Recognizing and managing hereditary and acquired thrombotic thrombocytopenic purpura in infants and children

We describe how infants and children with hereditary and acquired autoimmune thrombotic thrombocytopenic purpura (TTP) initially present and how they can be promptly diagnosed and effectively managed. These are uncommon disorders that are commonly misdiagnosed and can be rapidly fatal. TTP is caused by a severe deficiency of the plasma protease, A disintegrin and Metalloprotease with a ThromboSpondin type 1 motif, member 13 (ADAMTS13). Measurement of ADAMTS13 activity is becoming easily accessible. A common presentation of hereditary TTP is neonatal severe hemolysis and hyperbilirubinemia. However, the median age of diagnosis is not until 5.5 years. Plasma is effective treatment for exacerbations and for prophylaxis. Plasma may be replaced by recombinant ADAMTS13 when it becomes available. Acquired TTP is more frequent in older children, in whom it is more common in girls and is commonly associated with systemic lupus erythematosus. For acquired TTP, plasma exchange and immunosuppression are the current treatment for acute episodes; caplacizumab is now commonly used in adults and may replace plasma exchange.

Evidence-Based Strategies and Recommendations for Preservation of Central Venous Access in Children

Children with chronic illness often require prolonged or repeated venous access. They remain at high risk for venous catheter-related complications (high-risk patients), which largely derive from elective decisions during catheter insertion and continuing care. These complications result in progressive loss of the venous capital (patent and compliant venous pathways) necessary for delivery of life-preserving therapies. A nonstandardized, episodic, isolated approach to venous care in these high-need, high-cost patients is too often the norm, imposing a disproportionate burden on affected persons and escalating costs. This state-of-the-art review identifies known failure points in the current systems of venous care, details the elements of an individualized plan of care, and emphasizes a patient-centered, multidisciplinary, collaborative, and evidence-based approach to care in these vulnerable populations. These guidelines are intended to enable every practitioner in every practice to deliver better care and better outcomes to these patients through awareness of critical issues, anticipatory attention to meaningful components of care, and appropriate consultation or referral when necessary.

Rituximab for treatment of inhibitors in haemophilia A. A Phase II study

The development of antibodies against infused factor VIII (FVIII) in patients with haemophilia A is a serious complication leading to poorly controlled bleeding and increased morbidity. No treatment has been proven to reduce high titre antibodies in patients who fail immune tolerance induction or are not candidates for it. The Rituximab for the Treatment of Inhibitors in Congenital Hemophilia A (RICH) study was a phase II trial to assess whether rituximab can reduce anamnestic FVIII antibody (inhibitor) titres. Male subjects with severe congenital haemophilia A and an inhibitor titre ≥5 Bethesda Units/ml (BU) following a FVIII challenge infusion received rituximab 375 mg/m² weekly for weeks 1 through 4. Post-rituximab inhibitor titres were measured monthly from week 6 through week 22 to assess treatment response. Of 16 subjects who received at least one dose of rituximab, three (18.8%) met the criteria for a major response, defined as a fall in inhibitor titre to <5 BU, persisting after FVIII re-challenge. One subject had a minor response, defined as a fall in inhibitor titre to <5 BU, increasing to 5-10 BU after FVIII re-challenge, but <50% of the original peak inhibitor titre. Rituximab is useful in lowering inhibitor levels in patients, but its effect as a solo treatment strategy is modest. Future studies are indicated to determine the role of rituximab as an adjunctive therapy in immune tolerisation strategies.

Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Neonates and children differ from adults in physiology, pharmacologic responses to drugs, epidemiology, and long-term consequences of thrombosis. This guideline addresses optimal strategies for the management of thrombosis in neonates and children.

METHODS

The methods of this guideline follow those described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

RESULTS

We suggest that where possible, pediatric hematologists with experience in thromboembolism manage pediatric patients with thromboembolism (Grade 2C). When this is not possible, we suggest a combination of a neonatologist/pediatrician and adult hematologist supported by consultation with an experienced pediatric hematologist (Grade 2C). We suggest that therapeutic unfractionated heparin in children is titrated to achieve a target anti-Xa range of 0.35 to 0.7 units/mL or an activated partial thromboplastin time range that correlates to this anti-Xa range or to a protamine titration range of 0.2 to 0.4 units/mL (Grade 2C). For neonates and children receiving either daily or bid therapeutic low-molecular-weight heparin, we suggest that the drug be monitored to a target range of 0.5 to 1.0 units/mL in a sample taken 4 to 6 h after subcutaneous injection or, alternatively, 0.5 to 0.8 units/mL in a sample taken 2 to 6 h after subcutaneous injection (Grade 2C).

