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Abstract Aims It is unclear whether activated partial thromboplastin time (aPTT) or anti‐Xa is more accurate for monitoring heparin anticoagulation in mechanical circulatory support (MCS) patients. This study investigates the relationship between aPTT and anti‐Xa in MCS patients and identifies predictors of discordance. Methods and results aPTT and anti‐Xa were simultaneously measured in a prospective cohort of MCS patients receiving unfractionated heparin at a tertiary academic medical centre. Therapeutic aPTT and anti‐Xa levels were 60–100 s and 0.3–0.7 IU/mL, respectively, and concordance was defined as both levels being subtherapeutic, therapeutic, or supratherapeutic. To identify predictors of discordance, both a machine learning random forest model and a multivariate regression model were applied to patient demographics, device type, and 14 laboratory variables; 23 001 pairs of simultaneously measured aPTT/anti‐Xa were collected from 699 MCS patients. aPTT and anti‐Xa were concordant in 35.5% of paired observations and discordant in 64.5% (aPTT > antiXa 61.5%; aPTT antiXa) was associated with high INR, eGFR, and total bilirubin, as well as low platelets, haemoglobin, pre‐albumin, white blood cell count, and haptoglobin. Total artificial heart and durable ventricular assist devices were more likely to be associated with aPTT > anti‐Xa than temporary MCS devices. Conclusions aPTT and anti‐Xa were frequently discordant in MCS patients receiving heparin anticoagulation. Clinical conditions common in MCS patients such as concurrent warfarin use, malnutrition, haemolysis, and thrombocytopenia, as well as durable type of MCS devices were associated with a high aPTT relative to anti‐Xa.

IntroductionSepsis is a common cause of morbidity and mortality in the neonatal intensive care unit (NICU). The frequency and severity of sepsis-associated coagulopathy as well as its relationship to illness severity are unclear.MethodsWe performed a single-center, retrospective, observational cohort study of all infants admitted to the University of Florida Health (UF Health), level IV NICU between January 1st 2012 to March 1st 2020 to measure the frequency of sepsis-associated coagulopathy as well as its temporal relationship to critical illness in the NICU population. All clinical data in the electronic health record were extracted and deposited into an integrated data repository that was used for this work.ResultsWe identified 225 new sepsis episodes in 216 patients. An evaluation for sepsis-associated coagulopathy was performed in 96 (43%) episodes. Gram-negative pathogen, nSOFA score at evaluation, and mortality were greater among episodes that included a coagulopathy evaluation compared with those that did not. Abnormal coagulation results were common (271/339 evaluations; 80%) and were predominantly prothrombin times. Intervention (plasma or cryoprecipitate) followed a minority (84/271; 31%) of abnormal results, occurred in 40/96 (42%) episodes that were often associated with >1 intervention (29/40; 73%), and coincided with thrombocytopenia in 37/40 (93%) and platelet transfusion in 27/40 (68%). Shapley Additive Explanations modeling demonstrated strong predictive performance for the composite outcome of death and/or treatment for coagulopathy in neonates (f1 score 0.8, area under receiver operating characteristic curve 0.83 for those with abnormal coagulation values). The three most important features influencing the composite outcome of death or treatment for coagulopathy included administration of vasoactive medications, hematologic dysfunction assessed by the maximum nSOFA platelet score, and early sepsis (≤72 h after birth).ConclusionsA coagulopathy evaluation was performed in a minority of NICU patients with sepsis and was associated with greater illness severity and mortality. Abnormal results were common but infrequently associated with intervention, and intervention was contemporaneous with thrombocytopenia. The most important feature that influenced the composite outcome of death or treatment for coagulopathy was the administration of vasoactive-inotropic medications. These data help to identify NICU patients at risk of sepsis-associated coagulopathy.

