Challenges in the diagnosis of thrombotic thrombocytopenic purpura

INTRODUCTION

Immune-mediated TTP (iTTP) is a rare condition without pathognomonic signs and symptoms. For this reason, the diagnosis of iTTP may be delayed or even missed, with potentially catastrophic consequences.

AREAS COVERED

The authors performed an extensive literature review on the diagnosis of iTTP and its challenges combined with their own experience in a referral center for patients with iTTP.

EXPERT OPINION

Although a definitive diagnosis of iTTP depends on the ADAMTS13 activity result, timely testing is rarely available at many centers to which patients present. If less complex tests were to become available, they would decrease the chances of late and/or missed diagnoses of iTTP throughout the world. While clinical scores to estimate the likelihood of iTTP exist, they are not well known, and can be misleading if used in the wrong context. Furthermore, the three scoring systems (PLASMIC, Bentley, and French) only moderately correlate with each other, which further complicates the landscape. The existence of these scores and how they should be used in practice is but one opportunity that can be seized through more robust programs to educate nonspecialist clinicians on how to recognize and treat patients with iTTP.

The females have spoken: A patient-centered national survey on the administration of emergent transfusions with the potential for future fetal harm

BACKGROUND

Traumatic hemorrhage is the leading cause of preventable death. Early in the resuscitation, only RhD-positive red blood cells are likely to be available, which poses a small risk of causing harm to a future fetus if transfused to an RhD-negative females of childbearing age (CBA), that is, 15 to 49 years old. We sought to characterize how the population, in particular females of CBA, felt about emergency blood administration vis-a-vis potential future fetal harm.

METHODS

A national survey was performed using Facebook advertisements in three waves from January 2021 to January 2022. The advertisements directed users to the survey site with seven demographic questions and four questions on accepting transfusion with differing probabilities for future fetal harm (none/any/1:100/1:10,000). Acceptance of transfusion questions were scored on 3-point Likert scale (likely/neutral/unlikely). Only completed responses by females were analyzed.

RESULTS

Advertisements were viewed 16,600,430 times by 2,169,805 people with 15,396 advertisement clicks and 2,873 surveys initiated. Most (2,256 of 2,873 [79%]) were fully completed. Majority (2,049 of 2,256 [90%]) of respondents were female. Eighty percent of females (1,645 of 2,049) were of CBA. Most females responded "likely" or "neutral" when asked whether they would accept a lifesaving transfusion if the following risk of fetal harm were present: no risk (99%), any risk (83%), 1:100 risk (85%), and 1:10,000 risk (92%). There were no differences between females of CBA versus non-CBA with respect to the likelihood of accepting lifesaving transfusion with any potential for future fetal harm ( p = 0.24).

CONCLUSION

This national survey suggests that most females would accept lifesaving transfusion even with the potential low risk of future fetal harm.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Different-sized extracellular vesicles derived from stored red blood cells package diverse cargoes and cause distinct cellular effects

BACKGROUND

The formation of extracellular vesicles (EVs) occurs during cold storage of RBCs. Transfusion of EVs may contribute to adverse responses in recipients receiving RBCs. However, EVs are poorly characterized with limited data on whether distinct vesicles are formed, their composition, and potential biological effects.

STUDY DESIGN AND METHODS

Stored RBC-derived EVs were purified using protocols that separate larger microvesicle-like EVs (LEVs) from smaller exosome-like vesicles (SEVs). Vesicles were analyzed by electron microscopy, content of hemoglobin, heme, and proteins (by mass spectrometry), and the potential to mediate lipid peroxidation and endothelial cell permeability in vitro.

RESULTS

SEVs were characterized by having an electron-dense double membrane whereas LEVs had more uniform electron density across the particles. No differences in hemoglobin nor heme levels per particle were observed, however, due to smaller volumes, SEVs had higher concentrations of oxyHb and heme. Both particles contained antioxidant proteins peroxiredoxin-2 and copper/zinc superoxide dismutase, these were present in higher molecular weight fractions in SEVs suggesting either oxidized proteins are preferentially packaged into smaller vesicles and/or that the environment associated with SEVs is more pro-oxidative. Furthermore, total glutathione (GSH + GSSG) levels were lower in SEVs. Both EVs mediated oxidation of liposomes that were prevented by hemopexin, identifying heme as the pro-oxidant effector. Addition of SEVs, but not LEVs, induced endothelial permeability in a process also prevented by hemopexin.

CONCLUSION

These data show that distinct EVs are formed during cold storage of RBCs with smaller particles being more likely to mediate pro-oxidant and inflammatory effects associated with heme.

Pitfalls in Diagnosing Thrombotic Thrombocytopenic Purpura in Sickle Cell Disease

Thrombotic thrombocytopenia purpura is characterised by microangiopathic haemolytic anaemia and red cell fragmentation on the peripheral smear, neurological involvement and thrombocytopenia. Diagnosis in the context of sickle cell disease can be challenging due to the inherent haemolytic state and the multitude of other associated complications of the latter. Specifically, fat embolism syndrome characterised by respiratory failure, neurological impairment and thrombocytopenia can be misdiagnosed this way. Confirmation of a diagnosis of thrombotic thrombocytopenic purpura requires demonstration of very low levels (<10%) of the metalloproteinase ADAMTS13 which in fat embolism syndrome is normal. Existing scoring systems used to estimate the pre-test probability for thrombotic thrombocytopenic purpura cannot be applied in patients with sickle cell disease due to the chronic underlying haemolysis. Here, we analyse the diagnostic approach in published cases of thrombotic thrombocytopenic purpura affecting patients with sickle-cell disease. The vast majority of cases were characterised by severe respiratory failure before any other manifestation, a feature of fat embolism syndrome but not of thrombotic thrombocytopenic purpura, and all received red cell transfusion prior to receiving therapeutic plasma exchange. Despite the potential overestimation of the pre-test probability using the existing scoring systems, a large number of cases still scored low. There were no cases with documented low ADAMTS13. In the majority this was not tested, while in the 3 cases that ADAMTS13 was tested, levels were normal. Our review suggests that due to many overlapping clinical and laboratory features thrombotic thrombocytopenic purpura may be erroneously diagnosed in sickle cell disease instead of other complications such as fat embolism syndrome and confirmation with ADAMTS13 testing is essential.

Over-transfusion with blood for suspected hemorrhagic shock is not associated with worse clinical outcomes

BACKGROUND

We evaluated patient outcomes after early, small volume red blood cell (RBC) transfusion in the setting of presumed hemorrhagic shock. We hypothesized that transfusion with even small amounts of blood would be associated with more complications.

STUDY DESIGN AND METHODS

Retrospective review of trauma patients admitted to a Level 1 trauma center between 2016-2021. Patients predicted to require massive transfusion who survived ≥72 h were categorized according to units of RBCs transfused in the first 24 h. A Cox regression model stratified by dichotomized ISS and adjusted for SBP <90 mm Hg and pulse >120 bpm on arrival was used to estimate hazard ratios (HRs) for outcomes of interest.

