Transfusion of blood products and nosocomial infection in surgical patients

Red blood cell transfusion associated with increased morbidity and mortality in patients undergoing elective open abdominal aortic aneurysm repair

BACKGROUND

Red blood cell (RBC) transfusions are associated with increased mortality and morbidity. The aim of this analysis was to examine the association between RBC transfusions and long-term survival for patients undergoing elective open infrarenal abdominal aortic aneurysm (AAA) repair with up to 15 years of follow-up.

METHODS

Prospective cohort study using data from The Danish Vascular Registry from 2000-2015. Primary endpoint was all-cause mortality. Secondary endpoints were in-hospital complications. Transfused patients were divided into subgroups based on received RBC transfusions (1, 2-3, 4-5 or > 5). Using Cox regression multi-adjusted analysis, non-transfused patients were compared to transfused patients (1, 2-3, 4-5, >5 transfusions) for both primary and secondary endpoints.

RESULTS

There were 3 876 patients included with a mean survival of 9.1 years. There were 801 patients who did not receive transfusions. Overall 30-day mortality was 3.1% (121 patients) and 3.6% (112) for all transfused patients. For the five subgroups 30-day mortality was: No transfusions 1.1% (9 patients), 1 RBC 1.2% (4 patients), 2-3 RBC 2.2% (26 patients), 4-5 RBC 1.9% (14 patients) and > 5 RBC 7.9% (68 patients). After receiving RBCs, the hazard ratio for death was 1.54 (95% CI 1.27-1.85) compared to non-transfused patients. There was a significant increase in mortality when receiving 2-3 RBC: HR 1.32 (95% CI 1.07-1.62), 4-5 RBC: 1.64 (1.32-2.03) and >5 RBC: 1.96 (1.27-1.85) in a multi-adjusted model.

CONCLUSION

There is a dose-dependent association between RBC transfusions received during elective AAA repair and an increase in short- and long-term mortality. Approximately 25% of included patients had preoperative anemia. These findings should raise awareness regarding potentially unnecessary and harmful RBC transfusions.

The effects of anaemia and transfusion on patients with traumatic brain injury: A review

BACKGROUND

Anaemia in traumatic brain injury (TBI) is frequently encountered. Neurosurgical texts continue to recommend transfusion for hematocrit below 30%, despite clear evidence to do so. Transfusion should increase oxygen delivery to the brain, but it may also increase morbidity and mortality.

METHODS

This study reviewed the relevant literature to better understand the risks of anaemia and benefits of correction of anaemia by transfusion.

RESULTS

Of the 21 studies reviewed, eight found that anaemia was harmful to patients with TBI; five found no significant outcome; seven found transfusion was associated with higher rates of morbidity and mortality; two found that transfusion lowered mortality and increased brain tissue oxygen levels; and ten found no correlation between transfusion and outcome. However, the levels of anaemia severity and the outcome measurements varied widely and the majority of outcomes focused on crude measurements rather than detailed functional assessments.

CONCLUSIONS

No division of response based on gender difference or impact of anaemia in the post-hospital treatment setting was observed. A randomized control trial is recommended to determine the impact of anaemia and transfusion on detailed outcome assessment in comparison of transfusion thresholds ranging from ≤ 7 g dL^-1 to ≤ 9 g dL^-1 in patients with moderate-to-severe TBI.

Pre-operative blood donation versus acute normovolemic hemodilution in cardiac surgery

Introduction:

Acute normovolemic hemodilution (ANH) and preoperative autologous blood donation (PABD) have questionable efficacy, viral and bacterial infection risks, intermittent blood shortages as homeostasis problem, electrolyte and hemodynamic disturbances.

Materials and Methods:

In this cross sectional survey, we studied 70 patients undergoing open heart coronary artery bypass grafts [CABG] and different valvular replacement 1 ml surgery (35 in ANH, 35 in PABD) in Shaheed Modares - Hospital. We measured electrolytes and homeostatic factors to evaluate the influence of two transfusion methods on homeostatic function and hemodynamic balance.