Abstract Background Unfractionated heparin (UFH) is primarily monitored using activated partial thromboplastin time (APTT). However, the recent introduction of anti-activated factor X (anti-Xa) activity testing has provided a direct evaluation of Xa inhibition by anticoagulants. This study aimed to investigate discrepancies between APTT and anti-Xa activity during UFH monitoring in critically ill patients and explore their underlying causes. Methods This study analyzed 271 pairs of laboratory test results from blood samples of 99 critically ill patients receiving continuous intravenous UFH. Theoretical APTT values were calculated using fitted curve equations from spiked sample measurements with anti-Xa activity. Samples were categorized into three groups based on the measurement of the APTT/theoretical APTT ratio: the lower group ( 120%). Results The overall concordance rate between APTT and anti-Xa activity was 45%, with a 55% discrepancy rate. The lower group frequently showed apparent heparin overdoses, while coagulation factor activities in the lower and upper groups were higher and lower, respectively, than those in the concordant group. Particularly, the lower group exhibited higher factor VIII activity levels than the upper and concordant groups. Conclusions Discrepancies between APTT and anti-Xa activity were frequently observed, influenced by changes in coagulation factors activity levels. The lower and upper groups were classified as pseudo-heparin-resistant and coagulopathy types, respectively. Accurate monitoring of heparin in critically ill patients is crucial, especially in cases of pseudo-heparin resistance, where APTT values may wrongly indicate inadequate heparin dosing despite sufficient anti-Xa activity. Understanding these discrepancies is important for managing heparin therapy in critically ill patients. Trial registration: Not applicable.

Objectives Thrombin generation assays and activated partial thromboplastin time (aPTT)-based clot waveform analysis (CWA), are some examples of global coagulation assays. Each modality evaluates different aspects of the clot forming process to globally define haemostasis with exclusive measurement parameters. Data on CWA are emerging, but its performance against other haemostatic assays is yet to be ascertained. This study evaluates the correlation between aPTT-based CWA and CAT parameters across a range of INR in warfarin-treated patients.Patients/Methods A prospective study consisting of patients on warfarin anticoagulation with varying INR levels. CWA and CAT were performed for the study subjects.Results 54 samples were included covering an INR range from 1.33–6.89, with a mean of 4.31 +/- 1.13. For CAT parameters, endogenous thrombin potential (ETP) and peak thrombin were assessed. Both unadjusted and adjusted (adjusted for final plateau transmittance) aPTT-based CWA were evaluated for parameters min1 (maximum velocity), min2 (maximum acceleration) and max2 (maximum deceleration). Peak thrombin showed significant correlation with all CWA parameters (min1: r = 0.435, P

Background: Gold mining is the world's leading source of anthropogenic mercury pollution, negatively impacting not only miners but also the surrounding inhabitants; it has many effects on human health, especially cardiovascular problems, which lead to coagulation disorders and an increase in morbidity and mortality rate. The present study aimed to determine the prothrombin time (PT) and partial thromboplastin time (PTT) among Sudanese gold mining workers exposed to mercury. Methods and Results: This cross-sectional study was carried out among mining workers in the Red Sea state. A total of 50 mining workers were enrolled in the case group, and 50 non-mining apparently healthy subjects were the control group. About 5 ml of whole blood samples were collected in 3.2% sodium citrate blood collection tubes. Platelet poor plasma (PPP) for prothrombin time (PT) and partial thromboplastin time (PTT) measurements was obtained by using high-speed centrifugation. PT and PTT tests were performed using a standard method (Practical-Haemostasis.com.) with a Helena C2 coagulometer (Germany) and reagents manufactured by the Bio-med trademark (China). The mean age of miners was 33.5±11.5 years and occupation time - 1.94±2.1 years. The mean value of PTT was greater in the case group than in the control group (42.43±6.18 sec vs. 37.76±5.33 sec, P=0.000). In the age subgroup 40 years: 14.04±1.38 sec vs. 13.15±1.35 sec (P=0.045), respectively. The correlation analysis revealed a significant, direct correlation between PTT and occupation time (r=0.357, P=0.011). Conclusion: Prolonged coagulation time, notably PTT, has been revealed among mining workers, implying that these workers may have a clinically silent state of coagulation abnormalities.

