Changes of Lung Compliance in Pediatric Patients after Surgical Correction of Left to Right Shunt

Background: Low values of lung compliance have been reported in patients with increased pulmonary blood flow due to intracardiac left to right(L-R) shunt. The compliance had returned to within normal limits 4 to 6 weeks after surgical correction of the shunt. We investigated whether lung compliance was improved immediately after surgical correction of the shunt. Methods: Fifty four pediatric patients who were undergoing repair of intracardiac L-R shunt were evaluated. Lung compliance, arterial oxygen tension(PaO2) and arterial to end-tidal carbon dioxide tension difference(Pa-ETCO2) were measured after induction of anesthesia and at the completion of surgery. Left atrial pressure(LAP) was monitored. Lung compliance and end-tidal carbon dioxide tension were measured by monitoring system built in Cato anesthetic ventilator system. Results: Lung compliance was significantly lower after surgery(6.57±6.46 ml/mbar) than after induction of anesthesia(7.71±7.18 ml/mbar). After surgery, PaO2 was significantly decreased and Pa-ETCO2 significantly increased than after induction of anesthesia. The decrease in lung compliance after surgery significantly correlated with a decrease in PaO2(r=0.43) and an increase in Pa-ETCO2 (r=0.47) but not correlated with LAP. Conclusions: Although surgical correction of intracardiac L-R shunt reduces pulmonary blood flow, the lung compliance decreases in immediate postoperative period. Therefore a deterioration of postoperative lung compliance may need judicious management for pulmonary and hemodynamic instability.ope