Results:

We compared 70 patients (38 male [54.3%] and 32 female [45.7%]) with mean age 54.8 years undergoing open heart surgery (CABG and valvular). In ANH group, significant decrease was detected in Na (28.5%) K (2.5%), prothrombin time (PT) (88.57%), partial thromboplastin time (PTT) (94.28%), creatine phosphokinase (CPK) (11.4%), lactic dehydrogenase (LDH) (11.43%), albumin (Alb) (17.14%), globulin (91.43%) and total protein (80%). Mean initial and post-operative hemoglobin was 14.12 ± 1.06 versus 11.97 ± 0.98, hematocrit 42.22 ± 3.45 versus 35.40 ± 2.88, systolic blood pressure 124.1 ± 14.4 versus 110.88 ± 15.6 (reduction 22.86%) diastolic blood pressure 76.02 ± 10 versus 69.26 ± 11 (reduction 3%) and pulse rate was 75.45 ± 10 versus 84.45 ± 12 (12%) in this case difference between two groups was strongly significant (P = 0.001). In PABD group, significant decrease was detected in Na (20%), K (2.5%), PT (91.43%) PTT (80%), CPK (8.57%), LDH (5.72%), Alb (57.15%), globulin (71.43%) and total-protein (62.85%), the value of hemodynamic changes were in normal range.

Conclusion:

Though autologous blood transfusion (ANH and PABD) was preferable to allogeneic transfusion in cardiac surgical patients; but PABD offers more advantages in homeostasis, hemodynamic stability and electrolyte balance.

The impact of two different transfusion strategies on patient immune response during major abdominal surgery: a preliminary report

Blood transfusion is associated with well-known risks. We investigated the difference between a restrictive versus a liberal transfusion strategy on the immune response, as expressed by the production of inflammatory mediators, in patients subjected to major abdominal surgery procedures. Fifty-eight patients undergoing major abdominal surgery were randomized preoperatively to either a restrictive transfusion protocol or a liberal transfusion protocol (with transfusion if hemoglobin dropped below 7.7 g dL(-1) or 9.9 g dL(-1), respectively). In a subgroup of 20 patients randomly selected from the original allocation groups, blood was sampled for measurement of IL-6, IL-10, and TNFα. Postoperative levels of IL-10 were higher in the liberal transfusion group on the first postoperative day (49.82 ± 29.07 vs. 15.83 ± 13.22 pg mL(-1), P < 0.05). Peak postoperative IL-10 levels correlated with the units of blood transfused as well as the mean duration of storage and the storage time of the oldest unit transfused (r(2) = 0.38, P = 0.032, r(2) = 0.52, P = 0.007, and r(2) = 0.68, P<0.001, respectively). IL-10 levels were elevated in patients with a more liberal red blood cell transfusion strategy. The strength of the association between anti-inflammatory IL-10 and transfusion variables indicates that IL-10 may be an important factor in transfusion-associated immunomodulation. This trial is registered under ClinicalTrials.gov Identifier: NCT02020525.

Acute respiratory distress syndrome after spontaneous intracerebral hemorrhage*

OBJECTIVES

Acute respiratory distress syndrome develops commonly in critically ill patients in response to an injurious stimulus. The prevalence and risk factors for development of acute respiratory distress syndrome after spontaneous intracerebral hemorrhage have not been reported. We sought to determine the prevalence of acute respiratory distress syndrome after intracerebral hemorrhage, characterize risk factors for its development, and assess its impact on patient outcomes.

DESIGN

Retrospective cohort study at two academic centers.

PATIENTS

We included consecutive patients presenting from June 1, 2000, to November 1, 2010, with intracerebral hemorrhage requiring mechanical ventilation. We excluded patients with age less than 18 years, intracerebral hemorrhage secondary to trauma, tumor, ischemic stroke, or structural lesion; if they required intubation only during surgery; if they were admitted for comfort measures; or for a history of immunodeficiency.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data were collected both prospectively as part of an ongoing cohort study and by retrospective chart review. Of 1,665 patients identified by database query, 697 met inclusion criteria. The prevalence of acute respiratory distress syndrome was 27%. In unadjusted analysis, high tidal volume ventilation was associated with an increased risk of acute respiratory distress syndrome (hazard ratio, 1.79 [95% CI, 1.13-2.83]), as were male sex, RBC and plasma transfusion, higher fluid balance, obesity, hypoxemia, acidosis, tobacco use, emergent hematoma evacuation, and vasopressor dependence. In multivariable modeling, high tidal volume ventilation was the strongest risk factor for acute respiratory distress syndrome development (hazard ratio, 1.74 [95% CI, 1.08-2.81]) and for inhospital mortality (hazard ratio, 2.52 [95% CI, 1.46-4.34]).