Acquired hemophilia (AH) is a potentially life-threatening hemorrhagic disorder. We report the second confirmed case of COVID-19-associated AH in a 45-year-old female which, unfortunately, expired as her treatment failed. She presented to the emergency department with abnormal bleeding and spontaneous hemoptysis about ten days after a removal surgery of her epiglottis tumor. Aggregation tests, such as partial thromboplastin time (PTT), are recommended in patients with COVID-19 infection that have bleeding episodes.

Abstract Background The use of direct oral anticoagulants (DOACs) is a convenient therapeutic option for patients at risk of thrombosis. DOACs interfere with clot‐based testing for the identification of lupus anticoagulant antibodies (LACs) in patients with antiphospholipid syndrome (APS), a common cause of acquired thrombotic disease. Objectives To evaluate a commercially available reagent DOAC‐Stop for the removal of DOAC interference encountered in LAC testing. Patients/Methods We collected a cohort of 73 test samples from patients on DOAC therapy identified at a large institutional coagulation laboratory from March to December 2019, along with samples from 40 LAC positive and negative control patients not on therapy. Samples were treated with DOAC‐Stop and tested for anti‐Xa activity and thrombin time for the removal of apixaban, rivaroxaban, argatroban, and dabigatran activity from patient samples. Treated and untreated samples were tested using the activated partial thromboplastin time, silica clotting time, and dilute Russell’s viper venom time to evaluate the reliability and utility of DOAC‐Stop. Results DOAC‐Stop markedly reduced DOAC interference from test samples (P

Introduction: According to some studies, magnesium in pharmacological concentrations has antithrombotic effects, causing platelet dysfunction in vitro and in vivo. This study was performed with aim to evaluate the effect of magnesium sulfate on blood coagulation status in pregnant women with preeclampsia. Methods: This cross-sectional study was performed in 2013-2014 on 56 pregnant women with mild preeclampsia. Platelet count and magnesium levels, bleeding time (BT), prothrombin time (PT), and activated partial thromboplastin time (aPTT) were measured before and two hours after magnesium sulfate injection. Data were collected and analyze by SPSS software (version 16) and paired t-test and Chi-square test. P

Background and Aims: Coagulation dynamics after donor hepatectomy are complex. Having complete knowledge of the actual changes in the coagulation status during donor hepatectomy is important to prevent complications such as pulmonary embolism, deep vein thrombosis, and bleeding. Hence, the present study aimed to study the coagulation dynamics following open donor hepatectomy both by thromboelastography (TEG) and conventional coagulation tests (CCT). Methods: A total of 50 prospective liver donors were included. TEG and CCT [activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalised ratio (INR), fibrinogen, and platelet counts] were performed for each patient before surgery (baseline), on postoperative day (POD) 0, 1, 2, 3, 5, and 10. Results: TEG showed hypercoagulability in 28%, 38%, 30%, 46%, 42%, and 48% patients; in contrast INR showed hypocoagulability in 58%, 63%, 73%, 74%, 20%, and 0% patients on POD 0,1,2,3,5, and 10, respectively. Patients demonstrating hypercoagulability on TEG had significantly decreased reaction time (P = 0.004), significantly increased maximum amplitude (P < 0.001), and alpha angle value (P < 0.001). Postoperatively, INR, PT, and aPTT values increased significantly, while platelets and fibrinogen levels decreased significantly when compared to their baseline values. There was no coagulation-related postoperative complication in any of the patients. Conclusion: Hypercoagulability after donor hepatectomy is common. TEG showed hypercoagulability and did not show any hypocoagulability as suggested by the CCT. In patients undergoing donor hepatectomy, CCT may not reflect the actual changes incoagulation status and tests such as TEG should be performed to know the correct nature of changes in coagulation following donor hepatectomy.

Hemostasis is a very elaborate process, and its knowledge is essential for every interventional radiologist. Abnormal coagulation parameters are associated with an increased risk of bleeding and require appropriate management. This review aims to briefly discuss the pathophysiology of hemostasis, the role of currently available pharmacological agents affecting hemostasis, and the management of hemostasis during various percutaneous interventional procedures. A preprocedure proforma, when used as a checklist, can reduce procedure-related complications.

