Effect of fluid resuscitation on acute skeletal muscle ischemia-reperfusion injury after hemorrhagic shock in rats.

BACKGROUND

Severe extremity wounds with vascular injury are common in military trauma, and tourniquets are commonly used for hemorrhage control. The complications of tourniquet use in the setting of trauma are not well studied. This study investigated the combined effect of hemorrhagic shock and fluid resuscitation with Hextend (HX; BioTime, Inc) or lactated Ringer's (LR) on skeletal muscle subjected to tourniquet-induced ischemia-reperfusion injury.

STUDY DESIGN

Thirty male Sprague-Dawley rats underwent 33% arterial hemorrhage followed by 3 hours of tourniquet application. Before reperfusion, 10 animals each were resuscitated with lactated Ringer's (3 times shed volume) or HX (shed volume). Ten control animals received no resuscitation. Rats were euthanized 2 hours after tourniquet release and the tibialis anterior and medial gastrocnemius muscles were examined for edema (muscle wet weight) and viability (nitroblue tetrazolium reduction). Contralateral muscles served as controls for each animal, with results expressed as the ratio of the tourniquet limb to contralateral limb values.

RESULTS

The tibialis anterior and medial gastrocnemius muscles in all groups experienced edema, with all weight ratios greater than one. Resuscitation with HX resulted in significantly (p < 0.05) greater edema than did no resuscitation in both muscles and greater edema than with lactated Ringer's in the medial gastrocnemius. All groups experienced a loss of viability as well, with nitroblue tetrazolium reduction ratios less than one. Resuscitation with HX resulted in significantly less viability loss than did no resuscitation in the medial gastrocnemius. No significant differences in viability were seen in the tibialis anterior.

CONCLUSIONS

Resuscitation with HX or lactated Ringer's does not adversely affect muscle viability in ischemia-reperfusion injury. HX may be a better clinical choice when skeletal muscle ischemia-reperfusion injury is a risk, despite greater edema.