Washing of irradiated red blood cells in paediatric cardiopulmonary bypass: is it clinically useful? A retrospective audit.

OBJECTIVE: Despite the introduction of smaller cardiopulmonary bypass (CPB) circuits for paediatrics, it is frequently necessary to add irradiated red blood cell concentrate (IRBC) to maintain adequate haemoglobin levels and the oxygen carrying capacity. Irradiation of blood weakens the cell membranes and results in an increase of lactate and potassium concentration. In addition, prolonged shelf time of IRBC may enhance its lactate level. To avoid the adverse effects of increased lactate and potassium concentration during paediatric bypass, prewashing of homologous blood in a cell-saving device was implemented at our institution. A retrospective audit of clinical data was performed to assess the relevance of this method. METHODS: Preceding the introduction of the blood pre-washing, we investigated 14 units of IRBC for lactate, potassium levels and shelf time. Afterwards, we evaluated the CPB and laboratory data from 69 patients with body weight <10 kg and the lactate levels in the priming of the bypass circuit. RESULTS: The shelf time of blood units was 7.6 ± 2.7 days (minimum 5, maximum 14 days) with lactate concentration of 12.6 ± 2 mmol/land potassium concentration of 16.2 ± 4.7 mmol/l. In the priming after pre-washing, the lactate concentration was significantly lower than the standard priming (2.5 ± 0.9 vs 4.5 ± 20 mmol/l, p = 0.002). At the start of bypass, the lactate concentration after pre-washing was still lower (1.5 ± 0.4 vs 1.9 ± 0.9 mmol/l; p = 0.04), but at the end of bypass we detected a significant increase of lactate in the pre-washed group (1.5 ± 0.4 vs 2.2 ± 1.1 mmol/l, p = 0.01). There was no significant difference between the groups at the end of bypass (1.8 ± 0.9 vs 2.2. ± 1.1 mmol/l, p = 0.17). Other clinical and patient data were not significantly different. CONCLUSIONS: Our retrospective audit shows that pre-washing of IRBCs is not associated with decreased lactate levels at the end of CPB compared with standard use of IRBCs, suggesting that the added value of pre-washing of IRBCs on minimisation of lactate levels during CPB remains doubtful.

Low molecular starch versus gelatin plasma expander during CPB: does it make a difference?

BACKGROUND: Non-protein plasma expanders carry a risk of potentially severe allergic reactions. As prime for cardiopulmonary bypass, we routinely use a gelatin plasma expander. Plasma expanding during anesthesia is achieved with high molecular starch (200/0.5 kDalton) in combination with Ringer Lactate solution (RL) and in the Intensive Care Unit (ICU) with a low molecular starch (130/0.4 kDalton). We evaluated the feasibility of low molecular starch in combination with RL (group LMSRL) versus gelatin plasma expanding (group GPE) for priming CPB circuits in patients undergoing cardiac surgery in a randomized prospective trial. METHODS: One hundred and eighty adults who underwent primary valve or coronary artery bypass graft (CABG) surgery were equally stratified into 3 series of 60 patients with the routinely used oxygenators; Capiox RX-25, CML Duo and Quadrox-D. Then they were randomised by drawing lots and allocated into the LMSRL or GPE groups. We compared hematocrit, hemoglobin, platelet count, activated clotting time (ACT), lactate and colloid osmotic pressure (COP), blood loss, transfusion need, urine production and ICU stay. In addition, we monitored the average trans-oxygenator fluid resistance (AFR) for each type of oxygenator. RESULTS: The COP is significantly lower in the LMSRL group (20mmHg +/- 0.2 versus 18 mmHg +/- 0.2, p < 0.0001); as was the total use of plasma expanders (3846 ml +/- 98 versus 3059 ml +/- 77, p < 0.001). All other parameters were not significantly different. When comparing the observed AFR for the three types of oxygenators, a lower AFR in the LMSRL group (p < 0.02) was noted for the Capiox RX-25. CONCLUSIONS: This study shows a lower need for plasma expanders in patients who receive only starch plasma expanders. Further, we noted a lower COP in the LMSRL group, but since the mean COP was >17 +/- 0.2 mmHg, this cannot be considered of clinical importance. In conclusion, our study result supports the use of low molecular starch as a good alternative choice for priming CPB.