Background: So far, no study has investigated the effects of plasma transfusion in the patients with sepsis, especially in the terms of prognosis. Therefore, we aimed to explore the association of early fresh frozen plasma (FFP) transfusion with the outcomes of patients with sepsis.Methods: We performed a cohort study using data extracted from the Medical Information Mart for Intensive Care III database (v1.4). External validation was obtained from the First Affiliated Hospital of Wenzhou Medical University, China. We adopted the Sepsis-3 criteria to extract the patients with sepsis and septic shock. The occurrence of transfusion during the first 3-days of intensive care unit (ICU) stay was regarded as early FFP transfusion. The primary outcome was 28-day mortality. We assessed the association of early FFP transfusion with the patient outcomes using a Cox regression analysis. Furthermore, we performed the sensitivity analysis, subset analysis, and external validation to verify the true strength of the results.Results: After adjusting for the covariates in the three models, respectively, the significantly higher risk of death in the FFP transfusion group at 28-days [e.g., Model 2: hazard ratio (HR) = 1.361, P = 0.018, 95% CI = 1.054–1.756] and 90-days (e.g., Model 2: HR = 1.368, P = 0.005, 95% CI = 1.099–1.704) remained distinct. Contrarily, the mortality increased significantly with the increase of FFP transfusion volume. The outcomes of the patients with sepsis with hypocoagulable state after early FFP transfusion were not significantly improved. Similar results can also be found in the subset analysis of the septic shock cohort. The results of external validation exhibited good consistency.Conclusions: Our study provides a new understanding of the rationale and effectiveness of FFP transfusion for the patients with sepsis. After recognizing the evidence of risk-benefit and cost-benefit, it is important to reduce the inappropriate use of FFP and avoid unnecessary adverse transfusion reactions.

Abstract Background A prolonged activated partial thromboplastin time (APTT) of unknown cause is one of the most frequent reasons why outpatients are referred for hemostasis consultation. Nevertheless, very few data are available on the relative contribution of individual causes of this common clinical scenario. Here, we present a systematic evaluation of all causes of APTT prolongation in a consecutive population of outpatients referred for specialized hemostasis consultation during a 14‐year period. Methods All cases referred to an academic specialized hemostasis outpatient unit due to APTT prolongation of unknown etiology whose prolonged APTT was confirmed in the first visit were included in the study. Data were obtained from the electronic medical records. Results Among 187 consecutive patients, the most frequent causes were antiphospholipid antibodies in 22.6%, contact pathway factor deficiencies in 17.4%, other coagulation factor deficiencies in 11.6%, and vitamin K deficiency/liver disease in 11.6%. A definite cause was not identified in 22.1% of patients. Presence of antiphospholipid antibodies, and absence of bleeding symptoms were both associated with significantly longer APTT values compared to other categories/clinical scenarios. The investigation of each case required a mean of 18.2 additional tests per patient, with estimated costs ranging from US$191.60 to US$1055.60. Conclusions Our results describe the main causes of APTT prolongation in outpatients, as well as estimates of resource use required to investigate this condition, thus providing evidence supporting the importance of measures to minimize the indiscriminate use of this assay.

Background: Traumatic brain injury as one of the main causes of mortality and disability is associated with changes in blood coagulation parameters and coagulopathy. Therefore, in this study, we aimed to investigate the association between prothrombin time (PT), partial thromboplastin time (PTT), international normalized ratio (INR), and platelet count with Glasgow coma scale (GCS) in patients with brain trauma. Methods: In this prospective study, 120 patients with a brain injury admitted to intensive care units (ICU) of Alzahra hospital in Isfahan, Iran, were randomly selected. PT, PTT, INR, and platelet counts were measured at the time of admission to the intensive care unit and 24 hours after it. Findings: At the beginning of admission to intensive care unit, GCS had a significant correlation with platelet count (r = 0.31, P < 0.010), and reverse and significant correlation with PT (r = -0.29, P = 0.001), PTT (r = -0.32, P < 0.010), and INR (r = -0.29, P = 0.001). Similarly, 24 hours after admission to the intensive care unit, GCS had a direct and significant correlation with platelet count and also a significant and inverse correlation with PT, PTT, and INR (P < 0.050 for all). Conclusion: GCS has a direct correlation with blood platelet level, and has an inverse correlation with PT, PTT, and INR, and therefore, these blood coagulation parameters can be used to predict the severity of brain trauma in patients with head trauma.

