IV Fluids
last authored: March 2011, David LaPierre
last reviewed:
Introduction
Intravenous (IV) fluids are a key treatment for dehydration and hemodynamic instability. They can be used for resuscitation or for maintenance. An IV has a number of parameters:
- fluid rate: how much you give by drip, for maintenance and for any increased losses
- electrolytes: ie sodium and potassium
- calories: dextrose
Types of Fluids
There are many options when choosing IV fluids.
glucose (g/L) |
Na+ (mEq/L) |
K+ (mEq/L) |
Cl- (mEQ/L) |
lactate (mEq/L) |
comments |
|
normal saline (0.9%) |
0 |
154 |
0 |
154 |
0 |
maintenance, resuscitation |
half-normal saline (0.45%) |
0 |
77 |
0 |
77 |
0 |
maintenance |
ringer's lactate |
0 |
130 |
4 |
109 |
28 |
3 MEq/L Ca2+ as well
|
D5W |
50 |
0 |
0 |
0 |
0 |
maintenance |
D5W + 1/2%NS |
50 |
77 |
77 |
|||
2/3 + 1/3 |
||||||
normal plasma |
Choosing IV fluids
Normal saline is the easiest to remember in terms of components. It can be used for resuscitation or for maintenance.
Potassium chloride (KCl) should be added to IV fluids if the patient is receiving nothing by mouth and has normal renal function, as the kidneys are constantly filtering potassium. It should be used with caution if renal function is impaired.
Adult Fluid Needs
Recuscitation
An adult bolus is normally 500-1000ml of nromal saline or ringer's lactate. Repeat as needed until stabilized; consider colloid after 2 boluses. If using colloids, one needs 3x the amount to restore fluid volume. In a recuscitation situation, if a few litres don't work, give blood, even uncrossmatched blood. The length of time spend in shock is important for survival.
Maintenance
Daily fluid needs for an adult are 2500-3000 ml, plus electrolytes.
Weight loss or weight gain are the best measure of fluid balance.
increased needsfever (12% per rise in degree celsius) tachypnea vomiting and diarrhea high output renal failure |
decreased needscongested heart failure mechanical ventilation oligouric renal failure |
If intake is limited to IV for more than a week, total parenteral nutrition should be instituted.
Pediatric Fluid Needs
80 cc/kg of children is blood
Recuscitation
A pediatric fluid bolus is 10-20 ml/kg. Regarding fluid types, NS or 1/2 NS are usually used in children, while in neonates, 1/4 - 1/2 NS are often used.
Maintenance
The 4-2-1 rule
ie a 25 kg child will require 65 cc's/hr. |
Holliday Segar formula
|
These amounts needs to be increased in situations of increased loss, ie fever or with burns.
Neonates have higher fluid requirements: ~150 ml/kg/day.
For caloric intake, D5W is used for most children and D10W - for neonates (less than 1 month).
Hanging IV Fluids
Macrodrip is the most common, delivering 1ml every 15 drops. Microdrip, used in precise situations, offers 1ml/60 drops.
Infusion rate is commonly calculated per hour. For example a rate of 125ml/hr would equal a 1000ml bag/8 hours.
After hourly flow rate has been calculated, determine minute flow rate (ie 125 ml/hr =
flow rate/hr / 60 = flow rate/min
Ensure the patient is aware of proper site placement, and is not experiencing signs or symptoms of phlebitis or interstitial extravasation.
Clinical Usage and Tips
Measure adequacy with urine output, aiming for 1-2 mg/kg/hr
Monitor for signs of dehydration and fluid overload:
dehyration
|
overload
|
Resources and References
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