The effect of transfusion of fresh whole blood versus platelet concentrates after cardiac operations

Epistaxis and thrombocytopenia as major presentations of louse borne relapsing fever: Hospital-based study

BACKGROUND

Louse-borne relapsing fever (LBRF) remains a cause of sporadic illness and occasional outbreaks in Ethiopia and other east African countries in overcrowded and unhygienic settings. In this article, we present clinical profiles and treatment outcome of patients treated as confirmed or probable cases of LBRF at Jimma Medical Center (JMC) in southwest Ethiopia.

METHODS

Patients treated as confirmed or probable cases of LBRF at JMC during a period of May-July 2022 were prospectively followed during their course of hospital stay. All patients were evaluated with blood film for hemoparasites, complete blood count, and liver enzymes on hospital presentation. They were followed with daily clinical evaluation during their hospital stay.

RESULT

Thirty-six patients were treated as cases of LBRF. All patients except one were from Jimma Main Prison in Jimma Town, Ethiopia. All the patients were male with mean age of 28.7 years (SD = 12.7). The diagnosis of LBRF was confirmed by detection of B. recurrentis in blood film of 14 (38.9%) of the patients; the rest were treated as presumptive case of LBRF. Fever, reported by all patients, and an acute onset epistaxis, 30 (83.3%), were the major reasons for healthcare visits. Twenty-two (61.1%) patients were having thrombocytopenia with a platelet count < 150,000/μL; nine (25%) of which had severe forms (<50,000/μL). All patients were treated with oral doxycycline and discharged with improvement after a mean length of hospital stay of 4.25 days (SD = 0.77), range 2-6 days. Public health emergency was activated within two days of the first cases and helped in delousing all the cases and their contacts.

CONCLUSION

LBRF remains a public health problem in Ethiopia in settings with poor personal hygiene. Patients with LBRF may present with severe thrombocytopenia and life-threatening bleeding. Early detection and treatment initiation prevents outbreak propagation and improves treatment outcome.

Single Institution Trial Comparing Whole Blood vs Balanced Component Therapy: 50 Years Later

BACKGROUND

Early close ratio transfusion with balanced component therapy (BCT) has been associated with improved outcomes in patients with severe hemorrhage; however, this modality is not comparable with whole blood (WB) constituents. We compared use of BCT vs WB to determine if one yielded superior outcomes in patients with severe hemorrhage. We hypothesized that WB would lead to reduced in-hospital mortality and blood product volume if given in the first 24 hours of admission.

STUDY DESIGN

This was a 1-year, single institution, prospective, observational study comparing BCT with WB in adult (18+y) trauma patients with active hemorrhage who required blood transfusion upon arrival at the emergency department. Primary endpoint was in-hospital mortality. Secondary endpoints included 24-hour transfusion volumes, in-hospital clinical outcomes, and complications.

RESULTS

A total of 253 patients were included; 71.1% received BCT and 29.9% WB. The WB cohort had significantly more penetrating trauma (64.4% vs 48.9%; p = 0.03) and higher Shock Index (1.12 vs 0.92; p = 0.04). WB patients received significantly fewer units of packed red blood cells (PRBCs) (p < 0.001) and fresh frozen plasma (FFP) (p = 0.04), with a lower incidence of ARDS (p = 0.03) and fewer ventilator days (p = 0.03). Kaplan Meier survival analysis revealed no difference in survival between the 2 transfusion strategies (p = 0.80). When adjusted for various markers of injury severity and critical illness in Cox regression analysis, WB remained unassociated with mortality (hazard ratio 1.25; 95% CI 0.60-2.58; p = 0.55).

CONCLUSIONS

There was no difference in survival rates when comparing BCT with WB. In the WB group, the incidence of ARDS, duration of mechanical ventilation, massive transfusion protocol (MTP) activation, and transfusion volumes were significantly reduced. Further research should be directed at analyzing whether there is a true hemorrhage-related pathophysiologic benefit of WB when compared with BCT.

Improved survival in critically injured combat casualties treated with fresh whole blood by forward surgical teams in Afghanistan

BACKGROUND

The objective of this study was to assess transfusion strategies and outcomes, stratified by the combat mortality index, of casualties treated by small surgical teams in Afghanistan. Resuscitation that included warm fresh whole blood (FWB) was compared to blood component resuscitation.

STUDY DESIGN AND METHODS

Casualties treated by a Role 2 surgical team in Afghanistan from 2008 to 2014 who received 1 or more units of red blood cells (RBCs) or FWB were included. Patients were excluded if they had incomplete data or length of stay less than 30 minutes. Patients were separated into two groups: 1) received FWB and 2) did not receive FWB; moreover, both groups potentially received plasma, RBCs, and platelets. The analysis was stratified by critically versus noncritically injured patients using the prehospital combat mortality index. Kaplan-Meier plot, log-rank test, and multivariable Cox regression were performed to compare survival.

RESULTS

In FWB patients, median units of FWB and total blood product were 4.0 (interquartile range [IQR], 2.0-7.0) and 16.0 (IQR, 10.0-28.0), respectively. The Kaplan-Meier plot demonstrated that survival was similar between FWB (79.1%) and no-FWB (74.5%) groups (p = 0.46); after stratifying patients by the combat mortality index, the risk of mortality was increased in the no-FWB group (hazard ratio, 2.8; 95% confidence interval, 1.2-6.4) compared to the FWB cohort.

CONCLUSION

In forward-deployed environments, where component products are limited, FWB has logistical advantages and was associated with reduced mortality in casualties with a critical combat mortality index. Additional analysis is needed to determine if these effects of FWB are appreciable in all trauma patients or just in those with severe physiologic derangement.

Treatment of combined traumatic brain injury and hemorrhagic shock with fractionated blood products versus fresh whole blood in a rat model

INTRODUCTION

Treatment of combined traumatic brain injury and hemorrhagic shock, poses a particular challenge due to the possible conflicting consequences. While restoring diminished volume is the treatment goal for hypovolemia, maintaining adequate cerebral perfusion pressure and avoidance of secondary damage remains a treatment goal for the injured brain. Various treatment modalities have been proposed, but the optimal resuscitation fluid and goals have not yet been clearly defined. A growing body of evidence suggests that in hypovolemic shock, resuscitation with fresh whole blood (FWB) may be superior to component therapy without platelets (which are likely to be unavailable in the pre-hospital setting). Nevertheless, the effects of this approach have not been studied in the combined injury. Previously, in a rat model of combined injury we have found that mild resuscitation to MABP of 80 mmHg with FWB is superior to fluid resuscitation or aggressive resuscitation with FWB. In this study, we investigate the physiological and neurological outcomes in a rat model of combined traumatic brain injury (TBI) and hypovolemic shock, submitted to treatment with varying amounts of FWB, compared to similar resuscitation goals with fractionated blood products-red blood cells (RBCs) and plasma in a 1:1 ratio regimen.