Abstract Background Orthostatic hypercoagulability is proposed as a mechanism promoting cardiovascular and thromboembolic events after awakening and during prolonged orthostasis. We evaluated early changes in coagulation biomarkers induced by tilt testing among patients investigated for suspected syncope, aiming to test the hypothesis that orthostatic challenge evokes procoagulatory changes to a different degree according to diagnosis. Methods One-hundred-and-seventy-eight consecutive patients (age, 51 ± 21 years; 46% men) were analysed. Blood samples were collected during supine rest and after 3 min of 70° head-up tilt test (HUT) for determination of fibrinogen, von Willebrand factor antigen (VWF:Ag) and activity (VWF:GP1bA), factor VIII (FVIII:C), lupus anticoagulant (LA1), functional APC-resistance, and activated prothrombin time (APTT) with and without activated protein C (C+/−). Analyses were stratified according to age, sex and diagnosis. Results After 3 min in the upright position, VWF:Ag (1.28 ± 0.55 vs. 1.22 ± 0.54; p

Background: Regarding the limited studies about effects of addiction on coagulation factors as a risk factor for increasing coagulation, and its relation to coronary artery disease, we decided to investigate the effect of opium on inflammatory and coagulation factors in a controlled setting.Methods: This case-control study was performed using two groups of smoking males addicted to opium (27 cases) and not addicted to opium (27 cases). After collecting demographic data, venous blood samples were gathered and sent to laboratory for measuring homocysteine, fibrinogen, prothrombin time (PT), partial thromboplastin time (PTT), International Normalized Ratio (INR), and C-reactive protein (CRP) quantity. In order to analyze the data, we used independent t-test plus Mann-Whitney test with significance level of P < 0.05.Findings: The average age in this study was 32.2 ± 6.2 in case group and 33.3 ± 6.2 in control group. Comparing case and control groups regarding age and education showed no significant difference (P = 0.598 and P = 0.848, respectively). Mean daily smoking in case group was 7.9 ± 5.4 and 8.1 ± 5.0 in control group. Mean smoking duration in case group and control group was 10.1 ± 6.5 and 9.0 ± 7.2 years, respectively. There was no significant difference between two groups regarding smoking duration (P = 0.567). Comparison of inflammatory and coagulation factors showed no significant difference except for CRP and fibrinogen for which P = 0.661 and P = 0.889, respectively. Consumption-based comparison of inflammatory and coagulation factors showed no significant difference except for PT in oral and inhaled consumptions which showed a significant difference (P = 0.035).Conclusion: Results of this study suggest that opium addiction can be an influential factor in blood parameters and can lead to inflammatory and coagulation processes complications.

Background: Different approaches are available to irrigate the arterial catheter, such as continuous and intermittent techniques. However, there is a disagreement regarding the most appropriate method. Aim: this study aimed to compare the effect of two continuous and intermittent irrigation methods on complications of arterial catheter and partial thromboplastin time (PTT) in patients with coronary artery bypass (CABG) surgery. Method: This randomized clinical trial was conducted on 60 participants undergoing coronary artery bypass grafting surgery in open-heart surgery ICU at Imam Reza hospital in Mashhad, Iran, in 2016. In continuous group, the arterial catheter was continuously irrigated with heparin solution at the rate of 2cc/h, and in the intermittent group with a syringe containing 5cc heparin solution every 3 hours. In both groups, catheter was monitored and recorded every 3 hours (until 48 hours and 3 times from enrollment) in terms of complications of partial thromboplastin time. Data were analyzed using SPSS version 16. Results: The findingsof independent t-test showed that the two groups are homogeneous in age (P =0.48). The result of Fisher's exact test revealed no significant difference between the two groups in terms of average incidence of complications during the first 24 hours (P=0.55) and second 24 hours (P=0.55) after catheterization. Also during the 48 hours after surgery, independent t-test results showed no statistically significant difference in partial thromboplastin time (P=0.53) between the two groups. Implications for Practice: According to the results of the research based on the lack of difference between continuous and intermittent irrigation methods up to 48 hours after catheter replacement in terms of arterial catheter complications, further long-term follow-up researches are recommended.