CONCLUSIONS

Development of acute respiratory distress syndrome is common after intubation for intracerebral hemorrhage. Modifiable risk factors, including high tidal volume ventilation, are associated with its development and in-patient mortality.

Innate immune activation after transfusion of stored red blood cells

The transfusion of red blood cells (RBCs), although necessary for treatment of anemia and blood loss, has also been linked to increased morbidity and mortality. RBCs stored for longer durations and transfused in larger volumes are often cited as contributory to adverse outcomes. The potential mechanisms underlying deleterious effects of RBC transfusion are just beginning to be elucidated. In this narrative review, we explore the hypothesis that prolonged RBC storage results in elaboration of substances which may function as danger associated molecular pattern molecules that activate the innate immune system with consequences unfavorable to healthy homeostasis. The nature of these chemical mediators and the biological responses to them offers insight into the mechanisms of these pathological responses. Three major areas of activation of the innate immune apparatus by stored RBCs have been tentatively identified: RBC hemolysis, recipient neutrophil priming, and reactive oxygen species production. The possible mechanisms by which each might perturb the innate immune response are reviewed in a search for potential novel pathways through which transfusion can lead to an altered inflammatory response.

Massive transfusion in traumatic shock

BACKGROUND

Hemorrhage after trauma is a common cause of death in the United States and globally. The primary goals when managing traumatic shock are the restoration of oxygen delivery to end organs, maintenance of circulatory volume, and prevention of ongoing bleeding through source control and correction of coagulopathy. Achieving these goals may require massive transfusion of blood products. Although use of blood products may be lifesaving, dose-related adverse effects are well described.

DISCUSSION

Complications of massive transfusion include interdependent derangements such as coagulopathy, hypothermia, acidosis, and electrolyte abnormalities, as well as infectious and immunomodulatory phenomena. This article explores the pathogenesis, implications, prevention, and treatment of these complications through the use of massive transfusion protocols. Particular attention is given to the optimal ratio of blood products transfused in large volume resuscitation and prevention of secondary coagulopathy.

CONCLUSIONS

Observational data indicate that the development and use of a massive transfusion protocol may reduce the morbidity and mortality associated with large-volume resuscitation of patients with hemorrhagic shock. Such protocols should include a pre-defined ratio of packed red blood cells, fresh frozen plasma, and platelets transfused; most commonly, the ratio used is 1:1:1. Additionally, such protocols should monitor for and correct hypothermia, hypofibrinogenemia, and electrolyte disturbances such as hypocalcemia and hyperkalemia.

Pulmonary complications of transfused blood components

Three transfusion complications are responsible for the majority of the morbidity and mortality in hospitalized patients. This article discusses the respiratory complications associated with these pathophysiologic processes, including definitions, diagnosis, mechanism, incidence, risk factors, clinical management, and strategies for prevention. It also explores how different patient populations and different blood components differentially affect the risk of these deadly transfusion complications. Lastly, the article discusses how health care providers can risk stratify individual patients or patient populations to determine whether a given transfusion is more likely to benefit or harm the patient based on the transfusion indication, risk, and expected result.

Towards hemostatic resuscitation: the changing understanding of acute traumatic biology, massive bleeding, and damage-control resuscitation

During the past decade there has been a profound change in the understanding of postinjury coagulation. Concurrently, new data suggest that a resuscitative strategy to minimize large volumes of crystalloid while recreating whole is associated with reduced morbidity and mortality. This article outlines the history of resuscitation and transfusion practices in trauma, the changing understanding of coagulation and inflammation, and clinical data driving changes in resuscitative conduct. Finally, the current state of the science suggests future basic science and clinical investigation that will drive changes in transfusion and resuscitation in severely injured military personnel and civilian patients.

Impact of shed blood products on stimulated cytokine release in an in vitro model of transfusion

BACKGROUND

Blood transfusion is reported to suppress the recipient's immune system. To avoid allogenic transfusion, post-operative shed blood retransfusion is a commonly used method. The aim of this study was to investigate the dose-related impact of post-operatively collected shed blood products on the stimulated cytokine release in an in vitro model of transfusion.

METHODS

Venous blood samples obtained from 20 patients undergoing hip arthroplasty were mixed with post-operatively collected unprocessed, processed, and irradiated shed blood as well as normal saline as a control. Shed blood was processed by centrifugation and separating the cellular fraction from the soluble fraction and washing the cellular fraction with phosphate buffered saline to eliminate any cell fragments and other substances. Mixing ratios were 1:3, 1:1, and 3:1. Endotoxin-stimulated release of Tumor Necrosis Factor-alpha (TNF-α) was measured after 24 h of culture by enzyme-linked immunosorbent assay.

