Der Anaesthesist
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Clinical Trial Controlled Clinical Trial
[Intraoperative contrast echocardiography for detection of a patient foramen ovale using a provocation test and ventilation with PEEP respiration].
Intraoperative paradoxical air embolism may occur even if a patent foramen ovale (PFO) is excluded by contrast transoesophageal echocardiography (TEE) under 20 cm H2O positive airway pressure. It is questionable whether the combination of PEEP and ventilation with a large tidal volume increases the sensitivity of contrast TEE in detecting a PFO. ⋯ The use of provocation manoeuvres including ventilation with PEEP and high tidal volumes might improve the ability to detect a PFO presenting with right-to-left interatrial shunt by intraoperative contrast TEE, but does not have 100% sensitivity. However, our results clearly indicate that ventilation with PEEP and high tidal volumes may predispose to paradoxical embolism.
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Patients with a prior myocardial infarction (MI) have a high risk of perioperative reinfarction compared with the normal population (5%-8% vs. 0.1%-0.7%) [10]. According to Rao [13], a reduction of this risk is possible when patients are monitored invasively and all haemodynamic parameters are kept within the physiological range. In most institutions it is not feasible to treat patients as Rao recommended: this would overstrain both hospital structure and financial resources. We studied the incidence of perioperative MI and other cardiac events in patients with prior MI. During the study period the anaesthesia and intensive care methods of our institution were neither changed nor influenced. In addition to this clinical evaluation, we performed perioperative Holter electrocardiographic monitoring and measured serum levels of the recently introduced marker troponin T (parts II and III). ⋯ Six of the 160 patients with prior MI developed a perioperative MI (3.8%); 2 of them (33%) died of cardiac causes (3rd and 6th postoperative day). All of these patients were in groups III or IV (interval > 6 months). Forty-two patients had one or more other cardiac events; arrhythmias (22) and ischaemia (14) were most common. Intraoperative hypotension was associated with postoperative MI (5 of 58 vs. 1 of 102). Preoperative congestive heart failure (4 of 18 vs. 3 of 121) and major surgery (7 of 68 vs. 0 of 71) led more often to postoperative left ventricular failure. Patients who received beta-blocking agents preoperatively had significantly fewer ischaemic cardiac events (0 of 28 vs. 14 of 90, 21 patients excluded with BBB) but differed in mean age (67 vs. 71 years). The use of beta-blocking agents was not associated with a reducti
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Case Reports
[Intraoperative airway obstruction during use of a laryngeal mask. A case report and fiber optic findings].
Laryngeal obstruction is a challenging complication during anaesthesia with a face mask or laryngeal mask and is due to insufficient analgesia in most cases. However, with a laryngeal mask in place it must be differentiated whether the airway obstruction is caused by the laryngeal mask itself or by other factors. Knowledge of the pathophysiology of the laryngeal closure and experience with the use of the laryngeal mask are essential for adequate treatment. Not the removal of a correctly inserted laryngeal mask which initially provided a satisfying airway, but the relaxation of laryngeal muscle activity by adequate anaesthesia is the first mandatory treatment if intraoperative airway obstruction occurs.
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alpha 2-Agonists are being used increasingly in anaesthesia and intensive care medicine because of their antihypertensive, analgesic and sedative properties. Platelets bear alpha 2-receptors on the cell surface. Stimulation of these receptors by agonists induces platelet aggregation. The present study examined whether in vitro incubation of blood with the alpha 2-agonists clonidine and dexmedetomidine decreases alpha 2-receptor density and hereby influences platelet aggregation. ⋯ This in vitro study showed that clinically relevant concentrations of 1 ng/ml clonidine or dexmedetomidine did not alter platelet aggregation or alpha 2-receptor density, even after 24 h exposure. However, 10 ng/ml dexmedetomidine was found to diminish significantly epinephrine-induced platelet aggregation, but did not change alpha 2-receptor density. This result showed that desensitization of platelet aggregation can occur without quantitative changes in alpha 2-receptors.
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Perioperative, mostly silent ischaemia in patients with coronary heart disease is difficult to detect by clinical examinations. ⋯ Perioperative Holter ECG monitoring is time-consuming, expensive, not very sensitive, and therefore not generally applicable for all patients with prior MI.