RELATIONSHIP BETWEEN LEUKOCYTE COUNT AND PATIENT RISK FOR EXCESSIVE BLOOD-LOSS AFTER CARDIAC-SURGERY

Objective: To evaluate the relationship between leukocyte counts and r isk for excessive blood loss after cardiac surgery when including nume rous demographic, operative, and laboratory factors in the comparison. Design: A prospective, clinical evaluation. Setting: A point-of-care laboratory and the cardiac surgical unit of a university-afilliated te rtiary center. Patients: Patient-related and hematologic variables wer e measured, using blood specimens obtained from 89 hospitalized patien ts who underwent cardiac surgery involving cardiopulmonary bypass. Int erventions: None. Measurements and Main Results: Demographic, operativ e, and transfusion-related data were recorded for each patient, Routin ely obtained measurements of laboratory based prothrombin time, partia l thromboplastin time, complete blood count, and bleeding time were re corded, Hemoglobin concentration, platelet count, and red and white bl ood cell counts were measured with an on-site instrument before initia tion (pre-cardiopulmonary bypass) and before discontinuation (end-card iopulmonary bypass) of cardiopulmonary bypass, Hematocrit was calculat ed using recorded variables, and white blood cell percent change value s were calculated using white blood cell counts from both periods, usi ng the following formula: [(end-cardiopulmonary bypass-pre-cardiopulmo nary bypass)/pre-cardiopulmonary bypass] x 100, When we excluded four patients who had a surgical source of post-cardiopulmonary bypass blee ding, significant (p<.0001) relationships were observed between white blood cell count (r(2) = .46) and white blood cell percent change valu es (r(2) = .71) and cumulative mediastinal chest tube drainage in the first 4 postoperative hours in 85 patients, Bayes theorem was used to evaluate the predictive ability of hematologic measurements in identif ying patients with excessive bleeding (n = 24), defined as >1000 mL of cumulative chest tube drainage in the first 24 postoperative hours, w hen compared with patients without excessive bleeding (n = 61), Demogr aphic and operative variables were similar between these patients exce pt that patients with excessive bleeding required more red blood cell, platelet, and plasma transfusions during the postoperative interval, Significantly (p<.0001) greater white blood cell percent change values were obtained in the excessive bleeding cohort (119 +/- 93 percent ch ange) when compared with patients without excessive bleeding (28 +/- 3 6 percent change). Conclusions: On-site measurements of white blood ce ll count, as an index of the inflammatory response to extracorporeal c irculation, may be useful in identifying patients at increased risk fo r excessive bleeding, Further studies are needed to examine whether wh ite blood cell counts during multiple cardiopulmonary bypass periods m ay identify patients with an exaggerated inflammatory response to extr acorporeal circulation, By using this information, physicians may be a ble to intervene with anti-inflammatory medications and blood preserva tion techniques.