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Pulsatile compared with nonpulsatile perfusion using a centrifugal pump for cardiopulmonary bypass during coronary
J J Driessen1, H Dhaese, G Fransen
1Department of Anaesthesiology, St Jan's Hospital, Brugge, Belgium.
Insights
Pulsatile cardiopulmonary bypass (CPB) may reduce the inflammatory response during coronary artery bypass grafting (CABG) surgery. Nonpulsatile flow was associated with lower blood pressure, greater complement activation, and more infections, suggesting pulsatile flow could be beneficial.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Immunology
Background:
- Cardiopulmonary bypass (CPB) is essential for cardiac surgeries like coronary artery bypass grafting (CABG).
- The mode of blood flow delivery (pulsatile vs. nonpulsatile) during CPB may influence patient outcomes.
- Centrifugal pumps are commonly used for CPB, and their flow characteristics can be modified.
Purpose of the Study:
- To investigate the influence of pulsatile versus nonpulsatile flow during CPB on perioperative systemic hemodynamics, oxygen exchange, and inflammatory markers in CABG patients.
- To compare the incidence of postoperative complications, such as respiratory tract infections, between the two perfusion modes.
Main Methods:
- A randomized study of 38 patients undergoing CABG, divided into two groups: one receiving pulsatile CPB and the other nonpulsatile CPB.
- Pulsatile flow was generated using a Sarns centrifugal pump modified for pulsatility.
- Measurements included systemic hemodynamics, oxygenation, complement activation (CH50), neutrophil counts (PMN), and elastase levels (E-alpha 1-PI).
Main Results:
- The nonpulsatile group exhibited lower mean arterial blood pressure and lower oxygen saturation (SvO2) during rewarming.
- Greater complement activation (decreased CH50) and higher elastase levels were observed in the nonpulsatile group.
- The nonpulsatile group had a significantly higher incidence of postoperative respiratory tract infections (9 vs. 2 patients).
Conclusions:
- Pulsatile flow during CPB may mitigate the systemic inflammatory response associated with cardiopulmonary bypass.
- The observed differences suggest potential clinical benefits of pulsatile perfusion, warranting further investigation into its impact on long-term outcomes.
Abstract:
The present study investigated the influence of pulsatile or nonpulsatile flow delivery with a centrifugal pump for cardiopulmonary bypass (CPB) during coronary artery bypass grafting (CABG) in two randomized groups of 19 patients each. All patients received a standard anaesthetic and surgical protocol. Pulsatile perfusion during CPB was created by accelerating the baseline pump speed of the Sarns centrifugal pump at a rate of 50 cycles per minute. Measurements included perioperative systemic haemodynamics and oxygen exchange, total haemolytic complement (CH50), polymorphonuclear (neutrophil) granulocyte (PMN) count and plasma granulocyte elastase bound to alpha 1-proteinase inhibitor (E-alpha 1-PI). Laboratory measurements were corrected for haemodilution. During and after CPB there were only a few significant differences between the groups in systemic haemodynamics and oxygenation, i.e. a lower mean arterial blood pressure after the end of CPB in the nonpulsatile group (65 mmHg, SD = 11 vs 76 mmHg, SD = 11) and a lower SvO2 during rewarming on CPB in the nonpulsatile group (62%, SD = 8 vs 67%, SD = 8). The decrease in percentage of PMNs in the total white blood cell count during CPB was greater in the nonpulsatile group than in the pulsatile group (from 61 to 46% vs 63 to 53% of prebypass value). The steep increase of PMN count at the end of CPB and postoperatively was comparable in both groups. The maximal decrease of CH50 levels, occurring after surgery, was significantly higher in the nonpulsatile group (70% SD = 15 vs 79%, SD = 16, of baseline value), suggesting a greater complement activation. E-alpha 1-PI levels increased significantly in both groups during and after CPB with higher peak levels, obtained at one hour after admission to an intensive care unit, in the nonpulsatile group (316 micrograms/l, SD = 102) than in the pulsatile group (247 micrograms/l, SD = 106). There was a partly inverse correlation between the peak postoperative elastase levels and the PaO2/FiO2 ratios at the first postoperative morning. This ratio was significantly lower in the nonpulsatile group (211, SD = 56) than in the pulsatile group (247, SD = 62). Postoperative respiratory tract infection was more frequent in the nonpulsatile group (n = 9) than in the pulsatile group (n = 2). Adding a pulsatile component to centrifugal blood pumping during CPB may have benefits with regard to the possibly detrimental whole body inflammatory response to CPB. Further studies are warranted to investigate whether these differences will affect clinical outcome.