Initial Fluid Therapy

• Fluid administration in the first 2–4 hours of presentation is typically more aggressive, depending on the degree of fluid loss.

• Goal: to correct hypovolemia

• Indications

  • Severe fluid loss

  • Mild fluid loss OR moderate fluid loss with:

    • Inability to tolerate oral fluids (due to e.g., intractable vomiting, inability to swallow, pain)

    • Dehydration or hypovolemia refractory to a trial of enteral fluid therapy

• Type of fluid: isotonic cystalloids, i.e., NS or Lactated Ringer's

• Rate and amount

  • Severe fluid loss (hypovolemic shock): Aggressive IV fluid boluses, e.g., 20 mL/kg (∼1000 mL in an average adult)

  • Patients with risk factors for fluid overload: Judicious IV fluid replacement

    • Consider noninvasive fluid responsiveness test, e.g., PLR test

    • Consider smaller volume fluid challenge, e.g., 5–10 mL/kg (∼500 mL in an average adult)

  • Titrate to individual patient needs (e.g., based on hemodynamic monitoring parameters)

• Reevaluate every 15–30 minutes during bolus administration, then hourly.

• Clinical deterioration

  • Continue fluid resuscitation and treat as hypovolemic shock.

  • Add replacement of ongoing GI fluid loss in patients with vomiting and diarrhea.

    
    

• Clinical improvement

  • Start enteral fluids (e.g., ORS) if no aspiration risk factors are present.

  • Address remaining continued fluid needs (e.g, maintenance fluids, free water deficit) and metabolic disturbances.

• Goal: to correct hypovolemia and dehydration using oral rehydration solutions

• Indications

  • Children: first-line therapy for mild fluid loss or moderate fluid loss due to gastroenteritis and/or diarrhea

  • Adults: mild fluid loss and moderate fluid loss due to acute watery diarrhea (e.g., cholera, traveler's diarrhea) and viral gastroenteritis.

• Compounded ORS (powdered)

  • Reduced-osmolarity ORS (hypotonic): WHO recommended

  • Traditional ORS

• Commercial ORS (premixed)

• Consider a preemptive antiemetic in patients with a history of recent vomiting (see “Overview of antiemetics”).

• Prescribe an initial volume and rate of ORS based on age and severity of fluid loss

• Encourage frequent small-volume ingestion to reduce the risk of abdominal discomfort and vomiting.

• Perform regular clinical reassessment (see “Clinical features of dehydration and hypovolemia”)

• Consider serial electrolytes and other hemodynamic monitoring parameters in at-risk patients

• Clinical deterioration

  • If ongoing vomiting:

    • Optimize antiemetics before further fluid intake.

    • Consider NG tube insertion.

  • Assess and treat continued fluid needs: e.g. ongoing GI fluid loss

  • Start parenteral fluid therapy: e.g., IV fluid replacement, subcutaneous fluid therapy

• Clinical improvement

  • Address remaining continued fluid needs (e.g, maintenance fluids, free water deficit) and metabolic disturbances.

  • Advance diet as tolerated.

Total ORS volume required in the first 4 hours for adults and children with mild fluid loss or moderate fluid loss can be approximated to 75 mL/kg.