RESULTS

A total of 3121 (24%) received RBC transfusion within the first 24 h. Massive transfusion protocol (MTP) was activated in 38% (1188/3121): 17% received no RBCs, 27.4% 1-3 units, 32.4% 4-9 units, and 22.7% ≥10 units. Mean ISS increased with each category of RBC transfusion. There was no difference in the risk of acute kidney injury (AKI), acute respiratory distress syndrome (ARDS), infection, cardiac arrest, venous thromboembolism or stroke for patients receiving 1-3 units compared to the non-transfused group or 4-9 units group (p > 0.05). Compared to those receiving ≥10 units, the 1-3 units group had a significantly lower risk of AKI, ARDS, and cardiac arrest.

DISCUSSION

Early empiric RBC transfusion for presumed hemorrhagic shock may subject patients to potential over-transfusion and end-organ damage. Among patients meeting clinical triggers for MTP, 1-3 units of allogeneic RBCs is not associated with worse outcomes.

Unusual, non-anaphylactic transfusion reactions associated with severe IgA and IgM deficiencies and anti-IgA

A few individuals with undetectable IgA develop anti-IgA, which is theorized to promote anaphylactic or anaphylactoid reactions to blood products. Here, we describe a recurrent, unusual reaction in a patient with no IgA or IgM, and anti-IgA present. The patient is a 49-year-old male with cirrhosis secondary to hepatitis C, who presented to the emergency department in January of 2014 with abdominal distension, leg swelling and dyspnea. He was severely anemic with a hemoglobin of 4.5 g/dL. Several minutes into a transfusion, he complained of chills, dyspnea and back pain. The transfusion was discontinued after &lt;10mL, and his symptoms resolved rapidly without further intervention. The patient’s blood pressure, heart rate and temperature before and after the reaction were 134/63 mmHg and 180/64 mmHg, 98 beats/minute (bpm) and 102 bpm, and 98.6⁰ F and 98.7⁰ F, respectively. A laboratory workup for hemolysis was negative pre- and post-transfusion and an “OK to transfuse” order was given if future blood products were indicated. The following day, another transfusion of PRBCs was stopped after &lt;75 mL due to similar symptoms, which again resolved rapidly; no vital signs changes or signs of hemolysis were noted. Because he was receiving other fluids concurrently with the PRBCs, it was recommended to transfuse future products slowly and to premedicate with furosemide. Although he tolerated three subsequent PRBC transfusions during the same admission, he developed the same clinical picture as soon as &lt;75mL of a platelet unit was started. At that time, unbeknownst to Transfusion Medicine, the primary care team ordered immunoglobulin levels and anti-IgA, and the results of these tests were entered into his electronic medical record (EMR) after discharge.

Approximately six years later, the patient was readmitted following a fall and was found to be thrombocytopenic. After receiving &lt;30 mL of platelets, he developed back pain and headache and the transfusion was aborted. His wife informed the primary provider that her husband was IgA-deficient. When Transfusion Medicine was notified, a review of his EMR showed undetectable IgA (&lt;6 mg/dL: reference: 46-236 mg/dL) and IgM (&lt;25 mg/dL; reference 43-279 mg/dL) and mildly increased IgG (1787 mg/dL; reference 650-1643 mg/dL) from 2014. Additionally, a high-titer IgG anti-IgA (&gt;1000 U/mL; reference &lt;99 U/mL), had been reported. In lieu of these findings, we changed his transfusion requirements to issue only washed PRBCs and IgA-deficient platelets and plasma, but he has not required any blood products since the last reaction. While a definitive cause and effect has not been established, this case suggests that severe IgA- and IgM-deficiency with IgG anti-IgA may be associated with nonspecific symptoms even with the transfusion of small volumes (&lt;75 mL). To our knowledge, similar reactions have not been previously reported.

From Activated Partial Thromboplastin Time to Antifactor Xa and Back Again

OBJECTIVES

Monitoring is essential to safe anticoagulation prescribing and requires close collaboration among pathologists, clinicians, and pharmacists.

METHODS

We describe our experience in the evolving strategy for laboratory testing of unfractionated heparin (UFH).

RESULTS

An intrainstitutional investigation revealed significant discordance between activated partial thromboplastin time (aPTT) and antifactor Xa (anti-Xa) assays, prompting a transition from the former to the latter in 2013. With the increasing use of oral factor Xa inhibitors (eg, apixaban, rivaroxaban, edoxaban, betrixaban), which interfere with the anti-Xa assay, we adapted our protocol again to incorporate aPTT in patients admitted on oral Xa inhibitors who require transition to UFH.

CONCLUSIONS

Our experience demonstrates key challenges in anticoagulation and highlights the importance of clinical pathologists in helping health systems adapt to the changing anticoagulation landscape.

Initial experimental experience of triple-knockout pig red blood cells as potential sources for transfusion in alloimmunized patients with sickle cell disease

BACKGROUND

Blood transfusion remains important in the treatment of patients with sickle cell disease (SCD). However, alloimmunization after blood transfusion is associated with patient morbidity and mortality. Triple-knockout (TKO) pigs (i.e., pigs in which the three known xenoantigens to which humans have anti-pig antibodies have been deleted) may be an alternative source of RBCs for these patients because many humans have no preformed antibodies to TKO pig RBCs (pRBCs).

METHODS AND MATERIALS

In an in vitro study, plasma from alloimmunized (n = 12) or non-alloimmunized (n = 12) SCD patients was used to determine IgM/IgG binding to, and CDC of, TKO pRBCs. In an in vivo study, after an estimated 25% of blood volume was withdrawn from two capuchin monkeys, CFSE-labeled TKO pRBCs were transfused. Loss of TKO pRBCs was monitored by flow cytometry, and 7 weeks later, 25% of blood was withdrawn, and CFSE-labeled monkey RBCs were transfused.

RESULTS

The in vitro study demonstrated that plasma from neither alloimmunized nor non-alloimmunized SCD patients bound IgM/IgG to, or induced CDC of, TKO pRBCs. In the in vivo study, survival of TKO pRBCs in the two capuchin monkeys was of 5 and 7 days, respectively, whereas after allotransfusion, survival was >28 days.

CONCLUSIONS

In conclusion, (1) in the present limited study, no antibodies were detected that cross-reacted with TKO pRBCs, and (2) TKO pigs may possibly be an alternate source of RBCs in an emergency if no human RBCs are available.

Perception of risk in massive transfusion as it relates to fetal outcomes: A survey of surgeons and nurses at one American trauma center

BACKGROUND

The use of blood products early in the resuscitation of bleeding trauma patients is widely accepted, but made difficult by limited supplies of D- red blood cell (RBC)-containing products. Use of D+ RBC-containing products would alleviate this issue, but could lead to alloimmunization. Risk associated with transfusing D+ RBC in emergency bleeding situations is being reconsidered. The level of concern surrounding emergency transfusion as it relates to future fetal harm was surveyed among surgeons and nurses.

METHODS

Faculty and staff in the Departments of Surgery and Nursing were surveyed on the risks of receiving an emergency RBC transfusion and the subsequent potential for fetal harm. Answers were grouped as likely to accept (likely/very likely) or refuse transfusion (unlikely/very unlikely). Participants were compared by sex, and women by child-bearing age, ([15-50 years] vs. [>50 years]).

