Calidad de hemocomponentes leucorreducidos: la validación del procedimiento de leucorreducción / Quality of WBC-reduced blood components: validation of leukoreduction process

Las Guías Internacionales y Nacionales regulan la práctica de leucorreducción para garantizar la calidad de los hemocomponentes leucorreducidos. La normativa local establece que el procedimiento deberá estar validado y que el nivel máximo de leucocitos residuales en productos leucorreducidos es 5 x 10 elevado a la 6. Para alcanzar dicho objetivo se analizan los factores críticos que influyen sobre el proceso de leucorreducción y se presentan métodos de recuento de leucocitos residuales, planes de muestreo y análisis estadístico.

Improved oxygenation in patients with mild lung dysfunction by leucocyte depletion during cardiopulmonary bypass

Cardiopulmonary bypass [CPB] has been shown to induce a systemic inflammatory response. This leads to release of toxic substances, such as elastase, which cause endothelial damage and adversely affect the outcome. Leucocyte depleting arterial filters have not dramatically improved lung function after cardiopulmonary bypass, but patients with pre-existing lung function may benefit from their use. This study was done to evaluate whether postoperative lung function could be improved by use of leucocyte filter during cardiopulmonary bypass. 30 patients with lung dysfunction having elective first-time coronary revascularization were randomized to either a leucocyte depleting or a standard 40mm arterial line filter during CPB. The alveolar-arterial oxygenation index was calculated before and 5min after CPB then at 1,2,4,8 and 18hr after surgery. Time to extubation was recorded. Preoperative, immediate postoperative and 24hr postoperative chest x-rays were scored for extravascular lung water. Activated white cells were identified using nitroblue tetrazolium, then total and activated white cell numbers counted after staining with leucoplate. Postoperative alveolar-arterial oxygenation were better in patients who received leococyte depletion during CPB [1.7 +/- 0.97 vs 3 +/- 1.74 in the control group, p<0.05] and also leucocyte filter reduced the total white cell count and was capable of selectively removing activated white cells during CPB. The duration of postoperative mechanical ventilation was less in the leucocyte depleted group [4.6 +/- 2.1 vs 8.1 +/- 4.8 hr in the control group, p<0.05]. The extravasular lung water scores immediately postoperatively were 13.0 +/- 8.7 in the study group vs 19.7 +/- 10.6 in the control group [p = 0.04] and at 24 hr postoperatively 9.5 +/- 7.6 vs -14.9 +/- 10 for controls. For patients with mild lung dysfunction, a leucocyte-depleting arterial line filter improves postoperative oxygenation, reduces extravascular lung water accumulation and reduces time on artificial ventilation after CPB. Leucocyte depleting filters may be an economic argument for every patient during CPB. Pulmonary dysfunction - after cardiopulmonary bypass remains an important clinical problem despite refinements in techniques of extracorporeal circulation and improvements in postoperative intensive care. The pathogenesis of postoperative lung injury consists of several steps .The initial step is a complement activation and release of inflammatory mediators as a result of blood exposure to the surface of the cardiopulmonary bypass circuit[1-5]. This causes the up regulation of leucocyte adhesive receptors CD11b /CD18 [known as Mac-1 or CR3][6] Furthermore the inflammatory cytokines induce the synthesis of ligand intercecullar adhesion molecules on the endotheliun cells, which lead to enhanced adhesiveness of endothelial for neutrophils[7]. In the phase of lung reperfusion at the termination of cardiopulmonary bypass neutrophils adhere to the endothelial surface of the pulmonary circulation creating a microenvironment that permits high concentration of toxic agents [such as elastase and oxygen radicals] released by activated neutrophils[8,9]. The technique of leucocyte depletion was developed in response to this with early studies using either cell separator technology, or leucocyte depleting trasfusion filters incorporated into the extracorporeal circuit[10-13]. The key benefits of leucodepletion are improved cardiac and lung function, especially an increased postoperative PaO2[10,11]. The leukoguard LG-6 arterial line filter [pall Biomedical Portsmouth, UK] removes leucocytes from the circulation although the systemic neutrophil count may[11,14,15] or may not be reduced[16-18]. Leucocyte depletion during cardiopulmonary bypass [CPB] may improve oxygenation in the early postoperative period in comparison with controls[11,16,18,19] and the duration of postoperative mechanical ventilation may also be reduced[11,16]. The benefit of leucocyte depletion may be small if the duration of bypass is short[20]. The aim of this study was to determine whether mechanical filtration of leucocytes during cardiopulmonary bypass improves the postoperative pulmonary function in human beings and to compare sequential total and activated white cells during CPB, using either a leucocyte depleting or standard arterial line filter