Hemodynamic effects of DBcAMP in patients with low cardiac output syndrome following open-heart surgery

Hemodynamic effects of DBcAMP given at 0.05 to 0.3 mg/kg/min for 30 minutes to patients with low cardiac output less than 2.21/min/m2, to patients on IABP and on dopamine or dobutamine were investigated after open-heart surgery. Hemodynamic improvements were observed in cardiac index from 1.81 +/- 0.3 (mean +/- SD) to 2.56 +/- 0.401/min/m2 (p less than 0.001), stroke index from 20.5 +/- 5.2 to 26.4 +/- 5.2 ml/best/m2 (p less than 0.001). TRP decreased from 1963.8 +/- 682.8 to 1153.9 +/- 449.0 (p less than 0.001). These changes were similar to those of Groups II (3.0 greater than or equal to C1 greater than or equal to 2.21/min/m2) and of Group III (C1 greater than 3.01/min/m2). Increases were also observed in CI from 2.28 +/- 0.67 to 2.96 +/- 0.671/min/m2 (p less than 0.001) and in stroke index from 24.4 +/- 7.2 to 29.5 +/- 6.4 ml/best/m2 (p less than 0.001) and significant decreases were observed in TPR and PVR in patients receiving dopamine or dobutamine. These results strongly suggest the inotropic action of DBcAMP was independent on the beta receptor activity and could be a powerful adjunct in the treatment of low cardiac output patients on whom the dopamine or dobutamine was ineffective.     

Influence of atrioventricular synchrony on hemodynamics in patients with normal and low ejection fractions following open heart surgery

The authors wished to test the hypothesis that atrioventricular synchrony has a relatively greater effect on hemodynamic parameters in postoperative patients with low ejection fractions compared to those with normal ejection fractions. Temporary pacing wires were placed on the right atrium and right ventricle of patients undergoing open heart surgery. Duplicate thermodilution cardiac outputs were determined during atrial pacing and ventricular pacing at 100 beats/min. Mean left atrial and systemic blood pressures were monitored. Thirteen patients with ejection fractions of 45 per cent or less (range 24 to 45%, mean 37.3%) were included in the low ejection fraction group, and 27 patients with ejection fractions of 59 per cent or greater (range 59 to 80%, mean 66.8%) were considered in the normal ejection fraction group. All hemodynamic parameters improved significantly when changing from ventricular pacing to atrial pacing in both the normal ejection fraction group and low ejection fraction group (P less than 0.05). The magnitude of change between the groups showed no significant difference for all parameters except left atrial pressure, which decreased by a greater percentage in the low ejection fraction group with atrial pacing (P less than 0.001). The atrial contribution to hemodynamic enhancement is important in patients with normal and low ejection fraction following open heart surgery. Patients with low ejection fractions do not sustain a relatively greater reduction in cardiac output, stroke volume index, or systemic blood pressure with loss of atrioventricular synchrony when compared to patients with normal ejection fractions.     

Midazolam following open heart surgery in children: haemodynamic effects of a loading dose

Our objective was to establish the safety and effectiveness of a loading dose of midazolam for postoperative sedation of children recovering from open heart surgery; a prospective randomized placebo-controlled double-blind study was done with subjects randomized to three groups according to loading dose. I=0.08 mg·kg⁻¹; II=0.04 mg·kg⁻¹; and III=0.00 mg·kg⁻¹ (placebo). An open label continuous midazolam infusion protocol followed. Haemodynamic parameters were monitored. The study was discontinued following an adverse event involving the 23rd subject. When data for all 23 subjects were combined, there was a mean decrease of 10% in blood pressure (BP) 30 min after the loading dose ( P <0.001). Heart rate change was less significant. Clinicians identified four hypotensive episodes as temporally associated with the midazolam load, two each in Groups I (0.08 mg·kg⁻¹) and III (placebo). One subject in Group I (the 23rd) became hypotensive within five min of receiving the loading dose, had a difficult clinical course and died four weeks postoperatively. We cannot conclude that the loading dose of midazolam had any systematic haemodynamic effect in our study population. Although the clinical course of the 23rd subject suggests a subset of more susceptible children (those who receive opioid analgesia with midazolam, are volume-restricted, and/or undergo more complex forms of surgical correction), many critical care patients are inherently physiologically unstable, and concluding clinically that blood pressure fluctuation is drug related may be erroneous.     

Effects of dopamine and dobutamine on systemic hemodynamics and myocardial metabolism in children after open heart surgery

The purpose of this study is to know the effects of Dopamine (DOA) and Dobutamine (DOB) on the systemic hemodynamics and myocardial metabolism in the acute phase after open heart surgery in children. Thirty patients with congenital heart disease were divided into following two groups. The first 14 cases were administered 5 and 10 micrograms/kg/min (gamma) of DOA, and the systemic hemodynamic and metabolic data were taken before and after the administration of the drug. The second 12 cases were given the same doses of DOB instead of DOA. DOA: The blood pressure was elevated by 10 gamma of DOA, and cardiac index (CI) and stroke volume index (SVI) rose up at both doses of DOA. On the other hand, systemic vascular resistance (SVR) and left atrial pressure (LAP) were decreased at both dosage levels. DOB: At the same dose of DOA, DOB increased HR and SVI, so CI rose up markedly. The systolic and mean blood pressure also rose up at both doses. CVP and LAP were depressed at either dosage level. SVR did not show an appreciable change. Myocardial metabolism: The two drugs tested did not exhibit the progress of anaerobic myocardial metabolism. The myocardial oxygen uptake rate increased with DOA, but decreased with DOB. This phenomena probably suggests that DOB dilates coronary vascular bed. From the above data, the following effects are expected by the use of each drug after open heart surgery in children: 1) an increase of cardiac output due to inotropic action by DOA, 2) powerful inotropic and chronotropic action by DOB.     