Abstract Background and Objectives: Although activation of blood coagulation system in response to physical activity has been identified to some extent, but the contribution of eccentric activity in comparison with isometric activity as resistance exercise, is not clear yet. Therefore, this research was carried out with the purpose of investigating the effect of one session of eccentric and isometric resistance exercise on some coagulation factors in male bodybuilders. Methods: In this semi-experimental study, 28 volunteers were randomly selected from male bodybuilders and divided into two experimental groups and one control group. One of the experimental groups performed eccentric exercise [controlled return (extension) of the elbow flexion movement involving an eccentric contraction] and another group performed isometric exercises (holding barbell while flexing elbows at 45 degrees. In order to assess coagulation indices, blood sampling was performed 15 minutes before and immediately after the exercise. Results: Thromboplastin and prothrombin times did not significantly change immediately after the exercise, but the number of platelets significantly increased in both isometric and eccentric types of exercise immediately after the exercise. Conclusion: The results of isometric and eccentric acute resistance exercise showed that the exercise had no negative impact on blood coagulation factors, and increased coagulation system activity reflects the increased number of platelets. The difference between the results of researches carried out in this direction can be resulted from the difference between the exercise protocols, methods and measurement time, and level of preparedness of the participants in the research.

Background and Objective: Fluctuation in the homeostasis system is one of the main causes of heart attacks. There are contradectry reports regarding the effect of regular exercise, particularly resistance training on hemostasis indeces. This study was done to determine the effect of 8 weeks of resistance training on hemostasis indeces and lipid profile in adult men. Methods: In this clinical trail study, 16 adult men were randomly divided into interventional and control groups. Subjects in interventional group participated in a resistance training program including a period 3 days a week for 8 weeks session. Body mass index, level of fibrinogen, protrombin time (PT), partial thromboplastin time (PTT), platelet count, D-dimer fibrinolytic factor, Cholesterol, Triglyceride, HDL and LDL were measured for each subject. Results: After 8 weeks of resistance training, the level of fibrinogen, PT, PTT and platelets count were significantly reduced and D-dimer fibrinolytic factor increased in interventional group in compared to controls (P

We report on a 57-year-old woman with a pontine haemorrhage and an extremely prolonged activated partial thromboplastin time (aPTT) of more than 240 s, suggestive of a coagulation disorder. Given the location of the haemorrhage, which is associated with a high mortality rate, recombinant factor VIIa was administered, although not all necessary laboratory analyses could be performed at that time. In our case, a deficiency of factor XII was found, which is not associated with an increased bleeding risk. In an acute setting, evaluation of a prolonged aPTT may cause diagnostic and therapeutic challenges, in particular in situations where additional laboratory investigations may not be readily available.