RESULTS

Ninety surveys were initiated with 76 fully completed. Male (n = 39) and female (n = 37) respondents were comparable. Most female respondents (30/37, 81%) were of childbearing age. Overall, both males (38/39, 95%) and females (33/37, 89%; p = .19) were likely to accept a transfusion in an emergency. There was no difference in transfusion acceptance if the risk of fetal harm was presented as 1% (p = .73) or 0.1% (p = .51). Most females (34/37, 92%) were not opposed to transfusion even if there was an unspecified risk of future fetal harm.

CONCLUSION

Most of the surgeons and nurses who responded would accept a transfusion in an emergency situation even if it might lead to harming a future fetus.

Civilian walking blood bank emergency preparedness plan

BACKGROUND

The current global pandemic has created unprecedented challenges in the blood supply network. Given the recent shortages, there must be a civilian plan for massively bleeding patients when there are no blood products on the shelf. Recognizing that the time to death in bleeding patients is less than 2 h, timely resupply from unaffected locations is not possible. One solution is to transfuse emergency untested whole blood (EUWB), similar to the extensive military experience fine-tuned over the last 19 years. While this concept is anathema in current civilian transfusion practice, it seems prudent to have a vetted plan in place.

METHODS AND MATERIALS

During the early stages of the 2020 global pandemic, a multidisciplinary and international group of clinicians with broad experience in transfusion medicine communicated routinely. The result is a planning document that provides both background information and a high-level guide on how to emergently deliver EUWB for patients who would otherwise die of hemorrhage.

RESULTS AND CONCLUSIONS

Similar plans have been utilized in remote locations, both on the battlefield and in civilian practice. The proposed recommendations are designed to provide high-level guidance for experienced blood bankers, transfusion experts, clinicians, and health authorities. Like with all emergency preparedness, it is always better to have a well-thought-out and trained plan in place, rather than trying to develop a hasty plan in the midst of a disaster. We need to prevent the potential for empty shelves and bleeding patients dying for lack of blood.

Plasma levels of S100A8/A9, histone/DNA complexes, and cell-free DNA predict adverse outcomes of immune thrombotic thrombocytopenic purpura

BACKGROUND

Immune thrombotic thrombocytopenic purpura (iTTP) is a life-threatening blood disorder, primarily resulting from autoantibodies against ADAMTS13. Infection or inflammation often precedes acute iTTP. However, the association of inflammation and inflammatory mediators with disease severity and outcome of acute iTTP is not fully assessed.

OBJECTIVES

Here, we determined plasma levels of S100A8/A9, histone/DNA complexes, citrullinated histone H3 (CitH3), and cell-free DNA (cfDNA) in a cohort of 108 acute episodes from 94 unique iTTP patients and healthy controls, and assessed the association of each of these biomarkers with the disease severity and mortality.

RESULTS

All acute iTTP patients had significantly increased plasma levels of S100A8/A9 (median 84.8, interquartile range [IQR] 31.2-157.4 µg/mL), histone/DNA complexes (median 55.7, IQR 35.8-130.8 U/mL), CitH3 (median 3.8, IQR 2.2-6.4 ng/mL), and cfDNA (median 937.7, IQR 781.3-1420.0 ng/mL) on the admission blood samples when compared with healthy controls. An increased plasma level of S100A8/A9, histone/DNA complex and cfDNA was associated with organ damage, coagulopathy, and mortality in iTTP. After being adjusted for age and history of hypertension, Cox proportional hazard regression analysis demonstrated that a hazard ratio (95% confidence interval) for an elevated plasma level of S100A8/A9, histone/DNA complexes, and cfDNA was 11.5 (1.4-90.9) (P = .021), 10.3 (2.7-38.5) (P = .001), and 12.8 (3.9-42.0) (P = .014), respectively.

CONCLUSION

These results indicate that inflammation or plasma inflammatory mediators such as S100A8/A9 or NETosis markers such as histone/DNA complexes and cfDNA may play a role in pathogenesis of iTTP, which may help stratify patients with a high risk of death during acute iTTP episodes.

Convalescent plasma-mediated resolution of COVID-19 in a patient with humoral immunodeficiency

Convalescent plasma (CP) is widely used to treat COVID-19, but without formal evidence of efficacy. Here, we report the beneficial effects of CP in a severely ill COVID-19 patient with prolonged pneumonia and advanced chronic lymphocytic leukemia (CLL), who was unable to generate an antiviral antibody response of her own. On day 33 after becoming symptomatic, the patient received CP containing high-titer (ID50 > 5,000) neutralizing antibodies (NAbs), defervesced, and improved clinically within 48 h and was discharged on day 37. Hence, when present in sufficient quantities, NAbs to SARS-CoV-2 have clinical benefit even if administered relatively late in the disease course. However, analysis of additional CP units revealed widely varying NAb titers, with many recipients exhibiting endogenous NAb responses far exceeding those of the administered units. To obtain the full therapeutic benefits of CP immunotherapy, it will thus be important to determine the neutralizing activity in both CP units and transfusion candidates.

Whole blood transfusion versus component therapy in trauma resuscitation: a systematic review and meta-analysis

BACKGROUND

Patients with hemorrhagic shock from trauma often require balanced blood product transfusion with red blood cells, plasma, and platelets. Resuscitation with whole blood resuscitation is becoming a common practice. We performed a systematic review and meta-analysis of studies comparing whole blood transfusion with balanced component therapy in patients suffering from traumatic hemorrhagic shock.

METHODS

We searched MEDLINE Ovid, EMBASE, and the Cochrane Library for human studies comparing whole blood with component blood therapy published from January 2007 to June 2019. We included studies from both civilian and military settings and that reported 24-hour, in-hospital, or 30-day mortality. We followed the Preferred Reporting Items in Systematic Reviews and Meta-Analyses (PRISMA) guidelines, assessing study quality, publication bias, and heterogeneity. We used meta-analytic models to determine the associations (odds ratio [OR] with 95% confidence interval [CI]) between whole blood transfusion and (1) 24-hour mortality, and (2) in-hospital or 30-day mortality.

RESULTS

A total of 1759 identified studies, 12 (reporting on n = 8431 patients) met inclusion criteria. There was heterogeneity in the design, setting, interventions, and outcomes of the studies. On meta-analysis, whole blood transfusion was not associated with 24-hour mortality (OR = 0.83; 95% CI = 0.56-1.24) or in-hospital/30-day mortality (OR = 0.79; 95% CI = 0.48-1.31).

CONCLUSION

In this systematic review and meta-analysis, compared with conventional component transfusion, whole blood was not associated with 24-hour or in-hospital mortality. However, there were important limitations with and heterogeneity among the primary studies. Additional study is needed to determine the effectiveness of whole blood.

Elicitation of prior probability distributions for a proposed Bayesian randomized clinical trial of whole blood for trauma resuscitation

BACKGROUND

Whole blood trauma resuscitation is conceptually appealing and increasingly used but lacks evidence. A randomized controlled trial is needed but challenging to design. A Bayesian approach might be more efficient and more interpretable than a conventional frequentist design. We report the results on an elicitation meeting to create prior probability distributions to help develop such a trial.

METHODS

In‐person expert elicitation meeting, based on Sheffield Elicitation Framework methodology. We used an interactive graphical tool to elicit the quantities of interest (24‐hour mortality and certainty required). Two rounds were conducted, with an intervening discussion of deidentified responses. Individual responses were aggregated into probability distributions.

