Articles: general-anesthesia.
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Anesthetic management and outcome were examined in patients with negative in vitro contracture tests for malignant hyperthermia (MH). Contracture testing was performed in a standardized fashion using 3% halothane alone and incremental doses of caffeine alone. Medical records were examined for 54 anesthetic exposures in 42 MH(-) patients who had received anesthesia since their MH testing. ⋯ Two of these patients also receive prophylactic iv dantrolene. These results suggest that "triggering" anesthetic agents may be safely administered to patients who test MH(-) by in vitro contracture testing. However, until the anesthetic experience of larger numbers of MH(-) patients is known, these results should be interpreted cautiously.
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A computer-based system was developed for monitoring cardiac output using the Fick principle during general anesthesia. The variables of the oxygen-consumption Fick equation were measured using the following system: oxygen uptake by an originally developed respiratory gas monitoring system, arteriovenous oxygen saturation difference by pulse and fiberoptic oximetry, and hemoglobin concentration by an in vitro oximeter. Fick cardiac output and systemic vascular resistance were calculated every 30 seconds. ⋯ The Fick cardiac output was significantly lower than the thermodilution cardiac output, especially in the low flow range. We demonstrated that this new monitoring system was clinically feasible and sufficiently accurate, under the limited circumstances of our study. The integration of routinely used equipment has made possible a frequently repeatable method for estimating cardiac output in patients.
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Seventy-four patients received general anaesthesia for Caesarean section. Seven percent of the elective group and 28% of the emergency patients reported dreaming or recall of voices during the procedure (p less than 0.05) at postoperative interview. One patient from each group reported feeling pain or suffocation. ⋯ A value greater than 13 mmHg picked up all patients who dreamed, with a false positive rate of 68%. Both of the 'aware' patients had provoked lower oesophageal contractility response of greater than 70 mmHg, an attribute shared by only 8% of the rest. The isolated forearm was particularly ineffective.
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A case of intraoperative awareness during a thoracotomy is described. The patient's recall coincided with an intraoperative period during which a Siemens 900B ventilator and a Siemens 952 isoflurane vaporiser were used. ⋯ This problem eventually was traced to a malfunctioning inlet control valve on the ventilator. This complication may have been prevented if the end-tidal anaesthetic concentration had been monitored intraoperatively.
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An 86-year-old man receiving antiarrhythmic treatment with an intravenous (IV) lidocaine infusion experienced a prolonged emergence from general anesthesia. A venous blood sample was sent for determination of the lidocaine concentration, the infusion was stopped, and the patient awakened 15 minutes later. ⋯ The overdose was the result of a miscalculated infusion rate, plus an underestimation of effects of age, cardiac disease, and general anesthesia on the rate of lidocaine biotransformation. Infusion of any drug during and after general anesthesia requires scrupulous attention to dosage determination and to the clinical condition of the patient receiving the infusion.