Poor prediction of blood transfusion requirements in adult liver transplantations from preoperative variables

Intraoperative red blood cell transfusion in liver transplantation: influence on patient outcome, prediction of requirements, and measures to reduce them

Objectives of this study are to quantify the need for blood transfusion during liver transplantation (LT) and confirm the importance of intraoperative blood transfusion as an independent prognostic factor for postoperative outcome. Furthermore, we try to detect useful variables for the preoperative identification of patients likely to require transfusion of packed red blood cell units (PRCUs) and identify measures to reduce transfusion needs. Data were collected prospectively between September 1998 and November 2000. One hundred twenty-two LTs were included in the study. Forty-two patients (34%) did not require transfusion of PRCUs. In multivariate analysis, transfusion of more than three PRCUs was found to be the only significant variable associated with prolonged hospital stay. In addition, excluding perioperative deaths, PRCU transfusion, using a cutoff value of six units, was the only variable to reach statistical significance (P =.008; risk ratio, 4.93; 95% confidence interval, 15 to 15.9) to predict survival in a multivariate analysis that also included Child's class and United Network for Organ Sharing (UNOS) classification. Moreover, only preoperative hemoglobin (Hb) level was found to significantly predict the need for transfusion of one or more PCRUs. Finally, only UNOS classification and placement of an intraoperative portacaval shunt were found to be statistically significant to predict the need to transfuse more than six PRCUs. We found the requirement of even a moderate number of blood transfusions is associated with longer hospital stay, and transfusion of more than six PRCUs is associated with diminished survival. Preoperative normalization of Hb levels and placement of an intraoperative portacaval shunt can diminish the number of blood transfusions during LT.

Institutional variability in transfusion practice for liver transplantation

We prospectively evaluated the institutional variability in perioperative transfusion therapy in orthotopic liver transplantation (OLT). Adult OLTs completed during a 12-mo period were studied until the 48th postoperative hour at 8 centers. A multivariate analysis using mixed-effects logistic regression included variables predisposing to blood loss and a center random effect. In addition, the influence of the calculated perioperative hemoglobin (Hb) loss on the individual probability of receiving red blood cells (RBCs), fresh frozen plasma (FFP), and platelets in excess of the overall median were explored. The analysis was performed on 301 cases. The overall median numbers transfused were 5 RBC units, 6 FFP units, and the median platelet dose was 5.10(11), with significant intercentric differences in the proportions of cases given more than the overall median. Intercentric differences remained significant after adjustment for factors independently associated with a large blood component use. Intercentric differences in RBCs, FFP, and platelet use decreased but persisted after adjustment for the perioperative Hb loss. Intercentric differences in RBC use disappeared after adjustment for the postoperative Hb concentration. The significant heterogeneity in transfusion therapy mandates reassessment of the rational use of blood products in OLT.

Review of the clinical practice literature on patient characteristics associated with perioperative allogeneic red blood cell transfusion

There is evidence to suggest that there exists considerable variation in red blood cell (RBC) transfusion practices, especially in the surgical specialties. This is in large part related to difficulties in defining specific transfusion threshold criteria, given that there is no minimum acceptable hemoglobin threshold concentration and there is variability in assigning importance to patient factors. The purpose of this study is to identify patient-related factors that might be associated with the need for allogeneic RBC transfusion in surgical patients. We systematically identified, selected, and reviewed all observational or interventional studies describing patient-specific or related variables associated with the need for allogeneic RBC transfusion in the surgical patient population. We also evaluated the methodological characteristics of the individual studies. Sixty-two studies met our inclusion criteria and were analyzed for this review. Most of these studies were conducted in patients undergoing cardiac surgery (n = 30) and orthopedic surgery (n = 16). Decreased preoperative red cell reserve was most frequently associated with RBC transfusions, being identified as a significant variable in 46 studies. The other factors commonly associated with transfusion were advancing age (n = 28), female gender (n = 21), and small body size (n = 14). Only 2 studies attempted to prospectively validate a predictive model for RBC transfusion based on the variables identified. This systematic review shows that preoperative anemia, advancing age, female gender, and small body size are often associated with perioperative allogeneic RBC transfusion. However, the retrospective nature of most of the studies and the small sample sizes make it difficult to formulate a clinically useful prediction rules regarding allogeneic RBC transfusion. Ongoing research in designing large prospective cohort studies evaluating transfusion patterns are needed to further elucidate how patient characteristics impact the transfusion threshold.

