Hemostasis in the Pregnant Woman, the Placenta, the Fetus, and the Newborn Infant

The hemostasis system is composed of procoagulant, anticoagulant, and fibrinolytic proteins that interact with endothelial and blood cells and with each other in a complex system of checks and balances to maintain blood flow while preventing both hemorrhage and thrombosis. Pregnancy is a unique physiological state in which biological alterations predispose both mother and fetus to both bleeding and clotting. The placenta is a vascular interface for maternal and fetal blood exchange which predisposes the mother to hemorrhage. Maternal hemostasis presents a compensatory hypercoagulability including elevated factor VIII, von Willebrand factor, fibrinogen and thrombin generation, decreased thrombin regulation with resistance to activated protein C and decreased free protein S, and decreased fibrinolysis with increased plasminogen activator inhibitors. The placental vascular surface is of fetal trophoblastic origin that derives many characteristics of endothelium but differs in that tissue factor is constitutively expressed. Ontogeny of fetal hemostasis is characteristic. Platelets, von Willebrand factor, factor VIII, and fibrinogen are expressed and mature early in gestation, while vitamin K-dependent and contact factors exhibit delayed development. The fetal hemostatic system has a decreased capacity to generate or regulate thrombin, resulting in a fragile balance with little capacity to compensate under stress conditions, particularly in the infant born prematurely. Dysfunction of the maternal/placental/fetal unit gives rise to gestational disorders including preeclampsia, fetal growth restriction, placental abruption, and premature delivery. Knowledge of normal hemostasis levels and function are critical to evaluate bleeding or clotting syndromes in the pregnant woman and her fetus or newborn infant.

Emicizumab initiation and bleeding outcomes in people with hemophilia A with and without inhibitors: A single-center report

BACKGROUND

Emicizumab, a bispecific antibody factor VIII mimetic, is approved for prophylaxis in hemophilia, and has different risks and side effects compared to factor VIII products.

OBJECTIVE

To better understand the early impact of emicizumab on our patients at the University of Colorado Hemophilia and Thrombosis Center (UCHTC), we evaluated adverse reactions, factor prophylaxis overlap, and bleeding rates after starting emicizumab through a quality improvement project.

PATIENTS/METHODS

A retrospective chart review and structured phone interview were conducted from June to September 2019 for all patients who had started emicizumab at the UCHTC. Data about emicizumab dosing, reactions, bleeding events, and bleeding treatment were collected in 68 children and adults (aged 0.55-79.8 years, on emicizumab a median 213 days; range, 51-1229 days) with hemophilia A (35.3% with past or current inhibitor).

RESULTS

Adverse reactions were primarily skin reactions, with no anaphylactic reactions or thrombosis. Bleeding events, defined as pain or swelling treated with factor or supportive measures, demonstrated wide variability, with 25 of 68 experiencing zero bleeds and 5 of 68 experiencing >8 bleeds per year. The most prevalent bleed type was traumatic musculoskeletal bleeding. Bleeding events occurred more often in the first 10 weeks after starting emicizumab, but no time period was without bleeding events. The majority of patients were prescribed every-week or every-2-week dosing, but some had alternative dosing frequency.

CONCLUSIONS

Real-world emicizumab use in our center was characterized by variations in prescribing practices and bleeding outcomes and lack of severe adverse reactions.

Validation of Outcome Instruments for Pediatric Postthrombotic Syndrome: Introducing the Peds-VEINES-QOL, a New Health-Related Quality of Life Instrument

BACKGROUND

 There is need for validated outcome measures for postthrombotic syndrome (PTS) following pediatric venous thromboembolism (VTE), with a focus on quality of life (QoL).

AIMS

 This article assesses reliability and validity of two PTS and two QoL scales for children following lower extremity VTE.

METHODS

 Pediatric patients following lower extremity VTE were recruited from three thrombosis clinics. The Manco-Johnson (MJ) and the modified Villalta (MV) PTS scales were compared with each other and with the generic pediatric health-related QoL, PedsQL, and a newly developed pediatric venous-specific QoL, the Peds-VEINES-QOL.

RESULTS

 Eighty children following VTE and 60 healthy control children were enrolled. Internal consistency measured by Cronbach's α was high for the two QoL scales, and moderate for the two PTS scales. Inter-rater reliability using intraclass correlation coefficients was moderate to high for the MJ, MV, and Peds-VEINES-QOL, and moderate for the PedsQL. Evidence of high internal consistency by Cronbach's α coefficients, and moderate to high interitem correlations support the premise that a single construct was measured by each instrument. Correlations between the four instruments indicate convergent validity.

