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R L Royster

Publications and source records attributed to R L Royster.

At least 37 records · Page 2Linked to original sources

Hemodynamic and renal effects of dopexamine and dobutamine in patients with reduced cardiac output following coronary artery bypass grafting.

OBJECTIVE: Dopexamine hydrochloride is a novel synthetic adrenergic agonist that combines the renal effects of dopamine with the hemodynamic effects of dobutatmine. Our study is designed to compare the hemodynamic, diuretic, and natriuretic effects of dopexamine and dobutamine in patients with reduced cardiac index following heart surgery. DESIGN: Prospectively randomized, blinded study. SETTING: Operating room and intensive care unit of a large, urban, academic medical center. PATIENTS: Twenty-eight patients undergoing elective coronary artery bypass grafting (CABG) with preoperative ejection fraction of at least 40 percent gave informed consent. The study group consisted of the ten patients who had a cardiac index < or = 2.5 L/min/m2 (while receiving no inotropic medication) immediately after separation from cardiopulmonary bypass. INTERVENTIONS AND MEASUREMENTS: Study patients were randomly given a starting dose of either 5 micrograms/kg/min of dobutamine (n = 5) or 2 micrograms/kg/min of dopexamine (n = 5). During the initial 30 min following separation from bypass, dosages were titrated incrementally to maintain cardiac index > or = 3.0/L/min/m2. Further titrations of the drug were done only if cardiac index fell below 3.0 L/min/m2 or if sustained tachycardia occurred during the 24-h study period. Data were collected at 5- and 10-min intervals for the first 30 min after separation from bypass, hourly for the next 8 h, then every 2 h for the remainder of the study period. RESULTS: Both drugs increased cardiac index by more than 50 percent over baseline (dobutamine 2.2 +/- 0.1 to 3.5 +/- 0.2 [p < 0.05]; dopexamine, 2.3 +/- 0.1 to 3.5 +/- 0.1 [p < 0.05] L/min/m2). The mean dose required to maintain cardiac index > or = 3.0L/min/m2 was 1.5 micrograms/kg/min for dopexamine and 3.5 micrograms/kg/min for dobutamine. There were no significant differences in either urinary output or net sodium excretion in the dopexamine group compared with the dobutamine group, and tachycardia (heart rate > 120 beats/min) was more common in the dopexamine group. CONCLUSIONS: Our study demonstrates that dopexamine produces hemodynamic, diuretic, and natriuretic effects similar to dobutamine in patients with reduced cardiac index following CABG.

Adrenergic beta-Antagonists↗

Myocardial dysfunction following cardiopulmonary bypass: recovery patterns, predictors of inotropic need, theoretical concepts of inotropic administration.

Clinical myocardial dysfunction following cardiopulmonary bypass commonly occurs in patients with good preoperative ventricular function. Following separation from cardiopulmonary bypass, ventricular function improves initially, but then begins to worsen and reaches a nadir between 4 and 6 hours after surgery with full recovery occurring around 24 hours postoperatively. However, in patients with preoperative ventricular dysfunction, the depression of ventricular function is more severe and recovery is longer. Despite this high frequency of myocardial dysfunction, many patients do well without requiring pharmacologic intervention after cardiopulmonary bypass to augment contractility and peripheral perfusion. Factors that may predict the need for inotropic support in patients following cardiopulmonary bypass include low ejection fraction, older age, cardiac enlargement, female sex, the length of cardiopulmonary bypass and the duration of aortic cross-clamping. The patient with preoperative ventricular dysfunction has many of these preoperative and intraoperative predictors for inotropic support. The pharmacologic regimen to support the myocardium during the recovery period following cardiopulmonary bypass must take into consideration the pathophysiologic processes of chronic congestive heart failure and reperfusion injury. Reduction of cyclic adenosine monophosphate (cAMP) levels is a fundamental problem in congestive heart failure and results from either down-regulation of beta-receptors or a defect in the G-regulatory proteins controlling adenylyl cyclase production. This diminishes the effectiveness of agents dependent on cAMP to produce an inotropic response. However, amplification of the reduced cAMP produced by beta-agonists may occur in association with the inhibition of cAMP breakdown resulting from phosphodiesterase inhibitors. All inotropic agents are usually effective in reversing the reperfusion-induced stunned myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Is it really free?

