Intravenous fluid therapy

See critical care quick reference for bolus doses by weight.

Background

Composition of Different Intravenous Fluids

Fluid	Osm	Na	Cl	Glucose(g/L)	pH	Buffer	K	Ca	Mg
Plasma	289	140	103		7.4	HCO3 22-32	4	5	2
Normal Saline (NS)	308	154	154	0	5.0	0	0	0	0
D5NS	560	154	154	50			0	0	0
Lactated Ringers	273	130	109	0	6.5	Lactate 28	4	3	0
Plasmalyte	295	140	98	0	5.0	Gluconate 23/Acetate 27	5	0	3
D5 1/2NS	406	77	77	500	4.5	0	0	0	0
D5W	252	0	0	50
5% Albumin	309	130-160	130-160		6.4-7.4		<1

Total Body Water

• Total Body Water (TBW) = 0.6 x weight (kg)
  • Of which, 2/3 is intracellular and 1/3 extracellular
    • 1/4 of extracellular is vascular

Maintenance Fluids

Adult

• Calculation 1
  • 100 cc/kg/d (4cc/kg/h) 1st 10 kg
  • 50 cc/kg/d (2cc/kg/h) 2nd 10 kg
  • 20 cc/kg/d (1cc/kg/h) each kg > 20
• Calculation 2
  • 1500 cc/m2/d (bsa (m2) = sqr rt [wt (kg) x ht (cm)]/3600
• Insensible losses = 300-400 cc/m2/d
• Adult Standard: D5 0.45%NS at 75-125 mL/hr + 20meq/L of KCl
• Deficit: % dehydration x baseline weight
• Daily volume needed = maintenance + deficit - fluid already given (i.e. boluses)
  • Hourly rate daily volume/24 hr
    • (or correct 1/2 of deficit in first 8 hr, remainder in next 16)

Pediatric

• Maintenance fluid default: D5-LR + 20meq/L of KCl or other isotonic solution
  • Isotonic fluids are now preferred (2019 AAP update)

Electrolytes

• Maintenance Na = 3 mEq/kg/d; K = 2 mEq/kg/d
• Deficit = [desired - measured mEq/L] x fD x wt (kg)
• fD (distribution factor) Na = 0.6, K = 0.6, Cl = 0.2-0.3, HCO3 = 0.5
• (Maintenance + deficit)/daily volume = concentration of electrolyte in fluid to be given
• 4mL/kg of H2O lost, ups Na by 1meq
• Normal saline (NS) = 154 mEq Na/L, 1/2 NS = 77 mEq/L, 1/4NS = 38 mEq/L

See critical care quick reference for drug doses by weight.

4-2-1 Rule

Rule

• mL/hr =
  • (4 x first 10kg) +
  • (2 x second 10kg) +
  • (1 x every 1kg after)
• Example: For a 34 kg infant, you should run the IVF at 74 mL/hr. Often people choose to round to multiples of 5.

Alternative Method

Weight (kg)	Fluid Rate	Example
<10	4 mL/kg per hour	8 kg infant: 4mL/kg per hour x 8 kg
10 to 20	40 mL/h + 2 mL/kg per hour per each add kg	15 kg child: 40 mL/h + 2 mL/kg per hour x 5 kg
>20	60 mL/h + 1 mL/kg per hour per each add kg	30 kg child: 60 mL/h + 1 mL/kg per hour x 10 kg

Quick Reference (Peds)

Age	WT (kg)	IVF (mL/hr)
Premature	2	8
Newborn	3.5	14
2mo	5	20
4mo	6.5	26
6mo	8	32
8mo	9	36
12mo	10	40
15mo	11	42
2yr	13	46
3yr	15	50
5yr	19	58

See Also

• Intravenous Fluids (Main)
• Critical care quick reference
• Vascular access

External Links

• MDCalc maintenance fluids
• http://www.aliem.com/paucis-verbis-composition-of-intravenous-fluids/