Acta anaesthesiologica Scandinavica
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Capnography and measurement of the respiratory minute volume were carried out on normal, conscious subjects during breathing of pure O2 via a Mapleson C modification of a Magill attachment, with and without continuous gas evacuation. The measurements were performed in two series, with intermittent discharge and with continuous evacuation. ⋯ The measurements indicated CO2 accumulation at a flow below 200% of the respiratory minute volume. There was no significant difference between the systems with and without evacuation.
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Exact placement is an essential prerequisite for long-term use of a central venous catheter. Reported data show an extremely wide range of catheteral misplacements: from less than 1% to more than 60%. Some approaches appear to be less advantageous than others, but the highest rates of misplacement occur in the cubital, external jugular and saphenous veins. ⋯ The total frequency for pure loop formation was 2.9%. The authors discuss numerous reported data on catheter malpositioning, according to the specific techniques used, and compare them with thier own results. The relatively low incidence in the present series is possibly due to the high proportion of cases where the supraclavicular subclavian approach was used, the omission of the sphrenous/femoral and cubital techniques, and to pre-determining the length of the inserted catheteral segments.
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Acta Anaesthesiol Scand · Jan 1976
Anesthesia for cesarean section IV: placental transfer and neonatal elimination of bupivacaine following epidural analgesia for elective cesarean section.
Epidural analgesia with bupivacaine was used for elective cesarean section, and repeated maternal and neonatal blood samples were collected over 24 h for calculation of drug concentration. A gas-chromatogrphic micro-method was used for the analysis. The aim of this investigation was to evaluate the placental transfer and the elimination rate of the drug. ⋯ The fetal-maternal ratio of concentrations at delivery was higher than in previous studies, most probably due to the protein-binding characteristics of bupivacaine and the dosage used. The biological half-life of the rapid phase of elimination (alpha-phase) in the newborn was shorter than in the mother (P less than 0.002), indicating a more rapid distribution process. The half-life of the slow phase of elimination (beta-phase) in the newborn was of the same magnitude as in the mother, indicating that neonatal elimination processes of bupivacaine may be well developed at birth.
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Acta Anaesthesiol Scand · Jan 1976
Breathing mechanics, dead space and gas exchange in the extremely obese, breathing spontaneously and during anaesthesia with intermittent positive pressure ventilation.
Breathing mechanics and gas exchange were studied in 10 extremely obese subjects (average weight 138 kg) prior to and during anaesthesia with mechanical ventilation. Breathing mechanics were analysed from measurements of transpulmonary pressure (during anaesthesia, trans-chest wall pressure as well) inspiratory gas flow and tidal volume. Gas exchange was studied by analysing inspired and from the Bohr equation, and the division into anatomical and alveolar dead space was arrived at by capnography. ⋯ A moderate hypoxaemia was recorded during spontaneous breathing, and the alveolar-arterial oxygen tension difference was slightly elevated. During anaesthesia this difference was markedly greater. It is concluded that the most probable reason for the relative hypoxaemia is right-to-left shunting.
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An open reservoir for the collection and evacuation of anaesthetic gases permits leakage to room air. The use of a closed reservior for the removal of overspill gas from anaesthetic circuits is described. Calibrated gas evacuation is carried out through an ejector flowmeter from the anesthetic circuit or from a closed reservoir, where the gas is collected via a relief valve. In order to eliminate the risk of high or low pressure in the reservoir employed, a relief valve and a dumping valve is included in the system.