Journal of anesthesia
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Journal of anesthesia · Jun 1994
Epidural anesthesia affects pulse oximeter readings and response time.
We investigated the effects of epidural anesthesia on pulse oximeter readings (Spo2) and response time because this type of anesthesia causes significant changes in microcirculation at measurement sites. Twenty patients were divided into lumbar epidural (L-EPI;n=10) and the cervical epidural (C-EPI;n=10) groups. Spo2 and skin blood flow (SBF) were measured at the finger and toe simultaneously by pulse oximeter and laser Doppler flowmeter, respectively. ⋯ The difference in the response time became larger in the C-EPI group and smaller or opposite in the L-EPI group after anesthesia. The difference in response time and SBF were significantly correlated (r=0.71;P<0.05). These results indicated that epidural anesthesia lowerd Spo2 and shortened the response time through vasodilation in the blocked area and caused the opposite reactions in the nonblocked area through compensatory vasoconstriction.
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Journal of anesthesia · Jun 1994
Effect of the lithotomy position on spinal anesthesia with hyperbaric tetracaine.
This study was performed to determine the effects of lithotomy position on the spread of analgesia and hemodynamics following spinal anesthesia with 0.5% hyperbaric tetracaine. Thirty patients who underwent hysterectomy due to myoma uteri were studied. ⋯ There were no significant differences between the groups in mean arterial pressure, heart rate, cardiac output, and in the cephalad spread of analgesia. The lithotomy position had no effect on the spread of analgesia or anesthetic course of spinal anesthesia with hyperbaric tetracaine.
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We observed the changes in partial pressure of arterial oxygen (PaO 2) and carbon dioxide (PaCO 2) before and during assumption of the lateral position prior to lumbar puncture in 81 patients to investigate whether lung volume decreased and ventilation was suppressed. PaO 2 significantly decreased while the patients were in the lateral position, while PaCO 2 remained unchanged. ⋯ The fact that closing volume increases with age implies that the decrease in functional residual capacity in the lateral position could have caused the decrease in PaO 2. It is therefore advisable to continuously monitor arterial oxygenation using a noninvasive monitor, such as a pulse oximeter, while performing spinal or epidural block, especially in elderly patients.
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Journal of anesthesia · Jun 1994
Differential effects of isoflurane, halothane, and ketamine on the regional methionine-enkephalinlike immunoreactivity in the mouse brain.
The widely used measurement index for anesthetic potency, minimum alveolar concentration (MAC), is hypothesized to be the sum of the effects on multiple neural systems whose contribution to anesthesia differs depending on the agents used. The present study, which compared the effects of halothane, isoflurane, and ketamine, at equipotent level of anesthesia, on the methionine-enkephalinergic neurons in 9 brain regions, showed a significant difference in the methionine-enkephalin-like immunoreactivity (Met-ENK-like IR) among the anesthetics in each region. The order of the Met-ENK-like IR was: halothane > ketamine > isoflurane in the caudatus putamen; halothane > isoflurane ≊ketamine in the nucleus accumbens and the ventral pallidum; halothane ≊isoflurane > ketamine in the globus pallidus, the nucleus dorsomedialis hypothalami, and the nucleus ventromedialis hypothalami; and halothane > isoflurane > ketamine in the arcuate nucleus, the periaqueductal gray, and the nucleus reticularis parvocellularis. These findings indicate that these three anesthetics affect the methionine-enkephalinergic neurons in the motor and pain controlling pathways in different fashions.