Introduction:
Fluid and electrolyte imbalance are the commonest problems encountered in newborns, especially during the first few days after birth to weeks. At the time of birth, the newborn will have excess extracellular fluid, which gradually decreases after birth. Special consideration is to be taken for preterm babies with low birth weight and sick neonates who experience greater fluid loss.
Why Do Newborns Face Fluid Loss During the First Week of Life?
Soon after birth, the newborn's body undergoes a lot of physiological changes in the total body water and solutes. So a smooth transition occurs from the aquatic in utero environment to the outer world. During this phase, the excess extracellular fluid, water, and sodium are excreted through the kidney, which has very little capacity.
How Can We Prevent Excess Water Loss in Newborns?
You may notice that the baby will lose weight after a few days of life compared to the actual birth weight. This is because the excess fluid is lost. There are a few things to prevent this excess water loss by applying barriers such as coconut oil, caps, and socks at the extremities.
What Is Fluid Therapy?
Fluid therapy is defined as the process of replacing the fluid lost from our bodies. It is divided into three ways. They are:
- Maintenance Fluids: The fluids that are given to equalize the ongoing fluid losses are known as maintenance fluids. The ongoing fluid losses can be categorized into sensible and non-sensible losses. The urine output and the fecal water constitute the sensible losses, whereas respiration and perspiration constitute the non-sensible losses. The sensible losses constitute the major portion of the ongoing fluids.
- Deficit Fluids: Deficit fluids are the fluids that are lost before the start of medical treatment. Clinical conditions such as dehydration with increased thirst, dry mucous membrane, and decreased urine output contributes to fluid loss. Once dehydration is established, rehydration therapy should be initiated. In the case of infants, breastfeeding is continued even if they have diarrhea.
- Replacement Fluids: These are fluids that are given in advance to meet the ongoing losses due to medical procedures such as surgeries etc.
What Happens When the Fluid Levels Are Imbalanced?
If the newborn faces an imbalance in the fluids and electrolytes in the body, then immediately fluid therapy should be started. Adequate fluid administration can prevent conditions such as hypovolemia (severe blood or fluid loss in the body), hyperosmolarity (blood has a higher concentration of sodium and potassium salts), and renal failure (a condition where the kidneys stop working).
What Are the Factors That Contribute to Fluid Loss?
The factors that contribute to fluid loss are:
- Physiologic Changes: The body water content changes drastically and continues till one year after birth. The total water content is about 80 % (40 % of extracellular fluid and 35 to 40 % of intracellular fluid) at 24 weeks of gestation, which gradually decreases to 60 % around one year after birth. This water loss is a normal physiologic process. The newborn should lose about 15 to 20 % of body weight. The excess water should be excreted; if it does not take place, it may be a concern for renal dysfunction.
- Hormone Effects: During the first week of neonatal life, there is increased vascular tone and increased levels of aldosterone. This results in enhanced distal tubular reabsorption and excretes a large sodium load. Similarly, the arginine vasopressin secreted in response to stress also increases after birth.
- Renal Hemodynamics: Soon after birth, there is increased blood pressure due to the renin-angiotensin activity, which increases the glomerular filtration rate. This results in the excretion of water from the body.
What Are the General Considerations to Be Followed?
-
For fluid calculation, if the neonate weighs lesser than the actual birth weight, then the birth weight is used for all calculations.
-
For neonates, a 500 ml fluid bag should only be used.
-
The intravenous fluids with the additives and the stock bags must be routinely changed every 24 hours.
-
The glucose and the amino acid concentration are to be considered for determining the site of injection.
-
If the glucose concentration is above 12.5 % - central venous access is needed.
-
If the amino acid concentration is more than or equal to 50 g/liter - central venous access is needed.
-
Inotropes such as adrenaline and noradrenaline are preferred for central venous access through dedicated inotropic lines.
-
Always label the patients on intravenous fluids. The labels should contain the following:
-
Date.
-
Patient's name.
-
A patient medical record number (MRN).
-
Signature of the nurses.
-
The label should be present on the following:
-
Fluid bag.
-
Intravenous line.
-
The pump.
How Are the Neonates Managed?
-
Always initiate the fluid therapy at 60 to 80ml/kg with 10 % dextrose in water (D10 W).
-
Infants less than 1500 grams or less than 26 weeks should be covered by a saran blanket. The inputs and the outputs should be monitored to minimize inadequate weight loss.
-
If the infant is less than 1000 grams, the electrolyte and the weight is recorded every six to eight hours.
-
If the infant is 1000 to 1500 grams, the weight and the electrolytes are recorded every 12 hours.
-
If the serum sodium is less than 145 with good urine output, then add 3 to 5 meq/kg of sodium.
-
If the serum sodium is greater than 145 meq/kg, then infusate without sodium is increased by 10 ml/kg.
-
If the potassium is less than 5meq/liter and the urine output is good, add potassium chloride 2 to 3 meq/kg to the intravenous fluids.
-
Gradually increase the fluid administration to 120 to 130 cc/kg over the first week of life.
How to Treat the Electrolyte Imbalance?
In case of renal dysfunction, electrolyte monitoring is necessary. Generally, electrolytes such as sodium, potassium, and chloride are replaced through the intravenous route. In children, 5 % dextrose solution with 0.2 % sodium chloride is used as the maintenance fluid. However, it should be used with proper monitoring as 0.2 % sodium chloride may cause hyponatremia (low levels of sodium in the blood).
What Happens if There Is Excess Fluid Therapy?
The administration of fluids should be very precise with intense care and monitoring, especially in newborns. Excess fluid administration may result in generalized edema and interfere with pulmonary and renal function. In low birth weight babies, excess fluid administration is known to be associated with:
-
Patent Ductus Arteriosus: A persistent opening present between two blood vessels in the heart that usually closes soon after birth.
-
Congestive Heart Failure: It is when the heart muscles fail to pump enough blood.
-
Intraventricular Hemorrhage: Bleeding seen inside the ventricles present in the brain.
-
Necrotizing Enterocolitis: The large intestines get inflamed, resulting in serious complications.
-
Bronchopulmonary Dysplasia: It is a breathing disorder that affects premature babies.
Conclusion:
It is always important to carefully assess the fluid and electrolyte balance in the newborn, which requires an understanding of the physiologic process. Pediatric clinicians play an important role because excess or inadequate fluid may result in complications. So maintaining the required level is crucial. Though it is a challenging condition, appropriate treatment can prevent serious effects. So it is always essential not to delay the medical treatment.
