Abstract TP293: Errors in Estimation of Body Weight in Thrombolysis for Acute Ischemic Stroke

Abstract

Introduction: Intravenous tissue plasminogen activator (IVtPA) is a proven treatment in acute ischemic stroke but relies on weight-based dosing in a time sensitive manner. Errors in body weight estimation are common and may result in over or under-dosing of IVtPA. Methods: With IRB approval, we prospectively screened 99 consecutive patients who received IVtPA for suspected acute ischemic stroke from November 1, 2015 to July 1, 2016 as part of a prospective IVtPA study. Patients were included in this analysis who had complete data. Data was collected on patient demographics, National Institutes of Health Stroke Scale (NIHSS), body weight, and times of last known normal (LKN) and IVtPA administration. A significant error in IVtPA dosing was defined as a >10% difference in actual versus calculated IVtPA dose. Results: Among 42 patients prospectively enrolled, the mean age was 65.8 years (range, 32 to 89) and 30 (79%) of patients were transfers from outside Emergency Rooms. Mean time from LKN to IVtPA administration was 2.4 hours (range. 0.7 to 4.8). Initial pre-IVtPA mean NIHSS was 14 (range, 3 to 26). The mean % error in IVtPA dose was +1.9% (range, -29% to + 21%). Ten patients (24%) had a significant error in IVtPA dosing of > 10% of the dose, and 8 (80%) were over-doses. Patients with significant IVtPA dosing error did not differ in terms of age (65.8 vs 65.8, p 0.99), sex (female 55.6% vs 38.9%, p 0.45), race (white 70% vs 47%, p 0.28), height (164.8 vs 171.0 cm, p 0.1), or time from LKN to IVtPA (2.8 vs 2.3, p 0.15). Patients with significant IVtPA dosing errors had significantly lower baseline weight (70.3 vs 90.0 kilograms, p 0.029) and higher NIHSS (18.7 vs 12.6, p 0.018). Conclusion: Dosing errors of > 10% of the calculated IVtPA dose occur in nearly one-quarter of acute stroke patients treated in the community, and patients with lower weight and higher NIHSS were at higher risk of dosing errors.