CONCLUSION

 The MJ and MV scales detect similar outcomes in children following VTE. As used, the MJ is slightly more sensitive to QoL because a positive diagnosis requires pain which is the leading factor in reduced QoL following deep vein thrombosis. When using the MV, a requirement for pain or abnormal use to diagnose PTS would make the MV a better predictor of QoL.

Antithrombin deficiency: A pediatric disorder

INTRODUCTION

Hereditary antithrombin (AT) deficiency is an autosomal dominant thrombophilic disorder. Guidelines do not support routine testing of children based on personal or familial thrombosis.

AIM

To investigate clinical, genetic and laboratory profiles of AT deficient children and their affected family members.

MATERIALS AND METHODS

Data were analyzed from a prospective cohort of pediatric patients with AT deficiency. The SERPINC1 gene was sequenced for all individuals with available DNA. AT, thromboelastography (TEG), calibrated automated thrombogram (CAT), D-dimer, thrombin-antithrombin complex (TAT) and factor VIII activity were performed on patient samples.

RESULTS

Thirty-six individuals from 11 families had AT deficiency (activities 45-70 U/dL) with incident thrombosis in 13 children and 10 adults (64% overall). Three neonates presented with middle cerebral artery and/or aortic occlusions with inferior vena cava and cerebral or renal vein thromboses in 2 of the 3. Two pre-pubertal children were symptomatic, one with cerebral venous sinus thrombosis who suffered recurrent arterial and venous thrombi. Both Type I and Type II AT deficiencies conferred a high severity of thromboses. Heterozygous SERPINC1 mutations were identified in seven families; three were novel, resulting in missense, splice site and frameshift alterations. Thrombin generation (CAT) was increased in all asymptomatic affected patients including 9 children and 1 adult.

CONCLUSIONS

Genetic AT deficiency often presents in infants and children, warranting laboratory evaluation based on personal and family history. Increased thrombin generation was detected in all asymptomatic children and adults, suggesting a possible role in detecting and monitoring individuals at risk for thrombosis.

Outcome measures in Haemophilia: Beyond ABR (Annualized Bleeding Rate)

Options for management of haemophilia are increasing rapidly with completely novel therapeutic approaches that cannot be compared using traditional factor assays. In addition, as prophylaxis regimens have improved, bleeding rates have decreased, and consequently, it is difficult to show an impact of novel therapies on rates of spontaneous bleeding. There is currently an urgent need for a panel of outcome measures to compare therapies that are dissimilar in many essential ways. Conventional objective outcome measures including joint physical examination and joint imaging continue to hold a central importance. Factor assays are essential for evaluation of products derived from native factor genes, but are not applicable to some extended half-life factors or non-factor bypassing agents. Global assays including thrombin generation and chromogenic assays of factor X activation are under investigation for their usefulness in haemophilia assessment. Bleeding rate is a conventional subjective patient-reported outcome that, while decreasing in frequency, is indispensable as an outcome given that the primary manifestation of haemophilia is bleeding. Other patient-reported outcomes such as pain intensity and interference, health-related quality of life and activities and participation are increasingly important to distinguish superior outcomes in comparative trials. This review of outcome measures for haemophilia presents examples of existing outcome measures with an emphasis on their strengths and limitations.

Factor VIII prophylaxis effects outweigh other hemostasis contributors in predicting severe haemophilia A joint outcomes

INTRODUCTION

The Joint Outcome Study (JOS) demonstrated that previously untreated children with severe haemophilia A treated with prophylactic factor VIII (FVIII) concentrate had superior joint outcomes at age 6 years compared to those children treated episodically for bleeding. However, variation in joint outcome within each treatment arm was not well explained.

AIM

In this study, we sought to better understand variation in joint outcomes at age 6 years in participants of the JOS.

METHODS

We evaluated the influence of FVIII half-life, treatment adherence, constitutional coagulant and anticoagulant proteins, and global assays on joint outcomes (number of joint bleeds, total number of bleeds, total MRI score and joint physical exam score). Logistic regression was used to evaluate the association of variables with joint failure status on MRI, defined as presence of subchondral cyst, surface erosion or joint-space narrowing. Each parameter was also correlated with each joint outcome using Spearman correlations.

