Journal of anesthesia
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Journal of anesthesia · Sep 1995
Spontaneous respiration should be avoided in frequency domain analysis of heart rate variability.
To determine whether spontaneous respiration is suitable for frequency domain analysis of heart rate (R-R interval) variability, we studied 15 volunteers (5 men and 10 women, aged 22-34 years) and evaluated the reproducibility of the power spectrum. Electrocardiograms were recorded for 5 min each with spontaneous and rate-controlled respiration (15 breaths·min-1), repeating the same protocol 1 week later. Fast Fourier transformation was performed using the digitized data of the R-R intervals. ⋯ Data were comparable for rate-controlled respiration. Since respiratory parameters strongly influenced the low- and the high-frequency R-R interval power spectra, spontaneous respiration should be avoided. A constant respiratory condition is required to interpret results of frequency domain analysis of R-R interval variability.
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Journal of anesthesia · Sep 1995
Comparison of the placental transfer of halothane, enflurane, sevoflurane, and isoflurane during cesarean section.
The concentrations of placental transfer of halothane (H), enflurane (E), sevoflurane (S), and isoflurane (I) were measured in 46 patients during cesarean section. The mean inhalation times of H (0.5%), E (1%), S (0.8%), and I (0.6%) were 13 min 27 s, 13 min 49s, 13 min 20s, and 8 min 8s, respectively. The mean concentrations in the maternal artery (MA) were 5.2mg·dl-1 in H, 12.3 mg·dl-1 in E, 5.2mg·dl-1 in S, and 2.4mg·dl-1 in I. ⋯ The Apgar scores in these four groups were not different from that in the group given only 66% nitrous oxide in oxygen as anesthetic (N2O group). The cardiovascular changes induced by skin incision were bigger in the N2O group than in the other groups. The use of a low concentration of H, E, S, or I is, therefore, suggested to be a useful and acceptable anesthetic method for cesarean section.
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Journal of anesthesia · Sep 1995
Effect of glucose concentration on the subarachnoid spread of tetracaine in the parturient.
We have studied the effect of glucose concentration on the spread of tetracaine spinal anesthesia in 40 parturient patients. Forty women undergoing cesarean section received a subarachnoid injection of tetracaine 8 mg dissolved in either 5% or 10% glucose solution. ⋯ The cumulative dose of ephedrine was higher with 10% glucose (19 ± 10 mg) than with the 5% glucose (13± 8 mg). In tetracaine spinal anesthesia, the rate of onset of analgesia was faster and the maximum level of analgesia was higher in the 10% glucose solution than in the 5% glucose solution.
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Journal of anesthesia · Sep 1995
The effects of isoflurane and sevoflurane on the left ventricular end-systolic pressure-volume relation in dogs.
The influence of two inhalational anesthetics, isoflurane and sevoflurane, on the end-systolic pressure-volume relations (ESPVR) of the left ventricle (LV) in situ was investigated in open-chest dogs anesthetized with α-chloralose. The LV volume was measured by a conductance catheter while the LV pressure was measured by a tipmicromanometer. The end-systolic elastance (Ees) of the LV was calculated as the slope of ESPVR which was elicited when the inferior vena cava was transiently occluded. ⋯ Isoflurane and sevoflurane caused equivalent decreases in Ees of 23% and 16% at 1 MAC, and 48% and 41% at 2 MAC, respectively. Dobutamine 3 μg·kg-1·min-1 produced a simultaneous restoration of Ees and recovery of the cardiac output at 1 and 2 MAC of both isoflurane and sevoflurane. We thus conclude that the depressant effect of sevoflurane on cardiac contractility is almost identical to that of isoflurane in the dog, and they are both reversed by the use of a low dose of dobutamine.