Treatment of Dehydration with Elevated Hemoglobin/Hematocrit and Nocturnal Vomiting
Administer isotonic intravenous fluids (0.9% normal saline or lactated Ringer's solution) immediately, as the presence of nocturnal vomiting suggests potential ileus or inability to tolerate oral rehydration, making IV hydration the definitive treatment approach. 1, 2
Initial Assessment and Fluid Selection
The elevated hemoglobin (151 g/L) and hematocrit (47%) confirm hemoconcentration from volume depletion, indicating extracellular fluid loss requiring replacement. 3, 4
Key diagnostic considerations:
- Calculate serum osmolality to determine the type of dehydration present. If measured serum osmolality >300 mOsm/kg, this confirms hypertonic dehydration requiring careful fluid management. 3, 1
- The presence of nocturnal vomiting is a critical red flag that may indicate ileus, making oral rehydration therapy contraindicated and potentially dangerous. 2
- Normal biochemistry and liver function suggest this is uncomplicated volume depletion rather than a metabolic crisis. 1
Fluid Resuscitation Protocol
Isotonic IV fluid administration:
- Use 0.9% normal saline or lactated Ringer's solution as first-line therapy for moderate to severe dehydration with vomiting. 3, 1
- Infusion rate should be 4-14 mL/kg/hour for adults, adjusted based on hemodynamic response. 3
- Continue IV rehydration until pulse, perfusion, and mental status normalize and vomiting resolves. 1, 2
- The induced change in serum osmolality should not exceed 3 mOsm/kg H₂O per hour to avoid complications. 3
Critical Management Considerations
Oral rehydration is contraindicated in this patient:
- The presence of nocturnal vomiting suggests possible ileus, where oral fluids would fail and potentially worsen abdominal distention. 2
- Oral rehydration solutions are absolutely contraindicated when ileus is present. 2
- Even if ileus is not confirmed, the inability to keep fluids down for extended periods (>24 hours) is a red flag requiring IV therapy. 1
Monitoring requirements:
- Reassess hydration status after 3-4 hours of IV fluid administration by checking vital signs, mental status, and clinical perfusion. 1
- Monitor for postural pulse changes (>30 beats/minute increase) or severe postural dizziness, which indicate ongoing significant volume depletion. 3
- Check serum electrolytes if clinical signs suggest abnormalities, particularly sodium and potassium. 2
Addressing the Vomiting
Antiemetic therapy is essential:
- Consider serotonin (5-HT3) antagonists or dopamine antagonists to control nausiting and vomiting, which will facilitate transition to oral intake once appropriate. 1
- Discontinue any contributing medications such as antimotility agents, anticholinergics, or opioids that could aggravate ileus. 2
Transition to Maintenance
Once rehydrated:
- Continue IV fluids until the patient can tolerate oral intake without vomiting. 1, 2
- Gradually introduce oral fluids with preferred beverages once vomiting resolves and bowel function returns (passage of flatus or stool). 1, 2
- Resume age-appropriate diet during or immediately after successful rehydration. 1
Common Pitfalls to Avoid
- Do not use oral rehydration therapy as first-line in patients with persistent vomiting or suspected ileus—this will fail and delay appropriate treatment. 2
- Avoid rapid correction of osmolality (>3 mOsm/kg/hour), which can cause cerebral edema and death, particularly if hypernatremia is present. 3
- Do not assume dehydration equals hypernatremia—check actual sodium levels, as hypovolemia can occur with hyponatremia, eunatremia, or hypernatremia, each requiring different fluid strategies. 4, 5
- Never administer antimotility drugs if ileus is suspected, as this can precipitate paralytic ileus with severe complications. 2