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Chris Barnes

Publications and source records attributed to Chris Barnes.

15 recordsLinked to original sources
PubMed2006

Immune thrombocytopenia following successful treatment of cancer in children.

A predisposition to developing immune thrombocytopenia (ITP) has not been reported in survivors of childhood cancer. We report a case series of childhood cancer survivors who developed an isolated thrombocytopenia in the presence of a normocellular bone marrow. Five children, two with endodermal sinus tumors and three with acute lymphoblastic leukemia, developed ITP at a median of 4 years (range: 0.2-8 years) after completion of therapy. We suggest the association of ITP in survivors of childhood malignancy may not be co-incidental as chemotherapy may cause persistent immune dysfunction.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Venous thromboembolic disease: a single-centre case series study.

AIM: The epidemiology of venous thromboembolism in children has likely changed since first being described a decade ago because of evolving management strategies and a greater awareness of predisposing factors for thrombosis in children. The Royal Children's Hospital commenced a 4-year prospective registry of venous thrombosis in 1999 to determine the current Australian epidemiology of venous thrombosis in infants and children. METHODS: A prospective, single-centre registry was established to determine the prevalence, aetiology, diagnostic criteria, management and outcome of venous thromboembolism in an Australian tertiary paediatric centre. RESULTS: The incidence of venous thrombosis was 8.0/10 000 hospital admissions. Fifty-eight per cent of infants and 49% of children were male. Seventy-seven per cent of venous thromboses in infants were associated with central venous cannulation compared with 47% in children. Doppler ultrasonography was the most frequently used diagnostic tool. Treatment strategies varied between age groups. The all-cause mortality rate for infants and children in this study was 8.4% (direct thrombus-related mortality 0%). Fifteen per cent of all patients demonstrated complete resolution of their venous thrombosis at discharge, with 48% demonstrating complete resolution at follow-up assessment. Fifteen per cent of patients experienced significant thrombosis-related morbidity at follow-up assessment. CONCLUSION: In this single-centre registry, venous thrombosis in infants and children occurred with greater frequency than has previously been reported and its epidemiology varied. Central venous catheterisation continues to be a common precipitant to venous thrombosis. Optimal diagnostic and treatment interventions for venous thromboembolism have not yet been determined for infants and children, despite the significant incidence of long-term sequelae.

Adolescent↗
PubMed2006

Developmental haemostasis. Impact for clinical haemostasis laboratories.

Developmental haemostasis is a concept, now universally accepted, introduced by Andrew et al. in the late 1980's. However, coagulation analysers and reagents have changed significantly over the past 15 years. Coagulation testing is known to be sensitive to changes in individual reagents and analysers. We hypothesised that the reference ranges developed by Andrew et al. may not be appropriate for use in a modern coagulation laboratory. Our study was designed to determine whether a current day coagulation testing system (STA Compact analyser and Diagnostica Stago reagent system) was sensitive to age-related changes in coagulation assays. This is the first large scale study since Andrew et al. to determine the age associated numerical changes in coagulation proteins. Our results confirm the concepts of developmental haemostasis elucidated by Andrew et al. However, our results clearly demonstrate that the absolute values of reference ranges for coagulation assays in neonates and children vary with analyser and reagent systems. The results confirm the need for coagulation laboratories to develop age-related reference ranges specific to their own testing systems. Without this, accurate diagnosis and management of neonates and children with suspected bleeding or clotting disorders is not possible. Finally we present age related reference ranges for D-dimers, TFPI, and endogenous thrombin potential, previously not described.

Adolescent↗
PubMed2005

Prothrombotic abnormalities in childhood ischaemic stroke.

