Acta anaesthesiologica Scandinavica. Supplementum
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Acta Anaesthesiol Scand Suppl · Jan 1995
Comparative StudyCentral venous versus mixed venous oxygen content.
Mixed venous oxygen content (commonly measured as oxygen saturation) is a highly relevant parameter in the monitoring of critically ill patients; unfortunately, its measurement requires catheterization of the pulmonary artery. Though less invasive, the central venous oxygen saturation is an unsatisfactory substitute, due to fluctuations in perfusion distribution and regional oxygen extraction in the course of illness. The present study examined the relation of oxygen contents in simultaneously withdrawn central venous and mixed venous blood samples from critically ill patients, in order to validate a hypothetical algorithm for the estimation of mixed venous oxygen content from a central venous sample: Although the proposed algorithm had a fairly high power of prediction, its merits in comparison to assuming simple proportionality between central venous and mixed venous oxygen content seemed marginal. However, as it is likely that the results so far are mathematically coupled, further prospective studies are necessary.
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Acta Anaesthesiol Scand Suppl · Jan 1995
The influence of arterial carbon dioxide on cerebral oxygenation and haemodynamics during ECMO in normoxaemic and hypoxaemic piglets.
To investigate the cerebrovascular response to changes in arterial CO2 tension during extracorporeal membrane oxygenation (ECMO) in normoxaemic and hypoxaemic piglets. ⋯ Since cerebrovascular reactivity to CO2 remains intact during ECMO in piglets, it is important to keep arterial CO2 tension stable and in normal range during clinical ECMO.
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Mivacurium has been little studied in infants and children without a volatile anaesthetic agent. We analysed onset time and maximal neuromuscular response after mivacurium 0.1 mg/kg, and the infusion requirement of mivacurium to maintain a 50, 90, or 95% neuromuscular block in 76 infants and children under N2O-O2-alfentanil anaesthesia. Furthermore, we assessed the time course of potentiation of 1 MAC end-tidal halothane or isoflurane on the infusion requirement of mivacurium. ⋯ In conclusion, mivacurium is easy to administer as bolus doses or continuous infusion in paediatric patients because its potency is similar in all patients from 1 month to 15 years of age. Halothane and isoflurane produce their maximal potentiation of neuromuscular block only after 30-60 min of administration. This potentiation is similar in magnitude in all patients, but takes place fastest in the youngest children.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Case ReportsHow far can we go with permissive hypercapnia? A case presentation and some biased comments with emphasis on maintaining normal haemoglobin level.
The respiratory management strategy of small tidal volume with permissive hypercapnia has been adopted to avoid further aggravation of lung injury due to high airway pressure with some impressive success (1). No consensus, however, has been established in terms of the rate of increase in PaCO2 and its upper limit. ⋯ The fact that PaCO2 may reach a very high level in the clinical setting and the well-known role of haemoglobin (Hb) in buffering CO2 led us to study effects of different Hb levels on pH and haemodynamic changes in response to acute CO2 loading in the blood. We will summarize the case report first with permission of authors (the case report was published in Japanese) (2) and then discuss the studies conducted in our animal laboratory.
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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.