CONCLUSIONS

The evidence supporting most recommendations for antithrombotic therapy in neonates and children remains weak. Studies addressing appropriate drug target ranges and monitoring requirements are urgently required in addition to site- and clinical situation-specific thrombosis management strategies.

Deep venous thrombosis screening in patients with inherited bleeding disorders and central venous catheters

Children with inherited bleeding disorders often require central venous catheters (CVCs). Although CVCs are known to be complicated by deep venous thrombosis (DVT), little is known about the timeline of DVT development or risk of post-thrombotic syndrome (PTS). The aim of this study was to determine the timeline and confirm the incidence of thrombosis in patients with bleeding disorders who have CVCs. In 2002, we instituted a screening programme to monitor for CVC-related complications in children with haemophilia and von Willebrand disease. This is a retrospective review of this cohort. All children with CVC followed up between 1 January 2000 and 1 June 2009 were evaluated for DVT every 24 months with contrast venography and Doppler sonography. An institutional PTS severity scale was utilized at each visit. Thirty-six patients had 37 CVCs placed. Thirty patients had imaging studies, with DVT observed in 14 (47%). Most cases of DVT were diagnosed at the first venogram (median CVC duration 26 months). There were no abnormal ultrasound results. Sixteen patients (44%) had clinical findings consistent with PTS, including 10 (71%) with an abnormal venogram. Dilated chest wall veins appeared to be more strongly associated with underlying DVT (positive predictive value of 0.8) than arm circumference discrepancy. Successful transition to use of peripheral veins occurred at a median of 11 months after abnormal venograms. CVC-related DVT is common in children with inherited bleeding disorders and likely occurs earlier than previously thought. Clinical signs of PTS are also common, but long-term sequelae and severity of PTS are not known.

Stroke in sickle cell anemia: alternative etiologies

Stroke is common in children with sickle cell anemia, but is rarely attributed to the traditional causes of stroke identified in other children. An 11-year-old girl with sickle cell anemia presented with severe headache and was found to have recurrent bilateral multifocal strokes in a cardioembolic pattern. Evaluation revealed the presence of a patent foramen ovale, antiphospholipid antibodies, and elevations in factor VIII and lipoprotein(a). Sickle cell anemia is itself a hypercoagulable state with potential for increased right heart pressures, both of which predispose to paradoxical embolization via right-to-left intracardiac shunting of emboli, thus causing stroke. The present case suggests that the more traditional etiologies for pediatric stroke may also cause stroke in children with sickle cell anemia.

Symptomatic ileofemoral DVT after onset of oral contraceptive use in women with previously undiagnosed May-Thurner Syndrome

OBJECTIVE

May-Thurner syndrome is characterized by left common iliac obstruction secondary to compression of the left iliac vein by the right common iliac artery against the fifth-lumbar vertebra. This anatomic variant results in an increased incidence of left-sided deep venous thrombosis (DVT). Furthermore, while a preponderance of left-sided DVT has been demonstrated in women during pregnancy and oral contraceptive use, patients are not typically screened for this condition after developing a left-sided DVT. As anticoagulation alone is ineffective for DVT treatment in the setting of May-Thurner anatomy, more aggressive treatment is warranted. Failure to diagnosis this condition predisposes these women to the unnecessary risks of recurrent DVT and post-thrombotic syndrome.

METHODS

We present the occurrence of 7 adolescent patients with previously undiagnosed May-Thurner syndrome who presented with DVT after the initiation of oral contraceptive steroids (OCP) use. All 7 patients elected to proceed with mechanical thrombolysis/catheter based thrombolysis followed by endovascular stenting and were postoperatively treated with 6 months of warfarin.

RESULTS

Mean patient age was 18.3 +/- 3.3 years (range, 16-24 years). Mean time to presentation after initiation of OCP was 5 weeks (range, 2-10 weeks). Mean time to intervention was 16.8 days (range, 10-24 days). All patients were treated with mechanical thrombectomy. Our rate of intraoperative clot resolution was 100%. All 7 patients were treated with self expanding nitinol stents after angioplasty of the iliac vein stenosis with resolution of the stenotic segment. Primary stent patency is 100% (7/7). Mean follow-up time is 13 +/- 13.84 months (range, 6-42 months). There have been no long-term complications related to surgical treatment or anticoagulation. All 7 patients have experienced resolution of left leg swelling and pain and have no evidence of post-thrombotic syndrome or DVT recurrence to date.

