Biomedical subjects
Publications and source records attributed to G Kreienbühl.
A case of a transient unilateral paresis of the N. laryngeus cranialis occuring after uneventful tracheal intubation and anaesthesia for laparoscopy is reported. The possible mechanisms of this paresis are discussed.
This paper reviews the literature on anaesthetic problems in extremely obese patients. The main concerns of the anaesthetist in these patients is pulmonary function, especially hypoxaemia. The pathogenesis of hypoxia is explained by an increased tendency to airway closure by the weight of fat, which compresses the thorax. The significance of the patient's position during and after operation is stressed. The Pickwick-Syndrome is extremely rare, even in large series of obese patients, but its diagnosis is important for therapeutic consequences. For anaesthesia in these patients neuroleptanaesthesia as well as classical inhalational procedures can be used.
In a prospective and randomized study, day-patients receiving halothane or enflurane-anaesthesia (n = 42 resp. 59) were followed up by questionnaire to detect subjective complaints. There was no difference between the two anaesthetic agents. Despite the high incidence of complaints (88%), most of the patients would choose day-stay care (75%) and general anaesthesia (77%) again.
Blood gases were measured in hibernating and hypothermic animals as a biological model of clinical hypothermia. Blood gas analyses from hamsters and dormice were carried out with the aid of permanent arterial catheters during normothermia and hibernation. In golden hamster pH increased from 7.30 to 7.46 during hibernation and PaCO2 decreased from 59.7 to 40.5 mm Hg. In dormice pH increased from 7.24 to 7.44 and PaCO2 decreases from 38.5 to 27.4 mm Hg. The actual bicarbonate concentration increased from 29 to 52 mMol in golden hamsters and from 16 to 34 mMol in dormice during hibernation. In experiments with induced hypothermia in golden hamsters under ketamine-anaesthesia there was no correlation between temperature and PaCO2. Despite the slight decrease in PaCO2 during hibernation we conclude that PaCO2 rather than total carbon dioxide content is held constant when temperature is changed. During clinical hypothermia it will probably be safe to keep PaCO2 constant.
Hypocapnia during extracorporeal circulation in hypothermia increases oxygen consumption. Po2 in mixed venous blood decreases. This probably reflects a decrease in tissue oxygen tension. Hyperventilation will therefore increase the risk of hypoxia in critically perfused tissues. Therefore we recommend to keep PaCO2 (T) constant at 40 mm Hg during hypothermia.
We describe a method to prestretch symmetrically cuffs of plastic endotracheal tubes. The tracheal wall pressure will be lower than the capillary pressure of the mucous membranes in tow third of the cases, if correctly prestrecthed cuffs are used. The importance of using truly high volume low pressure cuffs with a cuff diameter of a least 25 to 30 mm is stressed.