Quantitation of particulate microemboli during cardiopulmonary bypass: experimental and clinical studies.

An electronic particle-size analyzer (Coulter Counter ZM) was used to quantitate particulate microemboli 15 to 80 microns in size during cardiopulmonary bypass. Through both laboratory studies and clinical research, we confirmed three main causes of microemboli: (1) infusion of banked blood stored for more than 3 days; (2) use of cardiotomy reservoirs; and (3) use of bubble oxygenators. The regression equation between number of particles and blood storage time was Y = 3.7262X + 10.244 (r = 0.886; p < 0.01). The number of microemboli from cardiotomy reservoirs was 2.8 to 5.1 times that from other sources (p < 0.01). The number of solid particles from bubble oxygenators was 1.8 to 3.2 times that from membrane oxygenators (p < 0.01). Electron microscopy showed that a large number of solid particles more than 20 microns in size were formed during heart-lung bypass. They obstructed the microcirculation and damaged pulmonary capillary endothelial and alveolar epithelial cells. The degree of histological damage was related to the number and size of microemboli and the duration of pulmonary microcirculatory obstruction.

One-stage repair of absence of the aortopulmonary septum and interrupted aortic arch.

Absence of the aortopulmonary septum, interrupted aortic arch, aortic origin of the right pulmonary artery, intact ventricular septum, and patent ductus arteriosus is a rarely reported association. A 3-year-old boy underwent successful one-stage repair of this constellation of anomalies. A Dacron baffle was used both to close the huge aortopulmonary window and to direct blood to the right pulmonary artery. Type A interrupted aortic arch was repaired by direct anastomosis. Postoperatively, pulmonary artery pressure was less than half systemic pressure.

The design and application of a pediatric centrifugal pump.

This centrifugal pump (CP) includes two parts: the blood pump and the driving apparatus. They are connected by six twin magnetic disc plates and driven by a magnetic DC motor (120W). The blood pump had six leaves deadlocked between two plastic discs. Six leaves were set at 30 degrees angles, separately. In the lower chamber of the CP, there was an inlay magnetic disc, which is connected with the disc leaves by an axis. This axis was sealed by silicon rubber and a ceramic ring. The priming volume of the blood chamber was 34 ml. In vitro testing showed that the free hemoglobin caused by the CP was much less than that caused by a roller pump after 180 min. The effect of this CP on blood cell damage was also studied in an animal model. Six goats were placed on cardiopulmonary bypass for 180 min. Perfusion flow rates were maintained between 1.5 and 2.5 L/min. The plasma free hemoglobin was lower in the CP group (6.04 mg/dL) than in the roller pump group (32.25 mg/dL), p < 0.01. The CP has been used in ten pediatric patients undergoing cardiopulmonary bypass surgery. The patients' ages were from three to five years, and body weights were from 15 to 20 kg. Perfusion flow rates were maintained between 1.8 and 2.5 L/min, and bypass times were from 30 to 50 min. The rotation speeds were from 2000 to 2500 rpm. All the patients recovered smoothly, and no hemoglobinuria occurred.

[Hemodynamic effects of isoprenaline, dopamine, atrial and ventricular pacing during the early period after correction of tetralogy of Fallot].

The hemodynamic changes in 12 children (mean age 6 years) with Tetralogy of Fallot (TOF) were studied during the first 24 hours after surgical correction. The effects of isoprenaline and dopamine were compared. 7 of them using atrial and ventricular pacing also have their effects compared. The results show that patients with small left ventricles generally suffer low cardiac output or a trend to low cardiac output. The chronotropic drug (isoprenaline) was more effective than inotropic drug (dopamine) in increasing CI due to its ability in increasing HR and decreasing SVR. Atrial pacing was an effective method in increasing CI if the atrioventricular conduction is normal, while ventricular pacing did not increase CI at all.

Modified ultrafiltration in paediatric cardiopulmonary bypass.

Cardiopulmonary bypass (CPB), a nonphysiological procedure, is associated with haemodilution and the inflammatory response, causing the accumulation of body water and organ dysfunction. The purpose of this study was to evaluate the efficacy of modified ultrafiltration. Forty paediatric patients undergoing cardiac operations were randomized into a control group and a modified ultrafiltration group. Blood cells, protein and cytokine concentrations were recorded for 24 h postoperatively. As the fluid was removed at 50 ml/min, both blood cells and protein were concentrated by modified ultrafiltration (p < 0.001). The tumour necrosis factor (TNF)-alpha concentration was increased and interleukin-8 (IL-8) and endothelin (ET) concentrations were unaltered after ultrafiltration. After correction for albumin, TNF-alpha concentration changed little, and IL-8 and ET concentrations (36.75 +/- 12.35, 42.89 +/- 15.54) were decreased significantly (21.47 +/- 13.87, 26.06 +/- 12.54) after ultrafiltration. Modified ultrafiltration is an effective method for removing excess tissue fluid and concentrating blood after CPB. This technique can also filter out some cytokines.