flow volume loops. Peak inspiratory pressure and peak in spiratory flow rate, peak expiratory pressure (PEP) and peak expirator y flow rate, forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV(1)) were measured. Measurements were taken prior to epidu ral placement and at T-10 and T-4 levels. Peak inspiratory pressure, F EV(1)/FVC, FEV(1), FVC, peak expiratory flow rate, and peak inspirator y flow rate did not differ from baseline in either group. Patients rec eiving lidocaine showed a significantly greater decrease in PEP at bot h T-10 and T-4 levels. PEP is largely dependent on abdominal musculatu re. If a denser motor block is provided by 2% lidocaine with epinephri ne than by 0.5% bupivacaine, these muscles would be more affected, res ulting in a greater decrease in PEP. These results may have implicatio ns regarding choice of local anesthetic for epidural anesthesia in par turients with some degree of respiratory compromise undergoing cesarea n delivery.