How to hydrate a patient?

How to Hydrate a Patient

The oral route is always the first-line approach for hydration in all patients who can tolerate it; when oral intake is insufficient, use subcutaneous fluids for mild-to-moderate dehydration in older adults and cognitively impaired patients, reserving intravenous access for severe dehydration, shock, or when larger fluid volumes are needed. 1

Route Selection Algorithm

Step 1: Assess Patient's Ability to Take Oral Fluids

• If patient can drink: Encourage increased intake of preferred beverages (tea, coffee, juice, water—NOT sports drinks or oral rehydration solutions unless treating diarrheal illness) 1, 2
• If patient has diarrhea/vomiting: Use oral rehydration solution (ORS) at 50-100 mL after each stool for children <2 years, 100-200 mL for older children, and as much as tolerated for adults 1, 2, 3
• If patient refuses oral intake but not in shock: Consider nasogastric administration of fluids at 15 mL/kg/hour 1, 3

Step 2: Determine Type of Dehydration

Low-Intake Dehydration (High Osmolality):

• Serum osmolality >300 mOsm/kg or calculated osmolarity >295 mmol/L 1, 2
• Treatment: Hypotonic fluids (dilute the concentrated serum) 1
• If patient appears well: encourage oral fluids 1
• If patient appears unwell: subcutaneous OR intravenous hypotonic fluids (e.g., half-normal saline with 5% dextrose) 1

Volume Depletion (Normal Osmolality):

• From blood loss, vomiting, or diarrhea with electrolyte losses 1
• Treatment: Isotonic fluids (replace lost volume and electrolytes) 1

Step 3: Choose Parenteral Route Based on Clinical Severity

Subcutaneous (Hypodermoclysis) - Preferred for Mild-to-Moderate Dehydration:

• Indications: Older adults, cognitively impaired patients, reduced compliance, difficult IV access, home/nursing home settings 1, 4
• Advantages: Easier insertion, less patient interference, lower complication rates, similar efficacy to IV 1, 4
• Fluids: Use isotonic solutions (half-normal saline with 5% glucose, or two-thirds 5% glucose with one-third normal saline) 1
• Volume limits: Maximum 3000 mL/day total, maximum 1500 mL per infusion site, though typically <1000 mL/day is used 1
• Contraindications: Need for large volumes, hypertonic solutions, electrolyte-free solutions, coagulation disorders, skin problems at infusion site, severe malnutrition with inadequate subcutaneous tissue 1

Intravenous - Required for Severe Dehydration:

• Indications: Severe dehydration, shock, altered mental status, need for large fluid volumes, need for medications/nutrition via IV, subcutaneous route contraindicated 1, 2
• Fluids for volume depletion: Isotonic crystalloids (lactated Ringer's or normal saline) 1, 2
• Fluids for low-intake dehydration: Hypotonic solutions (half-normal saline with dextrose) 1

Special Population Considerations

Older Adults with Volume Depletion

• Assess for blood loss: Postural pulse change ≥30 beats/minute or severe postural dizziness preventing standing indicates significant volume depletion 1
• Assess for vomiting/diarrhea losses: ≥4 of these signs indicates moderate-to-severe depletion: confusion, non-fluent speech, extremity weakness, dry mucous membranes, dry tongue, furrowed tongue, sunken eyes 1

Patients with Dementia

• Parenteral fluids should be used only for limited periods during crisis situations of insufficient intake (e.g., febrile states, diarrhea) 1
• Subcutaneous route is particularly advantageous due to reduced patient interference with the line 1
• Avoid artificial hydration in terminal phase of life as it causes increased secretions, pulmonary edema, and discomfort without clear benefit 1

Children with Diarrheal Illness

• Use low-osmolarity ORS as first-line: 100 mL/kg over 3-4 hours for moderate dehydration 3
• Nasogastric ORS at 15 mL/kg/hour if refusing oral intake 3
• Switch to IV isotonic fluids (20 mL/kg bolus) only if ORS fails, severe dehydration develops, or persistent vomiting prevents oral/NG intake 3

Critical Monitoring Points

• Reassess hydration status after 3-4 hours of treatment and adjust based on clinical response 1, 2, 3
• Monitor for signs of worsening: continued high stool output, persistent thirst, sunken eyes, fever, altered mental status 1, 2
• Continue feeding throughout rehydration—never "rest the bowel" as early refeeding shortens illness duration 1, 3
• For severe cases, monitor vital signs, mental status, urine output, and consider laboratory parameters 2

Common Pitfalls to Avoid

• Do not use oral rehydration solutions (ORS) for simple low-intake dehydration—these are designed for diarrheal losses and are unnecessary for patients who simply need to drink more 1
• Do not rush to IV therapy when subcutaneous or oral routes are adequate—IV access has higher complication rates 1, 3, 4
• Do not withhold parenteral hydration as "basic care" without medical assessment—it should always be considered a medical treatment with risks and benefits carefully weighed 1
• Do not provide artificial hydration in actively dying patients—it increases secretions and pulmonary edema without improving comfort 1