Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Fentanyl and sufentanil anesthesia revisited: how much is enough?
This study was undertaken to determine if fentanyl and sufentanil could produce dose-related suppression of hemodynamic and hormonal responses to surgical stimulation. Eighty patients scheduled for elective CABG were studied in two consecutive protocols: protocol I was a randomized double-blind study of 40 patients who received a single dose of fentanyl (50 or 100 micrograms/kg) or sufentanil (10, 20, or 30 micrograms/kg). Hemodynamic measurements and hormonal concentrations (renin, aldosterone, cortisol, and catecholamines) were determined before and after induction and after intubation and sternotomy. ⋯ During protocol II, 24 patients had a hemodynamic response (average increase in SBP - 31 +/- 3%) and there were 15 catecholamine responses. There were no differences between dose groups in either protocol. It was concluded that in these dose ranges, suppression of hemodynamic or hormonal stress responses is not related to opioid dose.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study Clinical Trial Controlled Clinical Trial
Comparison of brachial and radial arterial pressure monitoring in patients undergoing coronary artery bypass surgery.
The pressure in either the radial (n = 88) or proximal brachial artery (n = 82) was compared with aortic pressure before and after cardiopulmonary bypass (CPB) in patients receiving coronary artery bypass grafts. Radial artery pressures were measured via 20-G 5-cm long catheters, brachial artery pressures via 20-G 12.7-cm catheters, and aortic pressures were measured via a luer port in the aortic perfusion cannula. Transducers were connected via 122-cm long tubing. ⋯ The prebypass brachial correlation (r) with aortic for systolic, diastolic, and mean were 0.90, 0.98, and 0.98; respective radial correlations with aortic were 0.78, 0.97, and 0.95. Postbypass brachial systolic, diastolic, and mean correlations were 0.91, 0.97, and 0.98; radial were 0.50, 0.93, and 0.83. Brachial artery pressures were more accurate and reliable than radial artery pressures.
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Maitre et al. recently evaluated the accuracy of a set of previously determined population pharmacokinetic parameters for the opioid alfentanil using data from an earlier study in which the drug had been administered using a computer-controlled infusion pump (CCIP). The present study evaluated the accuracy of these same parameters in a CCIP prospectively in two groups of clinically dissimilar patients: 29 healthy female day surgery patients and 11 relatively older and less healthy male inpatients. In addition, another set of pharmacokinetic parameters, previously determined by Scott et al. in the CCIP in 11 male inpatients was also evaluated. ⋯ In the 11 patients studied using the Scott et al. pharmacokinetic parameters, the MDPE was +1% and the MDAPE was 17%. The parameters of Scott et al. were further tested by simulating the serum concentrations that would have been achieved had they been used in the CCIP in the first 40 patients; results indicated MDPE of +2% and an MDAPE of 18%. Therefore, reasonably reliable and accurate target serum concentrations of alfentanil can be achieved using the pharmacokinetic parameters of Scott et al. in a CCIP.(ABSTRACT TRUNCATED AT 250 WORDS)
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The effects of 0.5-2.0 MAC (3.6-15%) desflurane on cerebral function, metabolism, and hemodynamics and on systemic metabolism and hemodynamics were examined in dogs. Desflurane produced a significant dose-related decrease in cerebral vascular resistance from 1.53 +/- 0.21 mmHg.ml-1.min.100 g at 0.5 MAC to 0.50 +/- 0.03 mmHg.ml-1.min.100 g at 2.0 MAC desflurane. This was accompanied by an increase in cerebral blood flow (CBF) from 61 +/- 7 ml.min-1.100 g-1 at 0.5 MAC to 78 +/- 3 ml.min-1.100 g-1 at 1.5 MAC desflurane. ⋯ At 0.5 MAC desflurane, intracranial pressure (ICP) was 15 +/- 5 mmHg, higher than normal, but did not change significantly with increasing concentrations of desflurane. Increasing concentrations of desflurane initially produced on the EEG the common pattern sequence of increasing depth of anesthesia with decreasing frequency and increasing amplitude progressing to burst suppression and then at 2.0 MAC desflurane to regular attenuation with interruption by periodic polyspiking, a pattern similar to that seen with isoflurane. At both 1.5 and 2.0 MAC the EEG pattern initially observed at that concentration changed to one with faster background activity with time.(ABSTRACT TRUNCATED AT 250 WORDS)
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Because currently available blood warmers are inadequate for infants and children requiring massive transfusion, the performance of a new high-efficiency pediatric blood warmer (System 250TM, LEVEL 1 Technologies Inc., Marshfield, Massachusetts) was evaluated and compared with a commonly used conventional blood warmer (Model DW1000A, American Pharmaseal, Valencia, California). Cold (5-6 degrees C), diluted red blood cells (RBC) (Hct = 30%) were infused through the warmers over a series of flow rates, and the resulting temperatures of the infusate were measured. The flow rates of diluted packed RBC were also measured over a series of infusion pressures. ⋯ Above a flow rate of 250 ml/min, however, the water bath of the System 250TM cooled significantly, resulting in a deterioration of performance and an output temperature of only 24.2 degrees C at a flow rate of 400 ml/min. With a 16-G catheter attached, the flow rate at a pressure of 300 mmHg was 223 ml/min through the System 250TM compared with 160 ml/min (P less than 0.05) for the conventional warmer. The System 250TM produced higher output temperatures and a lower resistance to flow compared with the conventional warmer, but flow rates of cold blood through the System 250TM should be restricted to 250 ml/min or less to ensure adequate warming.