Systemic Administration of Carbon Monoxide-Releasing Molecule-3 Protects the Skeletal Muscle in Porcine Model of Compartment Syndrome

Objectives: Acute limb compartment syndrome, a complication of musculoskeletal trauma, results in muscle necrosis and cell death. Carbon monoxide, liberated from the carbon monoxide-releasing molecule-3, has been shown protective in a rat model of compartment syndrome. The purpose of this study was to test the effect of carbon monoxide-releasing molecule-3 in a preclinical large animal model of compartment syndrome, with the ultimate goal of developing a pharmacologic adjunct treatment for compartment syndrome. Design: Animal research study. Setting: Basic research laboratory in a hospital setting. Subjects: Male Yorkshire-Landrace pigs (50-60kg). Interventions: Pigs underwent 6 hours of intracompartmental pressure elevation by infusing fluid into the anterior compartment of the right hind limb. Carbon monoxide-releasing molecule-3 was administered systemically (2mg/kg, IV) at fasciotomy, followed by 3-hour reperfusion. Measurements and Main Results: Muscle perfusion, inflammation, injury, and apoptosis were assessed in the skeletal muscle. Systemic leukocyte activation was assessed during compartment syndrome and reperfusion. Elevation of hind limb intracompartmental pressure resulted in significant microvascular perfusion deficits (44% 1% continuously perfused capillaries in compartment syndrome vs 76% +/- 4% in sham; p < 0.001), increased tissue injury (ethidium bromide/bisbenzimide of 0.31 +/- 0.07 in compartment syndrome vs 0.17 +/- 0.03 in sham; p < 0.05), apoptosis (fluorescence in vivo/bisbenzimide of 0.26 +/- 0.06 in compartment syndrome vs 0.13 +/- 0.03 in sham; p < 0.05), and systemic leukocyte activation (14.7 relative luminescence units/10(6) polymorphonuclear leukocytes in compartment syndrome vs 1.0 +/- 0.1 in baseline; p < 0.001). Systemic application of carbon monoxide-releasing molecule-3 at fasciotomy increased the number of continuously perfused capillaries (68% +/- 3%; p < 0.001), diminished tissue injury (ethidium bromide/bisbenzimide of 0.13 +/- 0.04; p < 0.05), apoptosis (fluorescence in vivo/bisbenzimide of 0.12 +/- 0.03; p < 0.05), and blocked systemic leukocyte activation (3.9 +/- 0.3 relative luminescence unit/10(6) polymorphonuclear leukocytes; p < 0.001). Conclusions: Administration of carbon monoxide-releasing molecule-3 at fasciotomy offered protection against compartment syndrome-induced microvascular perfusion deficit, tissue injury, and systemic leukocyte activation. The data suggest the potential therapeutic application of carbon monoxide-releasing molecule-3 to patients at risk of developing compartment syndrome.