CONCLUSIONS

Women on OCPs presenting with left-sided iliofemoral DVT should be screened for hypercoagulable disorders and underlying May-Thurner anatomy. Treatment of May-Thurner syndrome should include thrombolysis/thrombectomy and anticoagulation for current DVT in addition to angioplasty and stenting of the underlying obstruction.

Experience with intravenous enoxaparin in critically ill infants and children

OBJECTIVE

Subcutaneous administration of enoxaparin is often difficult in special populations, such as premature infants and critically ill children with severe edema. The difficulty achieving adequate anticoagulation in these patients has led to the employment of intravenous enoxaparin in some cases. However, little pharmacodynamic data are available for determining the appropriate dosing and monitoring (by anti-Factor Xa levels) of intravenous enoxaparin. The objective of this study is to report our experience with the use of intravenous enoxaparin in pediatric patients in the intensive care unit.

DESIGN

Retrospective review of medical records.

SETTING

Single institution pediatric intensive care unit.

PATIENTS

All pediatric patients receiving intravenous enoxaparin in the pediatric intensive care unit at Children's Medical Center Dallas between April 1, 2005 and March 31, 2006 were identified using hospital pharmacy records.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Seven patients were identified as having received intravenous enoxaparin while in the intensive care unit. Higher anti-Xa levels were found at 1-2 hrs after administration of intravenous enoxaparin rather than at the 4-6 hrs documented with subcutaneous administration and these levels decreased substantially 6-8 hrs after an intravenous dose. Mean therapeutic dose for children <1 yr of age was 2.40 mg/kg/dose (+/-sd 0.58). For children > or =1 yr of age, the mean therapeutic dose was 1.11 mg/kg/dose (+/-sd 0.13). The mean prophylactic dose for the two children was 0.93 mg/kg/dose (+/-sd 0.43).

CONCLUSIONS

Our data show that the pharmacodynamics of intravenous administration is different from subcutaneous administration and deserves further study.

Aspirin resistance in children with heart disease at risk for thromboembolism: prevalence and possible mechanisms

Aspirin is used to prevent thromboembolism in children with heart disease without evidence supporting its efficacy. Studies in adults report a 5%-51% prevalence of aspirin resistance, yet the mechanisms involved are poorly understood. Our aims were to determine its prevalence in these children and to explore its possible mechanisms. One hundred twenty-three cardiac patients routinely receiving aspirin were prospectively enrolled. Platelet function was measured by Platelet Function Analyzer (PFA)-100 using epinephrine and adenosine diphosphate (ADP) agonists. Aspirin resistance was defined as failure to prolong the epinephrine closure time following aspirin administration. Urine levels of 11-dehydro-thromboxane B(2) (11-dTXB(2)) were measured to determine inhibition of the cyclo-oxygenase pathway. The prevalence of aspirin resistance was 26%. Median ADP closure time was shorter for aspirin-resistant (79.60-115 s) than for aspirin-sensitive (100.60-240 s) patients (p < 0.01). 11-dTXB(2) levels did not correlate with aspirin resistance. Aspirin-resistant patients had higher 11-dTXB(2) levels before (7297 vs. 4160 pg/mg creatinine; p < 0.01) and after (2153 vs. 1412 pg/mg; p = 0.03) aspirin, with a similar percentage decrease in thromboxane (70.5% vs. 66.1%; p = 0.43). Our findings suggest that resistance is not entirely due to lack of inhibition of platelet thromboxane production. Alternative sources of thromboxane and thromboxane-independent mechanisms, such as ADP-induced platelet activation, may contribute to aspirin resistance.

Tissue plasminogen activator to prevent central venous access device infections: a systematic review of central venous access catheter thrombosis, infection and thromboprophylaxis

