Hemorrhagic shock in the rat: comparison of carotid and femoral cannulation.

BACKGROUND

The reservoir model of rat hemorrhagic shock is widely used. In this model, either the carotid or femoral artery can be cannulated to withdraw blood and measure pressure. In animals undergoing hemorrhage using the carotid approach, we observed seizure activity during the post-shock period, suggesting some degree of brain damage. The hypothesis of the present study is that survival in a model of severe hemorrhagic shock would be higher with femoral cannulation than with carotid cannulation.

MATERIALS AND METHODS

All animals (n = 90) were anesthetized with isoflurane using an anesthesia vaporizer while breathing spontaneously. In group 1, the left carotid artery and jugular vein were cannulated; in group 2, the left femoral artery and vein were cannulated. Following a period of hemorrhagic shock (20 to 30 mmHg for 30, 60, or 50-90 min), resuscitation was performed through the venous cannula by giving L-lactated Ringer's (21 mL/kg) and returning the shed blood.

RESULTS

In the carotid cannulation group, nearly 50% of the animals had seizures after resuscitation, and most of those animals died following the seizures. The 24-h survival rate in the femoral artery cannulation group was significantly higher than in the carotid artery cannulation group. Femoral cannulated animals had no seizures following reperfusion.

CONCLUSIONS

Femoral artery cannulation was associated with considerably better survival than carotid artery cannulation in this rodent model of hemorrhagic shock. The occurrence of seizures in animals undergoing carotid cannulation suggests brain damage from inadequate cerebral perfusion or subsequent reperfusion damage.