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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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
ReviewEffect of hypoxaemia on water and sodium homeostatic hormones and renal function.
Changes in body fluid homeostasis during acute hypoxaemia suggest a crucial role of renal function in acclimatization processes. Hypoxaemia stimulates sympathetic nervous activity, and also the cardiovascular system is affected with increases in heart rate and cardiac output. In most subjects, a hypoxic ventilatory response produces hypocapnia and respiratory alkalosis. ⋯ In view of the prompt increase in sodium and water excretion found during short-term hypoxaemia, the absence of such a response to more prolonged hypoxaemia suggests an adaptive time-dependent course of renal functional changes in hypoxaemia. Taken together, previous studies suggest that effects of acute hypoxaemia on renal haemodynamics are minor compared with effects on cerebral and coronary circulation. This might be the result of an appropriate resetting of autoregulatory mechanisms that would maintain the role of the kidney as a major sense organ to hypoxaemia and, subsequently, as a mediator of plasma volume regulation and erythropoietin synthesis.
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Acta Anaesthesiol Scand Suppl · Jan 1995
ReviewReversal of conscious sedation by flumazenil: current status and future prospects.
Flumazenil is safe and highly effective at reversing both benzodiazepine-induced sedation and amnesia. Bolus intravenous injection is the most appropriate technique when the goal is to fully reverse conscious sedation. Currently, the proven effective dose of flumazenil is 0.5 mg. ⋯ Depression of ventilatory responsiveness induced by benzodiazepines can be reversed effectively and promptly by flumazenil. Flumazenil must be immediately available as an emergency drug in any area where benzodiazepines are used. The clinical and economic benefits of elective and routine use of flumazenil have been demonstrated, but yet to gain widespread acceptance.
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Acta Anaesthesiol Scand Suppl · Jan 1995
Optimal values for oxygen transport during hypothermia in sepsis and ARDS.
Mild hypothermia (33 degrees C to 35.5 degrees C) is reported to improve oxygenation and survival in patients with lung failure (1). Although hypermetabolism may account for about 50% of the ventilatory demand in ARDS patients, the concept of reducing oxygen consumption (VO2) by lowering metabolic rate, has only recently gained attention (2). Our study was aimed to test whether mild hypothermia established by continuous veno-venous haemofiltration (CVVHF), could optimize values for oxygen kinetics in ARDS patients. ⋯ These results suggest that the inability to achieve optimal values for DO2 and VO2 during mild hypothermia induced by CVVHF could serve as a prognostic sign for fatal outcome. Although oxygen consumption is decreased during hypothermia, hypoxaemia may result due to alterations of the oxygen transport on a cellular basis. The relationship between oxygen transport and temperature during CVVHF therefore deserves further studies.