Pulsatile extracorporeal circulation--let it be?

Abstract

Cardiopulmonary bypass (CPB) is known to induce a whole body inflammatory response. Since the 1970's, a number of trials have explored the effects of pulsatile CPB on systemic organ function and inflammatory response. Clinical benefits of neuroprotection, improved myocardial and splanchnic perfusion, as well as attenuated systemic inflammatory response have been reported. However, skepticism for pulsatile CPB remains because of inconsistencies of clinical benefits and 'non-standardized' trials. Tarcan and colleagues compared clinical, haemodynamic, biochemical and haematological parameters in patients with chronic obstructive pulmonary disease undergoing CPB with pulsatile flow versus those without. They found higher circulating white cell count and lower neutrophil count at 1 hour post-operatively in the pulsatile group compared with non-pulsatile group, which was attributed to higher pulmonary neutrophil sequestration. In addition, the pulsatile CPB group had lower pulmonary vascular resistance at 1 hour post-operatively and shorter ventilation time. In the current study, confirmation for pulmonary neutrophil sequestration in the form of bronchoalveolar lavage (BAL) or histology would have been welcomed, and additional markers such as neutrophil elastase or matrix metello-proteinases in BAL, and other measurements of lung function may help clarify the association between neutrophil sequestration, lung injury and clinical endpoints. The role of pulsatile CPB in certain high-risk patients remain uncertain, and until more definite evidence of benefit is available, we should be cautious of its universal application.