Journal of cardiothoracic anesthesia
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J Cardiothorac Anesth · Dec 1990
Randomized Controlled Trial Clinical TrialHistamine blockade and cardiovascular changes following heparin administration during cardiac surgery.
Large doses of heparin given as a bolus may produce hypotension; however, conflicting reports exist about the mechanisms involved. This study was undertaken to determine the role of histamine in beef lung heparin-induced hypotension and the efficacy of histamine-receptor blockade in attenuating this undesirable side effect in patients undergoing cardiac surgery. Two hundred patients with good ventricular function were studied after they were randomized into four equal groups. ⋯ Those changes were significantly greater than in group II (P less than 0.025) and Group IV (P less than 0.005) patients, in whom no significant hypotension was found. In group III, mean arterial pressure decreased from 92 +/- 3 to 75 +/- 1 mm Hg (P less than 0.05) after 1 minute and returned toward baseline values after 4 minutes. Histamine levels increased significantly in all groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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J Cardiothorac Anesth · Dec 1990
Comparative StudyMyocardial recovery after cardiac surgery: a study of hemodynamic performance and electrophysiology during the first 18 postoperative hours.
Hemodynamic and vectorcardiographic variables were monitored in 23 patients with acquired heart disease, before and during the first 18 postoperative hours of cardiac surgery. The hemodynamic pattern directly after surgery was characterized by left ventricular depression and increased heart rate. Thus, stroke volume index had decreased from the preoperative 29 +/- 1 to 24 +/- 1 mL/beat/m2, and heart rate had increased from 61 +/- 2 to 94 +/- 4 beats/min. ⋯ Patients with a perioperative myocardial infarction had a vectorcardiographic pattern that was compatible with acute myocardial infarction. These patients had markedly elevated ST vector magnitude and QRS vector difference values, which were discernible during the first postoperative hours. The present data suggest that the timing of metabolic and electrophysiological recovery of the heart differ, and a computerized vectorcardiographic system may be of value in the early detection of perioperative myocardial infarction.
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J Cardiothorac Anesth · Dec 1990
Alpha-adrenergic agonist drugs, left ventricular function, and emergency from cardiopulmonary bypass.
The relationship between preoperative left ventricular (LV) dysfunction and the use of alpha-adrenoceptor agonists during weaning from cardiopulmonary bypass was studied in 102 patients undergoing coronary artery surgery. LV function was evaluated subjectively by examination of the 30 degree right anterior oblique left ventriculogram. Group 1 consisted of 75 patients with normal or mild impairment in LV function, whereas group 2 consisted of 27 patients with moderate-severe LV dysfunction. ⋯ Group 2 required significantly higher cumulative doses of phenylephrine after bypass compared with group 1 (1.69 +/- 0.70 mg, n = 9, v 0.24 +/- 0.04 mg, n = 27, P less than 0.05). Similarly, the dose of norepinephrine infusion in group 2 was 3.3 times that in group 1 (10 +/- 6 micrograms/min, n = 2, v 3 +/- 0.6 micrograms/min, n = 2, P = NS). The higher doses of alpha-adrenoceptor agonists required in patients with moderate-severe LV dysfunction may be due to differences in alpha-adrenoceptor agonist affinity and/or receptor density.
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J Cardiothorac Anesth · Dec 1990
The effective tracheal diameter that causes air trapping during jet ventilation.
Jet ventilation consists of injection of gas at high flow rates through a small-diameter tracheal catheter. Air trapping (increase in end-expiratory lung volume) can occur during jet ventilation if the diameter of the trachea proximal to the tracheal catheter tip is too small (at least at one point in the trachea) to permit complete exhalation of the tidal volume around the tracheal catheter (ie, through the effective tracheal diameter). A mechanical lung model was used to determine the critical effective tracheal diameter at which air trapping starts to occur during jet ventilation. ⋯ As A to D increased and E decreased, y increased. More importantly, exhalation time was measured over the full range of values for A to E, and it was found that for every possible combination of values for A to D, there was always a unique critical effective tracheal diameter, 4.0 to 4.5 mm, that began to cause a very large increase in expiratory time (and with a sufficiently rapid respiratory rate [greater than 12 beats/min in this experiment], air trapping). Thus, when lung/jet ventilation factors tend to promote entry of jetted gas into the lungs (increased A to D, decreased E), even a small tidal volume has difficulty exiting the lung, if E is smaller than 4.5 mm.(ABSTRACT TRUNCATED AT 250 WORDS)