Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · Aug 1990
Ventilation-perfusion relationships and atelectasis formation in the supine and lateral positions during conventional mechanical and differential ventilation.
Patients without respiratory symptoms were studied awake and during general anesthesia with mechanical ventilation prior to elective surgery. Ventilation-perfusion (VA/Q) relationships, gas exchange and atelectasis formation were studied during five different conditions: 1) supine, awake; 2) supine during anesthesia with conventional mechanical ventilation (CV); 3) in the left lateral position during CV; 4) as 3) but with 10 cm of positive end-expiratory pressure (PEEP) and 5) as 3) but using differential ventilation with selective PEEP (DV + SPEEP) to the dependent lung. Atelectatic areas and increases of shunt blood flow and blood flow to regions with low VA/Q ratios appeared after induction of anesthesia and CV. ⋯ Perfusion of regions with low VA/Q ratios and venous admixture were then diminished, while PaO2 was slightly increased; shunt blood flow and dead space ventilation were essentially unchanged. During CV + PEEP, there was a decrease in cardiac output, compared to CV in the lateral position. DV + SPEEP was more effective than CV + PEEP in decreasing shunt flow and increasing PaO2 in the lateral position; in addition to this, cardiac output was not affected.
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Acta Anaesthesiol Scand · Jul 1990
Randomized Controlled Trial Comparative Study Clinical TrialThe influence of pancuronium and vecuronium combined with balanced anaesthesia on haemodynamics and myocardial oxygen balance.
The effects of the non-depolarizing muscle relaxants pancuronium (Pancuronium) and vecuronium (Norcuron) (0.1 mg/kg) on myocardial blood flow, myocardial oxygen consumption, myocardial lactate balance, cardiovascular dynamics and electrocardiogram were studied in two groups of eight patients undergoing coronary artery bypass surgery. After induction of anaesthesia with 0.015-0.02 mg/kg flunitrazepam, isoflurane (0.5 vol%) and N2O/O2 (l/l), neuromuscular blockade was induced with pancuronium or vecuronium (0.1 mg/kg) combined with a single dose of 0.005 mg/kg fentanyl. Haemodynamic measurements were performed and the electrocardiogram was recorded before anaesthesia, in steady-state anaesthesia, after relaxation with pancuronium or vecuronium combined with fentanyl, and after intubation. ⋯ None of the other haemodynamic parameters differed significantly in either patient group. We did not observe ST-segment depressions or elevations in the ECG, increases in PCWP or myocardial lactate production. Therefore extended myocardial ischaemia can be excluded in our patients who received pancuronium or vecuronium for neuromuscular blockade.
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Acta Anaesthesiol Scand · Jul 1990
Insufficient effect of local analgesics in Ehlers Danlos type III patients (connective tissue disorder).
The analgesic effects of intradermal lidocaine infiltration and topical EMLA cream applications (eutectic mixture of local anaesthetics) were studied in 8 patients with Ehlers Danlos syndrome type III, a heritable disorder of connective tissue, and in 8 controls. Cutaneous analgesia was evaluated by sensory and pain thresholds to short argon laser stimulation, and the depth of cutaneous analgesia was measured by sensory and pain thresholds to controlled needle insertion. Five minutes after lidocaine infiltration, the laser-induced pain was abolished in both groups, but 1 h later only the skin of the controls remained analgesic. ⋯ Full analgesia was obtained for the controls after 60 and 120 min of application. The depth of cutaneous EMLA analgesia was significantly less for the patients compared to controls. The present quantitative findings support clinical observations that long-lasting cutaneous analgesia is difficult to obtain for this group of patients.
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Acta Anaesthesiol Scand · Jul 1990
Lung fluid balance evaluated by the rate of change of extravascular lung water content.
Lung fluid balance was studied in 27 mongrel dogs by measuring changes in extravascular lung water content (EVLW). The expression delta EVLWi, which is the difference in EVLWi per kilo bodyweight per hour between two measurement occasions, was used as an estimate of the rate of change of EVLW. EVLW was measured by a double-indicator dilution technique (EVLWi) using iced glucose and indocyanine green. ⋯ OA-induced oedema caused a mean maximum delta EVLWi of 5.1 ml/kg/h, indicating capillary leakage which, however, was self-limiting within 2 h after OA injection. In hydrostatic oedema there was a maximum delta EVLWi of 16.0 ml/kg/h. Delta EVLWi was negative after deflation of the left atrial balloon, indicating reabsorption of oedema.
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Acta Anaesthesiol Scand · Jul 1990
Anesthetic induction with thiopental: its effect on scalp topography of median nerve somatosensory evoked potentials.
The effects on median nerve somatosensory evoked potentials (SEPs) of analgesic doses of fentanyl, meperidine or morphine and of sodium thiopental (STP) anesthesia (4 mg/kg) were tested in 36 surgical patients. We also explored changes in SEP components as a function of their scalp location. Before and after medication, responses were recorded from the scalp overlying the parietal cortex (ipsi- and contralateral to the stimulated arm) and the precentral (contralateral) cortex. ⋯ The barbiturate increased the amplitudes of subcortical and early cortical components (N18, N20, P22, P25), whose latencies, however, were not significantly modified. The effect of STP on later SEP cortical components depended on their scalp topography: parietal N33 and P45 underwent significant changes in both latency and amplitude, whereas precentral N30 showed a significant amplitude increase only. Thiopental anesthesia produces clearer short-latency SEP recordings, from both parietal (components N20-P25) and precentral (P22, N30) areas.