Cardiopulmonary bypass does not induce lung dysfunction after pulmonary thrombarterectomy: role of pulmonary compliance

OBJECTIVES: Pulmonary endarterectomy is a heavy surgical procedure that is performed under cardiopulmonary bypass (CPB) and aimed to cure postembolic pulmonary hypertension. Reperfusion oedema is both the hallmark of successful surgical procedure and the most frequent postoperative complication. Post-CPB lung dysfunction was not mentioned in any report. We undertook a study to determine whether post-CPB lung dysfunction was present in these patients. METHODS: In a retrospective cohort study with matching on some baseline covariates, we selected 41 patients who had undergone pulmonary endarterectomy and in whom pre-, intra- and postoperative records were complete. The control group was composed of 39 patients operated on from elective cardiac surgery during the same period and matched with a study group for age, gender, body mass index, blood creatinine, diabetes and baseline partial pressure of oxygen/fraction of inspired oxygen ratio. Criteria for post-CPB lung dysfunction were partial pressure of oxygen/fraction of inspired oxygen ratio decrease and bilateral basal oedema. Explanatory variables for post-CPB lung dysfunction were coronary arterial bypass, pleura opening, static pulmonary compliance measured at the time of thorax closed then retracted, fluid infusion, transfusion and vasopressors. RESULTS: All patients operated on from pulmonary endarterectomy presented radiological oedema reperfusion in surgical unblocking areas. Among them, only 2 had bilateral basal oedema when compared to the 24 patients from the control group (P < 0.001). Partial pressure of oxygen/fraction of inspired oxygen ratio increased in the study group and decreased in the control group (30 ± 109 vs -67 ± 134 mmHg, P < 0.001). Control group patients with high-baseline pulmonary compliance were at risk for post-CPB lung dysfunction. CONCLUSIONS: Patients operated on from pulmonary endarterectomy were saved from post-CPB lung dysfunction. The latter could be induced by a mechanical phenomenon.