The recent unequivocal demonstration that prophylaxis, three to four weekly factor infusions, is effective in preventing joint disease in children with haemophilia, has provided impetus to initiate prophylaxis early in such children. Yet, nearly a quarter (22%) of the 83% who required central venous access devices for factor infusion developed central venous access catheter (CVAD)-related infection. This limitation of CVAD use prevents many families from initiating prophylaxis. The frequent occurrence of local thrombosis accompanying CVAD-related infection in surgical patients and autopsy cases, the thrombogenic plastic CVAD surfaces, and local clot formation at the insertion site, suggest the potential role of thrombolytic agents in preventing these infections. Yet, correlation between CVAD-related infection and local thrombosis in children with haemophilia are lacking, and thromboprophylaxis to prevent CVAD-related infection is controversial. Tissue plasminogen activator (t-PA), a recombinant serine protease glycoprotein that lyses plasmin-bound fibrin and is safe and effective in the treatment of occluded catheters, has not been evaluated in the prevention of these infections. We performed a literature review of CVAD-related infection, CVAD-related thrombosis, and thromboprophylaxis studies to evaluate the role of t-PA in the prevention of these infections in children with haemophilia. Metanalysis of published thromboprophylaxis trials demonstrate current prophylaxis regimens do not prevent CVAD infection, and further, that thrombosis and infection do not necessarily occur simultaneously. Pilot data demonstrate CVAD infection reduction in haemophilic children by monthly t-PA in 18 haemophilic children, suggesting the potential role of t-PA in CVAD infection prevention. Clinical trials to evaluate t-PA in CVAD infection prevention are justified.

Congenital Platelet Disorders

Congenital platelet disorders represent a rare group of diseases classified by either a qualitative or quantitative platelet defect. This article outlines the historical, clinical, laboratory, and genetic features of various inherited platelet disorders with attention given to updated information on disease classification, diagnosis, and genotypes. A separate discussion regarding management addresses the difficulty in treatment strategies, particularly in patients who develop alloimmunization to platelets.

Catheter-related deep venous thrombosis and other catheter complications in children with cancer

PURPOSE

Asymptomatic deep vein thrombosis (DVT) is a complication of central venous catheter (CVC) use in children with cancer, but its clinical significance is not well defined. Children with CVCs commonly experience two other CVC-related complications: occlusion and infection. The aim of this study was to determine the frequency of these two complications and their association with DVT.

PATIENTS AND METHODS

We conducted a retrospective cohort study of patients who were diagnosed with cancer. Data collected included number and type of catheter insertions, duration of use, reason for removal, associated catheter complications, and demographic information.

RESULTS

Catheters were placed in 287 patients for a total of 128,403 days (mean, 290 +/- 269 days/catheter). Of 21 patients (7%) diagnosed with CVC-related DVT, only five had specific signs or symptoms. Nineteen (90%) of these 21 children had prior history of catheter occlusion, and 10 of the 19 also experienced infection. Ten children (48%) were not identified as having DVT until they had had multiple catheters with recurrent complications. Odds of having DVT were higher in patients who had a single catheter complicated by repeated occlusions (odds ratio [OR], 3.7; P = .001) or infection (OR, 2.2; P = .016). Patients experiencing both infection and occlusion were at 6.4 times (P < .0001) higher risk of developing DVT.

CONCLUSION

Children with CVC-related DVT frequently have recurrent catheter complications. Unrecognized thrombosis may therefore be clinically important. Prospective studies are needed to determine if identification and treatment of occult DVT will prevent additional CVC-related complications and prolong the duration of catheter use.

Venous thrombosis and thromboembolism in children with osteomyelitis

OBJECTIVE

To determine the prevalence and clinical features of deep vein thrombosis (DVT) complicating osteomyelitis during childhood.

STUDY DESIGN

We retrospectively reviewed medical records of all patients with osteomyelitis admitted to Children's Medical Center Dallas between July 1, 2003 and December 31, 2004. Analysis was performed on patients with proximal upper or lower extremity, pelvic or vertebral osteomyelitis (a subgroup considered to be at highest risk for infection-related thrombosis).

RESULTS

Thirty-five patients had confirmed osteomyelitis of the proximal humerus, proximal tibia/fibula, femur, pelvis, or vertebrae. Ten of these 35 children (29%) developed DVT during the acute infection based on imaging studies performed. Eight thrombi occurred adjacent to the infection and two occurred in relation to central venous catheters. Six of the 10 children with DVT also had evidence of infection disseminated to lung, brain, or heart, compared with only 1 of 25 patients without DVT (P = .001). Hospitalization was longer in those with DVT than without (33.5 v. 14.2 days, P = .001).

CONCLUSION

Thromboembolic complications can occur in the setting of osteomyelitis, and affected patients may be at higher risk of disseminated infection.

Fatal central venous catheter-related infection in haemophilia

Central venous catheters (CVC) are frequently used in children with haemophilia to deliver factor infusions for the treatment or prophylaxis of bleeding. Complications of CVCs in patients with haemophilia include thrombosis and infection. We report a young boy with severe haemophilia A and an inhibitor who developed disseminated Staphylococcus aureus infection most likely related to a CVC. To our knowledge, this is the first reported case of fatal sepsis secondary to a CVC in a patient with haemophilia.