MATERIALS AND METHODS

40 male Lewis rats were divided into control and treatment groups. TBI was inflicted by a free-falling rod on the exposed cranium. Hypovolemia was induced by controlled hemorrhage of 30% blood volume. Treatment groups were treated either with fresh whole blood or with RBC + plasma in a 1:1 ratio, achieving a resuscitation goal of a mean arterial blood pressure (MAP) of 80 mmHg at 15 min. MAP was assessed at 60 min, and neurological outcomes and mortality in the subsequent 24 h.

RESULTS

At 60 min, hemodynamic parameters were improved compared to controls, but not significantly different between treatment groups. Survival rates at 48 h were 100% for both of the mildly resuscitated groups (MABP 80 mmHg) with FWB and RBC + plasma. The best neurological outcomes were found in the group mildly resuscitated with FWB and were better when compared to resuscitation with RBC + plasma to the same MABP goal (FWB: Neurological Severity Score (NSS) 6 ± 2, RBC + plasma: NSS 10 ± 2, p = 0.02).

CONCLUSIONS

In this study, we find that mild resuscitation with goals of restoring MAP to 80 mmHg (which is lower than baseline) with FWB, provided better hemodynamic stability and survival. However, the best neurological outcomes were found in the group resuscitated with FWB. Thus, we suggest that resuscitation with FWB is a feasible modality in the combined TBI + hypovolemic shock scenario, and may result in improved outcomes compared to platelet-free component blood products.

Whole blood for hemostatic resuscitation of major bleeding

Recent combat experience reignited interest in transfusing whole blood (WB) for patients with life-threatening bleeding. US Army data indicate that WB transfusion is associated with improved or comparable survival compared to resuscitation with blood components. These data complement randomized controlled trials that indicate that platelet (PLT)-containing blood products stored at 4°C have superior hemostatic function, based on reduced bleeding and improved functional measures of hemostasis, compared to PLT-containing blood products at 22°C. WB is rarely available in civilian hospitals and as a result is rarely transfused for patients with hemorrhagic shock. Recent developments suggest that impediments to WB availability can be overcome, specifically the misconceptions that WB must be ABO specific, that WB cannot be leukoreduced and maintain PLTs, and finally that cold storage causes loss of PLT function. Data indicate that the use of low anti-A and anti-B titer group O WB is safe as a universal donor, WB can be leukoreduced with PLT-sparing filters, and WB stored at 4°C retains PLT function during 15 days of storage. The understanding that these perceived barriers are not insurmountable will improve the availability of WB and facilitate its use. In addition, there are logistic and economic advantages of WB-based resuscitation compared to component therapy for hemorrhagic shock. The use of low-titer group O WB stored for up to 15 days at 4°C merits further study to compare its efficacy and safety with current resuscitation approaches for all patients with life-threatening bleeding.

Platelet Function and Cardiopulmonary Bypass

Cardiopulmonary bypass (CPB) is a nonphysiologic state that has many detrimental effects on a patient's hemostatic integrity. Exposure to the extracorporeal circuit and subsequent activation of the coagulation and fibrinolytic systems are factors that contribute to morbidity and mortality in cardiac surgical patients. These effects can be prevented in part or appropriately treated if practitioners understand the basic mecha nisms. This article reviews the effects of CPB on platelet function, the relationship of platelet function to post operative bleeding, the monitors available to measure platelet function, and the impact of antiplatelet therapy on bleeding in cardiac surgery.

Massive transfusion: an overview of the main characteristics and potential risks associated with substances used for correction of a coagulopathy

Massive transfusion (MT) is an empiric mode of treatment advocated for uncontrolled bleeding and massive haemorrhage, aiming at optimal resuscitation and aggressive correction of coagulopathy. Conventional guidelines recommend early administration of crystalloids and colloids in conjunction with red cells, where the red cell also plays a critical haemostatic function. Plasma and platelets are only used in patients with microvascular bleeding with PT/APTT values >1.5 times the normal values and if PLT counts are below 50×10(9)/L. Massive transfusion carries a significant mortality rate (40%), which increases with the number of volume expanders and blood components transfused. Controversies still exist over the optimal ratio of blood components with respect to overall clinical outcomes and collateral damage. While inadequate transfusion is believed to be associated with poor outcomes but empirical over transfusion results in unnecessary donor exposure with an increased rate of sepsis, transfusion overload and infusion of variable amounts of some biological response modifiers (BRMs), which have the potential to cause additional harm. Alternative strategies, such as early use of tranexamic acid are helpful. However in trauma settings the use of warm fresh whole blood (WFWB) instead of reconstituted components with a different ratio of stored components might be the most cost effective and safer option to improve the patient's survival rate and minimise collateral damage. This manuscript, after a brief summary of standard medical intervention in massive transfusion focuses on the main characteristics of various substances currently available to overcome massive transfusion coagulopathy. The relative levels of some BRMs in fresh and aged blood components of the same origin are highlighted and some myths and unresolved issues related to massive transfusion practice are discussed. In brief, the coagulopathy in MT is a complex phenomenon, often complicated by chronic activation of coagulation, platelets, complement and vascular endothelial cells, where haemolysis, microvesiculation, exposure of phosphatidyl serine positive cells, altered red cells with reduced adhesive proteins and the presence of some BRM, could play a pivotal role in the coagulopathy and untoward effects. The challenges of improving the safety of massive transfusion remain as numerous and as varied as ever. The answer may reside in appropriate studies on designer whole blood, combined with new innovative tools to diagnosis a coagulopathy and an evidence based mode of therapy to establish the optimal survival benefit of patients, always taking into account the concept of harm reduction and reduction of collateral damage.

2011 update to the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists blood conservation clinical practice guidelines

BACKGROUND

Practice guidelines reflect published literature. Because of the ever changing literature base, it is necessary to update and revise guideline recommendations from time to time. The Society of Thoracic Surgeons recommends review and possible update of previously published guidelines at least every three years. This summary is an update of the blood conservation guideline published in 2007.

METHODS

The search methods used in the current version differ compared to the previously published guideline. Literature searches were conducted using standardized MeSH terms from the National Library of Medicine PUBMED database list of search terms. The following terms comprised the standard baseline search terms for all topics and were connected with the logical 'OR' connector--Extracorporeal circulation (MeSH number E04.292), cardiovascular surgical procedures (MeSH number E04.100), and vascular diseases (MeSH number C14.907). Use of these broad search terms allowed specific topics to be added to the search with the logical 'AND' connector.

RESULTS

In this 2011 guideline update, areas of major revision include: 1) management of dual anti-platelet therapy before operation, 2) use of drugs that augment red blood cell volume or limit blood loss, 3) use of blood derivatives including fresh frozen plasma, Factor XIII, leukoreduced red blood cells, platelet plasmapheresis, recombinant Factor VII, antithrombin III, and Factor IX concentrates, 4) changes in management of blood salvage, 5) use of minimally invasive procedures to limit perioperative bleeding and blood transfusion, 6) recommendations for blood conservation related to extracorporeal membrane oxygenation and cardiopulmonary perfusion, 7) use of topical hemostatic agents, and 8) new insights into the value of team interventions in blood management.

