Hemodynamic effects of prostaglandin E1 during cardiopulmonary bypass in infants and children

Effects of prostaglandin E₁ (PGE₁) and phenoxybenzamine (POB) on the hemodynamics during cardiopulmonary bypass (CPB) were studied in 30 infants and children. Patients were grouped into three; PGE₁ was given to ten patients, POB to another ten, and the other ten patients served as the control. Vasodilative drugs were witheld. PGE₁ was infused at 0.01 to 0.02 μg/kg/min during CPB, and POB at 1.0 mg/kg within the initial 10 minutes of bypass. There was a significant drop in arterial and venous pressure at the time of initiation of bypass in both the PGE₁ and POB groups. In the PGE₁ group in particular, such a stable hemodynamic condition of over 60 mm Hg in mean arterial pressure, 7.5 to 12.5 cmH₂O in central venous pressure, 1300 to 1700 dynes·sec·cm⁻⁵ in systemic vascular resistance was maintained throughout CPB, as compared with the other two groups. PGE₁ contributed to an adequate diuresis and the preservation of platelets. Our findings indicate that PGE₁ has potential clinical advantages for application during CPB.     

Hemodynamic consequences of bronchial flow during cardiopulmonary bypass

Nine patients (seven men and two women) were studied while undergoing coronary artery bypass on cardiopulmonary bypass. Selective bronchial flow samples were obtained and analyzed for prostaglandin E2 levels, and the hemodynamic effects of this vasodilator were studied. Bronchial flow collection and measurements were performed during hypothermic cardioplegic arrest while the peripheral anastomosis was being completed, as described previously. This collected sample was reinfused abruptly to the pump circuit, but samples were also analyzed for specific radioimmunoassay antiserum for prostaglandin E2 levels. Urine levels were obtained both with and without indomethacin block. All nine patients were studied for the hemodynamic effects of rapidly reinfused bronchial flow. A 34% +/- 8.8% mean drop of blood pressure and peripheral vascular resistance were recorded (p less than 0.002). Three study groups were established: In Group I, serum prostaglandin assay was performed on six patients. Prostaglandin E2 levels showed an average of increase of 159% compared to the baseline (p less than 0.02). In Group II, urine prostaglandin was measured. Nine assays were performed on six patients. Analysis of the total urine production while on cardiopulmonary bypass showed an average increase in prostaglandin E2 of 300% (p less than 0.02). In Group III, combined serum and urine prostaglandin levels were measured in three patients before and after indomethacin block (50 mg four times a day for 48 hours before the operation). All of these patients demonstrated the same hypotensive phenomena with reinfusion of the bronchial flow. The urinary prostaglandin E2 output and serum prostaglandin E2 levels in bronchial flow were elevated. Overall, this group manifested a 50% reduction in prostaglandin E2 production over baseline values with indomethacin block (p less than 0.02) and a 300% increase in production during cardiopulmonary bypass (p less than 0.02). Our data suggest that significant amounts of prostaglandin E2 are released in the lung during the stress of cardiac operations. Rapid reinfusion of bronchial flow is responsible for hypotension during cardiopulmonary bypass. Pretreatment with indomethacin will not completely block prostaglandin E2 release in the lung during stress.     

Hemodynamic consequences of desmopressin administration after cardiopulmonary bypass

Desmopressin acetate is used to reduce blood loss after cardiac surgery. However, there have been reports that hypotension can occur with infusion of desmopressin and that postoperative blood loss is not reduced. In this randomized, double-blinded study, we investigated the effects of desmopressin on hemodynamics, coagulation, and postoperative blood loss in patients undergoing primary elective coronary artery bypass grafting (CABG). After reversal of heparin effect, 20 patients received desmopressin 0.3 micrograms.kg-1, infused over 15 min, and 20 patients received a placebo. Desmopressin produced a small but significant decrease in diastolic blood pressure when compared with the placebo (50.8 mmHg vs. 57.6 mmHg for the desmopressin- and placebo-treated groups, respectively; P = 0.0372). A 20% or greater decrease in mean arterial pressure was observed in 7 of 20 patients receiving desmopressin, whereas only one patient in the placebo-treated group experienced a decrease of this magnitude (P = 0.0177). Reductions in arterial pressure were secondary to decreases in systemic vascular resistance (SVR) (mean SVR before and after the drug infusion, 1,006 and 766 dyn.s.cm-5, respectively, for the desmopressin-treated group; and 994 and 1,104 dyn.s.cm-5, respectively, for the placebo-treated group; P = 0.0078).(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemodynamic effects of dobutamine and dopexamine after cardiopulmonary bypass in pediatric cardiac surgery*