Preoperative predictors of blood transfusion in colorectal cancer surgery

Transfusion is associated with multiple risks and morbidities. Little is known, however, about preoperative predictors of transfusion in gastrointestinal surgery patients. To identify factors that influence transfusion practices, we analyzed hospital discharge data from colorectal cancer surgery patients in Maryland between 1994 and 2000 (n = 14,052). The primary outcome variable was whether or not patients received a blood product ("Any Transfusion"). Characteristics independently associated with an increased risk of receiving Any Transfusion included: advanced age (>80 yr: OR 2.3; 95% CI 1.9-2.9; 70-79 yr: OR 1.6; 95% CI 1.4-2.0 vs. <60 yr), moderate to severe liver disease (OR 2.5; 95% CI 1.5-4.2), mild liver disease (OR 2.1; 95% CI 1.5-2.9), diabetes with complications (OR 2.1; 95% CI 1.6-2.6), chronic renal disease (OR 2.1; 95% CI 1.4-3.0), female gender (OR 1.3; 95% CI 1.2-1.5), chronic pulmonary disease (COPD) (OR 1.3; 95% CI 1.1-1.4), and metastatic disease (OR 1.2; 95% CI 1.1-1.4). Patients at hospitals with an annual case volume in the highest quartile were at an increased risk for receiving Any Transfusion (OR 2.1; 95% CI 1.3-3.4) and those with surgeons in the highest volume quartile (>12 cases/yr) were at a decreased risk (OR 0.8; 95% CI 0.6-0.99). The association between greater surgeon case volume and low transfusion rates was seen in all but the very high volume hospitals (>74 cases/yr). Blood product transfusion was associated with a 2.5-fold (95% CI 2.1-3.1) increased mortality, 3.7 day (95% CI 2.1-3.1) increase in hospital length of stay, and a 7120 dollars (95% CI 6472 dollars-7769 dollars) increase in total charges compared to patients that did not receive Any Transfusion. This data can be used by providers in discussions with patients regarding the risks for transfusion and in identifying patients in whom strategies to reduce transfusions should be evaluated.

Intraoperative blood losses and transfusion requirements during adult liver transplantation remain difficult to predict

PURPOSE

To identify preoperative factors associated with high blood losses during liver transplantation for chronic end-stage liver disease.

METHODS

Four hundred and ten consecutive patients were included in this retrospective study. Blood losses were calculated, based on transfusion requirements. The population was divided into two groups: the upper quartile was defined as the high blood loss (HBL) group and the lower three quartiles as the low blood loss group. Fourteen preoperative variables were collected. Qualitative variables consisted of the type of hepatopathy, Child-Pugh's classification, sex, the surgical team's experience, previous abdominal surgery and portal hypertension. Quantitative variables were age, hemoglobin concentration Hb, platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen concentration, fibrin degradation products (FDP) and euglobulin lysis time. Univariate analysis and stepwise multivariate analysis were conducted.

RESULTS

Patients in the HBL group required 12 units of red blood cell or more to maintain a Hb >/= 100g*L(-1). HBL was associated with severe liver disease, previous abdominal surgery, use of a venovenous bypass and little surgical experience in orthotopic liver transplantation (OLT). In the HBL group several hemostatic parameters were more disturbed before surgery. The multivariate analysis disclosed three independent variables associated with HBL: Hb and FDP concentrations and previous upper abdominal surgery. When combined, these resulted in a high specificity (98%) but low sensitivity to predict blood loss.

CONCLUSION

Despite our efforts we were unable to identify predictive risk factors of bleeding during OLT even in a homogeneous population. Centres should evaluate their practice individually in an attempt to identify patients at high risk of being transfused.