RESULTS

Unprocessed, irradiated shed blood and the soluble fraction caused a significant suppression of stimulated TNF-α release compared to control. The addition of the cellular shed blood fraction had no significant influence on the TNF-α release compared to control.

CONCLUSION

Shed blood and its components caused a dose-independent immunomodulation as indicated by a suppressed stimulated TNF-α release. Leukocytes seem to play a minor role, as we observed a sustained suppression after transfusion of γ-irradiated shed blood. Only the elimination of soluble factors by centrifugation and followed by an additional washing step prevented the observed suppression of TNF-α. Thus, we assume that washing of shed blood can prevent potential detrimental effects.

Analysis of infections in the first 3-month after living donor liver transplantation

AIM: To identify factors related to serious postoperative bacterial and fungal infections in the first 3 mo after living donor liver transplantation (LDLT).

METHODS: In the present study, the data of 207 patients from 2004 to 2011 were reviewed. The pre-, intra- and post-operative factors were statistically analyzed. All transplantations were approved by the ethics committee of West China Hospital, Sichuan University. Patients with definitely preoperative infections and infections within 48 h after transplantation were excluded from current study. All potential risk factors were analyzed using univariate analyses. Factors significant at a P < 0.10 in the univariate analyses were involved in the multivariate analyses. The diagnostic accuracy of the identified risk factors was evaluated using receiver operating curve.

RESULTS: The serious bacterial and fungal infection rates were 14.01% and 4.35% respectively. Enterococcus faecium was the predominant bacterial pathogen, whereas Candida albicans was the most common fungal pathogen. Lung was the most common infection site for both bacterial and fungal infections. Recipient age older than 45 years, preoperative hyponatremia, intensive care unit stay longer than 9 d, postoperative bile leak and severe hyperglycemia were independent risk factors for postoperative bacterial infection. Massive red blood cells transfusion and postoperative bacterial infection may be related to postoperative fungal infection.

CONCLUSION: Predictive risk factors for bacterial and fungal infections were indentified in current study. Pre-, intra- and post-operative factors can cause postoperative bacterial and fungal infections after LDLT.

Red Blood Cell Transfusion and Transfusion Alternatives in Traumatic Brain Injury

OPINION STATEMENT: Anemia develops in about 50% of patients hospitalized with traumatic brain injury (TBI) and is recognized as a cause of secondary brain injury. This review examines the effects of anemia and transfusion on TBI patients through a literature search to identify original research on anemia and transfusion in TBI, the effects of transfusion on brain physiology, and the role of erythropoietin or hemoglobin-based blood substitutes (HBBSs). However, the amount of high-quality, prospective data available to help make decisions about when TBI patients should be transfused is very small. Randomized transfusion trials have involved far too few TBI patients to reach definitive conclusions. Thus, it is hardly surprising that there is widespread practice variation. In our opinion, a hemoglobin transfusion threshold of 7 g/dL cannot yet be considered safe for TBI patients admitted to hospital, and in particular to the ICU, as it is for other critically ill patients. Red blood cell transfusions often have immediate, seemingly beneficial effects on cerebral physiology, but the magnitude of this effect may depend in part upon how long the cells have been stored before administration. In light of existing physiological data, we generally aim to keep hemoglobin concentrations greater than 9 g/dL during the first several days after TBI. In part, the decision is based on the patient's risk of or development of secondary ischemia or brain injury. An increasing number of centers use multimodal neurologic monitoring, which may help to individualize transfusion goals based on the degree of cerebral hypoxia or metabolic distress. When available, brain tissue oxygen tension values less than 15-20 mm Hg or a lactate:pyruvate ratio greater than 30-40 would influence us to use more aggressive hemoglobin correction (e.g., a transfusion threshold of 10 g/dL). Clinicians can attempt to reduce transfusion requirements by limiting phlebotomy, minimizing hemodilution, and providing appropriate prophylaxis against gastrointestinal hemorrhage. Administration of exogenous erythropoietin may have a small impact in further reducing the need for transfusion, but it also may increase complications, most notably deep venous thrombosis. Erythropoietin is currently of great interest as a potential neuroprotective agent, but until it is adequately evaluated in randomized controlled trials, it should not be used routinely for this purpose. HBBSs are also of interest, but existing preparations have not been shown to be beneficial-or even safe-in the context of TBI.

