Editors:Elham Reshid and Hailemariam Shimelis
The administration of intravenous (IV) fluids is one of the most common and universal interventions in medicine. However, the choice of IV flids has remained one of the most controversial subjects in critical care over the past half a century.
IV fluids are divided into plasma expanders (Colloids) and Crystalloids. Colloids are solutions that contain large molecules, which do not pass cell membrane. When infused, they remain in the intravascular compartment and expand its volume by drawing fluid from the extracellular space due to their high oncotic pressure. Crystalloids are solutions containing small molecules that easily flow across cell membranes and increase fluid volume in both interstitial and intravascular spaces.
It is recommended that the initial resuscitating fluid should be either Normal Saline (NS) (0.9% sodium chloride) or Ringer’s lactate (RL) (also called Hartmann’s solution) which are both crystalloids. Alternatives are the so-called collioids which constitute macro-sugar based solutes dissolved in saline with other electrolytes
(Dextrose in normal saline (DNS)) and it is usually given as maintenance dose after initial crystalloid infusion. Dextrose in water (DW) is also widely used as a maintenance fluid.
The most commonly used IV fluids are discussed below with their indications and contraindications.
NS and RL
- Both are used for volume resuscitation unlike colloids
- NS is just sodium chloride in water while RL has potassium chloride, sodium lactate and calcium in addition to sodium chloride
- Due to the lactate ion, RL is also used for alkalinization of urine in addition to fluid and electrolyte balance
- NS is the safest of all to be infused when other IV medication are also given and it is the only fluid used with administration of blood products
- NS is the fluid of choice for resuscitation efforts
- RL is also a first line fluid for resuscitation in certain patients such as those with burn injury
- RL should never be given simultaneously with blood through the same administration set as the calcium will bind to the citrate
- NS is contraindicated in hypertension, pulmonary edema and high sodium levels in the body
- RL should not be used in people with lactic acidosis (but used for metabolic acidosis), kidney failure (as it contains potassium), and liver disease (as they cannot metabolize lactate into bicarbonate)
- LR should not be given to patients whose pH is
greater than 7.5
DW and DNS
- DW is 5% glucose in water while DNS constitutes sodium chloride in addition to the 5% sugar
- Both are used for maintenance therapy after fluid resuscitation and are not used as volume expander
- Both are used in small amounts to correct “free water defiits” when it is needed to bring down a patient’s high sodium level
- Both are sources of calories on top of fluid and electrolyte replacement and are recommended in situation where glucose is needed
- Both should not be administered simultaneously with blood through the same administration set as they hemolyze blood
- Not used in the early postoperative period, as the body’s reaction to the surgical stress could lead to an increase in antidiuretic hormone (vasopressin)
- Patients at risk for intracranial pressure should not recieve DW, as it increases cerebral edema
- DNS should be used with great care in patients with congestive heart failure, severe renal insufficiency, and in clinical states where edema exists with sodium retention
- Special precautions should be taken in diabetic patients taking both IV fluids and are contraindicated in diabetic coma while patient is hyperglycemic