Effect of Combined Conventional & Modified Ultrafiltration After Cardiopulmonary Bypass in Neonates & Children Undergoing Pediatric-Congenital Heart Surgery
                   
Abstract

Background. Modified ultrafiltration has been touted as superior to Conventional Ultrafiltration (CUF) for attenuating the consequences of hemodilution after cardiac surgery with Cardiopulmonary Bypass (CPB) in children.

 

Ultrafiltration is a method used to reduce fluid volume and tissue edema, improved hemodynamics, increase hematocrit without the need for blood products and post operative recovery in children. Combined Conventional and Modified Ultrafiltration (MUF) may offer advantages in comparison with conventional or modified ultrafiltration. We conducted a retrospective cross sectional study to test the hypothesis that combined modified and conventional ultrafiltration have similar clinical effects when a standardized volume of fluid is removed.

Methods. From January 2008 to October 2009, a total of 271 pediatric patients undergoing cardiac surgery were collected from medical records retrospectively, were divided into 3 groups. Group I was undergo CUF, group II was MUF and group III was CUF + MUF. The using of CUF, MUF and CUF + MUF were randomized. CUF was performed during rewarming phase of CPB, MUF was performed after separation from CPB, continued until 10 minutes after the CPB and is independent of circuit volume. Sub analysis was between patient with Aristotle score above 5 and preoperative Pulmonary Hypertension (PH). Preoperative, intra operative, during CPB, post operative data in ICU such as hematocrit, hemodynamics, transfusion of blood products, icu stay, duration of ventilator, ultrafiltrate volume intra operatively, Low Cardiac Output Syndrome (LCOS) such as lactate, arterial and vein saturations were compared among groups.  

Results. There were no operative mortality. Total patients with CUF (n=68), MUF (n=8) and CUF+MUF (n=195). There were 136 male pts (50.2 %) and 135 female pts (49.8%), with median age 15 months and mean weight 12.8 ± 10.3 kg. In patients with Aristotle score above 5, CUF + MUF had greater ultrafiltrate volume (1304.5 ± 801.4 ml vs CUF 962.6 ± 567.5 ml and MUF 934.0 ± 816.9 ml ; p = 0.013). MUF group had a greater hematocrit (39.6% ± 12.5% vs CUF 32.8% ± 5.3% and CUF + MUF 32.9% ± 5.9%,  p = 0.514), and also greater hemoglobin level (13.2 ± 3.9 mg/mL vs CUF 10.9 ± 1.7 mg/mL, CUF + MUF 11.0 ± 2.1 mg/mL, p = 0.512). Median postoperative oxygenation (PaO2) was higher in MUF group (279 mmHg vs CUF 183 mmHg and CUF + MUF 137 mmHg, p = 0.132). MUF significantly reduced total transfusion volume of coagulation factors (RBC 120 mL vs CUF 130 mL, CUF + MUF 115 mL,  p = 0.530 ; FFP 80 mL vs CUF 100 mL, CUF + MUF 85 mL, p = 0.294 ; TC 0 mL vs CUF 70 mL, CUF + MUF 50 mL, p = 0.140). In patients with preoperative PH, CUF + MUF also significantly had greater ultrafiltrate volume (1313.6 ± 811.9 ml vs CUF 905.2 ± 577.1 ml and MUF 967.1 ± 674.9 ml ; p = 0.001). MUF group had a greater hematocrit (37.7% ± 10.9% vs CUF 32.5% ± 5.2% and CUF + MUF 33.0% ± 5.9%, p = 0.532), and also greater hemoglobin level (12.6 ± 3.5 mg/mL vs CUF 10.8 ± 1.7 mg/mL, CUF + MUF 11.0 ± 2.0 mg/mL, p = 0.538). Median postoperative oxygenation (PaO2) also higher in MUF group (262 mmHg vs CUF 184 mmHg and CUF + MUF 132.5 mmHg, p = 0.023). MUF also significantly reduced total transfusion volume of coagulation factors (RBC 110 mL

vs CUF 130 mL, CUF + MUF 120 mL, p = 0.337 ; FFP 59 mL vs CUF 100 mL, CUF + MUF 90 mL, p = 0.088 ; TC 0 mL vs CUF 70 mL, CUF + MUF 62.5 mL, p = 0.341). CUF + MUF have significant decreased in lactate level in 1 hour and 4 hours post operative in ICU (3.1 ± 1.6 to 2.9 ± 1.8 vs CUF 2.9 ± 1.3 to 1.9 ± 1.5 and MUF 3.3 ± 1.0 to 2.6 ± 1.1 ; p < 0.001), and also better vein saturation (73.1% ± 14.9% to 70.5% ± 14.0%, CUF 75.9% ± 10.3% to 72.3% ± 7.1%, MUF 64.3% ± 17.3% to 62.2% ± 15.6% ; p = 0.003). There were no significant difference among groups in duration of ventilator, icu stay, central venous pressure and mean arterial blood pressure post operatively.  

Conclusions. A combination of conventional and modified UF is effective and safe in pediatric patients undergoing cardiac surgery giving a higher UF volume when a standardized volume of fluid is removed. Combination of conventional and modified UF make  LCOS decreased if compare with other’s strategy. Ultrafiltration improved hemodynamics, hemostatic, and pulmonary functions. We recommend the use of combined UF in high-risk pediatric patients after cardiac surgery.

Key Words: Combined Conventional and Modified Ultrafiltration, Cardiopulmonary bypass, Pediatric Cardiac Surgery, Aristotle score, Pulmonary Hypertension. (The 20th Annual Congress of the Association of Thoracic and Cardiovascular Surgeons of Asia (ATCSA - Beijing, Oct 28 - 31  2010)