INTRODUÇÃO: A utilização correta de um plasma-controle para a comparação com o plasma do paciente nos testes de coagulação é fundamental para a garantia de um resultado seguro dessas provas laboratoriais. OBJETIVO: O presente estudo analisou a viabilidade do uso de um pool de plasma caseiro, realizado com cinco (P5) e 20 (P20) amostras a partir de pacientes normais, para ser utilizado como controle normal do tempo de tromboplastina parcial (TTP). MATERIAL E MÉTODO: Os dois pools de plasma caseiro foram analisados em relação a um controle normal comercial (AP). Foram 10 dias de experimento e a cada dia os dois pools caseiro eram feitos. Para cada dia foi feito o TTP de P5, P20 e AP. Todos os pacientes com solicitação de TTP, em cada dia do experimento, tiveram a relação de tempos (R) determinada frente a P5, P20 e AP. As ferramentas estatísticas utilizadas foram média (X), análise de variância e teste de Tukey. RESULTADOS: A análise estatística demonstrou que os valores de TTP são significativamente diferentes entre AP e P5 e entre AP e P20, mas não há diferença significativa entre P5 e P20. Quando a relação de tempos foi analisada, não houve diferença significativa entre AP, P5 e P20. CONCLUSÃO: O estudo demonstrou que pode ser utilizado como controle normal um pool de plasma caseiro, feito a partir de cinco ou 20 amostras.INTRODUCTION: Proper utilization of plasma control for comparison with the plasma of patients with coagulation tests is critical to ensure a safe outcome of these laboratory tests. OBJECTIVE: The purpose of this work was to know if in-house preparations of polled plasma can be used as a normal control of partial thromboplastin time (PTT). MATERIAL AND METHOD: We make two polled plasma, one with five (P5) samples and another with 20 (P20) samples, both of them from normal patients. Both pooled plasma were analyzed in comparison with a commercial lyophilized control (AP). The experiment was performed in 10 days, and P5 and P20 were made daily. At each day PTT was performed for P5, P20 and AP. All patients who asked for TTP, in each day of this experience, got a time relation (R) determined by a P5, P20 e AP. Tukey test was used as statistical analysis. RESULTS: Statistically significant differences were detected among the PTT for AP and P5, AP and P20, but no difference between P5 and P20 was observed. When the time relations were tested, there were no significant difference, among AP, P5, and P20. CONCLUSION: We found that in-house preparations of polled plasma (P5 and P20) can be used as a normal control of PTT.

Se reevaluó el rango de referencia del tiempo parcial de tromboplastina activada (TPTA). Se obtuvo un rango de referencia de 29 a 40 seg. con una media () de 34,01 seg. Con nuestro sistema de reactivos se alcanzaron resultados aceptables en cuanto a la sensibilidad a diferentes niveles de actividad de los factores VIII y IX, se logró una alta correlación en ambos casos (r2 = 0,9842 y 0,9846, respectivamente) cuando se relacionó el TPTa con los diferentes niveles de actividad de los factores VIII y IX. Se obtuvo una respuesta lineal en el intervalo de actividad de heparina utilizado normalmente en la terapia (0,2 a 0,5 UI/mL) y se alcanó una buena respuesta a altas concentraciones de heparina (0,8 UI/mL), expresada por un valor finito del TPTa. Se corroboró la necesidad de alargar el tiempo de incubación con el activador a 10 min para mejorar la sensibilidad del ensayo a la heparinaThe reference range of the activated partial thromboplastin time (APTT) was reevaluated. A reference range from 29 to 40 seconds with a mean () of 34.01 sec. was obtained. By using our system of reagents, acceptable results were obtained as regards the sensitivity to different levels of activity of factors VIII and IX. A high correlation was attained in both cases (r2 = 0.9842 and 0.9846, respectively) when the APTT was associated with the different levels of activity of factors VIII and IX. A linear response was obtained in the interval of heparin activity commonly used in therapy (0.2 to 0.5 UI/mL) and a good response was attained at high concentrations of heparin (0.8 UI/mL) expressed by a finite value of APTT. The need to extend the incubation time with the activator to 10 min. to improve the sensitivity of the test to heparin was corroborated

Abstract This resource includes a problem-based learning (PBL) case on the dichotomy of child abuse and hemophilia A. The author's preferred implementation of the case had instructors handing out the first four pages of the case in Session #1, the following six pages after hearing and discussing the research in Session #2, and handing out the postscript and the expected learning issues during Session #3. At the end of Session #1, the case will have lead the students to research issues related to child abuse and greenstick fracture. Laboratory results and family history given in Session #2 then turn the case to hemophilia A, and students are expected to draw a pedigree chart from the provided family history as part of this session. It is our conviction that the progression from assuming the more common cause to diagnosing the less common cause happens fairly often in real life. Our expectation is that no facilitator can be an expert in all aspects of a case. Therefore, a file with background information has been written and is included. At our university, medical genetics is taught in first and second semester, so this version of the case most naturally is directed at first-year medical students in a similar program. The case can fairly easily be tweaked to involve more pathology (for example, insert an X-ray) for use in medical schools that teach genetics in the second year. This case has been used in the Ross University PBL program once or twice a year. It has been generally well received by facilitators and students alike.