Der Anaesthesist
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Randomized Controlled Trial Comparative Study Clinical Trial
[Heat and moisture exchangers for conditioning of inspired air of intubated patients in intensive care. The humidification properties of passive air exchangers under clinical conditions].
Heat and moisture exchangers (HME) are used as artificial noses for intubated patients to prevent tracheo-bronchial or pulmonary damage resulting from dry and cold inspired gases. HME are mounted directly on the tracheal tube, where they collect a large fraction of the heat and moisture of the expired air, adding this to the subsequent inspired breath. The effective performance depends on the water-retention capacity of the HME: the amount of water added to the inspired gas cannot exceed the stored water uptake of the previous breath. ⋯ These data are simple to obtain without affecting the patient and can easily be interpreted. It was demonstrated that, compared to physiological conditions, the DAR Hygrobac and Gibeck Humid Vent 2P-HME coated with hygroscopic salts-were able to maintain sufficient inspiratory humidity and heat. The Pall-HME, solely a condensation humidifier, did not meet the physiological requirements.
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Induced hypotension is defined as a reduction in mean arterial blood pressure to 50-60 mm Hg in normotensive subjects. The aim of induced hypotension is to decrease intraoperative blood loss, decrease the need for blood transfusions and improve operating conditions. Most studies indicate that induced hypotension can decrease intraoperative blood loss by 50% in many surgical procedures; however, some studies report that blood loss is not significantly reduced. ⋯ Thus, major contraindications of induced hypotension are severe coronary artery disease, hypertension combined with arteriosclerosis of cerebral vessels and increased intracranial pressure in patients with cerebral disease. Complications are rare in otherwise healthy patients, but may be higher in elderly patients and those with underlying organ dysfunction. Therefore, careful assessment and selection of patients, together with consideration of the potential complications, appropriate choice of drugs and invasive beat-by-beat monitoring, are essential for the safe practice of induced hypotension.
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Only 53%-58% of patients with a subarachnoid haemorrhage (SAB) following the rupture of a cerebral aneurysm survive without neurological damage. Morbidity and mortality are closely related to the delayed ischaemic neurological deficit due to cerebral vasospasm. The following review gives an account of pathophysiological mechanisms; the importance of treatment with calcium antagonists, hypervolaemic haemodilution, and induced arterial hypertension is discussed in light of the current literature. ⋯ In view of the autoregulatory disturbances, systemic hypotension with its danger of decreased CBF must be prevented. The importance of hypervolaemic haemodilution and/or induced arterial hypertension is not clear. Despite therapeutic efforts, the number of patients who have survived a SAB without a substantial neurological deficit has not increased.
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The German Social Law has required quality assurance (QA) procedures since 1989. The measures must be suitable to allow "comparing investigations". In 1992 the German Society of Anaesthesiology and Intensive Care Medicine published recommendations for QA in anaesthesia: most problems during an anaesthetic should be documented in a standardised manner, and thus, a list of 63 pitfalls, events, and complications (PECs) and five degrees of severity were defined. ⋯ The types of PECs in our study had a similar distribution to those in other investigations, but there was a tendency to less frequent fatal PECs in ASA classes I to IV and more frequent ones in ASA class V. We expect better comparability when multicenter studies are done using identical methods in the next few years. Perhaps different patients collectives with special risks will be detected; efforts in quality improvement could focus on these patients.