摘要:

The effect of the volatile anesthetic desflurane on motor evoked potentials was examined in male rats. Animals underwent cortical stimulation using small platinum ball stimulating electrodes secured on the motor cortex. To record evoked compound muscle action potentials (CMAPs), single-shock electrical stimulation was delivered to the forelimb representation of the motor cortex. Muscle responses were readily obtained in the contralateral extensor muscles. The effect of desflurane was examined at various concentrations ranging from 0.7 to 11.4%. With increasing concentrations of desflurane, there was a progressive decrease in the CMAP amplitude and systemic blood pressure over the baseline values. This decrease became statistically significant (p= 0.0078) at 5.7% [1 maximum alveolar concentration (MAC)] concentration of desflurane. Although there was a decrease in heart rate, the results were not statistically significant (p= 0.03). No significant difference in the onset latency or the duration of the CMAP was noted at different concentrations of the anesthetic. We conclude that desflurane anesthesia significantly alters the amplitude of the muscle response evoked by motor cortex stimulation in experimental animals.

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

If the efficacy of hypothermia and barbiturates in ameliorating ischemic brain injury lies in reducing the cerebral metabolic rate of oxygen (CMRO2), the greater efficacy of mild hypothermia (34°C) compared with barbiturates is inconsistent with the 15–20% reduction of CMRO2caused by mild hypothermia compared with 50% caused by barbiturates. This paradox, we hypothesized, derives from the fact that whereas barbiturates lower CMRO2associated with EEG activity or thiopental (TP)-suppressible CMRO2, not essential for cellular viability, hypothermia lowers CMRO2associated with providing energy, i.e., adenosine triphosphate, to maintain transmembrane ion gradients or TP-nonsuppressible CMRO2, essential for neuronal viability. To test this hypothesis, we measured whole brain cerebral blood flow (CBF) and CMRO, in two groups of rats mechanically ventilated with 70% N2O/30% O2before and after TP-induced isoelectric EEG. In the normothermic group (n = 7), measurements were made at a brain temperature (Tb) of 38°C, while in the hypothermie group (n = 7), they were made at 34°C. In the normothermic group, TP-induced isoelectric EEG reduced CMRO2by 50%, from 7.92 ± 1.05 to 3.95 ± 0.70 ml 100 g−1min−1(X ± SD). Thus, at 38°C, TP-suppressible and TP-nonsuppressible CMRO2were both 50 ± 4% of total CMRO2. In the hypothermie group, decreasing Tbfrom 38 to 34°C caused a 17% decline in CMRO2, from 7.62 ± 1.92 to 6.28 ± 1.22 ml 100 g−1min−1(p > 0.05). AT 34°C, TP infusion lowered CMRO2to 2.15 ± 0.46 ml 100 g−1min−1. At 34°C, TP-suppressible and TP-nonsuppressible CMRO2values were 64 ± 7% and 36 ± 8% of total CMRO2, respectively. TP lowered CBF by 50% at both 38 and 34°C. In conclusion, mild hypothermia selectively lowers TP-nonsuppressible CMRO2associated with the maintenance of viability rather than EEG-associated or TP-suppressible CMRO2.

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:1996

数据来源: OVID