Anesthesia and analgesia
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Anesthesia and analgesia · Jul 1993
Randomized Controlled Trial Clinical TrialNerve stimulator polarity and brachial plexus block.
To determine whether needle polarity significantly affects nerve stimulation during peripheral nerve block, we performed a randomized double-blinded study of 10 patients undergoing axillary block for upper extremity surgery. Using an insulated needle, we determined the minimum current necessary to elicit muscle contraction with positive and negative needle polarity at two needle placements: (A) where stimulation was first observed and (B) where stimulation was maximal. At Position A, stimulation required significantly more current when the needle was positive (2.32 +/- 0.45 mA, mean +/- SEM) than when it was negative (1.05 +/- 0.23 mA, P < 0.001). ⋯ The mean ratio of positive to negative threshold stimulation current at Position B (3.11 +/- 0.20) was significantly greater than that at Position A (2.37 +/- 0.19, P < 0.05). Our results emphasize the importance of attaching the negative terminal of the nerve stimulator to the stimulating electrode. Use of the positive terminal could lead to abandoning a block if stimulation were not obtained at a low enough current; alternatively, motor contraction might not be observed before neural contact or vascular puncture.
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Anesthesia and analgesia · Jul 1993
Randomized Controlled Trial Comparative Study Clinical TrialForced-air warming maintains intraoperative normothermia better than circulating-water mattresses.
The hypothesis that forced-air warming preserves core temperature better than circulating-water mattresses was tested in: (a) 16 adults undergoing major maxillofacial surgery, including radical node resection and flap reconstruction; (b) 53 adults undergoing hip arthroplasty, having approximately 25% of their body surface area available for warming; (c) 20 infants undergoing minor maxillofacial surgery; and (d) 10 young children undergoing pelvic or femoral osteotomies. Patients having each type of surgery were randomly assigned to forced-air warming (approximately 40 degrees C) or conductive warming using a full-length circulating-water mattress at 40 degrees C. Forced-air warming was applied to the legs of the adults undergoing maxillofacial surgery and to one arm, the shoulders, and the neck in the adults undergoing hip arthroplasty; a U-shaped, tubular forced-air cover was positioned around the pediatric patients. ⋯ Furthermore, we needed to decrease the temperature of the warmer from high to medium (approximately 37 degrees C) in most patients assigned to forced-air warming to prevent hyperthermia. After 15 h of anesthesia, rectal temperatures in the adults undergoing maxillofacial surgery were 3.4 degrees C higher in the forced-air group (P < 0.01). After 4 h of anesthesia, esophageal temperatures had increased 0.8 +/- 0.5 degrees C in the patients warmed with forced-air and decreased 0.8 +/- 0.3 degrees C in those warmed by circulating-water mattresses (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Jul 1993
Randomized Controlled Trial Comparative Study Clinical TrialComparison of intrathecal fentanyl infusion with intrathecal morphine infusion or bolus for postoperative pain relief after hip arthroplasty.
The purpose of this study was to compare an intrathecal fentanyl infusion with intrathecal morphine infusion or bolus for postoperative pain relief after hip arthroplasty. Sixty patients scheduled to undergo hip joint replacement were studied. A 28-gauge (n = 12) or a 22-gauge (n = 48) spinal catheter was introduced through the L3-4 interspace, 3-4 cm into the subarachnoid space. ⋯ In Group I, supplementary intramuscular (IM) opioid was required more often (46 doses) than in Group II (18 doses) in 24 h (P < 0.01). The number of patients given IM administered opioid was larger in Group I (18 patients) than in Group II (8 patients) (P < 0.01). The IM opioid was requested sooner in Group I (18 patients, mean 480 min) after the intrathecal injection than in Group III (13 patients, mean 786 min) (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)