The influence of leukocyte filtration during cardiopulmonary bypass on postoperative lung function: A clinical study

Abstract

The accumulation of activated leukocytes in the pulmonary circulation plays an important role in the pathogenesis of lung dysfunction associated with cardiopulmonary bypass. Animal studies have demonstrated that the elimination of leukocytes from the circulation reduces postoperative lung injury and improves postoperative pulmonary function. We conducted a prospective randomized clinical study to evaluate whether postoperative lung function could be improved by use of a leukocyte filter during cardiopulmonary bypass. Elective coronary artery bypass grafting was done with a leukocyte-depleting arterial blood filter incorporated in the extracorporeal circuit (14 patients, leukocyte filter group) or without the filter (18 patients, control group). Blood samples collected at intervals before, during, and after operation were used for analysis of blood cell counts, elastase concentrations, and arterial blood gases. The use of the leukocyte filter caused no significant reduction in leukocyte count (p = 0.86). There were no differences in postoperative lung function between the groups, as assessed through (1) oxygenation index (290 for leukocyte filter group compared with 329 for control group, 95% confidence interval, 286 to 372, p = 0.21), (2) pulmonary vascular resistance (p = 0.10), and (3) intubation time (16.6 hours for leukocyte filter group versus 15.7 hours for control group, 95% confidence interval, 12.1 to 19.1 hours, p = 0.72). The levels of neutrophil elastase were significantly higher at the end of cardiopulmonary bypass in the leukocyte filter group (460 microgram/L in leukocyte filter group versus 230 microgram/L in control group, 95% confidence interval, 101 to 359 microgram/L, p = 0.003). We conclude that the clinical use of the present form of leukocyte-depleting filter did not improve any of the postoperative lung function parameters analyzed in this study.

The effects of various leukocyte filtration strategies in cardiac surgery

“…This was supported by Johnson et al, who measured PaO 2 and intra-pulmonary shunt (Qs/Qt) and found both to be worse in controls, although only in the first 4 h post CPB [55]. Subsequent studies report no impact on pulmonary function post-operatively, using a variety of indices [9,26,43,44,46]. More recent studies, however, describe beneficial effects of leukofiltration.…”

“…Whereas some studies showed similar elastase levels in the filtered and control patients [9,10,46], others have unexpectedly showed higher elastase levels following leukocyte filtration [35,43,44] and suggested this reflects increased elastase release by neutrophils trapped within the filter, rather than a higher activation of neutrophils within the tissues. Chen et al demonstrated a reduction in MDA [52] following leukocyte filtration, as did Allen et al in cyanotic infants [59].…”

“…Only eight studies within this section of the review did not record pre-and post-operative WCC. Of the 26 that did, 15 found no significant difference between filtered patients and controls at any point in the patients admission [9,22,23,27,[39][40][41][42][43][44][45][46][47][48][49][50]. The remaining 11 papers found reduced WCCs in the filtered group mainly during CPB, although these differences tended to disappear after CPB [10,26,35,[51][52][53].…”

“…[56]. Conversely, many other investigators found no impact on catecholamine or vasopressor use [27,43,49,53]. No study demonstrated an effect on peri-operative arrhythmias or cardiac arrest rates.…”

Leukocyte filtration fails to limit functional neutrophil activity during cardiac surgery

“…Several authors have been able to show, that reperfusion injury to cardiac and pulmonary tissue is diminished by leukocyte filtration in the arterial line [5,6] or the venous line [7], and that leukocyte filtration in the blood cardioplegia delivery system can improve myocardial protection [8]. Despite these promising results, postoperative complications including systemic immune response syndrome (SIRS), myocardial and pulmonary reperfusion injury, and cerebral damage remain critical issues [1,2,9].…”