What is the best course of action for a pregnant female with hyperemesis gravidarum (severe morning sickness), receiving D5 (5% dextrose solution) through a Peripherally Inserted Central Catheter (PICC) line, who presents with confusion and vertical nystagmus?

Wernicke's Encephalopathy in Hyperemesis Gravidarum

This patient has Wernicke's encephalopathy caused by thiamine deficiency precipitated by D5 infusion without thiamine supplementation—immediately discontinue D5, administer thiamine 500 mg IV three times daily (1,500 mg total daily dose), and hospitalize for continuous monitoring and neurological assessment. 1

Immediate Management (Within Minutes)

• Stop all dextrose-containing fluids immediately, as glucose administration in thiamine-deficient states precipitates or worsens Wernicke's encephalopathy 2, 3
• Administer thiamine 500 mg IV three times daily for suspected or confirmed Wernicke's encephalopathy—this is the highest dose protocol for acute neurological manifestations 1
• Vertical nystagmus combined with confusion in a hyperemesis gravidarum patient receiving IV dextrose is pathognomonic for Wernicke's encephalopathy until proven otherwise 4, 5

Critical Pathophysiology

• Pregnancy increases thiamine requirements, and hyperemesis gravidarum depletes thiamine stores within 7-8 weeks of persistent vomiting, with complete exhaustion possible after only 20 days of inadequate oral intake 1
• Dextrose infusion without thiamine is the classic iatrogenic trigger for Wernicke's encephalopathy in malnourished patients, as glucose metabolism consumes remaining thiamine stores 2, 3
• The triad of confusion, ataxia, and ophthalmoplegia (including vertical nystagmus) confirms the diagnosis clinically—do not wait for MRI confirmation to start treatment 5, 6

Hospital Admission and Monitoring

• Hospitalize immediately for continuous IV thiamine therapy and neurological monitoring 1
• Check electrolytes with particular attention to potassium and magnesium, as these are commonly depleted and must be corrected 1, 7
• Obtain MRI brain if diagnosis is uncertain, which will show increased T2/FLAIR signal in bilateral thalami, periaqueductal grey matter, floor of fourth ventricle, and superior cerebellar vermis 5
• Monitor for improvement in neurological signs, which typically begin within 2-3 days of thiamine replacement 5, 8

Thiamine Dosing Protocol

• Acute phase: Thiamine 500 mg IV three times daily (1,500 mg total) until neurological symptoms resolve 1
• Continue high-dose IV thiamine for at least 3-5 days, then transition to 200-300 mg IV daily once confusion and nystagmus improve 1
• After stabilization, maintain oral thiamine 50-100 mg daily until adequate oral intake is established and vomiting resolves 1

Antiemetic Management

• Continue or initiate appropriate antiemetics to control vomiting: metoclopramide is preferred as second-line agent with less sedation than promethazine 1
• For severe refractory cases, methylprednisolone 16 mg IV every 8 hours for up to 3 days may be necessary, though reserve as last resort 1
• Avoid ondansetron if patient is before 10 weeks gestation due to concerns about congenital heart defects 1

Fluid Management After Thiamine

• Once thiamine has been administered for at least 2-3 hours, resume IV hydration with normal saline or balanced crystalloid solutions 1, 7
• Avoid dextrose-containing solutions until thiamine stores are repleted (typically after 3-5 days of high-dose IV thiamine) 1, 2
• Correct electrolyte abnormalities, particularly hypokalemia and hypomagnesemia, which are common in hyperemesis gravidarum 1, 7

Common Pitfalls to Avoid

• Never administer dextrose before thiamine in any patient with hyperemesis gravidarum and prolonged vomiting—this is the most critical error that precipitates Wernicke's encephalopathy 2, 3
• Do not use prophylactic thiamine doses (100 mg daily) for acute Wernicke's encephalopathy—the required dose is 500 mg three times daily 1
• Do not delay treatment waiting for MRI confirmation, as neurological damage can become irreversible within days 5, 6
• Vertical nystagmus is less common than horizontal nystagmus in Wernicke's encephalopathy but is highly specific when present with confusion and ataxia 4, 5

Prognosis and Follow-up

• Neurological improvement typically begins within 2-3 days of thiamine replacement, with dramatic improvement by day 3-5 5, 8
• Some patients may develop persistent deficits including residual nystagmus, mild ataxia, or Korsakoff's psychosis (memory impairment) despite treatment 8, 3
• Continue thiamine supplementation throughout pregnancy: 300 mg orally daily once oral intake is tolerated 1
• Involve maternal-fetal medicine, neurology, and nutrition services for ongoing multidisciplinary management 1

Prevention Protocol for Future Cases

• All hyperemesis gravidarum patients receiving IV fluids or parenteral nutrition must receive thiamine 200-300 mg IV daily prophylactically before any dextrose administration 1, 2
• For patients on total parenteral nutrition, provide 200-300 mg thiamine daily given the increased metabolic demands, not the standard 2.5 mg/day 1
• Check thiamine status (RBC or whole blood thiamine diphosphate) every trimester in all hyperemesis gravidarum patients with inadequate weight gain 1