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Anesthesiology↗

Combined inotropic effects of amrinone and epinephrine after cardiopulmonary bypass in humans.

Amrinone, a phosphodiesterase inhibitor, and epinephrine, an alpha- and beta-adrenergic receptor agonist, are inotropic drugs used during cardiac surgery to reverse myocardial depression after cardiopulmonary bypass. However, these drugs have not been compared separately, or in combination, in this patient population. We hypothesized that the combination might have complementary actions in improving myocardial function. We, therefore, compared amrinone, epinephrine, and the combination of amrinone and epinephrine in a randomized, blinded, placebo-controlled study in patients undergoing coronary artery bypass grafting. Forty patients with ejection fractions > 0.45 were studied. Right ventricular ejection fraction pulmonary artery catheters and radial arterial catheters were inserted before fentanyl-midazolam anesthesia. After separation from bypass, patients received either a placebo (n = 20) or amrinone bolus (1.5 mg/kg, n = 20) at time 0 and a placebo (n = 20) or epinephrine (30 ng.kg-1.min-1, n = 20) infusion at time 5 min. This resulted in four study groups, n = 10 in each group. Data were collected every 2.5 min for 10 min. Epinephrine, amrinone, and the combination of both drugs significantly increased cardiac output, stroke volume, O2 delivery, and left ventricular stroke work. The increase in stroke volume (P < 0.05) was 12 +/- 6, 16 +/- 4, and 30 +/- 4 mL/beat with epinephrine, amrinone, and the combination of amrinone and epinephrine, respectively. The amrinone-epinephrine combination increased stroke volume as much as the sum of amrinone and epinephrine given separately. Systemic vascular resistance and pulmonary vascular resistance decreased with amrinone and amrinone-epinephrine, but not with epinephrine. Epinephrine increased mean arterial and mean pulmonary arterial pressures. Right ventricular ejection fraction did not significantly increase (P = 0.09) with epinephrine, but increased significantly with amrinone (0.45 to 0.53, P = 0.01), and with the combination (0.43 to 0.55, P = 0.006). These data indicate that amrinone and epinephrine effectively increase myocardial performance during cardiac surgery. Right ventricular function especially was improved with amrinone and the combination of amrinone and epinephrine. The combined effects of amrinone and epinephrine may be useful in patients recovering from the ischemia and reperfusion injury resulting from coronary artery bypass grafting.

Amrinone↗

Amrinone in cardiac surgical patients with left-ventricular dysfunction. A prospective, randomized placebo-controlled trial.

STUDY OBJECTIVE: To evaluate the efficacy of amrinone for facilitating weaning from cardiopulmonary bypass (CPB). DESIGN: Prospective, randomized, double-blind, placebo-controlled trial with epinephrine as "rescue" therapy. SETTING: Operating room of a large, metropolitan tertiary-care center. PATIENTS: Thirty-nine patients with preoperative left ventricular dysfunction undergoing cardiac surgery. Thirty-three patients underwent aortocoronary bypass grafting; six patients underwent valve replacement for severe mitral or aortic regurgitation. INTERVENTIONS: Patients received either amrinone (1.5 mg/kg loading dose plus 10 micrograms/kg/min maintenance infusion; n = 20) or placebo (n = 19) in a randomized double-blind fashion shortly (median, 10.5 min; range, 2 to 24 min) before separation from CPB. Inotropic drugs (other than the study drug) were withheld prior to separation from CPB unless safety considerations demanded that the protocol be broken. Patients who could not be weaned from CPB, as well as those with a cardiac index of 2.2 L/min/m2 or less after weaning from CPB, received epinephrine (60 to 120 ng/kg/min) by infusion. MEASUREMENTS AND RESULTS: Fourteen of 19 patients receiving placebo but only 1 of the 20 patients receiving amrinone (p = 0.00001) required epinephrine infusion to separate from bypass. The cardiac index of 4 patients receiving placebo (but no patients with amrinone) failed to exceed 2.2 L/min/m2 despite epinephrine infusion, requiring the protocol to be broken (p < 0.08). Blood concentrations of amrinone determined (only in the amrinone group) after separation from CPB confirmed that the dosage of amrinone produced an effective blood concentration. Fourteen of 19 patients receiving placebo and 17 of 20 patients receiving amrinone required an infusion of phenylephrine titrated to maintain systolic blood pressure less than 90 mm Hg. Seven patients (four with amrinone and three with placebo) required antiarrhythmic drug therapy. The outcome at 3 months was similar in the 2 groups. CONCLUSIONS: Amrinone by itself is an effective agent to facilitate weaning from CPB, and therapy with amrinone reduced the need for individualized titration of epinephrine. Amrinone is as effective as individualized titration of epinephrine (after CPB) to improve cardiac function. Patients in the group receiving amrinone had no greater need for vasoconstricting agents than did patients in the group receiving placebo; however, proactive administration of amrinone before separation from CPB appears to offer no greater benefit to high-risk patients than selective administration of drugs (epinephrine) only to those patients who demonstrate the need for drug support at the time of weaning.