Post-thrombotic syndrome is uncommon in childhood cancer survivors

Deep vein thrombosis occurs in up to 50% of children with tunneled central venous catheters (CVCs). CVC-related deep vein thrombosis involving the upper extremity is usually asymptomatic but can result in post-thrombotic syndrome (swelling, pain, skin changes, and functional impairment). In a cohort of childhood cancer survivors evaluated clinically a mean of 7.5 +/- 2.8 years after completion of therapy who previously had CVCs in place for a median 15.5 months, none of 50 patients (95% CI = 0% to 6%) had these features diagnostic of post-thrombotic syndrome. Five patients had arm circumference 3% to 5% greater ipsilateral to the prior CVC.

Thrombosis during infancy and childhood: what we know and what we do not know

Despite underlying illnesses, children have a greater chance to survive and are expected to live 6 to 8 decades following an episode of venous or arterial thrombosis. The disproportionate benefits of preventing thrombosis and its sequelae in pediatric patients are evident. Therefore, it is necessary to develop appropriate strategies for diagnosis and management of thromboembolic events in children and to understand their acute and long-term effects. There still are many unanswered questions and clinical trials are being designed to help study these important issues.

Consensus recommendations for use of central venous access devices in haemophilia

Venous access is essential for delivery of haemophilia factor concentrate. Wherever possible, peripheral veins remain the route of choice, and the use of central venous access devices (CVADs) should be limited to cases of clear need in patients with caregivers able to exercise diligence in CVAD care and should continue no longer than necessary. CVADs are of recognized value for repeated administration of coagulation factors in haemophilia, particularly for prophylaxis and immune tolerance therapy and in young children. Evidence to guide best practices has been fragmentary, and standardized methods for CVAD usage have yet to be established. We have developed management recommendations based upon available published evidence as well as extensive clinical experience. These recommendations address patient and CVAD selection; CVAD placement, care and removal; caregiver/patient guidance; and complications, including infection and thrombosis. In the absence of inhibitors, ports are recommended, primarily because of fewer associated infections than with external catheters. For patients with inhibitors, ports also appear to be associated with fewer infections. Infection is the most frequent complication, and recommendations to prevent and treat infections are supported by extensive clinical data and experience. Strict adherence to handwashing and aseptic technique are essential elements of catheter care. Evidence-based data regarding the detection and treatment of CVAD-related thrombotic complications are limited. Caregiver education is an integral part of CVAD use and the procedural practices of users should be regularly re-assessed. These recommendations provide a basis for sound current CVAD practice and are expected to undergo further refinements as new evidence is compiled and clinical experience is gained.

Phase I study of oral cyclophosphamide and oral topotecan for children with recurrent or refractory solid tumors

BACKGROUND

To determine the maximum-tolerated duration and dose-limiting toxicity of a daily schedule of orally administered cyclophosphamide and topotecan in pediatric patients with recurrent or refractory malignant solid tumors.

METHODS

Patients received oral cyclophosphamide (50 mg/m2/dose) in the morning followed by topotecan (0.8 mg/m2/dose) 8-12 hr later for an escalating number of consecutive days (10, 14, and 17 days).

RESULTS

Seventeen pediatric patients were treated with oral cyclophosphamide and topotecan for durations of 10-17 days for a total of 58 treatment courses. Reversible hematologic toxicity (neutropenia and thrombocytopenia) was the dose-limiting toxicity. Nonhematologic toxicities of greater than grade 3 were not observed. A partial response (neuroblastoma following myeloablative chemotherapy and stem cell rescue) and prolonged stable disease (medulloblastoma) were each observed in one patient.

CONCLUSIONS

The recommended duration of therapy with a daily schedule of both oral cyclophosphamide (50 mg/m2/day) and topotecan (0.8 mg/m2/day) for previously treated pediatric patients with recurrent or refractory solid tumors is 14 consecutive days. The observed dose limiting toxicity (DLT) was reversible neutropenia. This regimen was well tolerated in heavily pretreated patients and demonstrated activity against recurrent pediatric solid tumors.

