Hypertonic saline does not improve cerebral oxygen delivery after head injury and mild hemorrhage in cats

Objectives : To investigate the effects of hypertonic saline for resuscitation after mild hemorrhagic hypotension combined with fluid-percussion traumatic brain injury. Specifically, the effects of hypertonic saline on intracranial pressure, cerebral blood flow (radioactive microsphere method), cerebral oxygen delivery (cerebral oxygen delivery = cerebral blood flow x arterial oxygen content), and electroencephalographic activity were studied. Design : Randomized, controlled, intervention trial. Setting : University laboratory. Subjects : Thirty-four mongrel cats of either sex, anesthetized with 1.0% to 1.5% isoflurane in nitrous oxide/oxygen (70 :30). Interventions : Anesthetized (isoflurane) cats were prepared for traumatic brain injury, and then randomly assigned to the following groups : moderate traumatic brain injury only (2.7 ± 0.2 atmospheres [atm], group 1) ; mild hemorrhage (18 mL/kg) only, followed immediately by resuscitation with 10% hydroxyethyl starch in 0.9% saline in a volume equal to shed blood (group 2) ; or both traumatic brain injury (2.7 ± 0.1 atm) and mild hemorrhage, followed immediately by replacement of a volume equal to shed blood of 10% hydroxyethyl starch in 0.9% saline (group 3) ; or 3.0% saline (group 4). Measurements and Main Results : Data were collected at baseline, at the end of hemorrhage, and at 0, 60, and 120 mins after resuscitation (or at comparable time points in group 1). Intracranial pressure in group 1 was significantly increased by traumatic brain injury at the end of hemorrhage, immediately after resuscitation, and 60 mins after resuscitation (p