Recombinant human activated protein C improves pulmonary function in ovine acute lung injury resulting from smoke inhalation and sepsis

Marc O. Maybauer, Dirk M. Maybauer, John F. Fraser, Lillian D. Traber, Martin Westphal, Perenlei Enkhbaatar, Robert Cox, Ruksana Huda, Hal Hawkins, Naoki Morita, Kazunori Murakami, Akio Mizutani, David Herndon, Daniel L. Traber

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


OBJECTIVE: To investigate the effects of recombinant human activated protein C (rhAPC) on pulmonary function in acute lung injury (ALI) resulting from smoke inhalation in association with a bacterial challenge. DESIGN: Prospective, randomized, controlled, experimental animal study with repeated measurements. SETTING: Investigational intensive care unit at a university hospital. SUBJECTS: Eighteen sheep (37.2 ± 1.0 kg) were operatively prepared and randomly allocated to either the sham, control, or rhAPC group (n = 6 each). After a tracheotomy had been performed, ALI was produced in the control and rhAPC group by insufflation of 4 sets of 12 breaths of cotton smoke. Then, a 30 mL suspension of live Pseudomonas aeruginosa bacteria (containing 2-5 × 10 colony forming units) was instilled into the lungs according to an established protocol. The sham group received only the vehicle, i.e., 4 sets of 12 breaths of room air and instillation of 30 mL normal saline. The sheep were studied in the awake state for 24 hrs and were ventilated with 100% oxygen. RhAPC (24 μg/kg/hr) was intravenously administered. The infusion was initiated 1 hr post-injury and lasted until the end of the experiment. The animals were resuscitated with Ringer's lactate solution to maintain constant pulmonary artery occlusion pressure. MEASUREMENTS AND MAIN RESULTS: In comparison with nontreatment in controls, the infusion of rhAPC significantly attenuated the fall in Pao2/Fio2 ratio (control group values were 521 ± 22 at baseline [BL], 72 ± 5 at 12 hrs, and 74 ± 7 at 24 hrs, vs. rhAPC group values of 541 ± 12 at BL, 151 ± 29 at 12 hours [p < .05 vs. control], and 118 ± 20 at 24 hrs), and significantly reduced the increase in pulmonary microvascular shunt fraction (Qs/Qt; control group at BL, 0.14 ± 0.02, and at 24 hrs, 0.65 ± 0.08; rhAPC group at BL, 0.24 ± 0.04, and at 24 hrs, 0.45 ± 0.02 [p < .05 vs. control]) and the increase in peak airway pressure (mbar; control group at BL, 20 ± 1, and at 24 hrs, 36 ± 4; rhAPC group at BL, 21 ± 1, and at 24 hrs, 28 ± 2 [p < .05 vs. control]). In addition, rhAPC limited the increase in lung 3-nitrotyrosine (after 24 hrs [%]: sham, 7 ± 2; control, 17 ± 1; rhAPC, 12 ± 1 [p < .05 vs. control]), a reliable indicator of tissue injury. However, rhAPC failed to prevent lung edema formation. RhAPC-treated sheep showed no difference in activated clotting time or platelet count but exhibited less fibrin degradation products (1/6 animals) than did controls (4/6 animals). CONCLUSIONS: Recombinant human activated protein C attenuated ALI after smoke inhalation and bacterial challenge in sheep, without bleeding complications.

Original languageEnglish (US)
Pages (from-to)2432-2438
Number of pages7
JournalCritical care medicine
Issue number9
StatePublished - Sep 2006


  • 3-nitrotyrosine
  • Acute lung injury
  • Acute respiratory distress syndrome
  • Airway
  • Nitric oxide
  • Septic shock
  • Sheep

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine


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