Evaluation of Blood Pressure Changes Associated With High-Dose Thiamine in Intensive Care Patients

Introduction: High-dose thiamine may be prescribed for the empiric treatment of neuropsychiatric disorders due to alcohol consumption or severe deficiency. Due to a critical shortage impacting intravenous (IV) fluids, the administration of high-dose thiamine was changed from IV piggyback (IVPB) to IV push (IVP) within our health-system during September 2024. While previous studies focus on the safety of IVP from an adverse reaction standpoint, the immediate influence on blood pressure remains underreported.


Methods: This IRB approved, retrospective, single-center cohort study included patients administered IV high-dose thiamine, defined as doses ≥400 mg, within the intensive care unit from December 1, 2022-June 1, 2025. Thiamine doses administered as IVPB prior to September 2024 were compared to IVP doses after the change. Doses were excluded if administered while a patient was mechanically ventilated, on continuous vasopressors, dexmedetomidine or propofol, or within two hours of IV phenobarbital >260 mg or IV lorazepam equivalence >8 mg. The primary outcome compared the pre- and post- mean arterial pressure (MAP) immediately before and two hours after each thiamine dose. Secondary outcomes evaluated the high-dose thiamine discontinuation due to blood pressure changes and the initiation of vasoactive medications.


Results: Of 20 total patients included, 98 thiamine IVPB doses and 109 thiamine IVP doses were evaluated for analysis. Demographics were similar in terms of age, gender, weight, comorbidities, and admission chief complaint between groups. The median MAP immediately prior to dosing was comparable between IVPB and IVP administrations (96 [85-105] vs. 99 [88-107] mmHg, p=0.33). The median change in MAP two hours after dosing was not different between groups (94 [86-107] vs. 100 [87-109] mmHg, p=0.11). High-dose thiamine discontinuation due to blood pressure changes or initiation of vasopressors did not occur in either treatment group.


Conclusions: This study explores the safety associated with a medication administration change implemented out of shortage necessity. Our results demonstrate high-dose thiamine administered as IVP has a minimal change on MAP within two hours of dosing as compared to IVPB.