Thrombotic complications of central venous catheters in children

Use of central venous catheters has become standard in the treatment of many chronic conditions during childhood and for the acute treatment of critically ill infants and children. However, these catheters can be associated with numerous complications, including thrombosis at the tip or in the lumen causing difficulty with its overall function. Even more concerning is the occlusion of large veins into which the catheter is placed, which could predispose patients to pulmonary embolism or postthrombotic syndrome. Recent research has focused on identifying risk factors for catheter-related thrombosis in children and determining methods for diagnosing deep venous thrombosis associated with a catheter in the upper extremities. Evidence now exists that as many as 50% of children with catheters develop deep venous thrombosis; however, most events are clinically silent. Few clinical trials have studied prevention of catheter-related thrombosis in pediatric patients. Data regarding incidence, treatment, and long-term outcome of catheter-related thrombosis in children are limited. Although central venous catheters are extremely important in the supportive care of sick children, concerns remain about their immediate and long-term safety.

Arthroscopic synovectomy in children and adolescents with hemophilia

PURPOSE

To retrospectively review the authors' institutional experience with arthroscopic synovectomy in young patients with hemophilia.

PATIENTS AND METHODS

Patients with moderate or severe hemophilia seen in the authors' center were eligible to undergo synovectomy if they developed subacute or chronic synovitis that did not improve with prophylactic factor replacement. A single orthopedic surgeon performed all procedures. Each patient received aggressive physical rehabilitation and regular factor replacement for 6 weeks following surgery. Outcome data regarding the frequency of bleeding and range of motion were evaluated.

RESULTS

Twenty-eight arthroscopic synovectomies (11 knees, 12 ankles, 5 elbows) were performed on 26 joints in 20 hemophilia patients between November 1992 and May 2002. There were no intraoperative complications. One patient developed hemarthrosis 1 week postoperatively and another had a soft tissue hematoma at the incision site. Two patients required a second procedure on the same joint because of trauma that occurred 2 months following surgery. Follow-up data were available on 26 joints during the first year after the procedure. The frequency of hemarthrosis diminished significantly in that first year and was maintained for up to 5 years in all but three joints. Seventy-six percent of evaluable patients (19/25) had stable or improved joint function at their most recent comprehensive clinic visit. Patients whose range of motion worsened were older and required more than one procedure.

CONCLUSIONS

Arthroscopic synovectomy significantly reduces hemorrhage into the index joint and allows for stabilization of joint range of motion. This procedure should be considered in young hemophilia patients with chronic synovitis.

Severe Chronic Idiopathic Thrombocytopenic Purpura during Childhood: Definition, Management, and Prognosis

Chronic idiopathic thrombocytopenic purpura (ITP) can be categorized as mild, moderately severe, or severe. Severe chronic ITP during childhood is a rare disorder characterized by clinically significant mucocutaneous hemorrhage, usually in the setting of marked thrombocytopenia. It can cause substantial morbidity and rarely mortality. Many patients improve with time or even fully recover, but for those whose quality of life is negatively influenced by hemorrhage or side effects of conventional therapy (corticosteroids, intravenous immunoglobulin G, or anti-D), splenectomy is recommended. If splenectomy is unsuccessful or not feasible, other drug treatments are available, but few efficacy data exist, and the toxicity and cost of these treatments can be appreciable. Their use is best avoided outside of clinical trials conducted in specialty centers or in multi-institutional networks.

Catheter-related deep venous thrombosis in children with hemophilia

Central venous catheters (CVCs) are a common adjunct to hemophilia therapy, but the risk of CVC-related deep venous thrombosis (DVT) in hemophiliacs is not well defined. In a previous study, 13 patients with CVCs had no radiographic evidence of DVT. However, recent abstracts and case studies demonstrate that DVT does occur. Therefore, this study sought to determine the frequency of DVT in children with hemophilia and long-term CVCs and to correlate venographic findings with clinical features. All hemophilia patients with tunneled subclavian CVCs in place for 12 months or more were candidates for evaluation. Patients were examined for physical signs of DVT and questioned about catheter dysfunction. Contrast venograms were obtained to identify DVT. Fifteen boys with severe hemophilia were evaluated, including 9 from the initially studied group of 13. Eight patients had evidence of DVT, 5 of whom previously had normal venograms. Five of 15 patients had clinical problems related to the CVC, all of whom had DVT. Four of 15 patients had suggestive physical signs; 3 had DVT. The mean duration of catheter placement for all patients was 57.5 months (range, 12-102 months). For patients with DVT, the mean duration was 66.6 +/- 7.5 months, compared to 49.5 +/- 7.2 months for patients without DVT (P =.06). No patient whose CVC was in place fewer than 48 months had an abnormal venogram. Many hemophilia patients with CVCs develop DVT of the upper venous system, and the risk increases with duration of catheter placement.