Controversies related to red blood cell transfusion in critically ill patients

OBJECTIVE

To review the evolution of and controversies associated with allogenic blood transfusion in critically ill patients.

DATA SOURCES

Veterinary and human literature review.

HUMAN DATA SYNTHESIS

RBC transfusion practices for ICU patients have come under scrutiny in the last 2 decades. Human trials have demonstrated relative tolerance to severe, euvolemic anemia and a significant outcome advantage following implementation of more restricted transfusion therapy. Investigators question the ability of RBCs stored longer than 2 weeks to improve tissue oxygenation, and theorize that both age and proinflammatory or immunomodulating effects of transfused cells may limit efficacy and contribute to increased patient morbidity and mortality. Also controversial is the ability of pre- and post-storage leukoreduction of RBCs to mitigate adverse transfusion-related events.

VETERINARY DATA SYNTHESIS

While there are several studies evaluating the transfusion trigger, the RBC storage lesion and transfusion-related immunomodulation in experimental animal models, there is little research pertaining to clinical veterinary patients.

CONCLUSIONS

RBC transfusion is unequivocally indicated for treatment of anemic hypoxia. However, critical hemoglobin or Hct below which all critically ill patients require transfusion has not been established and there are inherent risks associated with allogenic blood transfusion. Clinical trials designed to evaluate the effects of RBC age and leukoreduction on veterinary patient outcome are warranted. Implementation of evidence-based transfusion guidelines and consideration of alternatives to allogenic blood transfusion are advisable.

Association between length of storage of red blood cell units and outcome of critically ill children: a prospective observational study

INTRODUCTION

Transfusion is a common treatment in pediatric intensive care units (PICUs). Studies in adults suggest that prolonged storage of red blood cell units is associated with worse clinical outcome. No prospective study has been conducted in children. Our objectives were to assess the clinical impact of the length of storage of red blood cell units on clinical outcome of critically ill children.

METHODS

Prospective, observational study conducted in 30 North American centers, in consecutive patients aged <18 years with a stay >or= 48 hours in a PICU. The primary outcome measure was the incidence of multiple organ dysfunction syndrome after transfusion. The secondary outcomes were 28-day mortality and PICU length of stay. Odds ratios were adjusted for gender, age, number of organ dysfunctions at admission, total number of transfusions, and total dose of transfusion, using a multiple logistic regression model.

RESULTS

The median length of storage was 14 days in 296 patients with documented length of storage. For patients receiving blood stored >or= 14 days, the adjusted odds ratio for an increased incidence of multiple organ dysfunction syndrome was 1.87 (95% CI 1.04;3.27, P = 0.03). There was also a significant difference in the total PICU length of stay (adjusted median difference +3.7 days, P < 0.001) and no significant change in mortality.

CONCLUSIONS

In critically ill children, transfusion of red blood cell units stored for >or= 14 days is independently associated with an increased occurrence of multiple organ dysfunction syndrome and prolonged PICU stay.

Association between length of storage of red blood cell units and outcome of critically ill children: a prospective observational study

INTRODUCTION

Transfusion is a common treatment in pediatric intensive care units (PICUs). Studies in adults suggest that prolonged storage of red blood cell units is associated with worse clinical outcome. No prospective study has been conducted in children. Our objectives were to assess the clinical impact of the length of storage of red blood cell units on clinical outcome of critically ill children.

METHODS

Prospective, observational study conducted in 30 North American centers, in consecutive patients aged <18 years with a stay >or= 48 hours in a PICU. The primary outcome measure was the incidence of multiple organ dysfunction syndrome after transfusion. The secondary outcomes were 28-day mortality and PICU length of stay. Odds ratios were adjusted for gender, age, number of organ dysfunctions at admission, total number of transfusions, and total dose of transfusion, using a multiple logistic regression model.

RESULTS

The median length of storage was 14 days in 296 patients with documented length of storage. For patients receiving blood stored >or= 14 days, the adjusted odds ratio for an increased incidence of multiple organ dysfunction syndrome was 1.87 (95% CI 1.04;3.27, P = 0.03). There was also a significant difference in the total PICU length of stay (adjusted median difference +3.7 days, P < 0.001) and no significant change in mortality.

