Near-infrared spectrophotometry is useful to detect the beneficial pharmacological effects of alprostadil on spinal cord deoxygenation.

The purpose of this study is to confirm our previous studies that near-infrared spectrophotometry (NIRS) can detect spinal cord ischemia earlier than evoked spinal cord potential (ESP), and to determine whether it can detect the pharmacological effect of prostaglandin E1 (PGE1) incorporated in lipid microspheres (alprostadil) on the spinal cord.NIRS probes were placed on the posterior side of the lower lumbar vertebrae, and oxygenated hemoglobin (oxy-Hb) of the spinal cord was monitored continuously in 14 male New Zealand white rabbits. The amplitude of ESP was recorded every minute. All rabbits underwent a normothermic infrarenal aortic cross-clamping (AXC) for 20 min, and all were pretreated with either an intravenous 3 microg/kg/10 min alprostadil (group A; n=4) or the same volume saline (group C; n=10).ESP amplitude started to show a linear decrease 6 min after the onset of AXC and was comparable between groups (P=.839). Oxy-Hb decreased rapidly just after the onset of AXC, followed by monoexponential decline. It reached a plateau at 10 min after the onset of AXC. Oxy-Hb of group A was significantly higher than that of group C (P=.014).NIRS can detect spinal cord ischemia earlier than ESP. It can detect the beneficial pharmacological effect of alprostadil on the spinal cord.