Investigation of efficacy of dexmedetomidine on acute lung injury in experimental lower limb ischemia-reperfusion model

Objective: Dexmedetomidine is an ?2-agonist which is suggested for the short-term sedation in intubated and mechanically ventilated patients monitored in intensive care units. The anti-inflammatory effects of dexmedetomidine have been showed in limited number of studies. The aim of this study is to investigate the efficacy of different doses of dexmedetomidine on acute lung injury in rat lower limb tourniquet-induced ischemia-reperfusion model.Method: Three hours of ischemia and three hours of reperfusion were applied by tourniquet to left lower limb of anesthetized female Wistar rats. Four groups, each consisting of 7 rats were included in the study. Subjects were grouped as, Group 1 (SHAM, n=7), Group 2 (I-R, n=7), Group 3 (I-R, 50 µg/kg Dexmedetomidine, n=7), Group 4 (I-R, 100 µg/kg Dexmedetomidine, n=7). Fifty µg/kg of dexmedetomidine in Group 3 and 100 µg/kg of dexmedetomidine in Group 4 were administered via intraperitoneal route at the 2nd hour of ischemia. At the end of the 1st hour of reperfusion, blood samples were collected from the subjects of all groups. At the end of the three hour reperfusion time blood and tissue samples were collected following thoracotomy from all anesthetized rats. TNF-? and IL-6 concentrations were assessed by ELISA method. Histopathological examination was assessed by light microscopy. Lung injury identifying criteria were scored between 0-4.Scoring system:0: no injury1: Injury up to 25 % of the area2: Injury of 25-50 % of the area3: Injury of 50-75 % of the area4: Diffuse injuryResults: There were no significant differences in serum TNF-? and IL-6 levels among groups. Lung injury scores were significantly different among groups (p=0,000). Histopathological scores of only ischemia-reperfusion generated group were significantly different than Group 1 (p=0,001), Group 3 (p=0,001) and Group 4 ( p=0,001). Furthermore, the scores of Group 1 were significantly different than Group 3 (p=0,001) and Group 4 (p=0,011). There were no significant difference in lung scores between different dose groups of dexmedetomidine.Conclusion: In this experimental lower limb tourniquet study, we concluded that dexmedetomidine is effective to decrease acute lung injury due to ischemia-reperfusion in this model.Keywords: Experimental, dexmedetomidine, reperfusion injury, acute lung injury