A multimodality approach lengthens warm ischemic time during aortic cross-clamping

To evaluate the effects of exsanguination, cerebrospinal fluid drainage (CSFD), steroids alone and in conjunction with CSFD on spinal cord perfusion pressure (SCPP), and neurological outcome following 70 min of normothermic spinal cord ischemia, we monitored proximal (Px BP) and distal (Ds BP) aortic blood pressure, cerebrospinal fluid pressure, and somatosensory evoked potentials (SEP) in 29 mongrel dogs. In all animals Px BP during aortic cross-clamping was controlled with partial exsanguination (40-50% circulating blood volume). Dogs were randomized into four groups (gp): gp 1 (n = 6) control; gp 2 (n = 8) steroids only (methylprednisolone 30 mg/Kg 10 min before aortic occlusion and 4 hr later); gp 3 (n = 8) CSFD only; gp 4 (n = 7) steroids and CSFD. Partial exsanguination effectively controlled Px BP during aortic cross-clamping in all groups. After the statistically significant decrease from preclamp values, mean Px BP did not differ among groups (78.9, 81.2, 80.5, and 80.3 mm Hg, respectively, P greater than 0.05). Mean Ds BP decreased from systemic values to 12.6, 16.8, 16.7, and 17 mm Hg, respectively, after aortic occlusion (P less than 0.05); these values did not differ from one another. CSFP did not change significantly from its baseline value while the aorta was cross-clamped in gp 1; CSFP was significantly reduced to 6.2 mm Hg in gp 2, steroid-treated animals (P less than 0.05 vs gp 1); a further significant reduction in CSFP was noted in gp 3 and 4 undergoing CSFD (0.07 and 0.67 mm Hg, respectively, P less than 0.05 vs gp 1 and 2).(ABSTRACT TRUNCATED AT 250 WORDS)