RESULTS

Fifteen experts participated. The pooled belief was that the median 24‐hour mortality of trauma patients with hemorrhagic shock treated with component therapy (the current standard of care) was 19% (95% credible interval [CrI], 6%‐45%), and the median 24‐hour mortality of those treated with whole blood, 16% (95% CrI, 5%‐39%). The pooled prior distribution for the relative risk had a median of 0.84 (95% CrI, 0.26‐3.1), indicating that the expert group had a 64% prior belief that whole blood decreases 24‐hour mortality compared to component therapy.

CONCLUSIONS

Experts had moderately strong beliefs that whole blood reduces the 24‐hour mortality of trauma patients with hemorrhagic shock. These data will assist with the design and planning of a Bayesian trial of whole blood resuscitation, which will help to answer a key question in contemporary transfusion practice.

An Automated Method for Direct Antiglobulin Testing and the Resulting Amount of Phototherapy Used at a Large Academic Medical Center

OBJECTIVE

To evaluate how clinical practice was affected by the change in direct antiglobulin testing (DAT) methodologies and subsequent stronger reported DAT results at our large academic medical center.

METHOD

We retrospectively reviewed DAT results of umbilical cord blood from infants with blood type A or B born to mothers with antibody-negative type O blood, based on records kept at the University of Alabama at Birmingham (UAB) Hospital, a 1400-bed academic medical center.

RESULTS

We randomly chose 50 neonates with positive DAT results who had been tested using the tube method and 50 whose testing had used the gel method. Although 86% of results with the tube method were positive microscopically, 52% and 40% of the DAT results with the gel method were 1+ and 2+ positive, respectively. Further, we observed an increase in the number of neonates treated with phototherapy who had been tested using the gel method.

CONCLUSION

We report that DATs performed using the gel method had increased DAT strength compared with tube testing, which led to increased use of phototherapy by our clinical colleagues.

Longitudinal assessments of plasma ADAMTS13 biomarkers predict recurrence of immune thrombotic thrombocytopenic purpura

Immune thrombotic thrombocytopenic purpura (iTTP) is primarily caused by immunoglobulin G (IgG)-type autoantibodies that bind and inhibit plasma ADAMTS13 activity and/or accelerate its clearance from circulation. Approximately 50% of patients with iTTP who achieve initial clinical response to therapy experience recurrence (ie, exacerbation and/or relapse); however, a reliable biomarker that predicts such an event is currently lacking. The present study determines the role of longitudinal assessments of plasma ADAMTS13 biomarkers in predicting iTTP exacerbation/recurrence. Eighty-three unique iTTP patients with 97 episodes from the University of Alabama at Birmingham Medical Center between April 2006 and June 2019 were enrolled. Plasma levels of ADAMTS13 activity, antigen, and anti-ADAMTS13 IgG on admission showed no significant value in predicting iTTP exacerbation or recurrence. However, persistently low plasma ADAMTS13 activity (<10 U/dL; hazard ratio [HR], 4.4; 95% confidence interval [CI], 1.6-12.5; P = .005) or high anti-ADAMTS13 IgG (HR, 3.1; 95% CI, 1.2-7.8; P = .016) 3 to 7 days after the initiation of therapeutic plasma exchange was associated with an increased risk for exacerbation or recurrence. Furthermore, low plasma ADAMTS13 activity (<10 IU/dL; HR, 4.8; 95% CI, 1.8-12.8; P = .002) and low ADAMTS13 antigen (<25th percentile; HR, 3.3; 95% CI, 1.3-8.2; P = .01) or high anti-ADAMTS13 IgG (>75th percentile; HR, 2.6; 95% CI, 1.0-6.5; P = .047) at clinical response or remission was also predictive of exacerbation or recurrence. Our results suggest the potential need for a more aggressive approach to achieve biochemical remission (ie, normalization of plasma ADAMTS13 activity, ADAMTS13 antigen, and anti-ADAMTS13 IgG) in patients with iTTP to prevent the disease recurrence.

Three neglected numbers in the CBC: The RDW, MPV, and NRBC count

The complete blood cell count (CBC) is one of the most frequently ordered laboratory tests, but some values included in the test may be overlooked. This brief review discusses 3 potentially underutilized components of the CBC: the red blood cell distribution width (RDW), the mean platelet volume (MPV), and the nucleated red blood cell (NRBC) count. These results have unique diagnostic applications and prognostic implications that can be incorporated into clinical practice. By understanding all components of the CBC, providers can learn more about the patient's condition.

Anti-Rh alloimmunization after trauma resuscitation

The AABB recently posted a bulletin (19-02) regarding their recommendations for the use of group O red blood cells (RBCs) during trauma. Though group O Rh(D)-negative RBC units are considered the 'safest', the demand of such units often exceeds the supply. Therefore, O Rh(D)-positive units are often used during the first parts of a massive transfusion protocol (MTP) or patients with particularly severe hemorrhage are switched over from O Rh(D)-negative to O Rh(D)-positive RBC units in order to preserve the O Rh(D)-negative supply. In light of these limitations, it is important to understand the risk of such policies to the patient. The reported risk of alloimmunization after exposure to Rh(D)-positive RBCs ranges widely from 3 to 70%. In response, we performed a retrospective review of 1,198 patients in our institution that had a MTP activation due to trauma. Of those patients, we focused on Rh(D)-negative patients that received at least 1 unit of Rh(D)-positive RBCs. Seventy-two patients met the criteria for inclusion, accounting for 6% of the total population. Of the 72 Rh(D)-negative patients, we identified 17% that formed new Rh group antibodies after exposure to Rh(D)-positive RBCS. All 10 of our alloimmunized patients (two of which were females of childbearing age) formed anti-D, while 3 patients also formed either anti-E or anti-C. Since this was a retrospective review, we did not perform repeated antibody screens for the entire study period, but did review all records for the entire period. We did note that we were more likely to detect an novel alloantibody if more antibody screens were performed during the patient's initial stay and during follow-up visits. We conclude that providing Rh(D) negative patients Rh(D) positive RBC units is not without risk and policies regarding such provisions should be carefully considered. As RBC shortages continue to be a part of daily practice, such issues may continue to be a challenge for the blood bank community.

Exome Sequencing Identifies Glycosylation Defects as a Probable Cause of Immune-Mediated Thrombotic Thrombocytopenic Purpura

Background

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal syndrome, resulting from autoantibodies against ADAMTS13. However, the mechanism underlying autoantibody formation is not known. Neither is known about the other genetic abnormality in the setting of severe deficiency of plasma ADAMTS13 activity.

Methods

Whole-exome sequencing (WES) was performed in 40 patients with iTTP who had plasma ADAMTS13 activity <10% and a positive inhibitor or elevated anti-ADAMTS13 IgG. Fifteen age- and ethnicity-matched subjects who never had iTTP were recruited as healthy controls.

