RESUMEN
OBJECTIVES: We observed that patients treated with continuous vecuronium or esmolol infusions showed elevated plasma sodium measurements when measured by the routine chemistry analyzer as part of the basic metabolic panel (Vitros 5600; Ortho Clinical Diagnostics, Raritan, NJ), but not by blood gas analyzers (RAPIDLab 1265; Siemens, Tarrytown, NY). Both instruments use direct ion-selective electrode technology, albeit with different sodium ionophores (basic metabolic panel: methyl monensin, blood gas: glass). We questioned if the basic metabolic panel hypernatremia represents artefactual pseudohypernatremia. DESIGN: We added vecuronium bromide or esmolol hydrochloric acid to pooled plasma samples and compared sodium values measured by both methodologies. We queried sodium results from the electronic medical records of patients admitted at Children's Hospital of Philadelphia from 2016 to 2018 and received vecuronium and/or esmolol infusion treatment during their admissions. SETTING: PICU of a quaternary, free-standing children's hospital. PATIENTS: Children admitted to the hospital who received vecuronium and/or esmolol infusion. MEASUREMENTS AND MAIN RESULTS: Sodium was measured in pooled plasma samples by basic metabolic panel and blood gas methodologies after adding vecuronium bromide or esmolol hydrochloric acid, leading to a dose-response increase in basic metabolic panel sodium measurements. A repeated measures regression analysis of our electronic medical records showed that the vecuronium dose predicted the Δ sodium (basic metabolic panel-blood gas) sodium within 12 hours of the vecuronium administration (p < 0.0018). Esmolol showed a similar trend (p = 0.13). This occurred primarily in central line samples with continuous vecuronium or esmolol infusions. CONCLUSIONS: Vecuronium and esmolol can falsely elevate direct ion-selective electrode sodium measurements on Vitros chemistry analyzers. Unexpectedly high sodium measurements in patients receiving vecuronium and/or esmolol infusions should be further investigated with an alternate sample type (i.e., peripheral blood) or measurement methodology (i.e., blood gas) to guide treatment decisions.
RESUMEN
BACKGROUND: Differentiating childhood immune thrombocytopenia (ITP) from other cause of thrombocytopenia remains a diagnosis of exclusion. Additionally factors that predict bleeding risk for those patients with ITP are currently not well understood. Previous small studies have suggested that immature platelet fraction (IPF) may differentiate ITP from other causes of thrombocytopenia and in combination with other factors may predict bleeding risk. METHODS: We performed a retrospective chart review of thrombocytopenic patients with an IPF measured between November 1, 2013 and July 1, 2015. Patients were between 2 months and 21 years of age with a platelet count <50 × 109 /l. Each patient chart was reviewed for final diagnosis and bleeding symptoms. A bleeding severity score was retrospectively assigned. RESULTS: Two hundred seventy two patients met inclusion criteria, 97 with ITP, 11 with bone marrow failure (BMF), 126 with malignancy, and 38 with other causes of thrombocytopenia. An IPF > 5.2% differentiated ITP from BMF with 93% sensitivity and 91% specificity. Absolute immature platelet number (AIPN) was significantly lower in ITP patients with severe to life-threatening hemorrhage than those without, despite similar platelet counts. On multivariate analysis, an IPF < 10.4% was confirmed as an independent predictor of bleeding risk at platelet counts <10 × 109 /l in patients with ITP. CONCLUSIONS: IPF measurement alone has utility in both the diagnosis of ITP and identifying patients at increased risk of hemorrhage. Further study is required to understand the pathophysiological differences of ITP patients with lower IPF/AIPN.