Adult↗

Pharmacologic cardiovascular support.

The availability of newer and better inotropic agents has led to their widespread application in critically ill medical and surgical patients. Although the elective use of inotropic drugs has been associated with adverse outcomes in patients with cardiomyopathy and chronic heart failure, inotropic drugs used as part of treatment protocols designed to optimize oxygen delivery to tissues have been shown to improve outcome in critical illness. Future research must be aimed toward better definition of clinical settings in which outcome can be improved with inotropes and toward identifying safer agents with fewer adverse side effects.

Animals↗

Is calcium or ephedrine superior to placebo for emergence from cardiopulmonary bypass?

To determine whether ephedrine or CaCl2 improves hemodynamics in cardiac surgery patients emerging from cardiopulmonary bypass, three sequential doses of either CaCl2 (200 mg/dose; n = 12), ephedrine (5 mg/dose; n = 12), or placebo (n = 12) were administered in a prospective, randomized, double-blind fashion. Thermodilution volumetric catheters were used to calculate right ventricular (RV) volumes and ejection fraction. The first dose of ephedrine improved RV stroke volume from 57 +/- 3 to 63 +/- 4 mL/beat (P < 0.05) and ejection fraction from 44 +/- 2% to 49 +/- 2% (P < 0.05). Subsequent doses maintained this improvement but without further change. In contrast, placebo and CaCl2 had minimal effects on RV end-systolic volume, stroke volume, and ejection fraction. After the third injection of ephedrine, mean arterial pressure had significantly increased from 78 +/- 2 to 93 +/- 4 mmHg (P < 0.05) in contrast to insignificant increments with placebo and CaCl2. Serum ionized calcium increased by 6% to 8% after each CaCl2 bolus but remained stable in the ephedrine and placebo groups. CaCl2 failed to improve RV performance in mildly hypocalcemic patients during separation from cardiopulmonary bypass. In patients with normal preoperative ventricular function, ephedrine more effectively improved RV performance and arterial blood pressure than placebo or CaCl2, and is a suitable short-acting drug to assist separation from cardiopulmonary bypass.

Adult↗

Dobutamine increases heart rate more than epinephrine in patients recovering from aortocoronary bypass surgery.

To determine whether epinephrine might prove to be a cost-effective substitute for dobutamine, two 8-minute infusions of either epinephrine (10 and 30 ng/kg/min, n = 28) or dobutamine (2.5 and 5 micrograms/kg/min, n = 24) were administered to 52 patients recovering in the intensive care unit (ICU) after aortocoronary bypass (CABG) surgery. At the higher dose, both drugs significantly (P < .05) increased cardiac index (CI), epinephrine from 2.8 +/- 0.1 at baseline to 3.3 +/- 0.1 L/min/m2, and dobutamine from 3.2 +/- 0.1 at baseline to 4.1 +/- 0.2 L/min/m2. Epinephrine increased CI significantly less than dobutamine. Both drugs significantly increased stroke volume index (SVI), epinephrine from 32 +/- 1 at baseline to 36 +/- 1 mL/beat/m2, and dobutamine from 36 +/- 1 at baseline to 40 +/- 2 mL/beat/m2. At the higher dose, the effects of the two drugs on SVI were indistinguishable. On the other hand, while the higher dose of both drugs significantly increased heart rate (HR), epinephrine from 88 +/- 2 at baseline to 90 +/- 2 beats/min and dobutamine from 89 +/- 2 at baseline to 105 +/- 3 beats/min, the increase following the higher dose of dobutamine was significantly greater than that seen after epinephrine. Effects of the two drugs on mean arterial pressure, central venous pressure, pulmonary artery occlusion pressure, systemic vascular resistance, pulmonary vascular resistance, and left-ventricular stroke work did not significantly differ. Similar results were obtained in the subset of patients with baseline CI less than 3 L/min/m2 who more closely resembled patients who might acutely require inotropic drug administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗

A randomized, blinded, placebo-controlled evaluation of calcium chloride and epinephrine for inotropic support after emergence from cardiopulmonary bypass.