Results

WES identified mutations in the genes involved in glycosylation, including O-linked glycosylation to be the major pathway affected in patients with iTTP. Mass spectrometry confirmed the changes in plasma levels of various glycoproteins in patients with acute iTTP when compared with those in the healthy controls. The altered glycosylation in glycoproteins may be responsible for the development of autoantibodies, susceptibility of von Willebrand factor to proteolysis by ADAMTS13, and the clearance of platelets in iTTP patients. Moreover, candidate gene analysis revealed that various genes involving in hemostasis, complement activation, platelet number and function, and inflammation were all affected in patients with iTTP, which may contribute to the onset, progress, severity, and long-term outcome of iTTP.

Conclusions

Our findings provide novel insight into a pathogenic mechanism underlying autoantibody production and the potential contribution of other genetic abnormalities in pathogenesis of iTTP in the individuals with severe deficiency of plasma ADAMTS13 activity.

Future Direction

Further studies are warranted to determine the specific glycosylation patterns of various plasma and cellular proteins in patients with iTTP and to determine the synergistic role of various gene mutations and severe ADAMTS13 deficiency in the pathogenesis of iTTP.

Can We Predict the Number of Circulating CD34+ Cells From the Complete Blood Cell Count Before and After Plerixafor in Patients With Lymphoproliferative Disorders?

Stem cell transplant is a common treatment for hematopoietic neoplasms. We use a standardized stem cell mobilization regimen consisting of the following: day 1, 6 mg of pegfilgrastim (pegylated formulation of granulocyte-colony stimulating factor); day 3, 24 mg of plerixafor (reversible CXCR4 antagonist) followed by peripheral blood stem cell collection (PBSC) on day 4 after collecting a sample to measure the circulating CD34+ cells by flow cytometry. Since the latter results are not available as quickly as a STAT complete blood count (CBC), we hypothesized that the difference in CBC parameters from DAY 3 TO DAY 4 could be useful to predict the final collection yield. To test our theory, we carried out the following process from September 2018 to February 2019: day 3, CBC with differential before plerixafor; day 4, CBC with differential and sample for CD34+ cells before starting PBSC. We collected the following data from the electronic medical records: gender, age, and CBC parameters preplerixafor (evening of day 3) and morning of day 4 (preapheresis) plus circulating CD34+ count. We used a paired Student t test to compare the results of each patient. Fifty-seven adults (35 males, 22 females) with a median age of 64 ± 13 years were included; 76% had the diagnosis of multiple myeloma. On day 3 (preplerixafor), the median hematocrit was 36 ± 8%, the WBC count was 29 ± 13 × 103/µL, and the platelet count was 189 ± 64 × 103/µL. On the next morning (day 4), the hematocrit and platelet counts were not significantly different at 36 ± 4% and 182 ± 60 × 103/µL, respectively (P > .05). However, the median WBC count was significantly higher with a median of 43 ± 16 × 103/µL (P = 2.5 × 10–20). In both CBCs with differential, neutrophils comprised the majority at 82% and 74% pre- and postplerixafor, respectively (P = .01), lymphocytes went from 7% to 8% (P > .05), and monocytes increased from 6% to 6.5% (P = .02). The median CD34+ count preapheresis was 40 ± 47 cells/µL. We did not find any strong correlation between day 3 and day 4 CBC parameters and the CD34+ count, with only a very weak trend for higher CD34+ cells with increasing day 4 WBC count (R2 = 0.225). We conclude that the precollection CD34+ cell count is the best way to predict the PBSC yield and must be performed in order to ensure the target number of CD34+ cells is met for a successful engraftment.

Longitudinal Changes of Plasma ADAMTS13 Activity, Antigen, and Autoantibodies in Patients With Immune-Mediated Thrombotic Thrombocytopenic Purpura

Background

Severe deficiency of plasma ADAMTS13 activity resulting from anti-ADAMTS13 IgG is the primary cause of immune-mediated thrombotic thrombocytopenic purpura (iTTP). Anti-ADAMTS13 IgG may bind and inhibit plasma ADAMTS13 activity and/or accelerate clearance of ADAMTS13 from the circulation. The present study aims to determine the initial and longitudinal changes of plasma ADAMTS13 activity, antigen, and anti-ADAMTS13 IgG and their relationships with clinical responses and outcomes of patients with iTTP after standard treatment.

Methods

Thirty-eight patients with a confirmed diagnosis of iTTP who underwent therapeutic plasma exchange (TPE) at UAB Medical Center were enrolled into the study. The study spanned from May 2015 to December 2018. An informed consent was obtained from each participant. Clinical and laboratory information was extracted from the electronic medical record and stored in the Alabama TTP Registry database. Plasma samples were collected prior to the initiation of and every 3 to 5 days after TPE until discharge. Plasma ADAMTS13 activity, antigen, and anti-ADAMTS13 IgG were determined using commercially available reagents. Mann-Whitney test, Fisher’s exact test, Spearman rank correlation, Cox proportional hazard regression, and Kaplan-Meier survival analysis were used to determine statistical significances.

Results

The median age of this cohort was 46.5 years old; 26 (68%) patients were female and 12 (32%) were male. Twenty-three patients (60%) were experiencing their initial episode while 15 (39%) had an exacerbation/relapse at the time of enrollment. All patients were diagnosed based on the findings of thrombocytopenia, microangiopathic hemolytic anemia, plasma ADAMTS13 activity (<10 U/dL), and inhibitor titer ≥0.4 BU or elevated anti-ADAMTS13 IgG. Following treatment with standard therapy (TPE, corticosteroids, and/or other immunosuppressives), plasma levels of ADAMTS13 activity and antigen increased with a concurrent reduction of anti-ADAMTS13 IgG. However, there were at least three distinct patterns of dynamic changes of these markers over time: (1) rapid increase, (2) slow increase or fluctuation, and (3) persistently low. More interestingly, those with the highest quartile of anti-ADAMTS13 IgG (HR = 4.2) and inhibitor titer ≥1.2 BU (HR = 3.2) at presentation, ADAMTS13 activity <20 U/dL 3 to 7 days during therapy (HR = 2.5), and ADAMTS13 activity <20 U/dL (HR = 3.2) or the lowest quartile of ADAMTS13 antigen at clinical response (HR = 2.8) were all associated with a higher risk of TTP exacerbation (the disease recurred within 30 days following a sustained normalization of platelet counts).

Conclusion

Initial and longitudinal assessment of plasma ADAMTS13 activity, antigen, inhibitor titer, and anti-ADAMTS13 IgG may be useful not only for diagnosis but also for predicting the risk of exacerbation. This may influence how we select a therapeutic modality for a better outcome. Long-term follow-up is necessary to determine whether these ADAMTS13 biomarkers at patient discharge are predictive of relapse and mortality.

Solving the calcium gluconate shortage in real-time: Mistakes made and lessons learned

PURPOSE

During a national shortage of calcium gluconate, we switched to calcium chloride for routine supplementation for peripheral blood stem cell (PBSC) collections. Subsequently, we analyzed the postprocedure ionized calcium level, as we aimed for an equivalent result compared to before the shortage.

METHODS

Pharmacy representatives helped us to find an "equivalent" substitute for calcium gluconate at 46.5 mEq in 500 mL normal saline, infused at 100 mL/hour. After instituting a presumably comparable protocol using calcium chloride (40.8 mEq in 250 mL normal saline at a rate of 100 mL/hour), we reviewed ionized calcium results post-PBSC procedures to compare with those obtained with calcium gluconate. Having noticed a difference in the mean values, we adjusted the rate of calcium chloride to reach our desired outcome.