CONCLUSIONS

Much has changed since the previously published 2007 STS blood management guidelines and this document contains new and revised recommendations.

Toward a definition of "fresh" whole blood: an in vitro characterization of coagulation properties in refrigerated whole blood for transfusion

BACKGROUND

The hemostatic property of "fresh" whole blood (WB) has been observed in military application and cardiac surgery and is associated with reduced blood loss, transfusion requirements, and donor exposures. The time from donation to transfusion defining "fresh" has not been systematically studied. We undertook an in vitro study of coagulation properties of refrigerated WB stored for 31 days.

STUDY DESIGN AND METHODS

Twenty-one WB units were obtained from healthy volunteer donors and stored under standard AABB refrigerated conditions. Samples were obtained on the day after donation and again on Days 2, 4, 7, 11, 14, 17, 21, 24, and 31. Tests included complete blood count, pH, pO2, pCO2, glucose, lactate, thromboelastography (TEG), and platelet function by light transmission aggregometry (LTA).

RESULTS

There was progressive decline in pH, pO2, glucose, and sodium, but progressive increase in potassium, pCO2, and lactate. TEG variables in all units were normal through Day 11; abnormal values in some variables in some units began on Day 14. Final aggregation levels exhibited no change from Day 1 to Day 21 with adenosine diphosphate and epinephrine, but a decline with collagen (Day 7) and ristocetin (Day 17).

CONCLUSION

This in vitro study of coagulation properties demonstrates preservation of normal integrated coagulation function to a minimum of 11 days under standard conditions of refrigerated storage of WB for transfusion. These observations strongly suggest that the hemostatic quality of WB may extend beyond current transfusion practices. If confirmed clinically, this would increase availability and extend benefits of reduced donor exposure and transfusion requirements.

Comparison of platelet transfusion as fresh whole blood versus apheresis platelets for massively transfused combat trauma patients (CME)

BACKGROUND

At major combat hospitals, the military is able to provide blood products to include apheresis platelets (aPLT), but also has extensive experience using fresh whole blood (FWB). In massively transfused trauma patients, we compared outcomes of patients receiving FWB to those receiving aPLT.

STUDY DESIGN AND METHODS

This study was a retrospective review of casualties at the military hospital in Baghdad, Iraq, between January 2004 and December 2006. Patients requiring massive transfusion (≥10 units in 24 hr) were divided into two groups: those receiving FWB (n = 85) or aPLT (n = 284) during their resuscitation. Admission characteristics, resuscitation, and survival were compared between groups. Multivariate regression analyses were performed comparing survival of patients at 24 hours and at 30 days. Secondary outcomes including adverse events and causes of death were analyzed.

RESULTS

Unadjusted survival between groups receiving aPLT and FWB was similar at 24 hours (84% vs. 81%, respectively; p = 0.52) and at 30 days (60% versus 57%, respectively; p = 0.72). Multivariate regression failed to identify differences in survival between patients receiving PLT transfusions either as FWB or as aPLT at 24 hours or at 30 days.

CONCLUSIONS

Survival for massively transfused trauma patients receiving FWB appears to be similar to patients resuscitated with aPLT. Prospective trials will be necessary before consideration of FWB in the routine management of civilian trauma. However, in austere environments where standard blood products are unavailable, FWB is a feasible alternative.

Warm fresh whole blood is independently associated with improved survival for patients with combat-related traumatic injuries

BACKGROUND

Increased understanding of the pathophysiology of the acute coagulopathy of trauma has lead many to question the current transfusion approach to hemorrhagic shock. We hypothesized that warm fresh whole blood (WFWB) transfusion would be associated with improved survival in patients with trauma compared with those transfused only stored component therapy (CT).

METHODS

We retrospectively studied US Military combat casualty patients transfused >or=1 unit of red blood cells (RBCs). The following two groups of patients were compared: (1) WFWB, who were transfused WFWB, RBCs, and plasma but not apheresis platelets and (2) CT, who were transfused RBC, plasma, and apheresis platelets but not WFWB. The primary outcomes were 24-hour and 30-day survival.

RESULTS

Of 354 patients analyzed there were 100 in the WFWB and 254 in the CT group. Patients in both groups had similar severity of injury determined by admission eye, verbal, and motor Glasgow Coma Score, base deficit, international normalized ratio, hemoglobin, systolic blood pressure, and injury severity score. Both 24-hour and 30-day survival were higher in the WFWB cohort compared with CT patients, 96 of 100 (96%) versus 223 of 254 (88%), (p = 0.018) and 95% to 82%, (p = 0.002), respectively. An increased amount (825 mL) of additives and anticoagulants were administered to the CT compared with the WFWB group, (p < 0.001). Upon multivariate logistic regression the use of WFWB and the volume of WFWB transfused was independently associated with improved 30-day survival.

CONCLUSIONS

In patients with trauma with hemorrhagic shock, resuscitation strategies that include WFWB may improve 30-day survival, and may be a result of less anticoagulants and additives with WFWB use in this population.

Review of current blood transfusions strategies in a mature level I trauma center: were we wrong for the last 60 years?

BACKGROUND

Recent military experience reported casualties who receive > 10 units of packed red blood cells (PRBC) in 24 hours have 20% versus 65% mortality when the fresh-frozen plasma (FFP) to PRBC ratio was 1:1 versus 1:4, respectively. We hypothesize a similar improvement in mortality in civilian trauma patients that require massive transfusion and are treated with a FFP to PRBC ratio closer to 1:1.

METHODS

Four-year retrospective study of all trauma patients who underwent emergency surgery in an urban Level I Trauma Center. Patients were divided into two groups; those that received < or = 10 units or > 10 units of PRBC during and after initial surgical intervention. Only patients who received transfusion of both FFP and PRBC were included in the analysis. The primary research question was the impact of initial FFP:PRBC ratio on mortality. Other variables for analysis included patient age, gender, mechanism, and Injury Severity Scale score. Both univariate and multivariate analysis were used to assess the relationship between outcome and predictors.

RESULTS

A total of 2,746 patients underwent surgical intervention of which 1,985 (72.2%) received no transfusion. Of those that received transfusion, 626 (22.8%) received < or = 10 units of PRBC and 135 (4.9%) > 10 units of PRBC. Out of the 626 patients that received < or = 10 units of PRBC, 250 (39.9%) received FFP and 376 (60.1%) received no FFP. All the patients that received > 10 units PRBC received FFP. In univariate analysis, a significant difference in mortality was found in patients who received > 10 units of PRBC (26% vs. 87.5%) when FFP:PRBC ratio was 1:1 versus 1:4 (p = 0.0001). Multivariate analysis in the group of patients that received > 10 units of PRBC showed a FFP:PRBC ratio of 1:4 was consistent with increased risk of mortality (relative risk, 18.88; 95% CI, 6.32-56.36; p = 0.001), when compared with a ratio of 1:1. Patients who received < or = 10 units of PRBC had a trend toward increased mortality (21.2% vs.11.8%) when the FFP:PRBC ratio was 1:4 versus 1:1 (p: 0.06).

