Anesthesiology
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In order to determine whether or not irritation of the nasal passage with commonly used volatile anesthetics can elicit airway reflexes, we investigated respiratory, laryngeal, and tracheal responses to nasal insufflation of three volatile anesthetics (enflurane, isoflurane, and halothane) in 13 patients anesthetized with flunitrazepam, pentazocine, and nitrous oxide. The trachea of each patient was intubated with a saline-filled double-cuffed endotracheal tube. Changes in breathing pattern were measured with a pneumotachograph while changes in laryngeal wall tension and tracheal wall tension were assessed by measuring changes in the proximal cuff pressure and the distal cuff pressure, respectively. ⋯ In these patients, nasal insufflation of 1 and 3% of each anesthetic did not produce any reflex response, whereas reflex responses were evident during nasal insufflation of 5% enflurane, isoflurane, and halothane. In all 13 patients, nasal insufflation of all three anesthetics at a concentration of 5% invariably produced changes in breathing pattern characterized by prolongation of expiratory time (TE). However, prolongation of TE was the most pronounced for enflurane (from a control value of 2.1 +/- 0.5 to a maximum value of 4.8 +/- 2.2 s [mean +/- standard deviation]), less for isoflurane (from 2.2 +/- 0.5 to 3.9 +/- 1.7 s), and the least for halothane (from 2.2 +/- 0.6 to 2.9 +/- 0.9 s).(ABSTRACT TRUNCATED AT 250 WORDS)
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The alpha 2-adrenergic agonist medetomidine produces systemic hemodynamic effects that are mediated by both peripheral and central nervous system actions. The current investigation was designed to characterize coronary and systemic hemodynamic effects of the D- and L-stereoisomers of medetomidine in conscious, chronically instrumented dogs with and without autonomic nervous system blockade. Dogs were instrumented for measurement of aortic pressure, coronary blood flow velocity, cardiac output, left ventricular pressure, rate of change in pressure (dP/dt), and subendocardial systolic shortening. ⋯ In dogs pretreated with hexamethonium (20 mg/kg), propranolol (2 mg/kg), and atropine methylnitrate (3 mg/kg) to produce autonomic nervous system blockade, D-medetomidine also produced an initial pressor response, but no secondary reduction in heart rate or arterial pressure occurred. The results indicate that the D-isomer of medetomidine is stereospecific for alterations in hemodynamics: the active D-isomer produces decreases in heart rate, arterial pressure, and the rate-pressure product via diminished sympathetic and/or augmented parasympathetic tone. This conclusion is supported by the absence of these changes after pharmacologic blockade of the autonomic nervous system.
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Randomized Controlled Trial Clinical Trial Retracted Publication
Blood conservation techniques and platelet function in cardiac surgery.
Postoperative alterations in platelet function induced by cardiopulmonary bypass (CPB) are of importance. The effect on platelet aggregation of three different techniques for reducing blood consumption was studied in 30 patients undergoing elective aortocoronary bypass grafting from the beginning of anesthesia until the 1st postoperative day. The patients were randomly divided into three groups, in which 1) a cell separator was used during and after CPB; 2) a hemofiltration device was used; and 3) high-dose aprotinin was used in order to reduce the need of homologous blood. ⋯ On the 1st postoperative day, platelet aggregation in the hemofiltration patients and the patients treated with aprotinin had normalized. Aggregation of patients pretreated with high-dose aprotinin was not different from that of the hemofiltration patients throughout the investigation. Blood loss was significantly highest in the cell-separator group (770 +/- 400 ml on the 1st postoperative day) but was not different between the hemofiltration (390 +/- 230 ml) and the aprotinin-treated patients (260 +/- 160 ml).(ABSTRACT TRUNCATED AT 250 WORDS)