Background: After surgical repair of congenital heart disease, inotropic support is sometimes necessary to wean from cardiopulmonary bypass. In pediatric cardiac surgery, dobutamine and dopamine are often used as inotropic support. Dopexamine is a synthetic catecholamine, which has positive inotropic and vasodilating properties. Because the hemodynamic effects of catecholamines are modified after cardiopulmonary bypass, the aim of this study was to investigate the effects of dobutamine and dopexamine on cardiac index and systemic vascular resistance index after cardiopulmonary bypass in pediatric cardiac surgery. Methods: The study was performed in a prospective, randomized, and double‐blinded cross‐over design. The investigation included 11 children for elective, noncomplex congenital heart surgery. After weaning from cardiopulmonary bypass and a 20‐min period of steady state, children received either 2.5 μg·kg^?1·min^?1 dobutamine or 1 μg·kg^?1·min^?1 dopexamine for 20 min. Cardiac index (transpulmonary thermodilution), mean arterial pressure, central venous pressure, stroke volume, systemic vascular resistance, and central venous oxygen saturation were determined. The primary outcome variable was cardiac index. Results: No difference in cardiac index was observed between the two groups (P = 0.594). Both drugs increased cardiac index, dopexamine from 3.9 ± 0.6 to 4.7 ± 0.8 l·min^?1·m^?2 (P = 0.003) and dobutamine from 4.1 ± 0.7 to 4.8 ± 0.7 l·min^?1·m^?2 (P = 0.004). During treatment with dobutamine, children presented with significantly higher mean arterial pressure (P = 0.003) and systemic vascular resistance index (P = 0.026). Conclusions: This trial demonstrates that low‐dose dobutamine and dopexamine both increase cardiac index during pediatric cardiac surgery but with different hemodynamic effects.     

Intraoperative echocardiographic imaging of coronary arteries and graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass.

BACKGROUND: No accepted approach exists for the intraoperative evaluation of the quality of coronary arteries and the technical adequacy of graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass. METHODS AND RESULTS: We assessed the accuracy of high-frequency epicardial echocardiography and power Doppler imaging in evaluating coronary arteries during coronary artery bypass grafting without cardiopulmonary bypass. To validate measurements of coronary arteries and graft anastomoses by high-frequency epicardial echocardiography and power Doppler imaging, we compared luminal diameters determined by these methods with diameters determined histologically in a study of off-pump coronary artery bypass grafting in 20 dogs. Technical errors were deliberately created in 10 grafts (stenosis group). The results of these animal validation studies showed that the maximum luminal diameters of coronary arteries and graft anastomoses measured by high-frequency epicardial echocardiography (HEE) and power Doppler imaging (PDI) correlated well with the histologic measurements: HEE = 1.027 x Histologic measurements + 0.005 (P <.0001); PDI = 0.886 x Histologic measurements + 0.0453 (P =.0001). Similar results were found in the evaluation of the stenosis group: PDI = 0.991 x Histologic measurements + 0.074 (P <.0001). Subsequently, we demonstrated the clinical applicability of this approach in 12 patients who underwent minimally invasive or off-pump coronary artery bypass grafting. Twenty graft anastomoses were examined intraoperatively by high-frequency epicardial echocardiography and power Doppler imaging, and luminal diameters determined by power Doppler imaging were compared with those determined by postoperative coronary angiography. The results demonstrated that graft anastomosis by power Doppler imaging correlated well with the angiographic measurements: PDI = 1.018 x Angiographic measurements - 0.106 (P <.0001). CONCLUSION: High-frequency epicardial echocardiography can provide meaningful information on the target coronary artery, and power Doppler imaging can accurately measure graft anastomoses and can detect technical errors and inadequacies during coronary artery bypass grafting without cardiopulmonary bypass.     

Transesophageal echocardiographic imaging of a new aortic cannula for differential perfusion during cardiopulmonary bypass

We describe the use of echocardiographic imaging to assist in the placement of an aortic cannula that provides differential perfusion of the arch and descending aorta during cardiac surgery in adults.     

Hemodynamic effects of intraaortic versus intravenous protamine administration after cardiopulmonary bypass in man.

A hemodynamic study of men undergoing elective coronary artery bypass surgery was undertaken to elucidate the side effects of protamine given into the ascending aorta (group A, n = 16) or into the central venous line (group V, n = 16). After termination of extracorporeal circulation, protamine was infused over 120 seconds, and the hemodynamic profile was continuously recorded. During the first minute, the systemic arterial pressure fell to about 60% of the preprotamine level in both groups, but the hemodynamic changes occurred more rapidly (p < 0.05) in group V than in group A, with maximal pressure drop at 61.7 +/- 2.7 vs 74.4 +/- 4.9 seconds. Following spontaneous restoration of the systemic blood pressure, the pulmonary artery pressure rose considerably in both groups, as did the pulmonary capillary wedge and central venous pressures, reaching higher levels in the intravenous group. The cardiovascular responses were again more rapid in group V than in group A (p = 0.004). The degree of systemic hypotension thus did not benefit from use of the intraaortic rather than the intravenous route for administering protamine. The more pronounced and more rapid pulmonary circulatory changes in the intravenous group suggest that the hemodynamic effects of protamine are initiated in the lungs.     

