The results indicated that the mixture of clonidine and yohimbine, in which either drug inhibited impulse conduction, produced conduction block in an additive manner, and that clonidine-induced conduction block was not reversed by coapplication with a specific alpha(2)-adrenergic antagonist idazoxan. These data suggest that clonidine's effects likely depend on mechanisms not mediated by alpha(2)-adrenergic receptors.
Background: Two hundred seventy-eight patients undergoing thoracic surgery were retrospectively analyzed to determine whether which variable can predict the identification of patients at risk of arterial hypoxemia developing during one-lung ventilation (OLV).Methods: According to the value of SpO2, the patients were divided two groups. Group L (n = 62) had SpO2 values of less than 95%, whereas group H (n = 216) those of more than 95%. Preoperative and intraoperative data, including past medical history, current therapy, and usual preoperative and intraoperative tests, were collected and used as predictable variables for arterial hypoxemia during OLV by binary logistic regression (forward conditional method) subsequent to independent t-test and Chi-square test, as appropriate.Results: Preoperative (past medical history with pulmonary resection of a lobectomy in dependent lung, hypertension, arrhythmias, and predicted diffusion capacity for carbon monoxide ≤ 70%) and intraoperative (arterial oxygen tension/inspiratory oxygen fraction during two-lung ventilation < 528 mmHg, right thoracotomy) variables were considered as predictable factors that identified patients at risk of arterial hypoxemia during OLV.Conclusions: Caution to the increased risk of arterial hypoxemia during OLV is needed in patients that have aforementioned preoperative and intraoperative variables.
Background: Opioids are the most widely used drugs to minimize the increase of blood pressure and heart rate in endotracheal intubation during the induction of anesthesia. The purpose of this study was to compare the effects of fentanyl, alfentanil, and remifentanil on the cardiovascular response to laryngoscopic endotracheal intubation.Methods: Eighty ASA I-II patients were randomly allocated to four groups. The patients received 10 ml intravenous saline (control group), 3μg/kg fentanyl (fentanyl group), 10μg/kg alfentanil (alfentanil group) or 0.5μg/kg remifentanil followed by an infusion of 0.1μg/kg/min remifentanil (remifentanil group). Anesthesia was induced with propofol and rocuronium and maintained with 2 vol% sevoflurane and 50% nitrous oxide in oxygen. The noninvasive blood pressure and heart rate were recorded before induction (baseline), after induction, before intubation, and at 1 min intervals until 5 min after endotracheal intubation.Results: Arterial pressure and heart rate after endotracheal intubation were lower in the fentanyl, alfentanil, and remifentanil groups than in the control group (P < 0.05). There were no significant differences for arterial pressure or heart rate in the fentanyl, alfentanil, and remifentanil groups at any time. There were no significant differences for the incidence of hypotension and bradycardia among the four groups.Conclusions: Administration of 3μg/kg fentanyl, 10μg/kg alfentanil and 0.5μg/kg remifentanil followed by an infusion of 0.1μg/kg /min remifentanil have a similar effect in the suppression of the cardiovascular response to laryngoscopic endotracheal intubation during the induction of general anesthesia.
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