Regional-Anaesthesie
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Regional-Anaesthesie · Oct 1988
[Influence of minimum current for peripheral nerve stimulation on the latency and success rate of sciatic blockade].
The efficacy of conduction anesthesia depends to a great extent on accurate application of the local anesthetic solution (LA) in close proximity to the nerve trunk. The problem with most peripheral nerve stimulators available in the past was that they did not provide a small enough electrical stimulus. Correct positioning of the needle could not be guaranteed if muscle contractions occurred. New current-controlled stimulators have recently been developed with low currents from 0.1 mA upwards. We studied the intensity of stimulus currents eliciting just-visible muscle contractions in the lower leg (m. triceps surae) to see how this influenced the latency and success rate of sciatic nerve block. ⋯ In a randomized study, 35 patients (18-68 years, ASA I and II) undergoing elective surgery were investigated. The block was performed by posterior approach using 30 ml 1% prilocaine. The stimulator was switched on with a frequency of 1 impulse/s and a stimulus current of 1 mA when the insulated needle was at a depth of 4 cm. In group 1 (n = 5) LA was injected when the first visible muscle contractions occurred at a current of 1.0 mA, but vanished if the current was diminished. In group 2 (n = 10) the needle was placed if a minimum current of 0.5 mA just triggered a muscular response. In group 3 (n = 10) the threshold current was 0.3 mA and in group 4 (n = 10) 0.1 mA. In all cases direct contact between the needle tip and the nerve was avoided.(ABSTRACT TRUNCATED AT 250 WORDS)
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Regional-Anaesthesie · Oct 1988
Comparative Study[Continuous sedation for regional anesthesia with propofol (Disoprivan) and midazolam (Dormicum). A comparative study].
Propofol was compared to midazolam with regard to its quality as a sedative in regional anesthesia. 81 patients undergoing varicose-vein stripping under epidural anesthesia were divided into two groups: 39 were given propofol and 42 were given midazolam. Both groups were then subdivided into 3 subgroups. 30 min after epidural block, a bolus of propofol 1 mg/kg or midazolam 0.03 mg/kg was given followed by infusion of equipotent solutions: propofol 1.0, 1.5, or 2.0 mg/kg/h or midazolam 0.03, 0.045, 0.06 mg/kg/h. Continuous registration of blood pressure, respiratory rate, and end-expiratory pCO2 was carried out and blood gas analysis was performed every 30 min. ⋯ Clinically unimportant changes of circulatory and respiratory parameters were seen. Blood gas analyses showed hypercapnia greater than 50 mmHg in some patients. Brief apnea occurred after bolus propofol in 7.7% of cases and pain during injection in 66.6%. Restlessness: propofol 28.2%, midazolam 9.5%. Upper airway obstruction: propofol 30.8%, midazolam 57.1%. Recovery time after infusion ranged from 130 s with propofol to 26 min with midazolam. Postoperative evaluation included the following questions and responses: Sedation pleasant? propofol 97.5%, midazolam 100%. Sleep during surgery? propofol 94.8%, midazolam 83.5%. Prolonged tiredness? propofol 25.6%, midazolam 69%. Postoperative nausea? propofol 38.5%, midazolam 14.2%. Vomiting? propofol 17.9%, midazolam 11.9%. Our study showed that propofol is highly suitable as a sedative for regional anesthesia in spite of injection pain and frequent postoperative nausea. It is superior to midazolam because of the significantly shorter recovery time, providing improved control-lability and reduced posthypnotic sleep.