Leukocyte filtration and aprotinin: synergistic anti-inflammatory protection

Long-term leukocyte filtration should be avoided during extracorporeal circulation

Filtration during extracorporeal circulation (ECC) not only removes but also activates leukocytes; therefore, long-term leukocyte filtration may cause adverse effects. In the present study, we tested this hypothesis by priming ECC with 300 mL of canine blood and examining filtration effects in 3 groups (n = 6 each) during 60 min ECC. In the control group (Group C) blood was filtrated with an arterial filter for 60 min; in long-term (Group L) and short-term (Group S) groups, blood was filtrated with a leukocyte filter for 60 and 5 min. We found that about 90% of leukocytes were removed after 5 min of filtration in both Groups L and S. Although leukocyte count continued to reduce, mean fluorescent intensities of CD11/CD18, free hemoglobin, and neutrophil elastase increased in Group L and were higher than those in Groups C and S at 60 min. Leukocyte rupture, cytoplasmic leakage, and circulating naked nuclei were also found in Group L. The data support our hypothesis that long-term filtration can induce inflammation and lead to leukocyte destruction.

Leukocyte-Aprotinin Atrial Fibrillation Study (LAFFS): Impact of Aprotinin and Leukofiltration on Atrial Fibrillation, Renal Insufficiency and Encephalopathy Post-Cardiopulmonary Bypass

Purpose: Atrial fibrillation remains the leading postoperative complication following cardiopulmonary bypass. A randomized trial was undertaken to evaluate the effectiveness of leukocyte filtration and aprotinin, applied separately and in combination, on the incidence of post-operative atrial fibrillation. A secondary component of the study was the impact of these adjunct interventions on post-surgical renal and neurological dysfunction. Methods: A total of 1,220 patients undergoing primary isolated coronary artery bypass grafting were randomly assigned to one of four treatment groups. The control group (305 patients) received standard cardiopulmonary bypass with moderately hypothermic (34ºC) cardioplegic arrest. In the filtration group (310 patients) leukocyte reducing filters were incorporated into the bypass circuit and deployed strategically. The aprotinin group (285 patients) received full Hammersmith dose aprotinin. The combination therapy group (320 patients) received both aprotinin and leukocyte filtration. Results: The incidences of atrial fibrillation were 25% in the control group, 16% in the filtration group, 19% in the aprotinin group and 10% in the combination therapy group (P < 0.001). Renal dysfunction was detected in 3% of the control group, 2% of the filtration group, 8% of the aprotinin group, and 5% of the combination group (P < 0.005). Neurological dysfunction occurred in 2% of the control group, 2% of the filtration group, 1% of the aprotinin group, and 2% of the combination group (P = n.s.). Conclusions: Combination therapy with aprotinin and leukocyte filtration markedly reduced atrial fibrillation post-cardiopulmonary bypass, and was more effective than the individual treatments. Aprotinin treatment increased the incidence of renal dysfunction, and the addition of leukocyte filtration partially mitigated this detrimental effect of aprotinin. Thus, strategic leukocyte filtration augments aprotinin's anti-arrhythmic effects while suppressing its nephrotoxic sequelae.

Does Systemic Leukocyte Filtration Affect Perioperative Hemorrhage in Cardiac Surgery? A Systematic Review and Meta-Analysis

Cardiopulmonary bypass causes a systemic inflammatory reaction. Activation of leukocytes is an important part of this process, and is known to directly contribute to the development of postoperative coagulopathy, and thus hemorrhage. The removal of leukocytes from the cardiopulmonary bypass circulation, using specialized filters, has been proposed as one method for attenuating this inflammatory response. However, there is no consensus on its effectiveness. We used meta-analytical techniques to systematically assess the literature reporting on the potential effect of systemic leukofiltration on perioperative hemorrhage. Random effects modeling was used to calculate overall estimate, and heterogeneity was assessed. Systemic leukofiltration made no significant impact on chest tube drainage in the first 24 hours (weighted mean difference [WMD], x23.9 ml; 95% confidence interval [CI], x95.48-47.61; p = 0.51) or on the total packed red cell transfusion requirements of each patient (WMD, 7.84 ml; 95% CI, x80.13-95.81; p = 0.86). The studies performed in this area thus far are highly heterogeneous, due in part to relatively poor-quality design and inadequate matching of their study groups. Although further high-quality trials on systemic leukofiltration may be appropriate, other strategies to reduce the coagulopathy associated with cardiopulmonary bypass should be sought and evaluated.

Atrial Fibrillation After Aortic Arch Repair Requiring Deep Hypothermic Circulatory Arrest: Incidence, Clinical Outcome, and Clinical Predictors

OBJECTIVE

To delineate the incidence, outcome impact, and clinical predictors of atrial fibrillation (AF) after adult aortic arch repair requiring deep hypothermic circulatory arrest (AAR-DHCA) AIMS: To determine the incidence of AF after AAR-DHCA, to determine whether AF after AAR-DHCA affects mortality or stay in the intensive care unit (ICU), to determine multivariate predictors for AF after AAR-DHCA, and to determine whether aprotinin protects against AF after AAR-DHCA.

STUDY DESIGN

Retrospective and observational.

STUDY SETTING

Single large university hospital.

PARTICIPANTS

All adults undergoing AAR-DHCA in 2000 and 2001.

MAIN RESULTS

The cohort size was 144. Antifibrinolytic exposure was 100%, aprotinin 66% and aminocaproic acid 34%. The incidence of AF was 34.0%. AF was not significantly associated with increased mortality or prolonged ICU stay. Advanced age was a multivariate risk factor for AF. Lower temperature nadir during DHCA was protective against postoperative AF. Aprotinin had no demonstrable effect on AF after AAR-DHCA.

CONCLUSIONS

AF after AAR-DHCA is common but does not independently increase mortality or ICU stay. The risk of AF after AAR-DHCA increases with age but decreases with the degree of hypothermia during DHCA. Aprotinin does not appear to affect the risk of AF after AAR-DHCA.

The effects of various leukocyte filtration strategies in cardiac surgery

It is known that cardiopulmonary bypass causes an inflammatory reaction with an associated morbidity and mortality. Several anti-inflammatory strategies have been implemented to reduce this response, including leukocyte removal from the circulation using specialised filters. The aim of this study is to systematically review the available evidence on leukocyte filtration in cardiac surgery, focusing on its effect on systemic inflammation and whether this has influenced clinical outcomes. Five electronic databases were systematically searched for studies reporting the effect of leukocyte filtration at any point within the cardiopulmonary bypass circuit in humans. Reference lists of all identified studies were checked for any missing publications. Two authors independently extracted the data from the included studies. Whilst systemic leukodepleting filters do not appear to consistently lower leukocyte counts, they may preferentially remove activated leukocytes. Small improvements in early post-operative lung function in patients receiving systemic leukodepletion have been reported, but this does not lead to reduced hospital stay or decreased mortality. There is substantial evidence that cardioplegic leukocyte filtration attenuates the reperfusion injury at a cellular level, but this has not been translated into clinical improvements. Finally, whilst various strategies involving multiple leukocyte filters, or the incorporation of pharmacological agents into leukocyte-depleting protocols have been evaluated, the current available results are not conclusive. Our study suggests that there is not enough high quality or consistent evidence to draw guidelines regarding the use of leukocyte-depleting filters within routine cardiac surgical practice.