Anesthesiology
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The effects of HCl infusion on multipoint mean pulmonary arterial pressure (PAP)/cardiac index (CI) plots in pentobarbital-anesthetized dogs whose lungs were ventilated alternately in hyperoxia (fraction of inspired O2 [FIO2], 0.4) and hypoxia (FIO2, 0.1) were investigated. Over the range of CI studied (1 to 5 l.min-1.m-2), hypoxia increased PAP in 22 dogs (responders) and did not affect PAP in 16 other dogs (nonresponders). In eight nonresponders, two repetitions of alternated 0.4 and 0.1 FIO2 exposures did not restore hypoxic pulmonary vasoconstriction (HPV), defined as a hypoxia-induced increase in PAP at a given flow. ⋯ In eight responders, 2 M HCl infusion (2 mmol.kg-1.h-1) together with a 7% sodium bicarbonate infusion (adjusted to maintain arterial pH unchanged) did not affect hyperoxic or hypoxic PAP/CI plots. Pretreatment with 1 g acetylsalicylic acid iv (6 dogs) did not affect the pulmonary vasoreactivity to HCl-induced (2 M HCl, 2 mmol.kg-1.h-1) metabolic acidosis. It was concluded that in intact dogs: 1) metabolic acidosis enhances HPV; 2) at the given dose, HCl does not produce pulmonary vascular effects unrelated to the circulating blood pH; and 3) it is unlikely that the pulmonary vasoreactivity to metabolic acidosis is mediated by products of the cyclooxygenase pathway.
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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)