Journal of anesthesia
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The relationship between the age and the spread of analgesia from different epidural anesthetic doses was examined by studying analgesic dose responses in cervical epidural analgesia. Two different anesthetic doses (5 ml or 10 ml) of 2% mepivacaine were injected into the cervical epidural space at a constant pressure (80 mmHg) using an intravenous apparatus, and the spread of analgesia to pinprick was assessed. The significant correlation was found between the patient's age and the number of spinal segments blocked (5 ml : r = 0.8498, P < 0.01, 10 ml : r = 0.5988, P < 0.01). ⋯ The analgesic dose-response relation in patients over 60 years of age differed from that in patients under 39 years of age and doubling the epidural dose did not double the number of spinal segments blocked. Progressively more extensive analgesia was obtained from a given dose of local anesthetic with advancing age. It was difficult to limit the extent of analgesia by injecting a smaller dose of local anaesthetic in the elderly.
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Journal of anesthesia · Sep 1987
Tracheal tube cuff pressure--study on tube size and inflating gases.
The effect of nitrous oxide on the cuff pressure was studied from the following points of view. One was the size of tubes and the type of cuff. The other was the effects of different gas mixture in the cuff. ⋯ In the group of air, the cuff pressure increased as well as experiment I. However in the group of mixtured gas, there were almost no changes in the cuff pressure. This means that if the cuff is inflated with a mixtured gas in which nitrous oxide is under the equivalent condition, the cuff pressure would not change.
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Journal of anesthesia · Sep 1987
Epidural pressure and its relation to spread of epidural analgesia.
The relationships between the epidural pressures following the injection of local anesthetic solution and the spread of epidural analgesia were investigated. In 46 patients, 15 ml of 2% mepivacaine was injected into the lumbar epidural space at a constant rate (1 ml/sec) using an electropowered syringe pump. Injection pressures and residual pressures were recorded and the spread of analgesia to pinprick was assessed. ⋯ The spread of analgesia closely correlated with the epidural pressures during and following the injection of local anesthetic solution. The most close correlation was found between the epidural pressure immediately after the completion of injection and the spread of analgesia (r = -0.5659, P < 0.001). In conclusion, the lower the terminal injection pressure and the residual pressures associated with higher age, the wider the spread of epidural analgesia.
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Journal of anesthesia · Sep 1987
Venodilator effects of adenosine triphosphate and sodium nitroprusside; comparisons during controlled hypotension.
Adenosine triphosphate as well as sodium nitroprusside has been used for hypotensive anesthesia. The purpose of this study was to examine the possibility that two hypotensive drugs may exert different effects on venous capacitance during controlled hypotension. In rats anesthetized with ketamine, mean arterial pressure was lowered to 50 mmHg by intravenous infusion of adenosine triphosphate or sodium nitroprusside. ⋯ However, the decrease in MCFP by adenosine triphosphate (0.8 +/- 0.1 mmHg) was less (P < 0.01) than that by sodium nitroprusside (2.3 +/- 0.3 mmHg). These results suggest that at a comparable level of arterial hypotension venodilator effect of adenosine triphosphate was less than that of sodium nitroprusside. Less venodilatation during adenosine triphosphate-induced hypotension may contribute to the maintenance of cardiac output during hypotensive anesthesia.
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Journal of anesthesia · Mar 1987
Spread of epidural analgesia following a constant pressure injection--an investigation of relationships between locus of injection, epidural pressure and spread of analgesia.
(1) The spread of epidural analgesia following injection of 15 ml of 2% mepivacaine was 17.3 +/- 0.6, 14.3 +/- 0.4, and 13.3 +/- 0.7 spinal segments in cervical, thoracic, and lumbar epidural analgesia, respectively. The patient's age showed significant correlation with the spread of epidural analgesia in cervical (r = 0.5776, p < 0.001), thoracic (r = 0.3758, p < 0.01), and lumbar area (r = 0.8195, p < 0.001). ⋯ The lower epidural pressure associated with higher age, the wider spread of analgesia. There was no significant correlation between the residual pressure at 60 seconds and the age or the spread of analgesia.