Journal of cardiothoracic anesthesia
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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.
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J Cardiothorac Anesth · Dec 1988
Randomized Controlled TrialInfluence of acute preoperative hemodilution on right ventricular function.
In a randomized study, the effects of acute, preoperative hemodilution (HD) (12 mL/kg) on right ventricular function were investigated in coronary artery surgery patients with reduced left ventricular function (ejection fraction < 50%) and significant stenosis of the right coronary artery (RCA). Blood was replaced either by hydroxyethyl starch (HES) solution (ratio 1:1; HD-HES; n = 15) or by Ringer's lactate, (RL) (ratio 2.5:1; HD-RL; n = 15). Fifteen comparable patients without HD served as a control group. ⋯ Furthermore, right ventricular function of the hemodiluted patients was not impaired by the subsequent ECC procedure. None of the traditionally measured parameters could be correlated significantly to the right ventricular thermodilution variables. It is concluded that moderate HD does not change right ventricular function even when the RCA is significantly stenosed.
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J Cardiothorac Anesth · Dec 1988
Regional hemodynamics and oxygen supply during isovolemic hemodilution in the absence and presence of high-grade beta-adrenergic blockade.
Studies were performed in 16 pentobarbital-anesthetized dogs to evaluate regional circulatory effects of isovolemic hemodilution in the absence (group 1) and presence (group 2) of high-grade beta-adrenergic blockade with propranolol. Regional blood flow measured with 15 microm radioactive microspheres was used to calculate regional oxygen supply. In group 1, hemodilution with 5% dextran (40,000 molecular weight) reduced arterial hematocrit and oxygen content by approximately one half and had heterogeneous effects on regional blood flows. ⋯ In group 2, intravenous administration of propranolol (1 mg/kg) itself decreased blood flow in the spleen and myocardium and had no other regional effects. Hemodilution after propranolol caused regional circulatory changes that were essentially similar to those in the absence of propranolol. It is concluded that (1) during isovolemic hemodilution, oxygen supply to the brain and myocardium is maintained at the expense of oxygen supply to less critical organs, and (2) this pattern of regional circulatory response during hemodilution remains intact in the presence of high-grade beta-adrenergic blockade with propranolol.