Objective: Patients with a chronic alcohol use disorder presenting to the ICU may be deficient in important vitamins and electrolytes and are often prescribed a "banana bag" as a reflexive standard of therapy. The difficulty of diagnosing Wernicke's encephalopathy in the critical care setting is reviewed. Furthermore, whether the contents and doses of micronutrients and electrolytes in standard banana bags meet the needs of critically ill patients with an alcohol use disorder is assessed based on available evidence.
Data source: MEDLINE/PubMed (1966 to June 2015) database search, the Cochrane Database of Systematic Reviews, and manual selection of bibliographies from selected articles.
Study selection and data extraction: Articles relevant to Wernicke's encephalopathy, vitamin and electrolyte deficiencies in patients with alcohol use disorders, and alcoholic ketoacidosis were selected. Articles were narratively synthesized for this review.
Data synthesis: Of these deficiencies, thiamine is the most important for the practicing clinician to assess and prescribe replacement in a timely manner. Based on a pharmacokinetic assessment of thiamine, the banana bag approach likely fails to optimize delivery of thiamine to the central nervous system. Folic acid and magnesium may also merit supplementation although the available data do not allow for as strong a recommendation as for prescribing thiamine in this setting. There is no available evidence supporting the prescription of a multivitamin.
Conclusions: Based on the published literature, for patients with a chronic alcohol use disorder admitted to the ICU with symptoms that may mimic or mask Wernicke's encephalopathy, we suggest abandoning the banana bag and utilizing the following formula for routine supplementation during the first day of admission: 200-500 mg IV thiamine every 8 hours, 64 mg/kg magnesium sulfate (approximately 4-5 g for most adult patients), and 400-1,000 μg IV folate. If alcoholic ketoacidosis is suspected, dextrose-containing fluids are recommended over normal saline.