CONCLUSIONS

In critically ill children, transfusion of red blood cell units stored for >or= 14 days is independently associated with an increased occurrence of multiple organ dysfunction syndrome and prolonged PICU stay.

Is allogeneic blood transfusion a risk factor for sternal dehiscence following cardiac surgery? A prospective observational study

Sternal dehiscence following cardiac surgery has a multifactorial etiology. Significant risk factors contributing to sternal dehiscence include chronic obstructive pulmonary disease (COPD), obesity, or re-exploration due to bleeding or pericardial tamponade. We have focused on the role of allogeneic blood transfusion as a factor leading to the poor healing of surgical wounds. A prospective observational study of 1553 elective and emergency cardiac surgery patients was performed between January 2003 and June 2007. All of the patients enrolled in this study underwent median sternotomy. We studied the relationship between sternal dehiscence following cardiac surgery and the total number of packed red blood cells transfused. The incidence of sternal dehiscence in the study group was 3.4%. Diabetic patients did not have a higher incidence of wound dehiscence. Although COPD, obesity, and re-exploration contributed to sternal dehiscence, the number of allogeneic blood transfusions during the perioperative period was an important independent risk factor for sternal dehiscence. Patients with sternal dehiscence received an average of 7.6 transfusion units (TU) of allogeneic blood versus 1.6 TU of allogeneic blood in the group without sternal dehiscence (P < 0.00005). The dehiscence affected patients without any other significant risk factor who received 6 or more TU, or patients with at least one significant risk factor who received 4 or more TU of allogeneic blood. According to our results, the total amount of allogeneic blood transfused is an important risk factor contributing to sternal dehiscence. Regardless of other risk preconditions, the transfusion of 6 or more TU could result in sternal dehiscence following cardiac surgery.

Comparison of Hemoglobin-based oxygen carriers to stored human red blood cells

Since the inception of allogeneic blood transfusion, the search for an alternative to the use of stored packed red blood cells has been underway. Over the last 10 years, modified hemoglobin solutions in the form of hemoglobin-based oxygen carriers (HBOCs) have made significant strides toward becoming clinically available and useful. Although HBOCs are not yet ready for regular use in the clinical arena, this may change in the near future as HBOC products continue to improve and as the elucidation of the mechanisms of any adverse effects becomes clearer. In the mean time, we must further the development of alternative strategies for the "hemoglobin bridge" so desperately needed by many critically ill patients.

Length of storage and in vitro immunomodulation induced by prestorage leukoreduced red blood cells

BACKGROUND

The relationship between length of storage of red blood cell (RBC) units and biochemical changes has been well studied, but little is known about the progression of cellular immunomodulative properties in blood recipients. This study aims to quantify in vitro T-cell activation and cytokine release by white blood cells, after incubation with supernatants from leukoreduced RBCs.

STUDY DESIGN AND METHODS

Whole blood cultures were incubated with supernatant from five leukoreduced RBC units stored for 1, 6, 10, 15, 24, and 42 days. Supernatant-induced T-cell activation was evaluated by quantifying CD25 expression. Supernatant-induced cytokine production was determined by measuring interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha levels.

RESULTS

No cytokines were detected in RBC supernatants even after 42 days of storage. However, IL-6 levels in whole blood culture increased significantly when incubated with supernatant from RBC units stored for 1, 6, and 15 days, by factors of 1.7 +/- 0.3, 1.7 +/- 0.3, and 1.4 +/- 0.3, respectively. TNF-alpha levels were significantly decreased on Days 24 and 42 of storage by factors of 0.50 +/- 0.42 and 0.33 +/- 0.21, respectively. IL-10 levels were significantly increased on Days 1 and 42 of storage by factors of 2.3 +/- 1.3 and 3.2 +/- 2.8, respectively. After an initial increase in IL-6 and TNF-alpha production, there was a significant linear decrease in their levels measured from units stored for longer times. No significant changes in CD25 expression were observed over time.

CONCLUSION

Although no cytokines were measured in the supernatants from leukoreduced RBCs, these supernatants exhibited variable immunomodulatory effects related to their length of storage.

Anemia and red blood cell transfusion in neurocritical care

INTRODUCTION

Anemia is one of the most common medical complications to be encountered in critically ill patients. Based on the results of clinical trials, transfusion practices across the world have generally become more restrictive. However, because reduced oxygen delivery contributes to 'secondary' cerebral injury, anemia may not be as well tolerated among neurocritical care patients.