Mediastinal infection following open heart surgery

31 cases of mediastinal infection occurred in 7164 patients who had undergone open heart surgery under CPB were reviewed in the period of 1981-1989. The over-all incidence was 0.43%. Analysis of the clinical material showed that mediastinal infection was mostly associated with the following predisposing factors: (1) prolonged CPB time; (2) rethoracotomy; (3) open cardiac massage; (4) tracheostomy; (5) combined severe circulatory or/and respiratory complications. 28 patients were treated by mediastinal debridement and 27 of them were irrigated with 0.5% betadine or/and antibiotic solutions. Debridement was done a second time in 5 patients with smooth recovery. There were 15 deaths (48.4%), of which 4 were caused by rupture of cardiac or aortic incisions, 5 by multisystemic complications and 6 by severe infection. The mortality was significantly higher in the cases with combined circulatory or/and respiratory complications (72.2%) than in the cases of simple mediastinal infection (15.4%).     

Effects of docarpamine on hemodynamics after open heart surgery in children.

Docarpamine is a dopamine prodrug which has been selected from a large number of dopamine derivatives in order to develop an orally effective dopamine. The pharmacokinetics after oral administration of docarpamine have not yet been studied in children undergoing open heart surgery. This study examined the effects of docarpamine on hemodynamics and evaluated its safety in 11 children undergoing open heart surgery for congenital heart disease. This study began when the patientOs postoperative condition was stabilized by continuous dopamine infusion into the vein at a rate of 5 micro g/kg/min. The patients were administered 40 mg/kg of docarpamine every 8 hours, and hemodynamics were measured every 4 hours for 16 hours after the initial docarpamine administration. Immediately after the initial docarpamine administration, the dose of dopamine was reduced to 3 micro g/kg/min. Infusion of dopamine was stopped 8 hours after the initial docarpamine administration. Systemic systolic and diastolic blood pressure and heart rate showed no significant changes. Mean right atrial pressure decreased 4 hours after docarpamine administration. Mixed venous oxygen saturation and mean velocity of circumferential fiber shortening increased significantly after docarpamine administration. No significant changes were observed in urine volume. All patients could be weaned from dopamine within 8 hours. No changes were observed in ECG, and no arrhythmia-inducing action was noted. Our study indicates that 40 mg/kg oral doses of docarpamine produce plasma dopamine concentration equivalent to those of a 3 to 5 micro g/kg/min dopamine infusion. Our data suggest that docarpamine is a safe and effective drug for children who have undergone open heart surgery.     

Ventilatory support following open heart surgery

One thousand consecutive patients undergoing open heart surgical procedures were evaluated for the need for ventilation in the postoperative period. All cases of mitral valve replacement (237) and double valve replacement (85) were electively ventilated. Fifty-two other patients required ventilation for various reasons which included low cardiac output with inotropic support, ventricular arrhythmias, left atrial pressure above 18 mm Hg, bleeding, hypo or hyperthermia, unsatisfactory blood gases, neurological problems, overdosage of narcotics, incomplete reversal of relexants and flooded lungs at the end of operation. Twenty patients needed ventilation beyond 4 days. Prolonged ventilatory support was maintained with nasotracheal tube and only 3 patients required tracheostomy after 12 days for cerebral and pulmonary complications. The pulmonary complications encountered during postoperative ventilation were stiff lungs, copious secretions and bleeding in 20 patients.     

The effects of milrinone on hemodynamics in patients undergoing cardiac surgery

The phosphodiesterase inhibitor, milrinone is used to treat low cardiac output syndrome, especially after cardiac surgery. But there were few reports about the precise hemodynamic effects at separation from cardiopulmonary bypass (CPB). We examined the hemodynamic effects of milrinone in 24 patients undergoing elective coronary artery bypass graft (CABG). Patients were assigned to the milrinone group (n = 12) and the control group (n = 12). Before separation from CPB, milrinone was administered as a loading dose of 50 micrograms.kg-1 into the reservoir of CPB at rectal temperature 33.5 degrees C and simultaneously a continuous infusion of 0.5 microgram.kg-1.min-1 was started. In addition, dopamine and nitroglycerine were administered in both groups. Hemodynamic measurements were performed before CPB, just after the weaning from CPB, 15, 30, 60 minutes after the weaning from CPB. Cardiac index increased significantly (P < 0.01) in the milrinone group as compared with the control group. Systemic vascular resistance index and mean arterial pressure decreased significantly (P < 0.0001, P < 0.05, respectively) in the milrinone group as compared with the control group. There were no significant differences in heart rate, mean pulmonary arterial pressure, pulmonary artery occlusion pressure, mean right atrial pressure, stroke volume index, and pulmonary vascular resistance index between the two groups. These hemodynamic effects showed that milrinone supported cardiac performance after CPB for CABG.