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Estimated Versus Actual Weight When Dosing rt-PA in Acute Ischemic Stroke: Is There a Difference?

Graves, Alexandra; VerHage, Anna; Richlik, Brian; Makic, Mary Beth Flynn

Journal of Neuroscience Nursing: August 2013 - Volume 45 - Issue 4 - p 180–185
doi: 10.1097/JNN.0b013e318298641b

Introduction: Intravenous (IV) recombinant tissue plasminogen activator (rt-PA) is the standard of care for patients exhibiting signs of acute ischemic stroke. IV rt-PA uses weight-based dosing, and often an estimated weight is used. The clinical effects of using estimated weight in dosing IV rt-PA remain unclear. The goal of this descriptive study was to determine if there was a significant difference in estimated versus actual weight dosing of rt-PA.

Methods: A retrospective chart review was performed to compare estimated versus actual patient weight. The sample consisted of patients from the hospital database who received IV rt-PA during June 2009–June 2010. Patients were included if they presented to the emergency department with stroke symptoms, received IV rt-PA, and had documented estimated and actual weights. Recorded (prescribed) dosing of IV rt-PA was compared with the suggested dosing using the admission weight. The differences between the weights and doses were calculated, analyzed, and categorized as being underdosed or overdosed.

Results: Twenty-six charts met the inclusion criteria. Using descriptive statistics and tests of difference, the mean estimated weight was 79.9 kg (±3.92 kg) and the mean actual weight was 78.5 kg (±3.86 kg); four patients had an estimated weight discrepancy of ≥5 kg. Six had correct estimated dosing; however, all of these patients were greater than 100 kg and received the maximum dose of 90 mg. Eleven patients’ estimated weights were underestimated, resulting in underdosing of IV rt-PA. Nine estimated weights were overestimated, leading to overdosing of the medication, but none of the dosing overages exceeded 10%. No statistical significance was found between the two groups’ estimated weights or dosing errors, t(26) = 0.69, p = .79.

Discussion: Results from this study found documented estimated weights were not significantly different from actual weights and the precision of estimated weight were similar to weights obtained using a scale. Despite these results, methods for obtaining actual weights in the emergency department for high-risk patients should be explored.

Questions or comments about this article may be directed to Alexandra Graves, RN MS ANP-BC, at She is the Clinical Director of Stroke Services at the University of Colorado Hospital, Aurora, CO.

Anna VerHage, RN BSN CCRN CNRN, works in the Neurosurgical ICU at the University of Colorado Hospital, Aurora, CO.

Brian Richlik, RN BSN CCRN CNRN, is a Level IV Clinical Nurse in the Neurosurgical ICU and is a Member of the Stroke Council at the University of Colorado Hospital, Aurora, CO.

Mary Beth Flynn Makic, PhD RN CNS CCNS, is a Research Nurse Scientist, University of Colorado Hospital, and an Associate Professor (Adjoint) at the College of Nursing, University of Colorado, Aurora, CO.

The authors declare no conflicts of interest and have no disclosures.

© 2013 American Association of Neuroscience Nurses