Marc Zumberg

Activated Partial Thromboplastin Time Versus Antifactor Xa Heparin Assay in Monitoring Unfractionated Heparin by Continuous Intravenous Infusion

Background: Unfractionated heparin (UFH) has been used clinically for 5 decades. Despite being a cornerstone of anticoagulation, UFH is limited by its unpredictable pharmacokinetic profile, which makes close laboratory monitoring necessary. The most common methods for monitoring UFH are the activated partial thromboplastin time (aPTT) and antifactor Xa heparin assay (anti-Xa HA), but both present challenges, and the optimal method to monitor UFH remains unclear. Objective: To compare the performance of the aPTT with the anti-Xa HA for efficiency and safety of monitoring intravenous UFH infusions. Methods: This was a single-center, retrospective, observational cohort study conducted in an 852-bed academic medical center. Results: One hundred patients receiving intravenous UFH for a variety of indications were enrolled in the study; 50 were assigned to each group. The mean (SD) time to achieve therapeutic anticoagulation was significantly less in the anti-Xa HA group compared with the aPTT group (28 [16] vs 48 [26] hours, p < 0.001). In addition, a greater percentage of anti-Xa HA patients compared to aPTT patients achieved therapeutic anticoagulation at 24 hours (OR 3.5; 95% CI 1.5 to 8.7) and 48 hours (OR 10.9; 95% CI 3.3 to 44.2). Patients in the anti-Xa HA group also had more test values within the therapeutic range (66% vs 42%, p < 0.0001). A significant difference was seen between the 2 groups in the number of aPTT or anti-Xa HA tests performed per 24 hours (p < 0.0001) and number of infusion rate changes per 24 hours (p < 0.01), both favoring the anti-Xa HA group. Conclusions: Monitoring intravenous UFH infusions with the anti-Xa HA, compared to the aPTT, achieves therapeutic anticoagulation more rapidly, maintains the values within the goal range for a longer time, and requires fewer adjustments in dosage and repeated tests.

Management of a patient with a mechanical aortic valve and antibodies to both thrombin and factor V after repeat exposure to fibrin sealant.

We describe a patient who developed a markedly prolonged PT, PTT, and thrombin time 13 days after repeat exposure to fibrin sealant during coronary artery bypass grafting and aortic valve replacement. Evaluation revealed an inhibitor to bovine thrombin that cross‐reacted with human thrombin. In addition an inhibitor to human coagulation factor V was identified. Despite coagulation abnormalities there was no evidence of bleeding. Nevertheless, effective anticoagulation was required to minimize the thrombotic complications associated with the patients prosthetic valve. We elected to take a conservative approach and not utilize pharmacologic anticoagulation until there was diminution in the effect of the acquired inhibitors. We report on our patients course and review the available literature addressing the management of patients demonstrating inhibitors to blood coagulation factors after repeat exposure to fibrin sealants. Am. J. Hematol. 64:59–63, 2000.

The Use of Anti-Xa Assay to Monitor Intravenous Unfractionated Heparin Therapy

Continuous infusion unfractionated heparin (UH) has traditionally been monitored using the activated partial thromboplastin time (aPTT). The use of this test to monitor heparin therapy is not based on randomized controlled clinical trials, and the test is associated with significant intra- and inter-patient variability that is not related to circulating blood heparin activity. Due to these and other limitations, the use of aPTT alone to monitor UF has been questioned. Many laboratories are now transitioning to monitoring actual heparin activity (by anti-factor Xa analysis). In this review, we discuss the limitations of using the aPTT to monitor UH therapy and additionally the limitations of solely using heparin activity to monitor therapy. We also include a discussion of the challenges with monitoring heparin therapy in the pediatric population.

A case series of atypical presentations of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a heterogeneous disease primarily characterized by thrombocytopenia and microangiopathic hemolytic anemia. Therapeutic plasma exchange has dramatically improved mortality, allowing for emergence of refractory, relapsing, and atypical presentations. In this article, we describe four cases of TTP presenting with minimal schistocytes, mild elevation of lactate dehydrogenase, and symptoms suggestive of macrovascular arterial involvement. With increasing reports of less common presentations of TTP, clinicians should consider this diagnosis in cases of unexplained arterial thrombosis, thrombocytopenia, or hemolytic anemia. Testing for a disintegrin and metalloprotease with thrombospondin Type 1 motif, Member 13 ADAMTS13 activity was extremely useful to help confirm the diagnosis in our series of patients. J. Clin. Apheresis, 2012.

