Differing effects of anesthetics on splanchnic arterial blood flow during hemorrhagic shock

The effect of anesthesia on splanchnic blood flow was examined during hemorrhagic shock and resuscitation. Sprague-Dawley rats were anesthetized with the inhalation anesthetic, methoxyflurane, or pentobarbital (65 mg/kg). Transonic Doppler flow probes were placed around the superior mesenteric artery (SMA) and the abdominal aorta, and the animals were subjected to acute hemorrhage (or sham) to 30 mmHg for 90 min followed by 30 min of resuscitation with shed blood (n = 6/group). At 90, 105, and 120 min, sham animals in both anesthetic groups showed comparable blood pressures with a 50% decrease in SMA and aortic blood flow. Acute hemorrhage decreased SMA blood flow by 94.5 +/- 0.01 and 86.0 +/- 2.8%, respectively, in the pentobarbital and methoxyflurane groups, with similar changes occurring in aortic blood flow. During resuscitation, arterial pressure remained significantly depressed and SMA blood flow decreased by 65% in the pentobarbital group, whereas blood pressure returned to control levels and SMA blood flow increased to 56% of control values (P < 0.001) in the methoxyflurane group. The findings indicate that the choice of anesthetic agent may significantly impact splanchnic blood flow and needs to be taken into account when designing experiments examining effects of hemorrhagic shock.