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[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.
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Anaesthesiol Reanim · Jan 1998
Review[Ethics in preclinical emergency medicine--on the topic of medical futility and resuscitation efforts].
In prehospital emergency medicine, physicians are repeatedly faced with the question of when cardiopulmonary resuscitation (CPR) efforts should be withheld or terminated since they are clearly futile. Here, futile means the goal of saving life cannot be achieved. Determining futility involves qualitative und quantitative aspects. ⋯ Thus, unilateral decisions by emergency physicians to withhold CPR are only justified in special cases when it is obvious that CPR and preservation of life would not be in the patient's interest. When in doubt, resuscitation attempts must be made. The futility of these efforts may emerge later in hospital, or information becomes available regarding the patient's will which justifies an end to therapy.
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Despite intensive therapeutic efforts, adult respiratory distress syndrome (ARDS) is still associated with a lethality ranging from 50 to 80%. Besides hypoxemia, fatal outcome is caused by myocardial insufficiency due to a progressive decrease in pulmonary vascular conductance. Inhalation of NO can selectively dilate pulmonary vessels in ventilated lung regions, thus increasing mean pulmonary artery conductance and decreasing venous admixture. ⋯ In severe ARDS, oxygenation significantly improves with the initiation of NO inhalation, but this effect declines over time. With NO, FiO2 and ventilatory pressures can be lowered. Whether the theoretically reduced oxygen toxicity and the reduced invasiveness of mechanical ventilation with NO reduces patient mortality must be determined in larger patient groups.