CONCLUSION

An FFP to PRBC ratio close to 1:1 confers a survival advantage in patients requiring massive transfusion.

The effect of recombinant activated factor VII on mortality in combat-related casualties with severe trauma and massive transfusion

BACKGROUND

The majority of patients with potentially survivable combat-related injuries die from hemorrhage. Our objective was to determine whether the use of recombinant activated factor VII (rFVIIa) decreased mortality in combat casualties with severe trauma who received massive transfusions and if its use was associated with increased severe thrombotic events.

METHODS

We retrospectively reviewed a database of combat casualty patients with severe trauma (Injury Severity Score [ISS] >15) and massive transfusion (red blood cell [RBCs] >/=10 units/24 hours) admitted to one combat support hospital in Baghdad, Iraq, between December 2003 and October 2005. Admission vital signs and laboratory data, blood products, ISS, 24-hour and 30-day mortality, and severe thrombotic events were compared between patients who received rFVIIa (rFVIIa) and did not receive rFVIIa (rFVIIa).

RESULTS

Of 124 patients in this study, 49 patients received rFVIIa and 75 did not. ISS, laboratory values, and admission vitals did not differ between rFVIIa and rFVIIa groups, except for systolic blood pressure (mm Hg) 105 +/- 33 and 92 +/- 28, p = 0.02 and temperature ( degrees F) 96.3 +/- 2.1 and 95.2 +/- 2.4, p = 0.03, respectively. Interactions between all vital signs and laboratory values measured upon admission, to include systolic blood pressure and temperature, were not significant when measured between rFVIIa use and 30-day mortality. Twenty-four-hour mortality was 7 of 49 (14%) in rFVIIa and 26 of 75 (35%) in rFVIIa, (p = 0.01); 30-day mortality was 15 of 49 (31%) and 38 of 75 (51%), (p = 0.03). Death from hemorrhage was 8 of 14 (57%) for rFVIIa patients compared with 29 of 37 (78%) for rFVIIa patients, (p = 0.12). The incidence of severe thrombotic events was similar in both groups.

CONCLUSIONS

The early use of rFVIIa was associated with decreased 30-day mortality in severely injured combat casualties requiring massive transfusion, but was not associated with increased risk of severe thrombotic events.

Risks associated with fresh whole blood and red blood cell transfusions in a combat support hospital

OBJECTIVE

Fresh whole blood (FWB) and red blood cells (RBCs) are transfused to injured casualties in combat support hospitals. We evaluated the risks of FWB and RBCs transfused to combat-related casualties.

DESIGN

Retrospective chart review.

SETTING

Deployed U.S. Army combat support hospitals.

SUBJECTS

Donors of FWB and recipients of FWB and RBCs.

MEASUREMENTS AND RESULTS

The storage age of RBCs at transfusion was measured as an indicator of overall risk associated with the storage lesion of RBCs between January 2004 and December 2004 at one combat support hospital. Between April 2004 and December 2004, FWB was prescreened only at one combat support hospital for human immunodeficiency virus, hepatitis C virus, and hepatitis B surface antigen before transfusion. To estimate the general incidence of infectious agent contamination in FWB units, samples collected between May 2003 and February 2006 were tested retrospectively for human immunodeficiency virus, hepatitis B surface antigen, hepatitis C virus, and human lymphotropic virus. Results were compared between FWB samples prescreened and not prescreened for infectious agents before transfusion. At one combat support hospital in 2004, 87 patients were transfused 545 units of FWB and 685 patients were transfused 5,294 units of RBCs with a mean age at transfusion of 33 days (+/- 6 days). Retrospective testing of 2,831 samples from FWB donor units transfused in Iraq and Afghanistan between May 2003 and February 2006 indicated that three of 2,831 (0.11%) were positive for hepatitis C virus recombinant immunoblot assay, two of 2,831 (0.07%) were positive for human lymphotropic virus enzyme immunoassay, and none of 2,831 were positive for both human immunodeficiency virus 1/2 and hepatitis B surface antigen by Western blot and neutralization methods, respectively. The differences in the incidence of hepatitis C virus contamination of FWB donor units between those prescreened for hepatitis C virus (zero of 406; 0%) and not prescreened (three of 2,425; 0.12%) were not significant (p = .48).

CONCLUSIONS

The risk of infectious disease transmission with FWB transfusion can be minimized by rapid screening tests before transfusion. Because of the potential adverse outcomes of transfusing RBCs of increased storage age to combat-related trauma patients, the risks and benefits of FWB transfusions must be balanced with those of transfusing old RBCs in patients with life-threatening traumatic injuries.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

The Use of Fresh Whole Blood in Massive Transfusion

BACKGROUND

Most indications for whole blood transfusion are now well managed exclusively with blood component therapy, yet the use of fresh whole blood for resuscitating combat casualties has persisted in the U.S. military.

METHODS

Published descriptions of whole blood use in military and civilian settings were compared with use of whole blood at the 31st Combat Support Hospital (31st CSH) stationed in Baghdad in 2004-2005.

FINDINGS

Concerns about logistics, safety, and relative efficacy of whole blood versus component therapy have argued against the use of whole blood in most settings. However, military physicians have observed some distinct advantages in fresh warm whole blood over component therapy during the massive resuscitation of acidotic, hypothermic, and coagulopathic trauma patients. In this critical role, fresh whole blood was eventually incorporated as an adjunct into a novel whole-blood-based massive transfusion protocol.

CONCLUSIONS

Under extreme and austere circumstances, the risk:benefit ratio of whole blood transfusion favors its use. Fresh whole blood may, at times, be advantageous even when conventional component therapy is available.

A trial of fresh autologous whole blood to treat dilutional coagulopathy following cardiopulmonary bypass in infants

BACKGROUND

Transfusion of fresh whole blood is superior to blood component therapy in correcting coagulopathies in children following cardiopulmonary bypass (CPB); however, a supply of fresh homologous whole blood is difficult to maintain. We hypothesized that transfusion of fresh autologous whole blood obtained prior to heparinization for CPB and infused following CPB would be associated with improved coagulation function when compared with standard therapy.

METHODS

A total of 32 infants 5-12 kg undergoing noncomplex open cardiac surgery were randomly assigned to either the treatment or control group. In the treatment group, 15 ml x kg(-1) of autologous whole blood was collected into a CPDA bag prior to heparinization while 15 ml x kg(-1) of 5% albumin was infused intravenously. After reversal of heparin, coagulation tests were drawn in both groups, and the autologous whole blood was infused over 20 min in the treatment group.

