Asymmetric ARDS following pulmonary resection: CT findings - Initial observations

PURPOSE: To investigate whether asymmetric distribution of acute respiratory distress syndrome (ARDS) following lobectomy is due to compensatory hyperexpansion of the residual lung within the hemithorax operated on and to discern if this distribution reflects true asymmetry of the disease process. MATERIALS AND METHODS: Retrospective review of the intensive care unit. database was performed over a period of 6 years to identify all cases of lung injury following lung surgery that satisfied the American-European consensus criteria for ARDS. Time to onset following surgery, time of subsequent computed tomographic (CT) examination, patient age and sex, and nature of surgery were recorded as well, as eventual patient status (le, death or discharge). Availability of both preoperative and postoperative CT scans was required for inclusion for further analysis. These images were analyzed on a commercial CT workstation for the volume of lung resected and the pre- and postoperative volume and density of each lung. Expected postoperative densities (preoperative density adjusted for volume) were compared with observed postoperative densities. RESULTS: Review disclosed 583 patients who underwent lobectomy or segmentectomy, Seventeen patients (2.9%) developed postoperative ARDS. Nine of these patients had pre- and postoperative CT scans available for analysis. In eight of nine cases, density increased more in the nonoperated lung than in the operated lung (P = .01). The degree of density increase in the nonoperated lung was significantly greater (305 mg/mL; range, 48-449 mg/mL than that in the operated lung (13 mg/mL; range, - 198 to 231 mg/mL; P < .001). CONCLUSION: Following lobectomy, there appears to be a truly asymmetric form of ARDS rather than compensatory hyperexpansion of the residual lung on the operated side. (C) RSNA, 2002.