Successful implementation of a packed red blood cell and fresh frozen plasma transfusion protocol in the surgical intensive care unit.

Background Blood product transfusions are associated with increased morbidity and mortality. The purpose of this study was to determine if implementation of a restrictive protocol for packed red blood cell (PRBC) and fresh frozen plasma (FFP) transfusion safely reduces blood product utilization and costs in a surgical intensive care unit (SICU). Study Design We performed a retrospective, historical control analysis comparing before (PRE) and after (POST) implementation of a restrictive PRBC/FFP transfusion protocol for SICU patients. Univariate analysis was utilized to compare patient demographics and blood product transfusion totals between the PRE and POST cohorts. Multivariate logistic regression models were developed to determine if implementation of the restrictive transfusion protocol is an independent predictor of adverse outcomes after controlling for age, illness severity, and total blood products received. Results 829 total patients were included in the analysis (PRE, n=372; POST, n=457). Despite higher mean age (56 vs. 52 years, p=0.01) and APACHE II scores (12.5 vs. 11.2, p=0.006), mean units transfused per patient were lower for both packed red blood cells (0.7 vs. 1.2, p=0.03) and fresh frozen plasma (0.3 vs. 1.2, p=0.007) in the POST compared to the PRE cohort, respectively. There was no difference in inpatient mortality between the PRE and POST cohorts (7.5% vs. 9.2%, p=0.39). There was a decreased risk of urinary tract infections (OR 0.47, 95%CI 0.28-0.80) in the POST cohort after controlling for age, illness severity and amount of blood products transfused. Conclusions Implementation of a restrictive transfusion protocol can effectively reduce blood product utilization in critically ill surgical patients with no increase in morbidity or mortality.

GM-CSF versus G-CSF: engraftment characteristics, resource utilization, and cost following autologous PBSC transplantation

BACKGROUND G-CSF and GM-CSF have both been shown to decrease the time to hematopoietic recovery when administered after autologous BM or peripheral stem cell re-infusion. However, few studies have compared G-CSF and GM-CSF to determine which is the preferred myeloid growth factor. METHODS This study compares a prospectively accrued cohort of 22 patients receiving GM-CSF with a historical cohort of patients who received G-CSF commencing Day + 6 after autologous PBSC transplantation. Patients were matched based on disease type and stage, CD34(+) cell dose/kg, conditioning regimen, and prior treatment. Time to myeloid engraftment, growth factor utilization, antibiotic utilization, fever incidence, and cost were compared. RESULTS The median time to neutrophil and platelet engraftment was similar in the two groups (ANC > 500 /mm(3), GM-CSF 12 versus G-CSF 11, P = 0.69). There was a trend towards more days of temperature > 38.0 masculine C (six versus three, P = 0.05) and febrile neutropenia (three versus two, P = 0.06) in the GM-CSF arm. There was a trend towards increased use of i.v. antibiotics in the GM-CSF cohort (7.6 days versus 5.5 days, P = 0.06). More chest X-rays (1.5 versus 1.0, P = 0.03) were ordered, and more blood cultures drawn (4.2 versus 2.7, P = 0.05) as part of fever evaluation in the group treated with GM-CSF. Resource utilization based on actual wholesale pricing (AWP) favored the G-CSF cohort. Applying a sensitivity analysis, GM-CSF became cost-effective when priced below

Feasibility of Extended-interval Follow-up for Patients Receiving Warfarin.

94 per 250 micro g, despite greater resource utilization. DISCUSSION This study suggests that engraftment characteristics are similar with GM-CSF and G-CSF following PBSC transplantation. Resource utilization for fever treatment and evaluation may be greater with GM-CSF. Determination of which agent is more cost-effective depends on institutional acquisition costs.

