Conjunctival microcirculation is associated with cerebral cortex microcirculation in post-resuscitation mild hypothermia: A rat model.

Abstract

This study aimed to compare the changes in sublingual and conjunctival microcirculation occurring with cerebral cortex microcirculation changes during mild hypothermia in a rat model of cardiac arrest. Twenty-four rats were randomized into mild hypothermia (M) or normothermia (C) groups. Ventricular fibrillation was electrically induced and left untreated for 8minutes, followed by 8minutes of cardiopulmonary resuscitation. The core temperature in group M reduced to 33±0.5°C at 13minutes after restoration of spontaneous circulation and was maintained for 8hours. In group C, the core temperature was maintained at 37±0.2°C. The hemodynamics and microcirculation in the sublingual region, bulbar conjunctiva, and cerebral cortex were measured at baseline and 1, 2, 3, 4, 6, and 8hours after restoration of spontaneous circulation. The M group showed significantly worse sublingual microcirculation at 6hours post-resuscitation. However, microcirculation in the conjunctiva and cerebral cortex at 3hours post-resuscitation were better in the M group. In the M group, microcirculation in the cerebral cortex was significantly correlated with that in the conjunctiva but not the sublingual microcirculation. Changes in conjunctival microcirculation are closely related to cerebral cortex microcirculation during mild hypothermia, indicating that cerebral cortex microcirculation could be monitored by measuring conjunctival microcirculation.