Metabolic acidemia due to saline absorption during transurethral and transcervical surgery: a report of 2 cases.

BACKGROUND: The development of endoscopic systems that include bipolar electrocautery has enabled the use of normal saline irrigation in transurethral or transcervical endoscopic surgery. However, excessive saline absorption can cause hyperchloremic metabolic acidosis. CASE PRESENTATION: Patient 1: A 76-year-old man was scheduled for transurethral resection of the prostate with saline irrigation. Approximately 140 min after the surgery, abdominal distension and cervical edema were observed. Abdominal ultrasound examination indicated a subhepatic hypoechoic lesion, which suggested extravasation of saline. Arterial blood gas analysis revealed hyperchloremic metabolic acidosis. The patient was extubated 2 h after the operation with no subsequent airway problems, and the electrolyte imbalance was gradually corrected. Patient 2: A 43-year-old woman was scheduled for transcervical resection of a uterine fibroid with saline irrigation. When the drape was removed after the operation was finished, notable upper extremity edema was observed. Arterial blood gas analysis revealed hyperchloremic metabolic acidosis. The patient's acidemia, electrolyte imbalance, and neck edema gradually resolved, and the patient was extubated 16 h after the operation without subsequent airway problems. CONCLUSIONS: Anesthesiologists should be aware of acidemia, cardiopulmonary complications, and airway obstruction caused by excessive saline absorption after saline irrigation in endoscopic surgery.

Pancuronium enhances isoflurane anesthesia in rats via inhibition of cerebral nicotinic acetylcholine receptors.

PURPOSE: This study was conducted to elucidate the mechanism of enhancement of volatile anesthetics by neuromuscular blocking agents in rats and to consider the relevance of this enhancement to clinical anesthesia. METHODS: Male Sprague-Dawley rats were used. After confirming a movement in response to tail clamping under 1.1 % isoflurane anesthesia, response was determined when the tail clamp was applied at several points after microinjection of pancuronium into the lateral ventricle. Arousal responses to microinjection of nicotine into the lateral ventricle were assessed with or without pretreatment with intraventricular pancuronium. The intravenous 50 % effective dose (ED50) and 95 % effective dose (ED95) for neuromuscular blockade with pancuronium administered in a cumulative fashion at 1.1 % isoflurane were calculated. RESULTS: Intraventricular pancuronium dose-dependently reduced the response to tail clamping, and the dose required to show immobilization of 50 % of rats (intraventricular ED50) was 1.62 µg/kg. Pretreatment with pancuronium at 6 µg/kg significantly reduced the effect of awakening by nicotine under isoflurane anesthesia (P = 0.044). The intravenous ED50 and ED95 for neuromuscular blockade were 63 µg/kg (90 % confidence interval [CI] 52-75 µg/kg) and 133 µg/kg (90 % CI 109-158 µg/kg), respectively. The ratio of intraventricular ED50 to intravenous ED50 was 0.026. CONCLUSION: Pancuronium microinjection into the lateral ventricle dose-dependently enhances the depth of isoflurane anesthesia, which might be caused by inhibition of neuronal nicotinic acetylcholine receptor transmission in the cerebrum. Intravenous injection of pancuronium at high doses might increase the cerebrospinal concentration to a level at which an effect can be observed.