Forty hemodynamically stable patients were randomized to receive an intravenous bolus of either calcium chloride (5 mg/kg) (n = 20) or placebo (n = 20) (phase I). Six minutes later, they received either an epinephrine (30 ng.kg-1.min-1) (n = 20) or placebo (n = 20) infusion (phase II). Hemodynamic and ionized calcium measurements were obtained in phase I at baseline and at 3 and 6 min after the bolus, and in phase II, at 3 and 6 min (study times 9 and 12 min) after initiation of the infusion. Compared with placebo, calcium did not significantly increase cardiac index but significantly increased mean arterial pressure. Calcium improved cardiac index from 2.46 +/- 0.12 (mean +/- SEM) to 2.74 +/- 0.12 L.min-1.m-2; likewise, placebo improved cardiac index from 2.51 +/- 0.15 to 2.74 +/- 0.15 L.min-1.m-2. Mean arterial blood pressure increased with calcium from 74 +/- 2 to 82 +/- 3 mm Hg compared with a placebo change of 74 +/- 2 to 76 +/- 2 mm Hg. Patients who received the epinephrine infusion (n = 20) demonstrated a significant increase in cardiac index at time 12 min compared with patients receiving only placebo (n = 20). Cardiac index of the epinephrine group increased from 2.56 +/- 0.15 to 2.92 +/- 0.22 L.min-1.m-2, whereas in the placebo group it decreased from 2.86 +/- 0.13 to 2.78 +/- 0.12 L.min-1.m-2. Prior administration of calcium did not alter the subsequent response to epinephrine (n = 10) compared with patients receiving epinephrine alone (n = 10). We conclude that cardiac index improves with time without drug therapy after bypass. Calcium chloride increases mean arterial blood pressure but not cardiac index immediately after cardiopulmonary bypass, whereas low-dose epinephrine significantly increases both cardiac index and mean arterial blood pressure without causing tachycardia in these patients. Calcium chloride (5 mg/kg) did not augment or inhibit the hemodynamic response to an epinephrine infusion.

Calcium↗

Calcium inhibits the cardiac stimulating properties of dobutamine but not of amrinone.

To contrast the effect of increasing blood calcium concentrations on the cardiovascular actions of intravenous beta-adrenergic agonists and phosphodiesterase inhibitors, 46 patients recovering from aortocoronary bypass surgery received either dobutamine or amrinone both in the presence and absence of a calcium infusion. Cardiac output, systemic arterial pressure, pulmonary arterial pressure, central venous pressure, pulmonary artery occlusion pressure, heart rate, and blood ionized calcium concentration were measured before and during infusions of dobutamine (2.5 and 5.0 micrograms/kg/min) and amrinone (0.75 mg/kg bolus + 10 micrograms/kg/min or 2.25 mg/kg bolus + 20 micrograms/kg/min). After the initial dobutamine infusion period, patients were randomly and blindly assigned to receive either a calcium or placebo infusion, and the dobutamine infusions were repeated. Because of the long duration of amrinone's actions, the amrinone maintenance infusion was continued while randomized, blinded infusion of either calcium or placebo was added. Dobutamine (5 micrograms/kg/min) increased cardiac output from 7.1 +/- 0.3 L/min to 9.1 +/- 0.4 L/min, and increased heart rate from 93 +/- 4 beats/min to 107 +/- 4 beats/min. Systemic vascular resistance decreased and stroke volume increased. Dobutamine had no significant effects on other hemodynamic values. Amrinone (2.25 mg/kg bolus + 20 micrograms/kg/min) increased cardiac output from 5.6 +/- 0.4 L/min to 6.9 +/- 0.5 L/min, and increased heart rate from 87 +/- 3 beats/min to 98 +/- 3 beats/min. Amrinone decreased mean arterial pressure, systemic vascular resistance, pulmonary artery occlusion pressure, central venous pressure, and pulmonary artery pressure. Calcium infusion increased arterial pressure (8 to 13 percent) but had no significant effects on any other hemodynamic parameters. Calcium reduced the increase in cardiac output produced by dobutamine by 30 percent, but it did not alter the cardiotonic actions of amrinone. Thus, calcium inhibits the cardiotonic actions of certain beta-adrenergic agonists, most likely by interfering with signal transduction through the beta-adrenergic receptor complex.