METHODS

The first portion of this paper is a narrative review of the physiologic implications of anemia, hemodilution, and transfusion in the setting of brain-injury and stroke. The second portion is a systematic review to identify studies assessing the association between anemia or the use of red blood cell transfusions and relevant clinical outcomes in various neurocritical care populations.

RESULTS

There have been no randomized controlled trials that have adequately assessed optimal transfusion thresholds specifically among brain-injured patients. The importance of ischemia and the implications of anemia are not necessarily the same for all neurocritical care conditions. Nevertheless, there exists an extensive body of experimental work, as well as human observational and physiologic studies, which have advanced knowledge in this area and provide some guidance to clinicians. Lower hemoglobin concentrations are consistently associated with worse physiologic parameters and clinical outcomes; however, this relationship may not be altered by more aggressive use of red blood cell transfusions.

CONCLUSIONS

Although hemoglobin concentrations as low as 7 g/dl are well tolerated in most critical care patients, such a severe degree of anemia could be harmful in brain-injured patients. Randomized controlled trials of different transfusion thresholds, specifically in neurocritical care settings, are required. The impact of the duration of blood storage on the neurologic implications of transfusion also requires further investigation.

Local and systemic consequences of large retroperitoneal clot burdens

BACKGROUND

There is a paucity of data regarding the impact of retroperitoneal hematoma (RPH) volumes, as detected by computed tomography (CT) scanning, on patient morbidity and mortality. Therefore, we wanted to determine the natural history of RPHs and the effect of size on local and systemic outcomes.

METHODS

We performed a volumetric analysis of CT-documented RPHs managed at our institution between 1985 and 2006 along with a retrospective chart review.

RESULTS

We included 81 cases of RPH in this study. The mean Acute Physiology, Age, and Chronic Health Evaluation II (APACHE II) score was 12.8 +/- 0.72 (score +/- SE). By univariate analysis, the size of the hematoma showed a significant correlation with the development of local mass effects, delayed mass effects, 6-month mortality, major morbidity, pulmonary complications, fluid overload, and the requirement for operative evacuation (p < 0.05). Receiver operating characteristic analysis revealed that a size > or = 1600 cm(3) was > 80% sensitive and specific for predicting a delayed mass effect or an increase in 6-month mortality. Multivariate analysis controlling for factors such as APACHE II and packed red blood cells transfused showed that the volume of the RPH was an independent predictor for the development of local mass effects, pulmonary insufficiency, and fluid overload.

CONCLUSIONS

Large RPHs are clearly associated with worse patient outcomes. Surgical intervention may be warranted for the treatment of RPHs > or = 1600 cm(3).

A physicochemical approach to acid-base balance in critically ill trauma patients minimizes errors and reduces inappropriate plasma volume expansion

BACKGROUND

This study assesses if a physicochemical (PC) approach to acid-base balance improves the accuracy of acid-base diagnosis, and reduces inappropriate fluid loading.

METHODS

Hundred consecutive patients with trauma admitted to a surgical intensive care unit at a level I trauma center were prospectively analyzed. Demographics, acid-base data and diagnoses, and interventions were collected. Patients were cared for by one physician using a PC approach, or four using conventional (CONV) acid-base balance techniques. The diagnoses and interventions made by CONV physicians were reviewed by the PC physician for accuracy and appropriateness using PC techniques. Data are mean +/- SD or percents; p values reflect PC evaluation of CONV analysis.

RESULTS

There were 50 PC patients and 50 CONV. There were no differences in age (p = 0.13), injury severity score (p = 0.21), number of operations (p = 0.87), transfusions (p = 0.87), or survival (p = 0.15). CONV missed 12 diagnoses of metabolic acidosis (p = 0.03), 10 of hyperchloremic metabolic acidosis (p = 0.003), 11 metabolic alkalosis (p = 0.02), and 19 tertiary disorders (p < 0.001). CONV missed 38 diagnoses of increased unmeasured ions (p < 0.001). PC normalized their acid-base balance sooner than CONV (3.3 days +/- 3.4 days vs. 8.3 days +/- 7.4 days, p < 0.01).

CONCLUSIONS

A PC approach improves acid-base diagnosis accuracy. CONV often miss acidosis (particularly those because of hyperchloremia), alkalosis, and tertiary disorders. Inappropriate volume loading follows in the wake of misinterpretation of increased base deficit using CONV and is avoided using PC. PC-directed therapy normalizes acid-base balance more rapidly than CONV.