Interscalene block anesthesia for shoulder surgery.

One hundred patients had major shoulder surgery with interscalene brachial and cervical plexus block anesthesia. Successful anesthesia was obtained by using this method in 82 patients. Failure was the result of incomplete anesthesia in 16 patients or the presence of a complication. Complications from high blood levels of anesthetic included loss of consciousness and respiratory depression in three patients and seizure in one. The block lasted a mean of eight hours, decreasing the need for postoperative analgesic medications. No postoperative medical complication developed. Ninety-one percent of the patients with successful blocks were satisfied with the procedure.

Cross-sensitivity in water vapor in the Engström EMMA.

Halothane, enflurane, and isoflurane vapor concentrations (0-3%) were simultaneously measured by a calibrated Engström EMMA and Beckman LB-2 gas analyzer, and were heated and/or humidified by an inline Bird humidifier. Data were treated by regression analysis for lines of best fit. Water vapor produced increasing cross-sensitivity as a function of temperature in all vapors measured by the Engström EMMA but not in the Beckman LB-2. At 38 degrees C cross-sensitivity by water vapor was 0.97, 0.92, and 1.12 volumes percent reading for halothane, enflurane, and isoflurane, respectively. Water vapor cross-sensitivity with the EMMA in the isoflurane selector position was statistically higher (P less than 0.05) than in the other two positions. We conclude that water vapor cross-sensitivity in the Engström EMMA is in excess of the manufacturer's specifications (0.3 volumes percent at 37 degrees C) and different with respect to the anesthetic gas being measured.

Brachial plexus anesthesia and axillary sheath elastance.

Large volumes of an anesthetic solution used during regional axillary anesthesia may produce elevated pressures within the axillary sheath that lead to arterial compression and diminished blood flow. We measured axillary sheath pressure as a function of injected volume in 20 patients scheduled for hand surgery. Bupivacaine without epinephrine was injected into the axillary sheath in 10-ml increments until a cumulative volume of 50 ml was attained. Elastance (delta P/delta V), where delta P equals change in pressure (mm Hg) and delta V equals change in volume (ml), was 0.8 +/- 0.1 (+/- SEM) mm Hg/ml in successful block and 0.09 +/- 0.1 mm Hg/ml in unsuccessful blocks. Axillary sheath pressure did not exceed mean arterial pressure for periods longer than 60 s. We conclude that vascular insufficiency resulting from arterial compression following axillary block anesthesia is unlikely.