Amrinone↗

Sodium nitroprusside infusion does not dilate cerebral resistance vessels during hypothermic cardiopulmonary bypass.

This study determined whether sodium nitroprusside (SNP) changes cerebral vascular resistance during stable, hypothermic cardiopulmonary bypass (CPB). Cerebral blood flow (CBF) was measured using Xenon clearance in 39 patients anesthetized with fentanyl. In 25 patients (group 1), CBF was measured before and during infusion of SNP at a rate sufficient to reduce mean arterial pressure (MAP) approximately 20%. In 14 other patients (group 2), CBF was measured before and during simultaneous infusion of SNP and phenylephrine; SNP was continued at a rate that had reduced MAP approximately 20% while phenylephrine was added in a dose sufficient to restore MAP to preinfusion levels. Patients within each group were randomized to maintenance of PaCO2 approximately 40 mmHg (groups 1a and 2a), uncorrected for body temperature, or to maintenance of PaCO2 approximately 50 mmHg (groups 1b and 2b). The following variables were maintained within a narrow range: nasopharyngeal temperature (26-29 degrees C), pump oxygenator flow (1.7-2.5 l.min-1.m-2), PaO2 (150-300 mmHg), and Hct (22-28 vol%). In each patient, controlled variables varied no more than +/- 5% between measurements. In group 1a (PaCO2 approximately 40 mmHg), MAP was 86 +/- 9 mmHg (mean +/- SD) before and 65 +/- 8 mmHg during SNP infusion (P less than 0.0001). CBF was 12 +/- 3 ml.100g-1.min-1 before and 10 +/- 2 ml.100(-1).min-1 during SNP infusion (P less than 0.01). In group 1b (PaCO2 approximately 55 mmHg), MAP was 86 +/- 11 mmHg before and 66 +/- 13 mmHg during SNP infusion (P less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗

Magnesium inhibits the hypertensive but not the cardiotonic actions of low-dose epinephrine.

Intravenous magnesium supplementation is often used to control cardiac arrhythmias and coronary artery vasospasm resulting from disturbances of magnesium homeostasis after coronary artery bypass surgery. Many such patients also require inotropic drug support of depressed myocardial function. However, increased serum magnesium concentrations directly depress cardiac contractility in animals and may interfere with catecholamine actions. To determine whether small intravenous doses of magnesium sulfate (MgSO4) interfere with the cardiotonic actions of epinephrine, we examined the hemodynamic effects of MgSO4 and epinephrine infusion in 17 cardiac surgical patients on their 1st postoperative day in a prospective, controlled study. In 11 patients, infusion of MgSO4 (7-mg.kg-1 bolus followed by 10 mg.kg-1.h-1 as a continuous infusion) increased serum magnesium concentrations by 44% (mean +/- standard error of the mean [SEM] of 0.8 +/- 0.1 to 1.2 +/- 0.1 mM; P less than 0.01) but had no significant effect on heart rate; mean arterial, central venous, or pulmonary arterial occlusion pressures; or cardiac output. Epinephrine infusion (30 ng.kg-1.min-1) significantly increased cardiac index (2.7 +/- 0.1 to 3.1 +/- 0.21.min-1.m-2; P less than 0.05); this effect was not altered by MgSO4 administration (n = 11). However, MgSO4 significantly blunted epinephrine's hypertensive action and prevented a significant increase in mean arterial pressure during concurrent MgSO4-epinephrine administration. Six placebo control patients were given two sequential infusions of epinephrine separated by a placebo infusion to rule out an effect of time on the hemodynamic response to epinephrine. Mean arterial pressure and cardiac index responses to epinephrine were identical before and after placebo infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗

Normal parathyroid hormone responses to hypocalcemia during cardiopulmonary bypass.

