Acta anaesthesiologica Scandinavica. Supplementum
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Acta Anaesthesiol Scand Suppl · Jan 1995
Oxygen and acid-base parameters of arterial and mixed venous blood, relevant versus redundant.
A complete pH and blood gas analysis of arterial and mixed venous blood may comprise more than forty different quantities. We have selected sixteen, including patient temperature. The arterial oxygen tension group includes the oxygen tension, fraction of oxygen in inspired air, and fraction of mixed venous blood in the arterial (total physiological veno-arterial shunting). ⋯ The mixed venous group includes mixed venous oxygen tension, and, when measured, cardiac output, and oxygen consumption rate. The acid-base status includes blood pH, arterial carbon dioxide tension, and extracellular base excess. Other quantities such as haemoglobin oxygen saturation, respiratory index, total oxygen concentration (oxygen content), oxygen extraction fraction, oxygen delivery, and several others, provide no essential additional clinical information and are therefore redundant.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Randomized Controlled Trial Clinical TrialIntubating conditions and neuromuscular effects of mivacurium during propofol-alfentanil anaesthesia.
In three groups of 20 patients, anaesthetized with propofol and alfentanil, tracheal intubation conditions and the onset of neuromuscular blockade after administration of three different doses of mivacurium chloride (0.11, 0.15, and 0.19 mg/kg = 1.5 x ED95, 2 x ED95, and 2.5 x ED95) were assessed. Intubation conditions were found to be clinically acceptable (good or excellent) in 83% of patients. ⋯ We conclude that mivacurium chloride allows smooth intubation in most patients within 60-90 s, even with the lowest dose (0.11 mg/kg), after a propofol-alfentanil induction of anaesthesia. However, because there were a few patients in whom intubating conditions were inadequate at 60-90 s, we are reluctant to advocate the preference of mivacurium chloride over suxamethonium for rapid sequence induction in emergency situations.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Notes on the apparent discordance of pulse oximetry and multi-wavelength haemoglobin photometry.
Multi-wavelength photometers, blood gas analysers and pulse oximeters are widely used to measure various oxygen-related quantities. The definitions of these quantities are not always correct. This paper gives insight in the various definitions for oxygen quantities. ⋯ The influence of fetal haemoglobin is insignificant in the neonatal use of pulse oximetry, in the range of 75% to 100% arterial oxygen saturation. However, a pulse oximeter underestimates the arterial oxygen saturation at the 25% level with 5%, if the pulse oximeter has been calibrated in human adults. Such a low level of arterial oxygen saturation can be present in the fetus during labor.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Review Comparative StudyFrom oxygen content to pulse oximetry: completing the picture in the newborn.
In recent years clinicians caring for sick preterm infants have come to depend on pulse oximetry to avoid hyperoxia, which means assuming saturation values for critical levels of oxygen tension. This prediction is made difficult by the shape of the haemoglobin-oxygen dissociation curve at critical values for arterial pO2 and by the effects of changes in acid-base balance on p50. Combined blood gas and co-oximetry measurements can be used to determine critical limits for pulse oximetry. ⋯ We demonstrated that, at 90% saturation, failure to use the fetal correction in the presence of high levels of fetal haemoglobin result in a 4% overestimate of saturation, with resultant underestimation of the safe range for pulse oximetry. Published values for extinction coefficients for fetal and adult blood at wavelengths used by pulse oximeters are inconsistent, but it appears that fetal haemoglobin does not bias pulse oximetry readings. Determining saturation limits by co-oximetry for use with pulse oximeters in preterm infants requires the description of the haemoglobin-oxygen dissociation curve with the correction for fetal haemoglobin.
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Acta Anaesthesiol Scand Suppl · Jan 1995
ReviewCentral antinociceptive effects of non-steroidal anti-inflammatory drugs and paracetamol. Experimental studies in the rat.
These studies were undertaken to investigate the site and nature of the antinociceptive effect of NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) and paracetamol in the central nervous system (CNS). ⋯ The antinociceptive effect of diclofenac involves a central nervous component which may be elicited from several defined areas in the CNS. Part of the antinociceptive effect seems to be mediated by descending inhibitory opioid, serotonin and/or other neurotransmitter systems interfering with visceral pain impulse traffic at the spinal level. NSAIDs and paracetamol interfere with nociception associated with spinal NMDA receptor activation. This effect involves an inhibitory action on spinal nitric oxide (NO) mechanisms. Possibly, the supraspinal antinociceptive effect of NSAIDs may be explained by an analogous action.