TBW = 0.6 X Weight (Kg) (Higher in Infants and Young Children)

TBW = 0.6 x weight (kg) (higher in infants and young children)

Reasons for starting IVF

- Maintenance therapy – maintains needs until oral fluids can be started/tolerated

- Deficit therapy – replace losses prior to starting IVF

- Replacement therapy – replace on going losses

**Always use the gut if possible***

Maintenance Fluids:

- based on fluid and electrolyte needs per kcal of basal metabolism

- Holliday Segar: for every 100kcal of energy expended approx. 50ml of fluid required to provide for skin, resp. and stool losses (insensible losses) and approx. 55 ml of fluid required for kidneys to excrete an ultrafiltrate with a specific gravity of 1.010 without the body having to concentrate the urine (solute losses). Therefore 100kcal expended approx. = 100mls of fluid required

- 100-50-20 rule or 4-2-1 rule

- Adjustments to “maintenance “ needed with fever (~12% increased for each degree Celsius above 38), activity, tachypnea, anuria, polyuria, increased insensible skin losses (burns, VLBW), etc.

- Na requirements = 3-5 mEq/kg/d

- K requirements = 2-3 mEq/kg/d (Always make sure the patient is urinating before adding potassium. Hyperkalemia is more dangerous than hypokalemia!)

- Dextrose:

• Only provides minimal calories
• Used to make IVF less hypotonic

Deficit Replacement:

- Fluid deficit (Liters) = % dehydration x weight (kg)

- % dehydration can be estimated by clinical observation based on physical exam, vitals and In/Outs

- % dehydration (Liters) = (pre-illness weight – illness weight) x100%

- Phase I: restore/preserve cardiovascular function to improve end organ perfusion

• Use 20ml/kg of volume expanding IVF (NS, LR) – give rapidly for severe dehydration and shock, may give over 1 hour for mild dehydration
• Repeat boluses as needed to restore perfusion

- Phase II: provide maintenance needs +remaining deficit + ongoing losses (if any) over the next 24-48 hours

• Use oral hydration as much as possible/tolerated, but may need to use a combination of IVF and oral intake.
• Give ½ of deficit in next 8 hours, the remaining ½ in the next 16 hours

Important Points

- All these calculations provide ESTIMATES of fluid and electrolyte needs. Every patient on IVF should be closely monitored and Ins and Outs recorded and evaluated.

- Most patients with normally functioning kidneys can tolerate higher or lower fluid/electrolyte loads, but while they are acutely ill IVF can help to minimize stress on the kidneys.

- Patients on prolonged IVF therapy need to have their electrolytes monitored.

- IVF are a medication and should only be used when needed to avoid complications.

Available IV Fluids

Contents of Oral Rehydration Solutions