Thrombin during cardiopulmonary bypass

Cardiopulmonary bypass (CPB) ignites a massive defense reaction that stimulates all blood cells and five plasma protein systems to produce a myriad of vasoactive and cytotoxic substances, cell-signaling molecules, and upregulated cellular receptors. Thrombin is the key enzyme in the thrombotic portion of the defense reaction and is only partially suppressed by heparin. During CPB, thrombin is produced by both extrinsic and intrinsic coagulation pathways and activated platelets. The routine use of a cell saver and the eventual introduction of direct thrombin inhibitors now offer the possibility of completely suppressing thrombin production and fibrinolysis during cardiac surgery with CPB.     

Hypoxaemia during cardiopulmonary bypass

Blood oxygenation was studied in patients undergoing cardiopulmonary bypass using the Rygg-Kyvsgaard bubble oxygenator. Oxygenation was satisfactory in perfusions carried out at normothermia and during hypothermia. During the rewarming phase of hypothermic perfusions hypoxaemia occurred. This could be prevented by a ganglion blocking agent (trimetaphan) given during the cooling phase.     

Hemodynamic effects of milrinone during weaning from cardiopulmonary bypass: comparison of patients with a low and high prebypass cardiac index

OBJECTIVE: To compare the hemodynamic effects of milrinone during weaning from cardiopulmonary bypass (CPB) in patients with a low pre-CPB cardiac index (CI) <2.5 L/min/m2) and in patients with a high pre-CPB CI (> or =2.5 L/min/m2). DESIGN: Prospective, randomized, double-blind study. SETTING: University hospital. PARTICIPANTS: Forty-eight patients scheduled for elective coronary artery bypass graft surgery. INTERVENTION: Patients were divided into 4 groups: (1) low pre-CPB CI/placebo, (2) low pre-CPB CI/milrinone, (3) high pre-CPB CI/placebo, and (4) high pre-CPB CI/milrinone. Patients received a loading dose of 20 microg/kg of milrinone followed by an infusion of 0.2 microg/kg/min or placebo 15 minutes before the anticipated weaning time. MEASUREMENTS AND MAIN RESULTS: In the low pre-CPB CI/ placebo group, low CIs and high systemic vascular resistances (SVRs) were observed after CPB. High doses of dopamine and dobutamine were needed, and infusion of epinephrine was used in 5 of the 12 patients for hemodynamic support. Milrinone improved CI and reduced SVR in the low pre-CPB CI/milrinone group. Norepinephrine was needed to maintain an adequate systemic blood pressure in 6 of the 12 patients, however. In the high pre-CPB CI/placebo group, satisfactory CIs and SVRs were observed during weaning from CPB with low doses of dopamine and dobutamine. Milrinone significantly increased CI and decreased SVR in the high pre-CPB CI/milrinone group: 10 of the 12 patients had CIs above the upper limit of normal, and 7 patients had SVRs below the lower limit of normal. CONCLUSION: Milrinone was effective during weaning from CPB in patients with a low pre-CPB CI. Milrinone in combination with norepinephrine was a good alternative to epinephrine for the treatment of myocardial dysfunction after CPB.     

Postoperative ventilatory and circulatory effects of extended rewarming during cardiopulmonary bypass

Postoperative effects of extended rewarming (ECR) after hypothermic cardiopulmonary bypass (CPB) were studied. All (n = 28) patients were rewarmed to a nasopharyngeal temperature exceeding 38 degrees C before terminating CPB. In 12 patients (control group) the rectal temperature (Tre) was 33.8 +/- 1.7 degrees C (mean +/- sd) at termination of CPB. In sixteen patients (ECR group) rewarming during CPB was continued to a Tre of 36.8 +/- 0.5 degrees C. Postoperative body temperatures, heat content, shivering, oxygen uptake, CO2 production and haemodynamic variables were measured. ECR reduced the heat gain required to complete core rewarming to 665 +/- 260 kJ, compared with 1037 +/- 374 kJ in the control group (p less than 0.01). The incidence of shivering was reduced (p less than 0.05) as well as shivering intensity and duration. In seven non-shivering ECR group patients this coincided with significantly reduced metabolic and ventilatory demands but these improvements were not valid for the group as a whole. The required ventilation temporarily during postoperative rewarming in both groups increased to 250 per cent of the basal need. Extending CPB rewarming (to at least 36 degrees C Tre) was inefficient when used as the sole measure to reduce the untoward effects of residual hypothermia during recovery after cardiac surgery with hypothermic CPB.