To determine whether the calcium-magnesium-parathyroid hormone-calcitriol (vitamin D) axis responds appropriately to the hypocalcemia that routinely follows initiation of cardiopulmonary bypass (CPB), we measured blood ionized calcium (CaI), total calcium (CaT), total magnesium (MgT), ultrafilterable magnesium (MgI), total protein, intact parathyroid hormone (PTH), and calcitriol concentrations at eight defined time points in 28 patients undergoing elective cardiac surgery. With the onset of CPB, CaI decreased from 1.14 +/- 0.02 to 0.91 +/- 0.03 mM, P less than 0.05) (n = 17), and then gradually returned to a normal value by the time of separation from CPB (0.98 +/- 0.01 mM). CaT, MgI, MgT, and total protein concentrations declined significantly upon initiation of CPB and remained depressed thereafter. PTH initially decreased upon initiation of CPB (from 50 +/- 8 to 24 +/- 9 pg/ml, n = 9, P less than 0.05), remained inappropriately decreased during the early phases of CPB, and then gradually increased to maximal concentrations in response to hypocalcemia (103 +/- 15 pg/ml) before emergence. Calcitriol concentrations (n = 8) were unchanged during surgery. Based on these initial results, which suggested an association between hypomagnesemia and the slow PTH response to hypocalcemia, measurements were repeated in 10 additional patients, to whom magnesium (Mg) (1 g MgSO4 in two separate intravenous doses) was administered. Mg administration neither altered the PTH response to ionized hypocalcemia nor hastened the return of CaI to normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitriol↗

Preoperative and intraoperative predictors of inotropic support and long-term outcome in patients having coronary artery bypass grafting.

The prognostic value of preoperative symptoms, preoperative left ventricular function, and intraoperative factors as related to postoperative outcome in coronary artery bypass grafting is unclear. This study was performed to identify risk factors that could be used as markers to predict immediate and long-term outcome, knowledge of which might allow physicians to modify these factors to decrease the likelihood of an adverse outcome. We retrospectively evaluated preoperative factors (including age, sex, New York Heart Association [NYHA] classification of symptoms, ejection fraction [EF], wall motion abnormalities, baseline left ventricular end-diastolic pressure [LVEDP], postradiographic contrast injection LVEDP, change in LVEDP with contrast injection, cardiac enlargement, and collateral vessels) and intraoperative factors (duration of bypass and aortic cross-clamp time) in 128 patients. The need for inotropic drug support was used as a marker of immediate outcome. A 36-mo follow-up used death and the postoperative NYHA classification of symptoms as markers of long-term outcome. The various factors associated with the use of inotropes and immediate outcome were analyzed by logistic regression. The factors related to inotrope use (and presumed adverse short-term outcome) in order of decreasing significance were lower EF, older age, cardiac enlargement, female sex, and higher baseline and postcontrast LVEDP. Patients with EF greater than or equal to 55%, but also having wall motion abnormalities and LVEDP change greater than or equal to 10 mm Hg, and all patients with EF less than 55% were more likely to require inotropic drug stimulation after cardiopulmonary bypass. Neither the change in LVEDP nor the presence of wall motion abnormalities independently predicted the need for postoperative inotropic support.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

Effects of amrinone on cardiac index, venous oxygen saturation and venous admixture in patients recovering from cardiac surgery.

The hemodynamic and oxygen transport effects of low-dose (0.75 mg/kg loading dose + 10 micrograms/kg/min infusion, n = 12) and high-dose (2.25 mg/kg loading dose + 20 micrograms/kg/min infusion, n = 12) amrinone were evaluated in extubated patients 24 h after CABG. At both doses, amrinone significantly (p less than 0.05) increased HR, but decreased mean arterial, mean pulmonary artery, central venous and pulmonary artery occlusion pressures. High-dose amrinone significantly decreased systemic vascular resistance. Arterial oxygen saturation decreased significantly following both low- (97.8 +/- 0.4 to 95.6 +/- 0.9 percent) and high- (98.8 +/- 3.4 to 93.9 +/- 1.2 percent) dose amrinone. Pulmonary shunt increased significantly following low-dose amrinone and markedly increased Qs/Qt after high-dose amrinone. Although amrinone significantly increased cardiac index in a dose-dependent fashion (low:3.0 +/- 0.2 to 3.3 +/- 0.3 L/min/m2; high:2.7 +/- 0.2 to 3.4 +/- 0.2 L/min/m2), mixed venous oxygen saturation did not change. Thus, mixed venous oxygen saturation may not predict the hemodynamic response to amrinone infusion in postoperative surgical patients.

Amrinone↗