Anesthesia and analgesia
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Anesthesia and analgesia · May 1997
Randomized Controlled Trial Clinical TrialHemodynamic effects of intravenous isoproterenol versus saline in the parturient.
The use of epinephrine as a test dose for epidural analgesia in obstetrics remains controversial. Isoproterenol as a test dose may be efficacious in the parturient. However, the effects of isoproterenol on the uterine blood flow (UBF) and umbilical blood flow (UMB) in the parturient are unknown. ⋯ UMB did not change. Other hemodynamic variables did not change. We conclude that isoproterenol, 5 micrograms, may be a suitable test dose for epidural analgesia in obstetrics.
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Anesthesia and analgesia · May 1997
Randomized Controlled Trial Clinical TrialThe effect of nasal continuous positive airway pressure on plasma endothelin-1 concentrations in patients with severe cardiogenic pulmonary edema.
We investigated the effects of nasal continuous positive airway pressure (CPAP) on plasma endothelin-1 (ET-1) concentrations in patients with cardiogenic pulmonary edema. Thirty patients were randomly assigned to two groups: 15 patients who received oxygen plus nasal CPAP (CPAP group), and 15 patients who received only oxygen by face mask (oxygen group). The heart rate and the mean pulmonary artery pressure decreased significantly in the CPAP group. ⋯ Arterial plasma ET-1 concentrations in the CPAP group compared with the oxygen group were significantly lower at 24 h. There was a correlation between the arterial plasma ET-1 concentrations and mean pulmonary artery pressure (r = 0.62, P < 0.001), and PaO2/FIO2 (r = -0.46, P < 0.01). Nasal CPAP led to an early decrease in plasma ET-1 concentrations, and improvement in oxygenation and hemodynamics.
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Anesthesia and analgesia · May 1997
Clinical Trial Controlled Clinical TrialHemodynamic effects of anesthesia in patients with ischemic heart failure chronically treated with angiotensin-converting enzyme inhibitors.
Anesthesia may induce hemodynamic instability in patients treated with angiotensin-converting enzyme inhibitors (ACEIs). To assess the hemodynamic effects of anesthesia in patients treated (n = 9) or not treated (n = 9) with ACEIs for ischemic left ventricle dysfunction after myocardial infarction, we studied 18 patients scheduled for elective coronary artery bypass graft surgery. Induction of anesthesia with fentanyl (5 micrograms/kg), flunitrazepam (30 micrograms/kg), and pancuronium (100 micrograms/kg) was followed by a significant decrease in mean arterial blood pressure in both groups (-18.6% +/- 8.1% in controls and -25.7% +/- 7.8% in ACEI-treated patients, P = 0.01). ⋯ In ACEI-treated patients, cardiac index decreased significantly (-27.3% +/- 11.6%, P = 0.01 from baseline and P = 0.03 when compared with controls), and systemic vascular resistance was unchanged (1.0% +/- 18.7%, NS from baseline and P = 0.04 when compared with controls). Two patients from each group experienced a transient severe hypotensive episode. ACEI treatment in patients with infarction-induced myocardial dysfunction does not increase the incidence of severe hypotension after induction of anesthesia.
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Anesthesia and analgesia · May 1997
The threshold for thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is reduced in the elderly.
Elderly patients become more hypothermic during surgery, shiver less postoperatively, and take longer to rewarm than younger patients. Similarly, the vasoconstriction threshold (triggering core temperature) is reduced approximately 1 degree C in elderly patients during nitrous oxide/isoflurane anesthesia. Accordingly, we tested the hypothesis that the vasoconstriction threshold in the elderly is also reduced approximately 1 degree C during nitrous oxide and sevoflurane anesthesia. ⋯ The data from five patients who did not vasoconstrict at minimum core temperatures of 33-34 degrees C were eliminated, leaving 10 patients in each group. The vasoconstriction threshold was significantly less in the elderly (35.0 +/- 0.8 degrees C) than in younger patients (35.8 +/- 0.3 degrees C), despite similar mean skin temperatures (mean +/- SD, P < 0.01, Student's t-test). Age dependence of thermoregulatory vasoconstriction during nitrous oxide/sevoflurane anesthesia is similar to that previously observed during nitrous oxide/isoflurane anesthesia.
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This investigation analyzed the changes in inspiratory airway pressures during transition from two-lung to one-lung ventilation in patients tracheally intubated with a double-lumen endotracheal tube (DLT) using a classical method of intubation without fiberoptic bronchoscopy. All patients were anesthetized in a standardized fashion. Ventilation was accomplished with the Siemens 900 constant-flow mechanical ventilator (Solna, Sweden). ⋯ When the DLT was in a correct position, Ppeak increased by a mean of 55.1% and Pplateau increased by a mean of 41.9%. When the DLT was malpositioned, this increase was significantly larger (74.9% and 68.8%, respectively). Three tests commonly used as markers of malpositioned DLTs were evaluated based on the data of this study, and it was established that, although the pressure differences related to position are statistically significant, as a single value, they cannot be used for clinical decision making.