Clinical Experience With Prophylactic Fondaparinux in Critically Ill Patients With Moderate to Severe Renal Impairment or Renal Failure Requiring Renal Replacement Therapy

AIMS The 2012 American College of Chest Physician Evidence-Based Management of Anticoagulant Therapy guidelines suggest an international normalized ratio (INR) testing interval of up to 12 weeks, rather than every 4 weeks, for patients with consistently stable INRs while taking vitamin K antagonists. We aimed to examine the feasibility of extended-interval follow-up in a real-world setting. METHODS Patients receiving stable warfarin therapy for ≥ 12 weeks at baseline began extended-interval follow-up with visits occurring at 6 weeks, 14 weeks, and every 12 weeks thereafter to a maximum of 68 weeks or until they were no longer suitable for extended-interval follow-up. A single INR excursion >0.3 from goal was permitted if a reversible precipitating factor was identified and the INR was expected to return to goal without dose adjustment. The primary outcome was the proportion of patients completing all study follow-up visits. RESULTS Of 48 patients enrolled, 47 had evaluable data. The most common indication for anticoagulation was atrial fibrillation/flutter (53.2%). At baseline, mean prior warfarin treatment duration was 6.7 ± 6 years and median number of weeks on a stable regimen was 24 weeks (IQR, 19-37.5). Eleven patients (23%) completed all study follow-up visits, whereas 17 (36%) did not maintain a stable INR past the 14-week follow-up. CONCLUSION A large proportion of patients with previously stable (≥ 3 months) INRs were not able to maintain stable INRs during extended-interval follow-up. More research is needed to identify patient characteristics predictive of success with extended-interval follow-up prior to broad implementation.

Management of granulomatous lymphocytic interstitial lung disease in a patient with common variable immune deficiency

Background: Fondaparinux has an increased bleeding risk in patients with a CrCl ≤ 50 mL/min and is contraindicated if CrCl < 30 mL/min. Data regarding dosing and anti-Xa monitoring are lacking in this population. Objective: To describe dosing, monitoring, and safety outcomes of prophylactic fondaparinux in critically ill patients with moderate to severe renal impairment, including renal replacement therapy (RRT). Methods: Retrospective analysis from October 2006 to November 2012 of patients ≥ 18 years old who received fondaparinux for ≥ 72 hours with ≥ 1 dose in an intensive care unit and a CrCl ≤ 50 mL/min or RRT during therapy. Participants were divided into 4 cohorts: moderate impairment (CrCl = 30-50 mL/min), severe impairment (CrCl < 30 mL/min), hemodialysis (HD), or continuous venovenous hemofiltration (CVVH). Outcomes included the incidence of clinically significant bleeding and thromboembolic events. Fondaparinux dose, dosing frequency, and anti-Xa level monitoring are described. Pharmacokinetic modeling was performed to assess drug accumulation. Results: In all, 95 patients met inclusion criteria: 64 (67.4%) with moderate impairment, 10 (10.5%) with severe impairment, 5 (5.3%) with HD, and 16 (16.8%) with CVVH. The median defined daily doses in the moderate, severe, HD, and CVVH cohorts were 2.5, 2.5, 0.9, and 1.9 mg. Anti-Xa monitoring occurred in 19 (20%) patients, although few concentrations were peaks. Clinically significant bleeding occurred in 4 (4.2%) patients. A pharmacokinetic model demonstrated drug accumulation. Conclusions: Empirical dose adjustments may be prudent in critically ill patients with renal dysfunction; however, the optimal fondaparinux dosage in this population remains unknown. Peak anti-Xa concentrations may help guide therapy.

Preclinical Medical Student Hematology/Oncology Education Environment

A 61-year-old woman presented with longstanding cough and progressive dyspnoea. She underwent an extensive evaluation and was diagnosed with common variable immunodeficiency (CVID) with granulomatous lymphocytic interstitial lung disease (GLILD). She was initially treated with subcutaneous immunoglobulin therapy, having declined intravenous immunoglobulin (IVIG) therapy. She also declined treatment with oral glucocorticoids. Over several months, she became increasingly symptomatic and developed increased pulmonary infiltrates, pleural effusions, mediastinal adenopathy, splenomegaly, pancytopenia and ascites. An interdisciplinary team composed of an immunologist, pulmonologist and haematologist deliberated over a therapeutic management approach. The patient received a recently reported immunotherapy regimen with azathioprine and rituximab. The therapy led to rapid improvement of her constitutional and respiratory symptoms, with clinical and radiographic improvement in her interstitial lung disease, lymphadenopathy, pleural effusions and ascites. This case report reviews the literature surrounding the diagnosis and management of GLILD.