Extracorporeal lung membrane provides better lung protection than conventional treatment for severe postpneumonectomy noncardiogenic acute respiratory distress syndrome

Abstract

We compared conventional treatment with pumpless extracorporeal lung membrane (Interventional Lung Assist [iLA] Novalung; Novalung GmbH, Hechingen, Germany) support in a pig model of postpneumonectomy severe acute respiratory distress syndrome. Adult pigs underwent a left thoracotomy without (group I) or with a left extrapericardial pneumonectomy and radical lymphadenectomy (groups II to V). After stabilization, pigs belonging to group II were observed only, whereas in those belonging to groups III to V, a surfactant-depletion severe (Pao(2)/Fio(2) < 100) postpneumonectomy acute respiratory distress syndrome was induced. This was followed by observation (group III); treatment with conventional therapy including protective ventilation, steroids, and nitric oxide (group IV); or femoral arteriovenous iLA Novalung placement, near-static ventilation, steroids, and nitric oxide (group V). Each group included 5 animals. Primary outcome was extubation 12 hours postoperatively or postpneumonectomy acute respiratory distress syndrome. A severe postpneumonectomy acute respiratory distress syndrome was obtained after 9 +/- 2 alveolar lavages over 90 +/- 20 minutes. In group V pigs, the iLA Novalung device diverted 17% +/- 4% of the cardiac output, permitted an oxygen transfer and carbon dioxide removal of 298.4 +/- 173.7 mL/min and 287.7 +/- 87.3 mL/min, respectively, and static ventilation (tidal volume, 2.2 +/- 1 mL/kg; respiratory rate, 6 +/- 2.9 breaths/min). All but 1 pig belonging to group V could be extubated compared with none in groups III and IV (P < .01), and only their lungs normalized cytokine release (P < .001) and surfactant (P < .03) and displayed fewer parenchymal lesions (P < .05). The pumpless extracorporeal lung membrane and near-static ventilation achieved a significantly better outcome than conventional treatment in this pig model of severe postpneumonectomy acute respiratory distress syndrome, probably because the injured lungs were not forced to work and this "rest" gave them more time to heal.