Masui. The Japanese journal of anesthesiology
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Nitrous oxide diffuses into endotracheal tube cuff and then overexpand the cuff. This causes upper airway obstruction and trauma in intubated patients during general anesthesia. On the other hand, pressure of endotracheal cuff is reported to decrease in time-related fashion under artificial ventilation with oxygen and air. ⋯ Clinically sealing pressure was 11.6 +/- 1.0 mmHg and necessary volume of air was 5.5 +/- 1.8 ml. The initial pressure of the inflated cuff gradually decreased to clinical sealing pressure during 130.9 +/- 30.5 min. In conclusion, when regurgitation should be prevented at the point of the clinically sealing pressure, pressure and volume of inflated cuff by air should be re-checked at an interval of about 2 hrs in intubated patients under general anesthesia without nitrous oxide.
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Continuous thoracic epidural anesthesia (T4/5) using 4-5 ml.h-1 of 1.5% lidocaine with 1:200,000 epinephrine and inhaled anesthesia using nitrous oxide, oxygen and sevoflurane were performed in two patients, (40 and 22 yr-old females) with myasthenia gravis. This combined anesthetic technique provided muscle relaxation for endotracheal intubation and optimal operating conditions, including muscle relaxation and stability of hemodynamics during transsternal thymectomy. Further, continuous epidural anesthesia using 4 ml.h-1 of 0.25% bupivacaine provided postoperative pain relief without other analgesics and stable postoperative respiratory conditions. In conclusion, we confirm the benefits of this technique which provides not only safe and stable conditions during the surgery, but also an improved comfort for patients in the postoperative period following transsternal thymectomy for myasthenia gravis.
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During inhalation anesthesia using N2O, the intracuff pressure has been reported to increase due to diffusion of N2O into the cuff. The excessive intracuff pressure may produce ischemia of the tracheal mucosa. In this study, the changes in the intracuff pressure of endotracheal tube with a cuff made of a material with high N2O gas-barrier properties were compared with those of the normal endotracheal tubes. ⋯ A marked increase of the pressure was observed after inhalation of N2O in standard and profile cuff groups. In gas-barrier cuff group, there was a tendency of increasing cuff pressure without a statistically significant difference. The present study suggests that the use of a cuff with a material of high N2O gas-barrier properties would be effective to prevent increased intracuff pressure by N2O diffusion, and this would be especially useful during long anesthesia and hypotensive anesthesia.
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It is known that the course of catheter placement is related to the firmness of catheter. This paper reports the results of roentgenographic analysis of the location of catheters (20G PERIFIX SOFT catheter-B. Braun Melsungen-blind tip with three side holes) inserted into the lumbar epidural space in 20 patients. ⋯ From the recent anatomical observation by MRI, epi-dural space takes various figures depend on the location. Since posterior median part is the widest part in lumbar region, catheter placement should be done in this area. This will increase the success of straight placement of the epidural catheter.
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We studied neuromuscular blocking effects of isoflurane using a neuromuscular transmission monitor in three myasthenia gravis patients. Severity of myasthenia gravis was different among three patients. ⋯ Also, TOF ratio decreased by 12% in a mild case, by 22% in a moderate case, and 48% in a severe case during isoflurane anesthesia. We conclude that in patients with more severe myasthenia gravis, neuromuscular blocking effect of isoflurane is more potentiated.