RESULTS

Twenty-seven procedures were analyzed on 15 unique patients. We used the Spectra OPTIA with a whole blood: anticoagulant ratio of 13:1. Ionized calcium levels post-PBSC collection with the first calcium chloride protocol were significantly higher (P = 0.003) in nine patients treated. Subsequently, we decreased the calcium chloride infusion rate to 75 mL/hour and achieved similar mean levels to calcium gluconate (P = 0.382).

CONCLUSION

Changes in replacement fluids for apheresis procedures can be complex, particularly when dealing with electrolytes that could be clinically significant at critically high or low levels. Once we recognized the need to take into account the amount of elemental calcium infused, we achieved the desired postprocedure ionized calcium results. This study can serve as a lesson for future shortages of infusions used during apheresis procedures.

Older Blood Is Associated With Increased Mortality and Adverse Events in Massively Transfused Trauma Patients: Secondary Analysis of the PROPPR Trial

STUDY OBJECTIVE

The transfusion of older packed RBCs may be harmful in critically ill patients. We seek to determine the association between packed RBC age and mortality among trauma patients requiring massive packed RBC transfusion.

METHODS

We analyzed data from the Pragmatic, Randomized Optimal Platelet and Plasma Ratios trial. Subjects in the parent trial included critically injured adult patients admitted to 1 of 12 North American Level I trauma centers who received at least 1 unit of packed RBCs and were predicted to require massive blood transfusion. The primary exposure was volume of packed RBC units transfused during the first 24 hours of hospitalization, stratified by packed RBC age category: 0 to 7 days, 8 to 14 days, 15 to 21 days, and greater than or equal to 22 days. The primary outcome was 24-hour mortality. We evaluated the association between transfused volume of each packed RBC age category and 24-hour survival, using random-effects logistic regression, adjusting for total packed RBC volume, patient age, sex, race, mechanism of injury, Injury Severity Score, Revised Trauma Score, clinical site, and trial treatment group.

RESULTS

The 678 patients included in the analysis received a total of 8,830 packed RBC units. One hundred patients (14.8%) died within the first 24 hours. On multivariable analysis, the number of packed RBCs greater than or equal to 22 days old was independently associated with increased 24-hour mortality (adjusted odds ratio [OR] 1.05 per packed RBC unit; 95% confidence interval [CI] 1.01 to 1.08): OR 0.97 for 0 to 7 days old (95% CI 0.88 to 1.08), OR 1.04 for 8 to 14 days old (95% CI 0.99 to 1.09), and OR 1.02 for 15 to 21 days old (95% CI 0.98 to 1.06). Results of sensitivity analyses were similar only among patients who received greater than or equal to 10 packed RBC units.

CONCLUSION

Increasing quantities of older packed RBCs are associated with increased likelihood of 24-hour mortality in trauma patients receiving massive packed RBC transfusion (≥10 units), but not in those who receive fewer than 10 units.

Characterization of Storage-Induced Red Blood Cell Hemolysis Using Raman Spectroscopy

BACKGROUND

The therapeutic efficacy and safety of stored red blood cells (RBCs) relies on minimal in-bag hemolysis. The accuracy of current methods of measuring hemolysis can suffer as a result of specimen collection and processing artefacts.

OBJECTIVE

To test whether Raman spectroscopy could be used to assess hemolysis.

METHODS

RBCs were stored for as long as 42 days. Raman spectra of RBCs were measured before and after washing, and hemolysis was measured in supernatant by visible spectroscopy.

RESULTS

Raman spectra indicated increased concentrations of oxyhemoglobin (oxyHb) and methemoglobin (metHb), and decreased membrane fluidity with storage age. Changes in oxyHb and metHb were associated with the intraerythrocytic and extracellular fractions, respectively. Hemolysis increased in a storage age-dependent manner. Changes in Raman bands reflective of oxyHb, metHb, and RBC membranes correlated with hemolysis; the most statistically significant change was an increased intensity of metHb and decreased membrane fluidity.

CONCLUSIONS

These data suggest that Raman spectroscopy may offer a new label-free modality to assess RBC hemolysis during cold storage.

Vascular access for therapeutic plasma exchange

Therapeutic plasma exchange is an apheresis modality in which plasma is separated from the blood cellular components ex vivo, discarded, and replaced with an isosmotic fluid (most commonly 5% albumin) to maintain appropriate oncotic pressure in the patient. Therapeutic plasma exchange is used in the treatment of many diseases and indications. The recent seventh edition of the American Society for Apheresis guidelines indicates approximately 72 diseases and 116 indications for which therapeutic plasma exchange may be effective. One of the critical aspects for the successful performance of therapeutic plasma exchange is appropriate vascular access to provide high blood flow for the collection and return phases of the procedure, especially because most patients who need therapeutic plasma exchange will require more than one treatment over days to weeks. This article provides an overview of the characteristics of therapeutic plasma exchange, the clinical diseases and indications that may be treated with therapeutic plasma exchange, and the different types of vascular access employed, with their advantages and disadvantages. The latter may include peripheral venous access and intravascular or implantable access devices, such as arteriovenous grafts and fistulas, central venous catheters, and central venous catheters tunneled with ports.

Mobilization of Hematopoietic Progenitor Cells for Autologous Transplantation Using Pegfilgrastim and Plerixafor: Efficacy and Cost Implications

Filgrastim (FIL) is the most common growth factor combined with plerixafor for autologous hematopoietic progenitor cell mobilization, but requires daily, multi-injection administration. We adopted a standardized mobilization regimen with pegfilgrastim (PEG) and upfront plerixafor, allowing for a single injection given the long half-life and slow elimination of PEG. Between 2015 and 2017, a total of 235 patients with lymphoma or plasma cell dyscrasias underwent mobilization with PEG 6 mg on day 1 and upfront plerixafor 24 mg on day 3, followed by apheresis on day 4 regardless of peripheral blood CD34⁺ cells. The median CD34⁺ cells/mm³ in peripheral blood on first day of collection was 48 and median collection yield was 7.27 × 10⁶ CD34⁺ cells/kg (range, 0.32 to 39.6 × 10⁶ CD34⁺ cells/kg) after a mean of 1.6 apheresis collections. Overall, 83% of patients achieved the mobilization target, and 95% reached the minimum necessary CD34⁺ cell yield to proceed with transplantation (2 × 10⁶ CD34⁺ cells/kg). Because FIL is weight-based and dosed daily, the cost comparison with PEG is influenced by patient weight and number of apheresis sessions required. A cost simulation using actual patient data indicates that PEG is associated with lower cost than FIL for the majority of patients. Autologous hematopoietic progenitor cell mobilization with PEG and plerixafor is practical, effective, and not associated with increased cost compared with FIL mobilization.

