Summary. Reliable venous access is essential to facilitate the administration of prophylactic factor concentrate or blood products in children with congenital coagulation disorders and immune tolerance therapy (ITT) regimens in those who develop high responding inhibitors. Poor venous access is even more problematic in very young children, the vast majority of whom will require the insertion of central venous access devices (CVADs). Previous studies have suggested that infection rates are low and that there are few long-term complications associated with CVAD usage. We have reviewed 86 CVADs that have been inserted, since 1988, in 58 children with congenital bleeding disorders, aged 6 d to 16´5 years, attending Great Ormond Street Hospital, London, and the National Children's Hospital, Dublin. The devices have remained in situ for 2 weeks to 92 months (median 22´5 months). Early (0±2 weeks) complications of CVAD insertion included nine bleeding episodes, one extravasation of factor concentrate, three allergic reactions to factor concentrate and five catheter infections. Overall, CVAD infection was the commonest problem encountered, with 52 devices (60%) becoming infected. Twenty-seven CVADs (31%) required removal. Infection rates in children without inhibitors (29/68) were 1/20 patient±months or 1´6 infections/1000 patient±days, but infection rates for those with inhibitors were 1/8´5 patient±months or 4´3/1000 patient±days. Staphylococcus epidermidis was the predominant organism (25/52) isolated. Blockage of CVAD (four) and catheter disconnection (four) were the most frequently occurring non-infectious long-term complications. Skin erosion of the port was also seen in three children, in one child at 20 months, in one at 29 months and in one at 34 months after insertion. This study demonstrates a high CVAD infection rate and highlights the long-term complications of CVAD usage.

Summary. The management of acute and surgical bleeding episodes in children with severe factor VIII or IX deficiency who develop high responding inhibitors presents a major therapeutic challenge to clinicians. Recombinant factor VIIa (rVIIa) is an effective, reliable and safe treatment that can be used to treat acute bleeding episodes prior to commencing an immune tolerance programme and to cover surgical procedures until the immune tolerance programme is successful. In a significant minority of patients, immune tolerance therapy is ineffective and an alternative haemostatic agent such as rVIIa is required for life-long treatment. The present study evaluated the use of rVIIa in a paediatric setting. Twelve children, aged 1-16 years, were treated successfully with rVIIa to prevent surgical bleeding in 20 surgical procedures (19 central venous access device insertion or removal, 1 dental extraction). Minor postoperative haematomata developed in 2 out of 20 cases after regular rVIIa therapy had been discontinued and resolved with a short course of rVIIa in both cases. Three children had six life-or limb-threatening bleeding episodes. All bleeding episodes resolved with regular rVIIa treatment although topical fibrin glue was needed in one child with a frenulum tear. One patient required two red cell transfusions for symptomatic anaemia resulting from two separate bleeding episodes. The rVIIa therapy was well tolerated and there was no evidence of treatment-related complications. We conclude that rVIIa is the treatment of choice for the management of surgery and acute life-or limb-threatening bleeding in children with haemophilia and high responding inhibitors.

SummaryThis retrospective survey of haemophilia A patients from multiple treatment centres in Ireland assessed the development of inhibitors following a switch in the prescribed treatment from recombinant factor VIII (rFVIII) produced by Chinese hamster ovary (CHO) cells (rFVIII-CHO) to rFVIII produced by baby hamster kidney (BHK) cells (rFVIII-BHK). Ninety-four patients participated in the survey. Most patients (89.4%) had severe haemophilia. One of 77 (1.3%) patients with no inhibitor history developed an inhibitor. This was a patient with moderate haemophilia A who developed a transient, low-titre (1 BU) de novo inhibitor following surgery. Recurrent inhibitors were detected in three of 17 patients with an inhibitor history during the 20-month post-switch study period. All patients continued on rFVIII-BHK therapy, and all tested negative for inhibitors at the time of their last inhibitor assay during the observation period. These results are consistent with the low levels of inhibitor formation demonstrated in phase III studies of previously treated patients receiving BHK-produced rFVIII and support the low risk of inhibitor formation following a change from rFVIIICHO to rFVIII-BHK.

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