Who is the Bad Guy in Perfusion Technologies? Priming Volume, Blood Air Interaction or Pump Type: A Prospective, Randomized Trial of Three Different Techniques

Objectives: Minimal extracorporeal circulation techniques or circuits (MECC) may reduce the side effects of conventional extracorporeal circulation (CECC). However, it is unclear how much of this reduction is caused by reducing priming volume and hemodilution or by avoiding blood-air contact and dispersion of mediastinal debris into the systemic circulation.

Methods: In a prospective randomized trial, 72 patients (mean age, 73 ± 5.3yrs; 83% male) referred for CABG were randomly assigned to MECC (priming volume 600 mL), CECC or no-suction-CECC (priming volume 1290 mL). Patient demographics, preoperative characteristics and postoperative outcome were analyzed by group-analyzed (ANOVA). The laboratory surrogate endpoints (renal function creatinine, inflammatory response (IL6, IL10, PMNelastase, TNFalpha, Procalcitonin), ischemia (CK, CKMB, tropT), coagulation (PTT, ACT, ADP, TRAP, ASPI) and haemolysis (free Hemoglobin) and clinical outcome data were measured at five different time points (T1-5). (NCT01306903).

Results: The study groups were very comparable for all preoperative variables; including established transfusion risk factors. Operation times (MECC 261 ± 79 min; CECC 264 ± 75 min; no-suction-CECC 231 ± 68 min) and perfusion times (MECC 115 ± 49 min; CECC 107 ± 37 min; no-suction CECC 99 ± 22 min) indicated a trend toward faster performance in the no-suction-CECC group (p > 0.05). Pro-inflammatory cytokines, ischemia and coagulation markers were postoperative significantly elevated by all cardiopulmonary bypass types and decreased to preoperative baseline levels at discharge (T5) without identifiable statistical differences between the three study groups. FreeHb was also not significant increased by centrifugal pump or cell saver procedures. Significant intraoperative hemodilution effects due to the different priming volumes were demonstrated (MECC Hb9,6 ± 1,1 g/dl; CECC Hb9,0 ± 0,8 g/dl; No-suction CECC Hb8,7 ± 1 g/dl; p = 0,01) only at the end of operation (T2).

Conclusions: Coronary revascularisation with MECC represents a suitable and partly beneficial procedure regarding hemodilution and transfusion. A significant trend in other surrogate endpoints could not be found. The question for the single bad guy in perfusion technologies is still unacknowledged.