Clinical factors and biomarkers predict outcome in patients with immune-mediated thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura is characterized by severe thrombocytopenia and microangiopathic hemolytic anemia. It is primarily caused by immunoglobin G type autoantibodies against ADAMTS13, a plasma metalloprotease that cleaves von Willebrand factor. However, reliable markers predictive of patient outcomes are yet to be identified. Seventy-three unique patients with a confirmed diagnosis of immune-mediated thrombotic thrombocytopenic purpura between April 2006 and December 2017 were enrolled from the Univeristy of Alabama at Birmingham Medical Center. Clinical information, laboratory values, and a panel of special biomarkers were collected and/or determined. The results demonstrated that the biomarkers associated with endothelial injury (e.g., von Willebrand factor antigen and collagen-binding activity), acute inflammation (e.g., human neutrophil peptides 1-3 and histone/deoxyribonucleic acid complexes), and activation of the complement alternative pathway (e.g., factors Bb and iC3b) were all significantly increased in patients with acute immune-mediated thrombotic thrombocytopenic purpura compared to those in the healthy controls. Moreover, failure to normalize platelet counts within 7 days or failure to markedly reduce serum lactate dehydrogenase by day 5, low total serum protein or albumin, and high serum troponin levels were also predictive of mortality, as were the prolonged activated partial thromboplastin time, high fibrinogen, and elevated serum lactate dehydrogenase, Bb, and sC5b-9 on admission. These results may help to stratify patients for more intensive management. The findings may also provide a framework for future multicenter studies to identify valuable prognostic markers for immune-mediated thrombotic thrombocytopenic purpura.

Rat Poisoning: A Challenging Diagnosis With Clinical and Psychological Implications

Rat poisoning should be considered in the differential diagnosis of a patient presenting with signs and symptoms of vitamin K deficiency without a more likely explanation. However, confirming this diagnosis may be difficult due to the varying sensitivities of available assays. A 40-year-old Caucasian woman presented to our hospital with chronic abdominal pain, hematuria, and a history of diarrhea of unknown etiology, despite an extensive work-up. Her laboratory evaluation results were consistent with vitamin K deficiency. Because she reported that she had not ingested warfarin, rat poisoning was suspected; however, the results of the first assay were negative. A second specimen was sent to another reference laboratory with a more sensitive assay, and the diagnosis of brodifacoum poisoning was confirmed. The patient was treated with oral vitamin K. If a patient presents with unexplained signs and symptoms of vitamin K deficiency, toxicological evaluation should be performed and repeat testing may be warranted, depending on the sensitivity of the original testing method.

Role of heme in lung bacterial infection after trauma hemorrhage and stored red blood cell transfusion: A preclinical experimental study

BACKGROUND

Trauma is the leading cause of death and disability in patients aged 1-46 y. Severely injured patients experience considerable blood loss and hemorrhagic shock requiring treatment with massive transfusion of red blood cells (RBCs). Preclinical and retrospective human studies in trauma patients have suggested that poorer therapeutic efficacy, increased severity of organ injury, and increased bacterial infection are associated with transfusion of large volumes of stored RBCs, although the mechanisms are not fully understood.

METHODS AND FINDINGS

We developed a murine model of trauma hemorrhage (TH) followed by resuscitation with plasma and leukoreduced RBCs (in a 1:1 ratio) that were banked for 0 (fresh) or 14 (stored) days. Two days later, lungs were infected with Pseudomonas aeruginosa K-strain (PAK). Resuscitation with stored RBCs significantly increased the severity of lung injury caused by P. aeruginosa, as demonstrated by higher mortality (median survival 35 h for fresh RBC group and 8 h for stored RBC group; p < 0.001), increased pulmonary edema (mean [95% CI] 106.4 μl [88.5-124.3] for fresh RBCs and 192.5 μl [140.9-244.0] for stored RBCs; p = 0.003), and higher bacterial numbers in the lung (mean [95% CI] 1.2 × 10(7) [-1.0 × 10(7) to 2.5 × 10(7)] for fresh RBCs and 3.6 × 10(7) [2.5 × 10(7) to 4.7 × 10(7)] for stored RBCs; p = 0.014). The mechanism underlying this increased infection susceptibility and severity was free-heme-dependent, as recombinant hemopexin or pharmacological inhibition or genetic deletion of toll-like receptor 4 (TLR4) during TH and resuscitation completely prevented P. aeruginosa-induced mortality after stored RBC transfusion (p < 0.001 for all groups relative to stored RBC group). Evidence from studies transfusing fresh and stored RBCs mixed with stored and fresh RBC supernatants, respectively, indicated that heme arising both during storage and from RBC hemolysis post-resuscitation plays a role in increased mortality after PAK (p < 0.001). Heme also increased endothelial permeability and inhibited macrophage-dependent phagocytosis in cultured cells. Stored RBCs also increased circulating high mobility group box 1 (HMGB1; mean [95% CI] 15.4 ng/ml [6.7-24.0] for fresh RBCs and 50.3 ng/ml [12.3-88.2] for stored RBCs), and anti-HMGB1 blocking antibody protected against PAK-induced mortality in vivo (p = 0.001) and restored macrophage-dependent phagocytosis of P. aeruginosa in vitro. Finally, we showed that TH patients, admitted to the University of Alabama at Birmingham ER between 1 January 2015 and 30 April 2016 (n = 50), received high micromolar-millimolar levels of heme proportional to the number of units transfused, sufficient to overwhelm endogenous hemopexin levels early after TH and resuscitation. Limitations of the study include lack of assessment of temporal changes in different products of hemolysis after resuscitation and the small sample size precluding testing of associations between heme levels and adverse outcomes in resuscitated TH patients.

CONCLUSIONS

We provide evidence that large volume resuscitation with stored blood, compared to fresh blood, in mice increases mortality from subsequent pneumonia, which occurs via mechanisms sensitive to hemopexin and TLR4 and HMGB1 inhibition.

Management of chronic myeloid leukemia in the setting of pregnancy: when is leukocytapheresis appropriate? A case report and review of the literature

BACKGROUND

Chronic myeloid leukemia (CML) is a common hematologic malignancy; however, its occurrence during pregnancy is unusual due to its low prevalence in females of childbearing age. There are conflicting reports of how to best manage CML in pregnancy, particularly in the setting of leukocytosis.

HEMAPHERESIS

A 30-year-old female was diagnosed with CML at 18 weeks' estimated gestational age. On initial presentation she reported fatigue, night sweats, and early satiety, and was found to have a white blood cell (WBC) count of 69.3 × 10⁹ /L and platelet count of 366 × 10⁹ /L. Her disease was managed during pregnancy using interferon-α alone despite persistent leukocytosis.

CONCLUSION

CML may be effectively managed during pregnancy, even in the setting of leukocytosis, without the application of leukocytapheresis. Management relies not only upon the coordination of drug therapy and fetal monitoring, but requires close communication between multiple medical disciplines. Leukocytapheresis has been safely performed during pregnancy and may be a suitable adjunct management strategy in pregnant patients diagnosed with CML with specific clinical presentations, such as hyperleukocytosis (WBC count > 150 × 10⁹ /L) and/or symptomatic leukostasis.