RESULTS

The treatment group had greater (P < 0.05) improvement in platelet count, prothrombin time, and fibrinogen than the control group.

CONCLUSIONS

We conclude that collection of fresh autologous whole blood prior to heparinization and reinfusion following CPB is associated with greater improvement of coagulation status after CPB in infants.

Fresh whole blood versus reconstituted blood for pump priming in heart surgery in infants

BACKGROUND

In an attempt to reduce the coagulopathic and inflammatory responses seen after cardiopulmonary bypass, the use of fresh whole blood during heart operations has become the standard of care for neonates and infants at many institutions. We compared the use of fresh whole blood with the use of a combination of packed red cells and fresh-frozen plasma (reconstituted blood) for priming of the cardiopulmonary bypass circuit.

METHODS

We conducted a single-center, randomized, double-blind, controlled trial involving children less than one year of age who underwent open-heart surgery. Patients were assigned to receive either fresh whole blood that had been collected not more than 48 hours previously (96 patients) or reconstituted blood (104 patients) for bypass-circuit priming. Clinical outcomes and serologic measures of systemic inflammation and myocardial injury were compared between the groups.

RESULTS

The group that received reconstituted blood had a shorter stay in the intensive care unit than the group that received fresh whole blood (70.5 hours vs. 97.0 hours, P=0.04). The group that received reconstituted blood also had a smaller cumulative fluid balance at 48 hours (-6.9 ml per kilogram of body weight vs. 28.8 ml per kilogram, P=0.003). Early postoperative chest-tube output, blood-product transfusion requirements, and levels of serum mediators of inflammation and cardiac troponin I were similar in the two groups.

CONCLUSIONS

The use of fresh whole blood for cardiopulmonary bypass priming has no advantage over the use of a combination of packed red cells and fresh-frozen plasma during surgery for congenital heart disease. Moreover, circuit priming with fresh whole blood is associated with an increased length of stay in the intensive care unit and increased perioperative fluid overload.

Autologous blood sequestration using a double venous reservoir bypass circuit and polymerized hemoglobin prime

Cardiac surgery often necessitates transfusion of homologous blood. Hemoglobin based oxygen carrying solutions (HBOCs) transport oxygen, suggesting use in cardiopulmonary bypass. HBOC was used in a novel oxygenator double-reservoir circuit that permits acute sequestration of a portion of the autologous blood volume during bypass. Two groups of seven mongrel dogs each were studied in an experimental bypass model using global myocardial ischemia and cardioplegia protection: HBOC group, initial venous return drained to a separate reservoir and hypothermic bypass was conducted with HBOC containing perfusate in a second bypass reservoir; Control group, crystalloid prime in a conventional circuit. Hemodynamics and metabolic and hematologic parameters were measured before and 60 min after aortic clamp removal and reinfusion of sequestered autologous blood. Blood gases, base excess, hematocrit, total hemoglobin, and platelet counts were measured. In the HBOC group, metabolic acidosis did not occur, and ventricular function was preserved. Net conservation of platelets was noted at study conclusion: control 33+/-13 x 10(3) per mm3 versus HBOC 48+/-13 x 10(3), p < 0.05. HBOC based priming in a double venous reservoir system permits bypass at very low hematocrit, with preservation of cardiac function. Net conservation of the platelet mass occurs, a portion of which is not exposed to the deleterious effects of hypothermia and cardiopulmonary bypass.

Transfusion medicine : support of patients undergoing cardiac surgery

There is still no alternative that is as effective or as well tolerated as blood; nevertheless, the search for ways to conserve, and even eliminate blood transfusion, continues. Based on hemoglobin levels, practice guidelines for the use of perioperative transfusion of red blood cells in patients undergoing coronary artery bypass grafting have been formulated by the National Institutes of Health and the American Society of Anesthesiologists. However, it has been argued that more physiologic indicators of adequacy of oxygen delivery should be used to assess the need for blood transfusion. Methods used for conserving blood during surgery include autologous blood donation, acute normovolemic hemodilution and intra- and postoperative blood recovery and reinfusion. The guidelines for the use of autologous blood transfusion are controversial and it does not appear to be cost effective compared with allogeneic blood transfusion in patients undergoing cardiac surgery. Similarly, the cost effectiveness of intra- and postoperative blood recovery and reinfusion need further evaluation. Treatment with recombinant human erythropoietin (rhEPO) remains unapproved in the US for patients undergoing cardiac or vascular surgery, but it is a valuable adjunct in Jehovah's Witness patients, for whom blood is unacceptable. The characterization of darbepoetin alfa, a novel erythropoiesis stimulating protein with a 3-fold greater plasma elimination half-life compared with rhEPO, is an important advance in this field. Darbepoetin alfa appears to be effective in treating the anemia in patients with renal failure or cancer and trials in patients with surgical anemia are planned. Desmopressin has been used to effectively reduce intraoperative blood loss. Topical agents to prevent blood loss, such as fibrin glue and fibrin gel, and agents that alter platelet function, such as aspirin (acetylsalicylic acid) or dipyridamole, need further evaluation in patients undergoing cardiac surgery. Aprotinin has been shown to preserve hemostasis and reduce allogeneic blood exposure to a greater extent than the antifibrinolytic agents tranexamic acid and aminocaproic acid. Controlled clinical trials comparing the costs of these agents with clinical outcomes, along with tolerability profiles in patients at risk for substantial perioperative bleeding are needed.

Blood transfusion support in pediatric cardiovascular surgery

The majority of children who undergo open-heart surgery with cardiopulmonary bypass (CPB) require perioperative blood transfusion. Blood product requirements are affected by factors such as patient age, underlying cardiac disease, complexity of the surgical procedure, and hemostatic alterations induced by CPB. Transfusion support may include the use of whole blood and/or individual blood components with transfusion practices varying widely based on individual preferences and blood product availability. Approaches to limit allogeneic blood exposure include the use of modified ultrafiltration and smaller bypass circuits, preoperative autologous blood donation and intraoperative blood salvage, and adjunctive antifibrinolytic agents. Potential advantages and disadvantages of the different blood products and pharmacological agents must be considered in managing the pediatric cardiac surgery patient.

