Acta anaesthesiologica Scandinavica
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Acta Anaesthesiol Scand · Jun 1981
Central haemodynamics and oxygen transport during CPAP with and without mandatory ventilations.
Ten patients, subjected 16 h earlier to open-heart surgery (aortocoronary bypass and/or aortic valve replacement), were studied during the weaning period after postoperative mechanical ventilation. Central haemodynamics and oxygen transport were assessed along with total oxygen consumption during continuous positive airway pressure with four mandatory ventilations per minute (mode CPAP + IMV) and, subsequently, during CPAP alone. ⋯ All parameters of haemodynamics, oxygenation and oxygen consumption were found to be essentially satisfactory and unchanged during both modes of ventilation. Our observations suggest that, as the parameters studied were unaltered with the change from CPAP + IMV to CPAP, the use of ventilatory support for these patients during the weaning period (in the form of four mandatory ventilations per minute) appears, in terms of central haemodynamics and oxygen transport, to be well tolerated in cases where adequate spontaneous ventilation is in doubt.
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Acta Anaesthesiol Scand · Jun 1981
Comparative StudyMyocardial oxygen consumption and coronary haemodynamics during fentanyl-droperidol-nitrous oxide anaesthesia in patients with ischaemic heart disease.
Eight patients with stable ischaemic heart disease were investigated to determine the effects of fentanyl (15 micrograms/kg) - droperidol (150 micrograms/kg) - nitrous oxide (75%) anaesthesia, without concomitant fluid challenge, on myocardial oxygen consumption and lactate uptake, and central and coronary haemodynamics. Anaesthesia induced reductions in mean arterial pressure (--35%, P less than 0.01), systemic vascular resistance (--30%, P less than 0.01), left ventricular stroke work index (--50%, P less than 0.01) and total body oxygen consumption (--23%, P less than 0.01), with no changes in heart rate, cardiac output or mean pulmonary arteriolar occlusion pressure. Mixed venous oxygen content increased (P less than 0.05). ⋯ No ST-T-segment depressions or dysrhythmias were recorded. These observations indicate that myocardial oxygenation was adequate in spite of the reduction in coronary perfusion pressure. There was poor correlation between changes in myocardial oxygen consumption and rate pressure product (R = 0.455) or triple produce (R - 0.375).
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Acta Anaesthesiol Scand · Jun 1981
Lumbar epidural anaesthesia with bupivacaine in old patients: effect of speed and direction of injection.
The spread of lumbar epidural analgesia was studied in 48 old urological patients (56-81 years). Bupivacaine 0.5% 20 ml was injected at either 1 ml/s with a Tuohy needle with the bevel directed cephalad (Group I) or caudad (II) and at 0.22 ml/s directed cephalad (III) or caudad (IV). Immediately after injection, the patients moved from a sitting to a horizontal position and analgesia was tested every 2 min by skin pin-prick. ⋯ The mean venous blood levels of bupivacaine were highest in Group III and lowest in Group I (n.s.). The highest individual bupivacaine blood level was 1.25 micrograms/ml 30 min after injection, while generally the highest concentrations appeared at 20 min after injection. The study indicated a lack of significant difference on varying the speed of injection or turning the Tuohy needle, but it has to be emphasized that this may apply only to bupivacaine, which has distinct physicochemical properties, and also to old patients with an age-dependently modified epidural space.
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Acta Anaesthesiol Scand · Apr 1981
Influence on cerebral blood flow of infusion of sodium bicarbonate during respiratory acidosis and alkalosis in the dog.
In anaesthetized dogs, a mixed acid-base disturbance was induced by adding a pronounced metabolic alkaline to an established respiratory acidosis or alkalosis. Cerebral blood flow (CBF) was measured by the radioisotope washout method. ⋯ Acid-base analysis of cerebrospinal fluid (CSF) indicated an increased bicarbonate concentration. Hypercapnia is suggested to facilitate the passage of bicarbonate over the blood-brain barrier, leading to cerebral vasoconstriction by means of increased extravascular pH.