Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1996
Comparative StudyCerebral microregional oxygen balance during chronic versus acute hypertension in middle cerebral artery occluded rats.
This study was performed to compare microregional 0(2) supply and consumption balance in spontaneously hypertensive rats (SHR), normotensive Wistar Kyoto rats (WKY), and in phenylephrine-induced acutely hypertensive WKY (WKY + ph) rats. Under isoflurane anesthesia, a middle cerebral artery (MCA) of SHR (n = 7) and WKY (n = 14) rats was occluded. Seven of the WKY rats were infused with phenylephrine (WKY + ph) to keep the mean arterial pressure (MAP) at the same level as that of the SHR. ⋯ The number of veins with low 02 saturation (SvO2 < 40%) in the ischemic cortex was significantly lower in the WKY + ph than in the SHR or in the WKY group. Our data suggest that in chronically hypertensive animals, cerebrovascular adaptations enable the microregional 02 balance in focal ischemia to be maintained at a level similar to that of normotensive animals. However, in normotensive animals with focal cerebral ischemia, an acute increase of MAP improves microregional O2 balance.
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Anesthesia and analgesia · Mar 1996
Spinal cord blood flow after intrathecal injection of ropivacaine: a screening for neurotoxic effects.
The study of spinal cord blood flow (SCBF) after spinal drug application is an important aspect of preclinical neurotoxicological screening. This investigation was designed to study how a new local anesthetic, ropivacaine, affects SCBF after intrathecal (IT) administration in the rat. SCBF was measured continuously in spontaneously breathing, enflurane/N2O-anesthetized rats, using the laser-Doppler flowmetry technique. ⋯ SCBF decreased significantly to approximately 45% of the predrug value after the high concentration of 20 mg/mL ropivacaine (200 micrograms given IT), and this reduction was reversible within a period of 20 - 40 min after the injection. Whereas a high concentration of ropivacaine caused a definite reduction in spinal cord blood flow when administered IT to anesthetized rats, clinically relevant concentrations induced only minor changes. These results suggest that ropivacaine may be used to induce spinal anesthesia without causing clinically relevant effects on SCBF.