Maintenance IVF rate

Maintenance IVF rate

Children: “4,2,1” Rule

• First 10 kg= 4cc/kg/h
• Second 10 kg= 2cc/kg/hr
• 1cc/kg/hr thereafter

e.g. in 46 kg child: 40+20+26 = 86 cc/hr


Adults: 

• wt (kg) + 40/hr.

e.g. in 70 kg patient: 70 + 40 = 110cc/hr

- Normal adult requires approximately 35cc/kg/d.
- Average adult IVF: 75-100 cc/hr
- Assumes no significant renal or cardiac disease and NPO. (If the patient is admitted to the renal service, consult them prior to writing orders; they will usually manage fluid balance themselves.)
- Must be adjusted for any existing dehydration, ongoing fluid loss or disease (e.g. 2/3 maintenance  for pneumonia, meningitis).
- Conversely, if the pt is taking some PO, the IVF rate must be decreased accordingly.
- No IVF if the patient is adequately taking PO fluids.
- Dehydration (= hyperosmolality, not synonymous with hypovolemia ) is treated with water or hypotonic fluid, e.g (D5W).
- Postoperative pain and narcotics can stimulate inappropriate ADH secretion (SIADH), hypotonic fluids are best avoided. Normal saline is usually safer.
- NPO and euvolemic patients: consider D5 ½ NS. D5 prevents catabolism.
- Daily lytes, BUN ,Cr, I/O, and weight should be monitored when giving significant IVF.

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IV Fluids 

Types of IV Fluids 

- Osmolarity: Three main types: Isotonic, Hypotonic or Hypertonic.

- Contents: Crystalloids vs. Colloids

- Crystalloids

• Clear solutions –of water, electrolytes or small molecules. E.g. Normal Saline
• For volume expansion. Safe, cheap but needs larger volume to cause intravascular expansion as 2/3 leaves vessels in 1 hour.

- Colloids

• Large molecules, stay intravascular, reduce edema by drawing fluid from the interstitial and intracellular compartments. e.g. Albumin 5% 

Common IV Fluids

- Normal Saline (NS): Isoosmolar.  0.9 % Saline,  Na: 154 mmol/l, Cl: 154, Osm: 308 mOsm/kg. 25% remains intravascular (good for resuscitation).

- ½ Normal Saline:  0.45 % Saline, Na: 77, Cl: 77, Osm: 154. Dehydration.

- Ringer’s lactate (LR): Na: 130, Cl: 109, Lactate: 28, K: 4, Ca: 3, Osm:273. Lactate is metabolized to bicarbonate in the liver, corrects metabolic acidosis; good in hypovolemia, trauma. Best avoid in heart and renal failure.

- D5 (or D5W): electrolyte free, 50 gm glucose/L, 170 kcal, 250 Osm. 10% of daily calories requirements. Only < 10 % remains intravascular (not good for resuscitation). Good for maintenance.

- D5 ½ NS. 50 gm glucose/L, Na: 77 Cl: 77.

- Albumin 5%: Na: 140, Cl: 128, albumin 50 mg/L, 265 Osm.

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Pediatric Rules

Simple rules in children

- Normal saline for initial boluses, dehydration, replacement of deficit/loss

- D5 NS or D5 ½ NS for maintenance.

- For rapid stabilization of vital signs; 20 ml/kg bolus of NS over 10-30 minutes. Can be repeated if necessary.

- Serum osmolality normal range is 285-295 mOsm/kg
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IVF Indications

IVF indications

-Establish or maintain a fluid or electrolyte balance

- Continuous or intermittent medication

- Bolus

- Keep vein open (KVO)

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TBW and Fluid Compartments

Total Body Water and Fluid Compartments

- Total Body Water (TBW in liters)= Wt (Kg) x .6 (m) .5 (f) , e.g. in 70 kg patient: TBW=70 x .6 = 42 L

- Fluid compartments within the body:

            - 2/3:1/3 rule:   - Intracellular Fluid (ICF) = 2/3 of TBW

                                    - Extracellular Fluid (ECF) =1/3 of TBW

                                    - Interstitial Fluid = 2/3 of ECF

                                    - Intravascular Fluid =1/3 of ECF

- Ideal Body Weight (IBW, in Kg)

- Male= 50kg + 2.3 kg for every inch over 5 feet (per 2.54cm > 1.524m)

- Female = 45.5kg + 2.3 kg for every inch over 5 feet (per 2.54cm > 1.524m)