Der Anaesthesist
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Recently, professional anaesthesiologists organizations, have set up recommendations for intraoperative monitoring. These recommendations are based upon the assumption that anaesthesia-related deaths are largely preventable and that extensive monitoring will reduce mortality. Hypoxaemia appears to be an important pathophysiological mechanism, and this is why oxygen monitoring is given a high priority in safety standards in anaesthesia. ⋯ Pulse oximetry is certainly highly recommended, but also has some deficiencies which are not sufficiently well known considering the popularity of this technique. Transcutaneous PO2 is considered mainly for historical reasons. Near infrared spectrometry is a new technique offering noninvasive and continuous monitoring of intracerebral oxygenation.
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Immediate-type hypersensitivity due to natural rubber (latex) products is an increasing problem for the anaesthetist, because a major part of products used for anaesthesia contains natural rubber. If the patient has a positive history of allergic symptoms after contact to natural rubber like urticaria, bronchospasm or anaphylaxis, preoperative skin tests, in vitro tests, and if necessary even the latex-glove-wearing test should be performed. If preoperative diagnosis of natural latex allergy is established, latex free anaesthesia is strictly recommended; otherwise life-threatening complications may ensue. ⋯ In addition to the treatment with drugs, latex-containing products should be immediately replaced by latex-free ones, in particular all persons should put on latex-free gloves. For prevention of anaphylactic episodes in sensitized patients the reader is provided with an exemplary list of latex-free products for anaesthesia. Because the incidence of immediate-type reactions to latex is still increasing, intraoperative occurrence of an anaphylactic reaction to an unknown agent is likely to be due to allergy to natural rubber.
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Hypoxic pulmonary vasoconstriction (HPV) was first described by von Euler and Liljestrand in 1946 and is still the only known vascular feedback control mechanism in the lung. This technique results in a redistribution of blood flow away from poorly ventilated areas into better ventilated regions, thus reducing shunt. HPV functions as a local mechanism that acts in response to alveolar hypoxia but in the smallest areas of the lung, making it an important mechanism in all situations where ventilation perfusion mismatch occurs. to be effective, HPV needs normal pulmonary areas into which blood flow can be diverted. ⋯ Examination of a histological lung section emphasizes that the small arteries are closely surrounded by alveoli gas on the outside and by mixed venous blood on the inside. Thus, the response is believed to be accounted for by each smooth muscle cell in the pulmonary arterial wall responding proportionally to the local oxygen tension in its vicinity and depending on alveolar as well as mixed venous oxygen pressure. The biochemical intracellular mechanism remains unknown.