What is the recommended normal saline administration for a 31kg patient with acute vomiting?

Normal Saline Administration for 31kg Patient with Acute Vomiting

For a 31kg patient with acute vomiting, oral rehydration solution (ORS) at 120-240 mL per vomiting episode (up to ~1 L/day) is the first-line treatment for mild-to-moderate dehydration; reserve intravenous normal saline only for severe dehydration, shock, or ORS failure, administering 20 mL/kg boluses (620 mL per bolus for this patient) until hemodynamic stability is achieved. 1

Assessment-Based Treatment Algorithm

Mild to Moderate Dehydration (First-Line)

• Start with ORS, not IV fluids 1
• For a 31kg patient (>10kg body weight): administer 120-240 mL ORS for each vomiting episode, up to approximately 1 L per day 1
• Continue ORS replacement as long as vomiting persists 1
• Vomiting is not a contraindication to ORS - most fluid is retained even when some is vomited 2
• If vomiting occurs during ORS administration, wait 10 minutes then continue more slowly with small sips at short intervals 2

When to Use IV Normal Saline Instead

Reserve intravenous normal saline for these specific scenarios: 1

• Severe dehydration with hemodynamic instability
• Shock or altered mental status
• Failure of ORS therapy (patient cannot tolerate oral intake)
• Presence of ileus

IV Normal Saline Dosing (When Indicated)

• Administer 20 mL/kg boluses of isotonic crystalloid (normal saline or lactated Ringer's) 1
• For this 31kg patient: 620 mL per bolus
• Repeat boluses until pulse, perfusion, and mental status normalize 1
• The American College of Emergency Physicians suggests initial rates of 5-10 mL/kg in the first 5 minutes for resuscitation 3

Important Clinical Considerations

Avoid Common Pitfalls

• Do not routinely use IV fluids for vomiting alone - this represents overtreatment when ORS is appropriate 1
• Do not use antiemetics like chlorpromazine as they have undesirable side effects and interfere with ORS continuation 2
• Popular beverages like apple juice, Gatorade, and soft drinks should NOT be used for rehydration 1

Adjunctive Therapy

• Consider ondansetron to reduce vomiting frequency and improve ORS tolerance, which decreases the need for IV rehydration 4
• For patients with ketonemia, an initial course of IV hydration may enable better tolerance of subsequent oral rehydration 1
• Dextrose-containing saline (vs plain 0.9% saline) may reduce circulating ketones and shorten vomiting duration, though it doesn't reduce hospitalization rates 4

Monitoring Requirements

• Establish continuous vital sign monitoring during rapid IV fluid administration 3
• Adjust electrolytes and administer dextrose based on chemistry values when using IV therapy 1
• Patients with congestive heart failure or chronic renal disease require close monitoring to prevent volume overload 3