Childhood ischaemic stroke, incorporating arterial ischaemic stroke and cerebral sinus venous thrombosis, is associated with significant morbidity and mortality in children. The majority of cases in children present with well-recognised risk factors. The appreciation of the role prothrombotic abnormalities have in disease states is developing rapidly. Prothrombotic abnormalities are abnormalities of the coagulation system, fibrinolytic system, endothelial cells or platelets that lead to a reduced threshold for pathological thrombus formation. Our understanding of the role of prothrombotic abnormalities in childhood ischaemic stroke is increasing and has a direct bearing on the development of effective management and prevention strategies. We provide a brief background of prothrombotic abnormalities and review the available literature on prothrombotic markers in childhood ischaemic stroke. Overall, prothrombotic abnormalities have been identified in 20-50% of children presenting with AIS and 33-99% of children with cerebral sinus venous thrombosis. There appear to be a number of associations emerging including an increased frequency of factor V Leiden mutation, elevated lipoprotein (a), protein C deficiency and antiphospholipid antibodies in children presenting with arterial ischaemic stroke. The pathogenic role of prothrombotic abnormalities as predisposing to initial and recurrent childhood ischaemic stroke is becoming increasingly evident. The impact on treatment, however, will only be clarified with carefully designed, multi-institutional prospective studies.

Biomarkers↗
PubMed2005

Reduced bone density in children on long-term warfarin.

Vitamin K is essential for development of normal bone density and achieving adequate peak bone mass in childhood and is thought to be important in preventing the development of osteoporosis in later life. Warfarin, a vitamin K antagonist, is being used with greater frequency in children. The long-term effect of warfarin on bone density of children is not known. We performed a case control study survey of bone density in children on long-term warfarin (n=17, average duration of warfarin treatment 8.2 y) compared with randomly selected controls (n=321). There was a marked reduction in bone mineral apparent density of lumbar spine between patients and controls [patients 0.10 g/cm3; 95% confidence interval (CI), 0.93-0.11 g/cm3, controls 0.12 g/cm3; 95% CI, 0.11-0.12 g/cm3, p<0.001). The lumbar spine areal bone mineral density Z-score of patients was reduced compared with controls [patients, -1.96 (95% CI, -2.52 to -1.40). This difference persisted after adjustment for age and body size. The etiology for the reduced bone density is likely to be multifactorial, however, screening of children on long-term warfarin for reduced bone density should be considered.

Adolescent↗
PubMed2004

Point of care monitoring of oral anticoagulant therapy in children: comparison of CoaguChek Plus and Thrombotest methods with venous international normalised ratio.

This paper reports the outcome of a research protocol aimed at optimising warfarin monitoring in a tertiary pediatric centre. The Thrombotest INR was the standard monitoring test employed to manage oral anticoagulant therapy in children at the Royal Children's Hospital (RCH), Melbourne. This study compares the results of this standard method to the novel CoaguChek INR monitor and the "gold standard" technique of venous INR sampling. The objectives were to determine 1) if point-of-care techniques of measuring the INR (Thrombotest and CoaguChek) are accurate and reliable compared to INR results obtained from venous sampling, processed in an accredited laboratory, and 2) if INR results generated by POC devices can be safely used to manage oral anticoagulant therapy in children. 18 children (10 females and 8 males) participated in the study. Ages ranged from 9 months to 21 years (Mean 11.9 years; SD 5.03 years). The agreement between CoaguChek and venous INR measurements (r = 0.885) was shown to be higher compared to Thrombotest and venous INR (r = 0.700). Compared to the venous INR, values obtained with Coaguchek and Thrombotest crossed into or out of the therapeutic range in 25% and 36% of cases respectively. In 88% of the CoaguChek cases and 57% Thrombotest cases, the difference from the venous result was less than 0.5. The CoaguChek method of INR monitoring is a more accurate and reliable method compared to Thrombotest, in the pediatric population tested, and can be safely used to manage oral anticoagulant therapy in children.

Adolescent↗
PubMed2004

Reduced bone density among children with severe hemophilia.

