Journal of cardiothoracic anesthesia
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J Cardiothorac Anesth · Feb 1989
Comparative StudyA comparison of radial, brachial, and aortic pressures after cardiopulmonary bypass.
Previous investigations have identified falsely low radial artery pressures after cardiopulmonary bypass (CPB). The present study investigates the relationship among radial, brachial, and aortic arterial pressures in 33 cardiac surgical patients following CPB. Two minutes after separation from CPB, clinically important (greater than or equal to 10 mmHg) underestimation of systolic aortic pressures occurred in 17 of 33 (52%) radial artery catheters, while occurring in seven of 33 (21%) brachial artery catheters. ⋯ Brachial artery systolic and mean pressures were higher than corresponding radial artery measurements two minutes after CPB (P less than 0.05), followed by gradual resumption of a normal brachial-to-radial pressure relationship over 60 minutes. Either vasospasm in the brachial and radial arteries or profound arteriolar vasodilation in the upper extremity might cause the observed central-to-peripheral arterial pressure differences. The progressive central-to-peripheral decrease in mean arterial pressure favors the latter mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)
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J Cardiothorac Anesth · Feb 1989
Cardiovascular effects of a nifedipine infusion during fentanyl-nitrous oxide anesthesia in dogs.
The hemodynamic effects of a nifedipine infusion were investigated in eight dogs given fentanyl/pancuronium/nitrous oxide/oxygen anesthesia. Nifedipine (20 micrograms/kg) was given intravenously over two minutes immediately prior to each 30-minute infusion at 2 micrograms/kg/min, 4 micrograms/kg/min, and 6 micrograms/kg/min. The range of plasma nifedipine levels obtained was 52.1 to 113.7 ng/mL. ⋯ Administration of calcium chloride (20 mg/kg) after the nifedipine infusion had no effect on SVR or MAP, but HR was significantly reduced. Serum epinephrine and norepinephrine levels increased after the infusion of nifedipine and suggested that fentanyl did not completely overcome the sympathetic response to the profound vasodilatation. The resulting tachycardia in combination with diastolic hypotension from nifedipine could have a detrimental effect on the myocardial oxygen balance.
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J Cardiothorac Anesth · Dec 1988
Continuous low-flow supracarinal and subcarinal oxygen insufflation in addition to intermittent positive-pressure ventilation does not improve gas exchange.
Recent studies in animals have demonstrated that continuous insufflation of oxygen near the tracheal carina results in ventilation and carbon dioxide removal that is proportional to the flow rate. The purpose of this study was to determine whether the addition of supracarinal and subcarinal low-flow oxygen insufflation to conventional intermittent positive-pressure ventilation (IPPV) of critically ill and anesthetized patients results in increased ventilation and improved oxygenation. In eight studies a supracarinal catheter (3.7 mm OD) was placed 1 to 2 cm above the carina, and in another eight studies two subcarinal catheters (1.7 mm OD) were placed 2 cm below the tracheal carina under direct vision with a fiberoptic bronchoscope. ⋯ Conversely, there was a significant decrease in mean arterial pressure and cardiac output with each incremental increase in continuous oxygen flow rate. It is concluded that use of continuous low-flow insufflation of oxygen with simple administration systems (catheters within the lumen of endotracheal tube) in addition to conventional IPPV is contraindicated at the present time. Further studies using different insufflation systems may prove to be worthwhile.
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J Cardiothorac Anesth · Dec 1988
Randomized Controlled Trial Comparative StudyPrebypass hemodynamic stability of sufentanil-O2, fentanyl-O2, and morphine-O2 anesthesia during cardiac surgery: a comparison of cardiovascular profiles.
Cardiovascular responses and the need for intervention with vasoactive agents were measured prospectively in a randomized study of 50 adult patients receiving sufentanil (n = 20), fentanyl (n = 20), or morphine (n = 10) anesthesia for cardiac surgery. Measurements were recorded and compared during induction and prebypass at intervals during which airway or surgically induced stress responses were likely to be greatest. Randomized, double-blinded doses of opioids were administered slowly and titrated according to clinical responses (hemodynamics) and the electroencephalogram. ⋯ Pharmacologic intervention was made when systolic arterial pressure deviated more than 30% from pre-event values and was uncontrolled by additional opioids. Interventions were necessary more often in patients receiving morphine (nine of ten) or fentanyl (12 of 20) than in patients receiving sufentanil (six of 20), P < 0.05. Results from this study suggest that morphine is a relatively unsatisfactory anesthetic, while sufentanil and fentanyl, at equi-anesthetic depths, provide stable and satisfactory hemodynamics.