Thromboelastography-guided transfusion algorithm reduces transfusions in complex cardiac surgery

Transfusion therapy after cardiac surgery is empirically guided, partly due to a lack of specific point-of-care hemostasis monitors. In a randomized, blinded, prospective trial, we studied cardiac surgical patients at moderate to high risk of transfusion. Patients were randomly assigned to either a thromboelastography (TEG)-guided transfusion algorithm (n = 53) or routine transfusion therapy (n = 52) for intervention after cardiopulmonary bypass. Coagulation tests, TEG variables, mediastinal tube drainage, and transfusions were compared at multiple time points. There were no demographic or hemostatic test result differences between groups, and all patients were given prophylactic antifibrinolytic therapy. Intraoperative transfusion rates did not differ, but there were significantly fewer postoperative and total transfusions in the TEG group. The proportion of patients receiving fresh-frozen plasma (FFP) was 4 of 53 in the TEG group compared with 16 of 52 in the control group (P < 0.002). Patients receiving platelets were 7 of 53 in the TEG group compared with 15 of 52 in the control group (P < 0.05). Patients in the TEG group also received less volume of FFP (36 +/- 142 vs 217 +/- 463 mL; P < 0.04). Mediastinal tube drainage was not statistically different 6, 12, or 24 h postoperatively. Point-of-care coagulation monitoring using TEG resulted in fewer transfusions in the postoperative period. We conclude that the reduction in transfusions may have been due to improved hemostasis in these patients who had earlier and specific identification of the hemostasis abnormality and thus received more appropriate intraoperative transfusion therapy. These data support the use of TEG in an algorithm to guide transfusion therapy in complex cardiac surgery.

IMPLICATIONS

Transfusion of allogeneic blood products is common during complex cardiac surgical procedures. In a prospective, randomized trial, we compared a transfusion algorithm using point-of-care coagulation testing with routine laboratory testing, and found the algorithm to be effective in reducing transfusion requirements.

Thromboelastography-guided transfusion algorithm reduces transfusions in complex cardiac surgery

Transfusion therapy after cardiac surgery is empirically guided, partly due to a lack of specific point-of-care hemostasis monitors. In a randomized, blinded, prospective trial, we studied cardiac surgical patients at moderate to high risk of transfusion. Patients were randomly assigned to either a thromboelastography (TEG)-guided transfusion algorithm (n = 53) or routine transfusion therapy (n = 52) for intervention after cardiopulmonary bypass. Coagulation tests, TEG variables, mediastinal tube drainage, and transfusions were compared at multiple time points. There were no demographic or hemostatic test result differences between groups, and all patients were given prophylactic antifibrinolytic therapy. Intraoperative transfusion rates did not differ, but there were significantly fewer postoperative and total transfusions in the TEG group. The proportion of patients receiving fresh-frozen plasma (FFP) was 4 of 53 in the TEG group compared with 16 of 52 in the control group (P < 0.002). Patients receiving platelets were 7 of 53 in the TEG group compared with 15 of 52 in the control group (P < 0.05). Patients in the TEG group also received less volume of FFP (36 +/- 142 vs 217 +/- 463 mL; P < 0.04). Mediastinal tube drainage was not statistically different 6, 12, or 24 h postoperatively. Point-of-care coagulation monitoring using TEG resulted in fewer transfusions in the postoperative period. We conclude that the reduction in transfusions may have been due to improved hemostasis in these patients who had earlier and specific identification of the hemostasis abnormality and thus received more appropriate intraoperative transfusion therapy. These data support the use of TEG in an algorithm to guide transfusion therapy in complex cardiac surgery.

IMPLICATIONS

Transfusion of allogeneic blood products is common during complex cardiac surgical procedures. In a prospective, randomized trial, we compared a transfusion algorithm using point-of-care coagulation testing with routine laboratory testing, and found the algorithm to be effective in reducing transfusion requirements.

Increased neonatal platelet deposition on subendothelium under flow conditions: the role of plasma von Willebrand factor

In vitro platelet function of umbilical cord blood and neonatal peripheral vein blood from full-term newborns was compared with that of adults. Citrated whole blood was subjected to shear stress (1300 s(-1)) on subendothelial extracellular matrix (ECM)-coated wells in a cone and plate(let) analyzer. Adhered platelets on the ECM were quantitated by image analyzer. Both umbilical cord and neonatal peripheral blood platelets demonstrated more extensive adhesion than adult platelets, and similar aggregate formation on ECM. The ability of neonatal platelets to form aggregates on ECM was confirmed by scanning electron microscopy. Similar activation of neonatal and adult platelets after subjection to shear stress, in the suspension phase, was established by flow cytometry, which showed an increase in fibrinogen binding and a decrease in glycoprotein Ib expression on platelet membrane. The difference in adhesion rates between neonatal and adult platelets was preserved even when the hematocrit level of the neonatal blood was adjusted to that of adults. Reconstitution of neonatal or adult platelet-rich plasma with autologous or heterologous red packed cells yielded no change in adhesion and aggregation. When von Willebrand factor-covered plates were used to prevent deposition of plasma von Willebrand factor on the surface, no difference in platelet adhesion was seen between neonatal and adult blood. In conventional aggregometry assay, the response to ristocetin of washed platelets of either neonatal or adult source was higher on addition of plasma from neonates than from adults. Our data suggest that the extensive neonatal platelet deposition on ECM is mediated by plasma von Willebrand factor, which is known to be more multimerized and, therefore, more active in neonates than in adults. This mechanism may provide balanced primary hemostasis in neonates despite the platelet hyporeactivity to agonists without application of shear stress.

Oxidized LDL binding to a macrophage-secreted extracellular matrix

Extracellular matrix (ECM), which was shown to be secreted by arterial wall cells, is a major part of the atherosclerotic lesion. ECM can contribute to low density lipoprotein (LDL) retention which can then lead to macrophage foam cell formation, the hallmark of early atherogenesis. The present study demonstrated that in addition to the known ability of endothelial cells and smooth muscle cells to produce ECM, macrophages can also secrete an ECM layer. The macrophage derived ECM was shown to contain the proteoglycans chondroitin sulfate, heparan sulfate and dermatan sulfate. Macrophage derived ECM can bind native LDL, as well as oxidized LDL (3 fold more than native LDL), and this binding is significantly increased in the presence of lipoprotein lipase. Glycosaminoglycans from the ECM (mainly chondroitin sulfate and heparan sulfate) participate in the binding of Ox-LDL to the macrophage derived ECM. These observations suggest that ECM is produced also by macrophages, and it can contribute to a specific and local delivery of atherogenic LDL to macrophages, leading to cellular cholesterol accumulation and foam cell formation.

Preoperative autologous blood donation and plateletpheresis in patients undergoing elective cardiac operations--factors that influence the need for homologous blood transfusion

An increased awareness of the adverse effects of homologous blood transfusion prompted us to initiate a blood conservation program consisting of preoperative autologous blood donation and platelet-rich plasma-pheresis. We studied 120 patients who underwent elective cardiac surgery at Aomori General Hospital between January 1991 and September 1994. If their hemoglobin values exceeded 12 g/ml, 400 g of whole blood was drawn 3 times before the operation. Platelet-poor plasma was collected 10 days before the operation and platelet-rich plasma was collected the day before the operation. However, despite participation in this program, 42 of 120 patients (35%) required homologous blood transfusion perioperatively. Factors that influenced the need for homologous blood transfusion were identified retrospectively, with the following found to be significant by univariate analysis: operative procedures performed, cardiopulmonary bypass time, and the amount of autologous blood and autologous plasma donated. Although the effectiveness of our blood conservation procedure remains to be verified, it reduced the need for the transfusion of homologous blood. Thus, additional units of autologous blood are required to obviate the need for homologous transfusion in patients undergoing long cardiopulmonary bypass procedures.

