Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · May 2004
Comparative Study Clinical TrialComparison of the concentration-dependent effect of sevoflurane on the spinal H-reflex and the EEG in humans.
It has been shown that spinal reflexes such as the H-reflex predict motor responses to painful stimuli better than cortical parameters derived from the EEG. The precise concentration-dependence of H-reflex suppression by anaesthetics, however, is not known. Here we investigated this concentration-response relationship and the equilibration between the alveolar and the effect compartment for sevoflurane. ⋯ The differences in EC(50) and slope of the concentration-response relationships for H-reflex suppression and the EEG parameters point to different underlying mechanisms. In addition, the differences in time constant for equilibration between alveolar and effect compartment confirm the notion that immobility is caused at a different anatomic site than suppression of the EEG.
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Acta Anaesthesiol Scand · May 2004
Comparative Study Clinical TrialComparison of the neuromuscular blocking effect of cisatracurium and atracurium on the larynx and the adductor pollicis.
Cisatracurium unlike atracurium is devoid of histamine-induced cardiovascular effects and this alone would be the greatest advantage in replacing atracurium for the facilitation of tracheal intubation. On the other hand, 2 ED(95) doses of cisatracurium (100 micro g/kg) do not yield satisfactory intubating conditions such as those seen with equipotent doses of atracurium and therefore the recommended intubating dose of cisatracurium is 3 ED(95). To understand this discrepancy better, we evaluated the potency and onset of atracurium and cisatracurium directly at the larynx adductors in humans. ⋯ The slow onset time at the laryngeal muscles after cisatracurium can be explained by the higher potency as compared with atracurium.
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Acta Anaesthesiol Scand · May 2004
Clinical TrialEffect of breathing pattern on the pressure-time product calculation.
The pressure-time product (PTP) is often used to compare conditions with different breathing patterns. Being the pressure-time product calculated with pressures changes over a minute, mechanical load and inspiration time per minute should be its main determinants. The aim of this study was to investigate if the method of PTP computation is affected by the breathing pattern when mechanical load and inspiratory time per minute are constant. ⋯ Changes in breathing pattern markedly affected the PTP independently by the mechanical load and the inspiratory time per minute. In these conditions it could not correctly estimate the metabolic cost of breathing. The use of a 'corrected' PTP, the mean inspiratory pressure per minute or the double product of the respiratory system, could overcome this limitation.
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Acta Anaesthesiol Scand · May 2004
Case Reports Comparative StudyPulmonary artery thermodilution cardiac output vs. transpulmonary thermodilution cardiac output in two patients with intrathoracic pathology.
In two adult patients, one with a severe hemorrhage and one with a partial anomalous pulmonary vein, cardiac output (CO) measurements were performed simultaneously by means of the bolus transpulmonary thermodilution technique (COao) and continuous pulmonary artery thermodilution method (CCOpa). In both cases, the methods revealed clinically significant different cardiac output values based upon the site of measurement and the underlying pathology. The assessment of cardiac output (CO) is considered an important part of cardiovascular monitoring of the critically ill patient. ⋯ Based on these results we assumed CCOpa equivalent to real CO during hemodynamically stable conditions, and secondly, a continuous cardiac output system based on pulse contour analysis (PCCO), such as the PiCCO system (Pulsion Medical System, Munchen, Germany). To calibrate this device, which uses a derivation of the algorithm of Wesseling and colleagues, an independently obtained value of CO by the transpulmonary thermodilution method (COao) is used. Clinical validation studies in patients without underlying intrathoracic pathology, comparing transpulmonary COao with the pulmonary technique (COpa), mostly yielded good agreement.
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Acta Anaesthesiol Scand · May 2004
Rapid response car as a supplement to the helicopter in a physician-based HEMS system.
The purpose of this study was to describe the use of a rapid response car (RRC) as a supplement to the ambulance helicopter in a mixed urban/rural region in Norway. ⋯ The RRC was essential for solving missions in periods of non-flying conditions. The RRC increased the availability of the advanced prehospital life support offered by the HEMS in this region. Taking the modest increase in cost into consideration, it seems reasonable that this HEMS, covering mixed urban and rural areas, is equipped with such a vehicle.