Reduction of doxorubicin-induced genotoxicity by Handroanthus impetiginosus in mouse bone marrow revealed by micronucleus assay

Handroanthus impetiginosus has long been used in traditional medicine and various studies have determined the presence of bioactive chemical compounds and potential phytotherapeutics. In this study, the genotoxicity of the lyophilized tincture of H. impetiginosus bark (THI) was evaluated in mouse bone marrow using micronucleus assays. The interaction between THI and genotoxic effects induced by the chemotherapeutic agent, doxorubicin (DXR), was also analyzed. Experimental groups were evaluated 24 to 48 h after treatment with N-nitroso-N-ethylurea (NEU; 50 mg/kg), DXR (5 mg/kg), sodium chloride (NaCl; 150 mM), and THI (0.5-2 g/kg). Antigenotoxic assays were carried out using THI (0.5 g/kg) in combination with NEU or DXR. Analysis of the micronucleated polychromatic erythrocytes (MNPCEs) indicated no significant differences between treatment doses of THI (0.5-2 g/kg) and NaCl. Polychromatic erythrocyte (PCE) to normochromatic erythrocyte (NCE) ratios did not indicate any statistical differences between DXR and THI or NaCl, but there were differences between THI and NaCl. A significant reduction in MNPCEs and PCE/NCE ratios was observed when THI was administered in combination with DXR. This study suggested the absence of THI genotoxicity that was dose-, time-, and gender-independent and the presence of moderate systemic toxicity that was dose-independent, but time- and gender-dependent. The combination of THI and DXR also suggested antigenotoxic effects, indicating that THI reduced genotoxic effects induced by chemotherapeutic agents.

Zika Virus and Patient Blood Management

Sporadic Zika virus infections had only occurred in Africa and Asia until an outbreak in Micronesia (Oceania) in 2007. In 2013 to 2014, several outer Pacific Islands reported local outbreaks. Soon thereafter, the virus was likely introduced in Brazil from competing athletes from French Polynesia and other countries that participated in a competition there. Transmission is thought to have occurred through mosquito bites and spread to the immunologically naive population. Being also a flavivirus, the Zika virus is transmitted by the Aedes mosquito that is endemic in South and Central America that is also the vector of West Nile virus, dengue, and chikungunya. In less than a year, physicians in Brazil reported a many-fold increase in the number of babies born with microcephaly. Despite initial skepticism regarding the causal association of the Zika virus epidemic and birth defects, extensive basic and clinical research evidence has now confirmed this relationship. In the United States, more than 4000 travel-associated infections have been reported by the middle of 2016 to the Centers for Disease Control and Prevention. Furthermore, many local mosquito-borne infections have occurred in Puerto Rico and Florida. Considering that the virus causes a viremia in which 80% of infected individuals have no symptoms, the potential for transfusion transmission from an asymptomatic blood donor is high if utilizing donor screening alone without testing. Platelet units have been shown to infect 2 patients via transfusion in Brazil. Although there was an investigational nucleic acid test available for testing donors, not all blood centers were initially required to participate. Subsequently, the US Food and Drug Administration issued a guidance in August 2016 that recommended universal nucleic acid testing for the Zika virus on blood donors.In this report, we review the potentially devastating effects of Zika virus infection during pregnancy and its implication in cases of Guillain-Barre syndrome in adults. Furthermore, we urge hospital-based clinicians and transfusion medicine specialists to implement perisurgical patient blood management strategies to avoid blood component transfusions with their potential risks of emerging pathogens, illustrated here by the Zika virus. Ultimately, this current global threat, as described by the World Health Organization, will inevitably be followed by future outbreaks of other bloodborne pathogens; the principles and practices of perioperative patient blood management will reduce the risks from not only known, but also unknown risks of blood transfusion for our patients.

Clinical Scoring Systems in Thrombotic Microangiopathies

Thrombotic microangiopathies (TMAs) are a group of rare but potentially lethal hematologic disorders characterized by platelet-rich thrombi in the microvasculature. In evaluating patients with TMA, it is crucial to identify those who have thrombotic thrombocytopenic purpura (TTP), a subtype of TMA that occurs due to a severe deficiency in ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motif, member 13). Individuals with TTP require urgent therapeutic plasma exchange, which is associated with a significant reduction in mortality; however, at most centers, the results of ADAMTS13 activity testing are usually not available for 3 to 5 days. Given the possible need for urgent intervention and the lack of timely test results to guide therapy, the assessment of patients with TMA represents an ideal situation for the deployment of diagnostic scoring systems to predict the presence of severe ADAMTS13 deficiency. Here, we review the literature surrounding clinical prediction tools in the diagnosis and prognostication of patients with TMA, describe the experience at our center with evaluating TMA patients, and discuss the utility of clinical scoring systems for TMA in the context of patient care.

Hospital-acquired anemia due to diagnostic and therapy-related blood loss in inpatients with myasthenia gravis receiving therapeutic plasma exchange

INTRODUCTION

Daily laboratory testing (DLT) is an important cause of iatrogenic anemia. Therapeutic plasma exchanges (TPE) represent another source of blood loss. This study investigated the contributions of DLT and TPE to changes in hemoglobin of inpatients with myasthenia gravis (MG) exacerbation.

STUDY DESIGN AND METHODS

All admissions for MG that included TPE between 2008 and 2012 were identified. The DLT- and TPE-related blood losses per patient were estimated based on the number of laboratory tests and TPE procedures. The primary endpoint was the difference between the discharge hemoglobin (Hgb) and the admission Hgb (ΔHgb). Univariate and multivariable analyses were used to identify clinical predictors of ΔHgb.

RESULTS

A total of 46 patients (52% male, average age of 58 years) had 90 hospitalizations and underwent 424 TPEs during the study-period. Their average length of stay (LOS) was 10.4 days, and total DLT and TPE-related blood losses were 107 and 94 mL, respectively. While 41% of patients were anemic on admission, 90% were anemic at discharge. The average ΔHgb was -2.2 g/dL. The patient's blood volume, renal function, admission number, LOS, and combined blood losses correlated with ΔHgb by linear regression, but only DLT was an independent predictor of ΔHgb in the multivariable analysis.

CONCLUSION

Approximately 50% of MG patients admitted for TPE developed hospital-acquired anemia, which was directly correlated with the volume of blood collected for laboratory tests. A variety of strategies to reduce DLT could circumvent this iatrogenic complication.

Fat Embolism Syndrome Secondary to Bone Marrow Necrosis in Patients with Hemoglobinopathies

Bone marrow necrosis with subsequent embolization of the fat and necrotic tissues into the systemic circulation causing fat embolism syndrome and multiorgan failure is a rare complication of patients with hemoglobinopathies. The exact etiology of this condition is not known. Because it occurs more often in patients with compound heterozygous conditions than in sickle cell disease, some patients are unaware of their predisposition. The initial symptoms are nonspecific, such as back and/or abdominal pain, fever, and fatigue, which may rapidly progress to respiratory failure and severe neurologic compromise. Common laboratory tests reveal anemia without reticulocytosis, thrombocytopenia, leukoerythroblastic picture with immature white cells and nucleated red blood cells, increased lactate dehydrogenase, high ferritin, and, sometimes increased creatinine. The diagnosis can be delayed because of an apparent lack of awareness about bone marrow necrosis with fat embolism syndrome, its rarity, and its similarities with other conditions such as thrombotic thrombocytopenic purpura. Although a bone marrow biopsy is diagnostic, waiting for it delays definitive treatment, which appears to be essential for the recovery of end-organ damage, such as neurologic and pulmonary damage. In our experience, either multiple units of red blood cell transfusion or, preferably, red cell exchange initiated promptly, is lifesaving.