A new method for quantitative analysis of whole blood platelet interaction with extracellular matrix under flow conditions

A new method and device in which whole blood platelet deposition and aggregation on extracellular matrix (ECM) under defined shear conditions is quantitatively evaluated was developed. A 0.25 mL aliquot of citrated whole blood is placed on ECM and a defined shear rate is applied for 2 min using a cone and plate device. This is followed by staining and measuring the number of stained objects, the percentage of ECM surface covered with stained objects and the average size of the objects using an image analyzer. When normal blood is analyzed, platelet deposition is a shear and a time dependent process, reaching maximal levels within 2 min at high shear rate (1300 s-1) of about 20% surface coverage and average aggregate size of about 40-50 microns 2. These two parameters demonstrated positive correlation with the platelet count and the hematocrit. Studies using samples from patients with von Willebrand disease (vWD) and Glanzmann's Thrombasthenia (GT) were performed and demonstrated the ability of the new method to detect these pathological conditions. Blood samples of vWD patients showed a very low adhesion and aggregation at high shear rate as reflected by very low surface coverage (5.2%) and average particle size of single platelets (21.3 microns2). GT samples at a high shear rate demonstrated surface coverage similar to normal blood samples (21.7%) but with average particle size of single platelets (21.3 microns2). The new method is an alternative method to clinically evaluate platelet function under close to physiological conditions.

Intraoperative plasmapheresis in cardiac surgery

OBJECTIVE

To determine the effects of intraoperative plasmapheresis on total transfusion requirements, mediastinal drainage, and coagulation.

DESIGN

The trial was prospective, randomized, and controlled.

SETTING

Inpatient cardiac surgery at a university medical center.

PARTICIPANTS

Two hundred ninety-three consecutive patients undergoing cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

Intraoperative plasmapheresis (IP) was performed in 147 patients before heparinization; platelet-rich plasma was reinfused immediately after heparin reversal.

MEASUREMENTS AND MAIN RESULTS

Mediastinal chest tube drainage during the first 12 postoperative hours was significantly less in the IP group (p = 0.022), but no difference was noted in total postoperative blood loss between the two groups. The amount of packed red cells and fresh frozen plasma transfused to the IP group in the intensive care unit was significantly lower (p = 0.02, p = 0.002, respectively); 51.4% of patients required no transfusion compared with the control group (34.5%) (p = 0.006). No differences were noted for data collected in the intensive care unit in terms of the mean duration of chest tube drainage, ventilator time, or any hematologic variables at baseline or at any subsequent time in the study.

CONCLUSIONS

After cardiac surgery, intraoperative plasma-pheresis reduces early postoperative bleeding and decreases the need for homologous transfusions.

Irradiation of fresh whole blood for prevention of transfusion-associated graft-versus-host disease does not impair platelet function and clinical hemostasis after open heart surgery

Since our previous studies suggested that the transfusion of 1 unit fresh whole blood (FWB) after cardiopulmonary bypass (CPB) using a bubble oxygenator may provide hemostatic benefit equivalent to 8-10 units of platelet concentrates, we have routinely used FWB at the termination of CPB. Two patients who received FWB and developed transfusion-associated graft-versus-host disease (TA-GVHD) prompted us to investigate the effect of irradiation of FWB on platelet and clinical hemostasis. Twenty-four patients were randomized to receive either 1 unit FWB (12 patients), or 1 unit irradiated FWB (IrFWB, 1,500 cGy,12 patients) after CPB. Platelet aggregation on extracellular matrix, studied by a scanning electron microscope and graded from 1 to 4 (from poor to excellent aggregation), was similar in both groups preoperatively [3.3 +/- 0.9 (FWB) and 3.5 +/- 0.5 (Ir FWB)], and at the end of CPB [1.8 +/- 1.2 (FWB) and 1.9 +/- 0.9 (IrFWB)]. Platelet aggregation was similar after transfusion of FWB (3.0 +/- 1.0) and after IrFWB (3.2 +/- 0.8), as was the increase in platelet count. Twenty-four hours total postoperative bleeding was similar (560 +/- 420 and 523 +/- 236 ml for FWB and IrFWB, respectively). We conclude that irradiation of FWB for prevention of TA-GVHD does not impair platelet aggregating capacity, and can be used when blood is donated by the patient's next of kin.

Massive transfusion in the neonate

The neonate who undergoes massive transfusion is at risk for transfusion-associated complications similar to the adult, but also faces some that are unique to the infant. By understanding the mechanics of the procedures that result in single or multiple blood volume exchange, the transfusion medicine physician can better assist his/her colleagues in the support of these patients.

Aprotinin improves hemostasis after cardiopulmonary bypass better than single-donor platelet concentrate

Platelet transfusion and aprotinin administration improve platelet function and clinical hemostasis after extracorporeal circulation. To compare two methods of improving postoperative hemostasis, we preoperatively randomized 40 patients undergoing various open heart procedures into two groups. Group A included 20 patients who, immediately after bypass, received single-donor plateletpheresis concentrates collected from ABO-compatible donors (Baxter Autopheresis-C System). They were compared with 20 patients who received high-dose aprotinin (6 x 10(6) KIU) before and during cardiopulmonary bypass (group B). Group A patients showed significantly higher platelet count after single-donor plateletpheresis concentrate transfusion (157 +/- 36 x 10(9)/L compared with 118 +/- 42 x 10(9)/L (p < 0.05). However, platelet aggregation on extracellular matrix was better in group B (3.4 +/- 0.7 versus 2.8 +/- 0.9; p < 0.05). Total 24-hour blood loss and exposure to homologous blood products were significantly less in group B (396 +/- 125 mL and 1.1 +/- 1.6 units compared with 617 +/- 233 mL and 5.4 +/- 3.4 units; p < 0.01). Despite higher platelet count in patients after single-donor plateletpheresis concentrates transfusion, hemostasis in patients receiving aprotinin is better due to improved platelet function.

Intraoperative hemodilution and autologous platelet rich plasma collection: two techniques for collecting fresh autologous blood

Intraoperative hemodilution (IH) and autologous platelet rich plasma (APRP) collection are two techniques used to obtain autologous blood in the operating room. They have been used to reduce allogeneic blood exposure in patients undergoing both cardiac and non-cardiac surgery. Both components have the advantage of providing fresh blood not subject to the storage lesion. Whole blood (IH) or platelet rich plasma is removed from the patient as anesthesia is induced and replaced with acellular fluid. The blood is transfused back after bypass or major bleeding has ceased. Although used commonly, the data supporting the use of either technique are controversial. Methodologic problems which have confounded studies evaluating their utility include: poorly defined transfusion criteria, concommitant use of other blood conservation techniques (i.e. cell salvage, pharmacologic agents, hypothermia, controlled hypotension) and changing transfusion practices with greater tolerance of normovolemic anemia. Randomized controlled studies with well defined up to date transfusion criteria are needed to identify patients likely to benefit from these techniques.

