Anaesthesiologie und Reanimation
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Anaesthesiol Reanim · Jan 1998
Review[Measuring muscle relaxation with mivacurium in comparison with mechano- and electromyography].
Based on survey of the literature, methodological problems of electromyographic and mechanomyographic neuromuscular monitoring are presented. Often mechanomyography (MMG) is accompanied by mechanical problems during the registration of the contractions in the operating theatre. In contrast to mechanomyography the registration of electromyographic signals is easier whereas the processing of electromyographic signals is more difficult. ⋯ A comparison of the mechanomyographic values and the electromyographic values leads to the following results: the MMG showed a significantly shorter onset time (p < 0.0001) and a significantly deeper maximum neuromuscular block (p = 0.0004) than the EMG. There were also significant differences between mechanomyographically and electromyographically measured recovery values regarding T1(75) (p = 0.0007), T1(90) (p < 0.0001), TOF0.8 (p = 0.0386) and T1(25-75) (p < 0.0001). On average, an ED95 of mivacurium showed a significantly slower recovery in the mechanomyogram than in the electromyogram.
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Anaesthesiol Reanim · Jan 1998
Randomized Controlled Trial Comparative Study Clinical Trial[Application of the laryngeal mask for elective percutaneous dilatation tracheotomy].
Percutaneous dilatational tracheostomy is an increasingly accepted procedure for bed-side tracheostomy. The exact positioning of the endotracheal tube, the localization of the point for puncturing the trachea and damage to the endotracheal tube and the cuff as well as to the bronchoscope due to the puncturing process are technical problems which can endanger the course of the operation. In a prospective randomized study, we examined whether use of the laryngeal mask airway (LMA) is a real alternative to the endotracheal tube during tracheostomy. ⋯ An increase in PetCO2 and a decrease in minute ventilation volume were observed in both groups. Regarding technical complications, the LMA is a safe alternative to the endotracheal tube. The choice of method should depend on the basic disease and the patient's ventilation requirements at the time of tracheostomy, while there is still a call for safe instruments guaranteeing sufficient sealing of the respiratory tract during the dilatational tracheostomy and simultaneous avoidance of technical problems during puncturing of the trachea and widening of the point of puncturing.
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Anaesthesiol Reanim · Jan 1998
Randomized Controlled Trial Comparative Study Clinical Trial[Augmentation of the neuromuscular blocking effect of mivacurium during inhalation anesthesia with desflurane, sevoflorane and isoflurane in comparison with total intravenous anesthesia].
To evaluate the enhancement of mivacurium-induced neuromuscular block by potent inhalational anaesthetic agents, dose-effect curves for mivacurium were determined in 84 patients scheduled for minor elective surgery during anaesthesia with 1.5 MAC (70% N2O) desflurane, sevoflurane and isoflurane and compared with those under total intravenous anaesthesia (TIVA). Acceleromyography (TOF-Guard) and train of four (TOF) stimulation of the ulnar nerve were used (2 Hz every 12 s). Mivacurium was administered in increments of 25 micrograms kg-1 until a depression of T1 > 95% was reached. ⋯ We conclude that the neuromuscular blocking effect of mivacurium is enhanced during anaesthesia with desflurane, isoflurane and sevoflurane compared with TIVA. The duration of action and the recovery time are prolonged. The dose of mivacurium used should be reduced if anaesthesia is maintained with volatile anaesthetics.
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Anaesthesiol Reanim · Jan 1998
Randomized Controlled Trial Comparative Study Clinical Trial[Effect of remifentanil on clinical and electroencephalographic parameters of depth of anesthesia in balanced anesthesia with propofol, enflurane or isoflurane].
Electrophysiological parameters are well-suited to detect changes in cerebral function. The present study investigates whether balanced anaesthesia with remifentanil during nociceptive stimulation is associated with changes in clinical and electrophysiological parameters indicating inadequate depth of anaesthesia. Following IRB approval and written informed consent, 23 patients (ASA: I; age: 36 +/- 11) scheduled for elective gynaecological laparoscopy were included in the study. Without any premedication, anaesthesia was induced with remifentanil (1.0 microgram/kg bolus injection), propofol (0.5 mg/kg added by repetitive (10 mg) bolus injections every 10 s until unconciousness) and vecuronium (0.1 mg/kg). Following endotracheal intubation (normoventilation: PetCO2: 36 bis 38 mmHg), remifentanil infusion was started with continuous doses of 0.5 microgram/kg/min over 5 minutes and maintained with 0.25 microgram/kg/min during surgery. Remifentanil was randomly combined with propofol (group 1: 100 micrograms/kg/min; n = 7), enflurane (group 2: 0.5 MAC; n = 8) or isoflurane (group 3: 0.5 MAC; n = 8). Monitoring included: heart rate (beats/min), mean arterial pressure (mmHg), oxygen saturation (%), endtidal CO2 (mmHg) and endtidal enflurane and isoflurane (%). EEG: 2-channel recordings of Fz versus mastoid and ECG (artefact control) during steady-state anaesthesia and surgery. Following fast-fourier-transformation (4 s; 256/s; 0.5 to 35.0 Hz), spectral power densities were calculated for the selected frequency bands. Auditory evoked potentials (AEP; middle latency) were registered simultaneously after binaural stimulation via head-phones click-stimulation (6 Hz; 75 dB above hearing threshold; 512 stimulations per average). Bandpass was 0.01 to 2.0 kHz. ⋯ Na, Pa, Nb (latencies; ms) and peak-to-peak amplitudes (NaPa, PaNb; microV). EEG and AEP recording technique [15]. The study protocol included baseline values from pre-intubation, pre-surgery, the respective post-stimulation values (1 min, 3 min, 5 min) and all data at five-minute intervals during surgery until emergence from anaesthesia. During steady-state study conditions with defined remifentanil applications, mean data indicate that in response to nociceptive stimuli no changes in clinical or electrophysiological parameters were observed. In contrast to other studies using different anaesthetic techniques, the present data from remifentanil indicate very stable haemodynamic and electrophysiological parameters (EEG, AEP) during noxious stimulations. Adjustable and with no plasma accumulation, remifentanil demonstrates potent antinociceptive effects resulting in signs of adequate anaesthesia.
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Since the beginning of this century, a few biopolymers have been used as basic materials for volume substitution. Aside from gelatin and dextran, modified starch (hydroxyethyl starch, HES) is currently the first-choice means. Due to special manufacturing processes, different hydroxyethyl starches are now available. ⋯ The molecular parameters of HES also influence other effects, such as cumulation in various organs and hemostasis. Critical reading of current HES literature shows that many questions still have to be answered. At the same time ways and means of optimizing differential volume substitution therapy and hemodilution therapy are emerging.