Effect of modified ultrafiltration in high-risk patients undergoing operations for congenital heart disease

BACKGROUND

Modified ultrafiltration (MUF) after cardiopulmonary bypass (CPB) in children decreases body water, removes inflammatory mediators, improves hemodynamics, and decreases transfusion requirements. The optimal target population for MUF needs to be defined. This prospective, randomized study attempted to identify the best candidates for MUF during operations for congenital heart disease.

METHODS

Informed consent was obtained from 100 consecutive patients with complex congenital heart disease undergoing operations with CPB. They were randomized into a control group (n = 50) of conventional ultrafiltration during bypass and an experimental group using dilutional ultrafiltration during bypass and venovenous modified ultrafiltration after bypass (MUF group, n = 50). Postoperative arterial oxygenation, duration of ventilatory support, transfusion requirements, hematocrit, chest tube output, and time to chest tube removal were compared between the groups stratified by age and weight, CPB technique, existence of preoperative pulmonary hypertension, and diagnosis.

RESULTS

There were no MUF-related complications. In patients with preoperative pulmonary hypertension, MUF significantly improved postoperative oxygenation (445 +/- 129 mm Hg versus control: 307 +/- 113 mm Hg, p = 0.002), shortened ventilatory support (42.9 +/- 29.5 hours versus control: 162.4 +/- 131.2 hours, p = 0.0005), decreased blood transfusion (red blood cells: 16.2 +/- 18.2 mL/kg versus control: 41.4 +/- 27.8 mL/kg, p = 0.01; coagulation factors: 5.3. +/- 6.9 mL/kg versus control: 32.3 +/- 15.5 mL/kg, p = 0.01), and led to earlier chest tube removal. In neonates (< or =30 days), MUF significantly reduced transfusion of coagulation factors (5.4 +/- 5.0 mL/kg versus control: 39.9 +/- 25.8 mL/kg, p = 0.007), and duration of ventilatory support (59.3 +/- 36.2 hours versus 242.1 +/- 143.1 hours, p = 0.0009). In patients with prolonged CPB (>120 minutes), MUF significantly reduced the duration of ventilatory support (44.7 +/- 37.0 hours versus 128.7 +/- 133.4 hours, p = 0.002). No significant differences were observed between MUF and control patients for any parameter in the presence of ventricular septal defect without pulmonary hypertension, tetralogy of Fallot, or aortic stenosis.

CONCLUSIONS

Modified ultrafiltration after CPB is safe and decreases the need for homologous blood transfusion, the duration of ventilatory support, and chest tube placement in selected patients with complex congenital heart disease. The optimal use of MUF includes patients with preoperative pulmonary hypertension, neonates, and patients who require prolonged CPB.

Adrenomedullin in patients at high risk for pulmonary hypertension

BACKGROUND

Adrenomedullin is a newly identified peptide with profound hypotensive effects. We investigated perioperative adrenomedullin levels among patients with congenital heart disease with and without pulmonary hypertension.

METHODS

Levels of plasma adrenomedullin, endothelin-1, and nitric oxide metabolites were measured in three groups: (1) low pulmonary flow (n=11); (2) high flow/low pulmonary arterial pressure (less than 60% systemic pressure) (n=9); and (3) high flow/high pressure (n=10). Samples were obtained preoperatively, on and off pump, and 3, 6, and 12 hours after bypass.

RESULTS

Adrenomedullin levels were highest in the low pulmonary flow group (189.7+/-15 pg/mL low flow versus 103.1+/-9.5 pg/mL high flow/low pulmonary and 139+/-17.5 pg/mL high flow/high pressure at 12 hours; p < or = 0.05). The arterial pressure/systemic pressure remained significantly lower in the high flow/low pulmonary pressure compared with the high flow/high pressure group (0.37+/-0.08 versus 0.62+/-0.11; p < 0.005). Perioperative endothelin-1 and nitric oxide levels remained low in the low pulmonary flow group but increased progressively in both high flow groups.

CONCLUSIONS

Circulating plasma adrenomedullin appears to affect baseline vascular tone in patients with intact endothelial function. It may interact with nitric oxide and endothelin-1 to help regulate blood pressure perioperatively in patients with congenital heart disease.

Dilutional and modified ultrafiltration reduces pulmonary hypertension after operations for congenital heart disease: a prospective randomized study

OBJECTIVE

A prospective randomized study was performed to test whether removal of endothelin-1, by ultrafiltration techniques, will reduce pulmonary hypertension after operations for congenital heart disease.

METHODS

Twenty-four patients with pulmonary hypertension (systolic pulmonary/systemic arterial pressure ratio > 60%) undergoing cardiac operations were randomized into a control group (n = 12) having conventional ultrafiltration and an experimental group (n = 12) undergoing dilutional ultrafiltration during and modified ultrafiltration after cardiopulmonary bypass. Plasma endothelin-1, nitric oxide metabolites, and cyclic guanosine monophosphate were assayed before bypass, 10 minutes into bypass, after bypass, and 0, 3, 6, and 12 hours after the operation in both groups, as well as in the ultrafiltrates and after modified ultrafiltration in the experimental group. Both groups received alpha-blockers (chlorpromazine and/or prazosin) postoperatively using the same guidelines.

RESULTS

The ultrafiltrates contained significant amounts of endothelin-1 (1.81 +/- 0.86 pg/ml, dilutional, and 6.44 +/- 1.82 pg/ml, modified ultrafiltrate). Endothelin-1 and the pulmonary/systemic pressure ratio were significantly lower in experimental compared with control patients. Nitric oxide metabolites and cyclic guanosine monophosphate increased similarly in both groups for 12 hours after the operation (p = not significant). Three of 12 control patients (25%) but no experimental patients had pulmonary hypertensive crises (p = 0.07). The experimental patients required significantly less ventilatory support (67 +/- 47 hours vs 178 +/- 139 hours for control patients, p = 0.048).

CONCLUSIONS

Dilutional and modified ultrafiltration reduce endothelin-1 and the pulmonary/systemic pressure ratio postoperatively and may become an important adjunct for preventing pulmonary hypertension after operations for congenital heart disease in high-risk patients.