A guideline nomogram to control intraoperative haemodilution in cardiac surgery

Intraoperative blood collection prior to cardiopulmonary bypass (CPB) is a common procedure in cardiac surgery. Its aims are to obtain fresh whole blood to be infused after CPB, to use autologous blood in the prime or to avoid too high levels of haematocrit (HCT) during CPB. Calculations to determine the amount of blood to be collected are generally based on theoretical assumptions. In this paper we have set up and controlled, on a clinical basis, a nomogram to be used in order to obtain a standard pre-CPB HCT equal to 38%, using a moderately hypervolaemic haemodilution based on blood collection simultaneous with fluid replacement. Thirty adult patients were evaluated in order to settle the nomogram; subsequently, the nomogram validity was checked on 100 adult patients. Statistical analysis revealed the good clinical usefulness of this instrument.

Comparison of blood reinfusion techniques used during coronary artery bypass grafting

A comparison of intraoperative autologous blood conservation techniques was carried out in 100 patients undergoing coronary artery bypass grafting. To facilitate comparisons of similar groups, patients were stratified into high-risk and low-risk groups based on the ratio of preoperative bleeding time to preoperative red blood cell volume. Our previous work suggested that patients with an elevated ratio have increased risk of excessive post-operative blood transfusion. We used this ratio to stratify the 100 patients to either the high-risk (39 patients) or low-risk (61 patients) strata. Within each stratum, patients were randomized to one of three groups: no intraoperative autologous blood conservation (control group), infusion of autologous platelet-rich plasma obtained from intraoperative plasmapheresis (PRP group), and infusion of autologous whole blood harvested immediately before cardiopulmonary bypass (whole blood group). Variables of postoperative blood loss and transfusion requirements were measured in each patient. Analysis of variance showed significant differences in blood product transfusions between groups. Patients in the high-risk stratum required significantly more blood product transfusions than those in the low-risk stratum (5.4 +/- 0.7 versus 2.0 +/- 0.6 units per patient; p < 0.001). In the high-risk stratum, PRP patients required significantly less postoperative blood transfusion compared with patients in the high-risk control group (2.9 +/- 2.1 versus 8.1 +/- 2.2 units per patient; p = 0.05). In the low-risk stratum, no intraoperative blood infusion method resulted in significant improvement in postoperative blood use.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet protection by low-dose aprotinin in cardiopulmonary bypass: electron microscopic study

To evaluate the effect of low-dose aprotinin during cardiopulmonary bypass on platelet function and clinical hemostasis, 30 patients undergoing various cardiopulmonary bypass procedures employing bubble oxygenators were randomized to receive either low-dose aprotinin (2 x 10(6) KIU in the cardiopulmonary bypass priming solution, 15 patients [group A]) or placebo (15 patients [group B]). Blood samples were collected before and after cardiopulmonary bypass to assess platelet count and aggregation on extracellular matrix, which was studied by a scanning electron microscope. On a scale of 1 to 4 preoperative mean platelet aggregation grades were similar in both groups (3.8 +/- 0.5 and 3.5 +/- 0.5 for groups A and B, respectively). Postoperatively, platelet aggregation on extracellular matrix decreased slightly in group A (2.8 +/- 1.3; p < 0.01) and significantly in group B (1.3 +/- 0.5; p < 0.001). Eleven of the 15 patients in group A remained in aggregation grade 3 or 4 compared with none of the group B patients. Platelet count was similar in both groups preoperatively and postoperatively. Total 24-hour postoperative bleeding and blood requirement were lower in the aprotinin group (487 +/- 121 mL and 2.3 +/- 1.0 units) than in the placebo group (752 +/- 404 mL and 6.8 +/- 5.1 units; p < 0.01). These results show that the use of low-dose aprotinin during cardiopulmonary bypass provides improved postoperative hemostasis, which might be related to the protection of the platelet aggregating capacity.

Coagulation defects in neonates during cardiopulmonary bypass

We examined components of the coagulation system in 30 neonates (age, 1 to 30 days) undergoing deep hypothermic cardiopulmonary bypass (CPB). A coagulation profile consisting of activated clotting time; prothrombin time; partial thromboplastin time; factors II, V, VII, VIII, IX, X, and I (fibrinogen); antithrombin III; platelet count; and heparin levels was evaluated before bypass, at three intervals during bypass (1 minute after initiation of bypass, stable hypothermic CPB, warm CPB), after weaning from CPB and administration of protamine, and 2 to 3 hours after skin closure. The initiation of CPB resulted in a 50% decrease in circulating coagulation factors and antithrombin III levels. Platelet counts were reduced by 70% with CPB initiation. Neither deep hypothermic temperatures nor prolonged exposure to extracorporeal surfaces had any additional effect on the coagulation profiles. This suggests that the coagulation system of a neonate undergoing CPB is profoundly and globally effected by hemodilution. We believe that treatment of post-CPB coagulopathy in neonates must address these global deficits.

Model for the regulation of platelet volume and responsiveness by the trans-membrane Na+/K(+)-pump

The correspondence between K+ uptake in platelets to their responsiveness was studied using 86Rb+ as an analogue of K+. An average 86Rb+ uptake rate of 0.73 (+/- 0.140) x 10(-15) mole Rb+/min-plt (n = 20) was observed. By the use of K(+)-influx inhibitors, we were able to distinguish three distinct 86Rb+ uptake pathways: an ouabain-sensitive (61% +/- 2% inhibitable) pump and two equivalent channels, only one of which is sensitive to furosemide. Other platelet parameters were also examined in conjunction with K(+)-uptake. Platelets incubated with ouabain exhibited an overall rise in their cell volume (MPV) with incubation time (delta MPV = 7.4 x 10(-17) L/min-1 plt-1). Concomitantly, over 24 hours, a steady decrease in platelet number was recorded by blood cell coulter, which correlated inversely with the counts of particles, which by their size resemble white blood cells (r = 0.89). On a cellular level, incubation with ouabain induced greater expression of surface fibrinogen-receptor (GPIIb), increased binding of FITC-labelled fibrinogen, and increased responsiveness to ADP. Our observations suggest the following sequence of events: Ouabain turns off the Na+/K(+)-ATPase pump, which leads to water accumulation in platelets and concomitant increased MPV. Greater expression of fibrinogen receptors on the distended platelet surface corresponds to spontaneous microaggregate formation as well as greater responsiveness to agonists. Our model links volume regulation, the expression of fibrinogen receptors, and the sensitivity of platelets to agonists to the activity of the Na+/K(+)-ATPase pump.