OBJECTIVE: Children with severe hemophilia are at risk for reduced bone mineral density (BMD) because of reduced weight-bearing exercise and hepatitis C infection. Reduced bone density in childhood is a risk factor for osteoporosis in later life. STUDY DESIGN: We performed a cross-sectional survey of bone density among 19 children with severe hemophilia, at the Royal Children's Hospital. Results were correlated with findings of blinded objective evaluations of the joints of the lower limb and with hepatitis C status. RESULTS: The mean lumbar bone mineral apparent density for patients was reduced (0.102 g/cm3), compared with that for control subjects (0.113 g/cm3). The mean areal BMD z score was -0.92, which was significantly reduced, compared with that for control subjects. The difference in bone density was independent of body size. There was a statistically significant relationship between the lumbar BMD z scores and the maximal single joint evaluation scores, but there was no difference based on hepatitis C status. CONCLUSIONS: Our results suggest that children with severe hemophilia have reduced BMD. Patients at risk are those with signs of hemophilic arthropathy. Because osteoporosis may complicate the future treatment of patients with hemophilia, screening of young patients for reduced bone density is recommended.

Adolescent↗
PubMed2004

Clostridium septicum myonecrosis in congenital neutropenia.

Severe congenital neutropenia (SCN) and Clostridium septicum myonecrosis is an uncommon and life-threatening association requiring urgent combined aggressive medical and surgical management. We report 2 cases of SCN (1 with known Kostmann's syndrome and 1 not known at presentation to have a congenital neutropenic disorder but subsequently received a diagnosis of cyclic neutropenia) who presented with spontaneous C septicum myonecrosis. The cases highlight the importance of response to recombinant human granulocyte colony-stimulating factor in obtaining a satisfactory outcome for these patients. Early, empirical use of recombinant human granulocyte colony-stimulating factor in patients who are suspected of having a congenital neutropenia and who present with life-threatening sepsis is recommended.

Child, Preschool↗
PubMed2004

Thrombophilia interpretation in childhood stroke: a cautionary tale.

Several authors have reported a link between childhood stroke and inherited thrombophilia in recent years. The impact of such a relationship on management and outcome is yet to be determined, as is the potential cost-benefit ratio associated with the performance of thrombophilic screening in children presenting with ischemic stroke. We present a case that highlights the need for clinical and radiologic examinations to remain the definitive criteria used to diagnose stroke in children. The diagnosis should not be influenced by the finding of a thrombophilic marker.

Blood Coagulation Factors↗
PubMed2003

Warfarin therapy in children who require long-term total parenteral nutrition.

OBJECTIVE: To determine whether warfarin can be safely administered to children who require long-term total parenteral nutrition (TPN), for the purpose of preventing central venous access device (CVAD)-related thrombosis. METHODS: A prospective cohort study was conducted of 8 children with short-gut syndrome or small intestinal anomalies. All patients received oral anticoagulant therapy (warfarin) managed by the hematology department at a tertiary pediatric center. Data collected included demographic details, nutritional intake, age, weight, history of deep vein thrombosis, number and functional duration of CVADs, warfarin requirements, and adverse event rates. RESULTS: A total of 15.2 warfarin years were studied prospectively. The target therapeutic range was achieved 51.1% of time. The mean dose of warfarin required to achieve the target therapeutic range (international normalized ratio) of 2.0 to 3.0 was 0.33 mg/kg/d. The mean duration between warfarin monitoring tests was 6.6 days. The median vitamin K intake per patient was 0.367 mg/kg/d (range: 0.018-2.85 mg/kg/d). Before commencing anticoagulant therapy, the mean CVAD duration was 160.9 days. Concomitant warfarin therapy was associated with a mean CVAD duration of 351.7 days. There were no major bleeding events, and no clinical extension of thrombosis was observed. CONCLUSIONS: This is the first published study to report uniform warfarin prophylaxis for CVADs in children. Warfarin therapy can be administered safely in children who require long-term TPN. Warfarin prophylaxis seems to prolong CVAD survival.

Adolescent↗