The use of micro-dose aprotinin with continuous infusion in coronary artery bypass surgery.

BACKGROUND: To evaluate the efficacy of aprotinin at a dose far less than standard. EXPERIMENTAL DESIGN: Retrospective, case-control study. SETTING: community-based, teaching hospital PATIENTS: one hundred one patients undergoing primary, non-emergent, coronary artery bypass during two, six-month periods were studied. INTERVENTIONS: during the first period aprotinin was not administered, and these patients served as controls (n = 52). During the second period all patients received aprotinin via a micro-dose regimen (n = 49). MEASURES: postoperative bleeding and blood product usage served as determinants of efficacy. RESULTS: A significant difference existed in postoperative bleeding with the mean thoracic drain outputs being reduced in the aprotinin group both at 6 hours (p = 0.0003) and in total (p = 0.0004). This was further supported by significantly higher hematocrits (p = 0.03) on the first postoperative day in patients receiving aprotinin. Likewise, there was a significant reduction in total blood product exposures (p = 0.04) and platelet usage (p = 0.02) in the aprotinin group with a tendency towards decreased red cell usage. Further, when all patients with a hematocrit < or =30% prior to bypass were excluded, the significant reduction in total blood product exposures persisted (p = 0.04), and there was a significant reduction in red cell usage (p = 0.04) with a trend towards decreased platelet usage (p = 0.06) in the aprotinin group. CONCLUSIONS: Micro-dose aprotinin significantly reduces postoperative bleeding and blood product usage in primary, non-emergent, CABG patients.

Test doses: optimal epinephrine content with and without acute beta-adrenergic blockade.

The authors studied the optimal epinephrine content of an epidural test dose, and determined criteria to identify intravascular injections in subjects with or without beta-adrenergic blockade. Nine healthy nonpregnant subjects 25-36 years of age were given intravenous infusions of saline or esmolol in random order. During each infusion, they received a series of five injections (3 ml each) of either saline, 1% lidocaine or 1% lidocaine containing 5, 10, or 15 micrograms of epinephrine. Thirty minutes after completing these two infusions, propranolol was administered as a bolus injection, and the series of five injections repeated. All injections were double blind and randomized. During saline infusion, all injections containing epinephrine significantly increased heart rate (HR) by an average of 31-38 beats/min when compared with that following plain lidocaine (P less than 0.05), and increased systolic blood pressure by an average of 17-26 mmHg (P less than 0.05 for the 15-micrograms dose only). During esmolol infusion, epinephrine injections increased HR by an average of 23-31 beats/min (P less than 0.05), and increased systolic blood pressure by an average of 18-30 mmHg (P less than 0.05 for 10 and 15 micrograms). After propranolol injection, epinephrine injections caused a decrease in HR by an average of 21-28 beats/min (P less than 0.05), whereas systolic blood pressure increased by an average of 22-35 mmHg (P less than 0.05 for 10 and 15 micrograms only). Without beta-adrenergic blockade, an increase in HR greater than or equal to 20 beats/min was 100% sensitive and specific for intravascular injection of 10 or 15 micrograms of epinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta 1-selective and non-selective beta-adrenoceptor blockade, anaerobic threshold and respiratory gas exchange during exercise.

The effect of oral doses of the beta 1-selective adrenoceptor antagonist atenolol (50 mg), the non-selective antagonist propranolol (40 mg) and placebo was investigated during exercise in a crossover comparison in six healthy but untrained subjects. Descriptors of ventilation, respiratory gas exchange, and arterialized blood lactate and glucose were obtained during steady state bicycle ergometric exercise at 20% and 60% of the subjects' previously determined maximal oxygen uptake (VO2 max). At these work intensities, the previously reported increase of respiratory exchange ratio (RER) during non-selective beta-adrenoceptor blockade was found to be trivial (placebo = 0.96 +/- 0.03 s.e. mean; propranolol = 0.97 +/- 0.01; atenolol = 0.97 +/- 0.04; 60% VO2 max, 10 min exercise) and only present during the early minutes of effort. Oxygen uptake and carbon dioxide production did not differ between treatments. Both drugs produced highly significant falls in peak expiratory flow (PEF) rates and tidal volume (VT) which were compensated by an increase in respiratory rate. PEF, 60% VO2 max: placebo = 3.8 +/- 0.3 l/s; propranolol 3.6 +/- 0.3 l/s (P less than 0.03); atenolol 3.1 +/- 0.3 l/s (P less than 0.01). VT, 60% VO2 max: placebo 2.0 +/- 0.1 l; propranolol 1.8 +/- 0.21 (P less than 0.05); atenolol 1.7 +/- 0.1 1 (P less than 0.01). Arterialized lactate was significantly elevated during work at 20% and 60% VO2 max, but rose progressively at the 60% VO2 max load. Ventilation, oxygen uptake and ventilatory equivalent for carbon dioxide also rose progressively at this workload. Ventilatory equivalent for oxygen showed no significant rise.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitation of plasma catecholamines by on-line trace enrichment high performance liquid chromatography with electrochemical detection.

A sensitive and specific procedure for quantifying plasma catecholamines using on-line trace enrichment high performance liquid chromatography with electrochemical detection (HPLC-EC) is described. Plasma catecholamines are off-line extracted using aluminum oxide and then on-line enriched on cation exchange enrichment HPLC columns and back-eluted using a potassium enriched mobile phase for further separation by ion-pair, reverse phase HPLC. The salient features of this method are (1) the on-line combination of distinct HPLC retention mechanisms for enrichment and separation of the catecholamines to yield optimal assay specificity, (2) a lower working limit of detection of 25 pg norepinephrine and epinephrine per milliliter plasma based upon an assayed plasma volume of 1 ml, (3) the generation of calibration curves using standard additions to a 'like' matrix, (4) a high daily sample throughput due to the lack of late-eluting chromatographic interferences and (5) use of an optimized aluminum oxide prepurification procedure. The advantages of this method relative to other HPLC-EC assays for plasma norepinephrine and epinephrine are discussed as are the general considerations to be addressed when defining performance characteristics of an assay.