Preoperative Treatment with Recombinant Human Growth Hormone Prevents Ischemia Reperfusion-Induced Diaphragmatic Dysfunction

Abstract

Background. Respiratory complications continue to be a major cause of morbidity and mortality following major vascular surgery. The recent UK Small Aneurysm Trial cited preoperative respiratory function as the major predictor of outcome following elective aortic surgery.Aim. The aim of this study was to investigate the effect of aortic clamping and revascularization on diaphragmatic muscle function in a small animal model and to evaluate the role of preoperative treatment with recombinant human growth hormone (rhGH) in preventing diaphragmatic muscle dysfunction.Methods. Male Sprague-Dawley rats (n = 18) were randomized into one of three groups: control (n = 6) underwent laparotomy only; IR (n = 6) had a laparotomy with infrarenal cross-clamping for 30 min followed by lower torso revascularization for 2 h; IR + rhGH (n = 6) were treated with rhGH (Genotropin 0.3 IU/kg/day) for 5 days before laparotomy and aortic cross-clamping for 30 min followed by lower torso revascularization for 2 h. Diaphragmatic muscle contractile function was assessed ex vivo using electrical field stimulation in a tissue bath.Results. Two hours of IR injury resulted in a significant impairment in diaphragmatic twitch (Control, 242.01 + 38.45 g; IR, 108.55 + 7.15 g). This impairment was prevented by pretreatment with rhGH (rhGH, 319.14 + 30.71 g; P < 0.01). Tetanic function was also significantly impaired by ischemia reperfusion injury (control, 605 + 77.63 g; IR, 228.12 + 14.38 g). Again, pretreatment with rhGH prevented this deterioration (IR + rhGH, 704.39 + 45.69 g; P < 0.05) compared with controls.Conclusion. The results of this study suggest that preoperative administration of rhGH may have a role in preventing the diaphragmatic dysfunction associated with infrarenal aortic cross-clamping and revascularization.