RESULTS

Prophylaxis treatment arm and FVIII trough were each found to reduce risk of joint failure on univariate logistic regression analysis. When controlling for treatment arm, FVIII trough was no longer significant, likely because of the high level of covariation between these variables. We found no consistent correlation between any laboratory assay performed and any joint outcome parameter measured.

CONCLUSION

In the JOS, the effect of prescribed prophylactic FVIII infusions on joint outcome overshadowed the contribution of treatment adherence, FVIII half-life, global assays of coagulation and constitutional coagulation proteins. (ClinicalTrials.gov number, NCT00207597).

Time-kill profiles of Enterococcus to antibiotics used for intravitreal therapy

BACKGROUND AND OBJECTIVE

To determine and then compare the time-kill profiles of Enterococcus to antibiotics used for intravitreal therapy.

PATIENTS AND METHODS

The time-kill profiles of four endophthalmitis isolates of Enterococcus faecalis, one vancomycin-resistant E. faecalis isolate, and three vancomycin-resistant isolates of E. faecium were determined against vancomycin, amikacin, cefazolin, gentamicin, ampicillin, ciprofloxacin, ceftazidime, clindamycin, and the combinations of vancomycin and amikacin, vancomycin and ceftazidime, vancomycin and gentamicin, vancomycin and ampicillin, cefazolin and gentamicin, and ampicillin and gentamicin.

RESULTS

No single antibiotic or combination was bactericidal (defined as 99.9% kill) to all isolates of Enterococcus. Gentamicin was bactericidal to all E. faecalis isolates. None of the tested antibiotics were bactericidal to vancomycin-resistant E. faecium.

CONCLUSIONS

The time-kill profiles demonstrated that vancomycin and ceftazidime did not produce a 99.9% kill for E. faecalis in this small study. Gentamicin combined with either cefazolin or ampicillin had somewhat better bactericidal activity and should be considered as an alternative therapy. Novel therapy may be necessary to treat endophthalmitis because of vancomycin-resistant Enterococcus, depending on the susceptibility patterns of the individual isolate and the response to initial therapy.

Influence of patient position on withdrawal forces during removal of lumbar extradural catheters

We have investigated the force required to remove lumbar extradural catheters from 88 parturients to determine the effects of patient positioning at removal, relative to the position at insertion. Parturients were allocated randomly to one of four groups: LS (lateral insertion, sitting withdrawal), LL (lateral insertion, flexed lateral withdrawal), SL (sitting insertion, lateral withdrawal) or SS (sitting insertion, sitting withdrawal). In both positions, the lumbar spine was kept maximally flexed. The force required to remove the catheter was measured at withdrawal. We found that the withdrawal force was influenced by the relationship between the position at removal and that at insertion, and we recommend that for ease of removal, patients should be placed in the same position as they were at the time of insertion. Compared with all other groups, the withdrawal force in patients in group LS was significantly greater (P < 0.05).

AIDS and the eye

The AIDS pandemic has finally emerged from the big cities to the small towns of this country, as patients with this disease are returning home to spend their last months and days in the care of their families. No physician will be spared from caring for patients with AIDS. This multisystem disease crosses the boundaries of primary and specialty medicine, and with its various manifestations, presents to virtually all health care professionals. This infection has an enormous impact on our society: economically, socially, and medically. The seriousness of this condition is reflected in the medical school curriculum at the University of Pittsburgh. AIDS education begins the first day of the first year for our medical students.

Coagulopathy with the use of hetastarch in the treatment of vasospasm

The use of colloid agents to achieve hypervolemia in the prevention and treatment of postsubarachnoid hemorrhage (post-SAH) vasospasm is included in the standard of care at many institutions. Risk profiles are necessary to ensure appropriate use of these agents. In a series of 85 patients with recent aneurysmal SAH, 26 developed clinical symptoms of vasospasm. Fourteen of the 26 were treated with hetastarch for volume expansion while the other 12 received plasma protein fraction (PPF). Clinically significant bleeding pathologies were noted in six patients who received hetastarch as a continuous intravenous infusion. Hetastarch increased partial thromboplastin time from a mean of 23.9 seconds to a mean of 33.1 seconds (p < 0.001) in all patients who received infusions of this agent, while no effect was noted in the 12 patients who received PPF infusions. No other coagulation parameters were altered. This study shows an increase in coagulopathy with the use of hetastarch as compared with the use of PPF for the treatment of postaneurysmal vasospasm.