Overview of Pediatric Fluid Management
Giving fluids to very sick children is crucial. Whether it’s in the emergency room or when a child is admitted to the hospital, starting fluid treatment early and correctly can help them get better quicker and can even save lives. Our body cells need water to work, and they get this from different fluid spaces in our body. Two main ones are the inside-the-cell-space (intracellular fluid) and the outside-the-cell-space (extracellular fluid).
Most of our body’s water exists within our cells. The amount of water in our body can vary according to our age; for example, babies have more water than adults do in comparison to their body size. Our body works hard to keep a balance of water and minerals, like sodium or potassium, but when we are sick these functions might not work as they are supposed to. When we lose too much water and these minerals, we become dehydrated, which can be dangerous for children and can make them more ill.
Babies and young children are especially sensitive to even a little dehydration for several reasons. They need more fluids because they have a faster metabolism, lose more fluids through their skin and can’t express their thirst easily.
Children might handle dehydration differently than adults. They have a more significant capacity to make up for fluid loss at first, so their signs like pulse and blood pressure may seem OK even when they’re losing a lot of fluid. As they continue to lose fluid, they try to keep their blood flow normal by increasing their heart rate. However, if children’s blood pressure gets too low (this is called hypotension), this is a late and dangerous sign.
Children who show signs of having poor blood flow to their body’s organs need to be given fluids into their vein quickly. These signs could be a slow return to normal color when the skin is pressed, a fast pulse, pale skin, not making enough urine or low blood pressure.
A fast pulse and slow return to normal skin color indicates medium dehydration. It’s crucial to give fluid and correct the loss to keep important organs like the heart functioning as they should and to reduce the risk of death.
Loss of body fluids due to diarrhoea usually occurs due to loss of fluid from the space outside their cells while the volume inside the cells is maintained. However, severe dehydration leads to early signs of a type of shock, which happens when the body doesn’t get enough blood flow. Dehydration is often measured by how much weight loss has occurred, but it is hard to know this when a child comes to the emergency department.
Doctors often divide dehydration into mild (5% body weight lost), moderate (10% body weight lost) and severe (more than 15% body weight lost). Very minor dehydration is when less than 3% of body weight is lost.
Knowing how severe the dehydration is important because the treatment given depends on this. However, it can be tough to accurately judge how much fluid has been lost. Symptoms might include decreased urination, dryness inside the mouth, dry skin, a fast pulse, slow return to normal color when skin is pressed and abnormal breather patterns.
Usually, doctor recommendations on treatment depend on how severe the dehydration is. Constant monitoring of things like pulse, blood pressure and physical signs help them judge this. A study showed that slow return of color when the skin is pressed, abnormal skin dryness and abnormal breathing are helpful in spotting 5% or greater dehydration. Normal-looking, moist inside mouth and eyes that are not sunken decrease the chances of dehydration.
Lab tests don’t usually help identify dehydration, with a few exceptions. Tests might be useful for identifying other problems that can happen with dehydration, such as problems with sodium levels or tracking the need for sugar in the fluid given. The most useful lab test for dehydration is a bicarb test, which measures the amount of bicarbonate – a type of salt – in the blood.
Anatomy and Physiology of Pediatric Fluid Management
Children need different amounts of fluids based on their metabolic rates. This is due to the fact that a higher metabolic rate can cause more fluid to be lost from the body. One important factor related to fluid intake is tonicity, which reflects the concentration of certain substances like sugars and electrolytes in the fluids. It’s important because it affects the size and health of our body’s cells.
Tonicity is closely related to fluid balance in the body, which is controlled by a hormone called antidiuretic hormone (ADH) and our sense of thirst. ADH encourages our bodies to hold onto water, while thirst tells us when to drink more fluids.
Isotonic solutions, which have the same sodium concentration as plasma, don’t change the volume of a cell. Hypotonic solutions, on the other hand, make cells swell up, while hypertonic solutions cause cells to shrink due to fluid moving out of them into the surrounding area. Electrolytes are the chemicals that determine tonicity, though sugars don’t have much effect unless you have diabetes and the sugar isn’t properly broken down by insulin.
Solutions that have equal amounts of sugar and sodium (as recommended by the World Health Organization) work with the body’s natural processes to absorb fluid in the gut. However, solutions with too much sugar can cause diarrhea, leading to more fluid loss. Studies show that drinking rehydration solutions is just as effective as getting fluids through an IV, as long as the person can tolerate drinking the fluids.
Why do People Need Pediatric Fluid Management
Acute gastroenteritis, a common condition that causes stomach flu or upset stomach, often leads to dehydration in children. Symptoms such as vomiting, diarrhea, and decreased drinking of fluids can contribute to this dehydration.
This condition leads to loss of fluid from the body, primarily through either diarrhea or vomiting. When a child becomes mildly to moderately dehydrated, the best method to replace lost fluid is typically by drinking. This is due to the way the body absorbs water and nutrients through the cells lining the intestine. Essentially, substances like electrolytes (chemicals required for your body) are transported through the cells creating a gradient which allows water to passively follow.
Drinks designed for rehydration contain just the right amounts of sodium, glucose, and have the correct osmolarity (concentration) to ensure that this transportation process works effectively. This prevents issues like excessive salt intake or further diarrhea. However, despite oral rehydration treatments being both safe and affordable, they are often underutilized.
Research has shown that oral rehydration therapy (drinking rehydration solutions) is just as effective as giving fluids by IV for children with moderate dehydration. In fact, a meta-analysis (an examination of relevant scientific studies) revealed no significant differences between oral and IV rehydration in terms of safety and effectiveness.
Administration of fluids via IV typically happens when oral rehydration fails. Under such circumstances, giving fluids through an IV might rehydrate more efficiently. This can be particularly pertinent in babies and young children, especially when vomiting accompanies diarrhea. Additionally, when a child’s urine output is low (a condition known as oliguria), it suggests severe dehydration and the need for IV fluids.
If a child is severely dehydrated or in shock, they should receive IV fluids as this allows the body to quickly restore adequate blood flow to the tissues. Similarly, children with difficulty breathing should also receive IV fluids for immediate relief.
When a Person Should Avoid Pediatric Fluid Management
Drinking fluids is usually the best way to rehydrate if you’re only slightly to moderately dehydrated. However, this might not be the best option in certain situations. For example, it’s not advised for very dehydrated children or those who are in shock.
There are also other conditions when rehydrating by drinking is not recommended:
- If your blood circulation is unstable or you’re in shock
- If your mental state is altered, meaning you might choke on the drink (this is called aspiration)
- If you can’t stop vomiting
- If your diarrhea is bloody
- If you’re having stomach pain, a blockage in your bowels, or a paralyzed intestine (known as paralytic ileus)
- If your sodium level is too low (hyponatremia)
- If you have a serious illness
- If you’re having a lot of trouble breathing
Equipment used for Pediatric Fluid Management
If a child is dehydrated, there are a variety of ways to get them hydrated again. Some of these methods involve directly inserting fluids into their body.
Here are few methods:
- Nasogastric tube: A flexible tube is placed through the nose, down the esophagus, and into the stomach for feeding or hydration purposes.
- Nasoduodenal tube: Similar to a nasogastric tube, this one is extended past the stomach to the small intestine’s first part called the duodenum.
- Orogastric tube: This tube is inserted through the mouth and ends up in the stomach. It serves the same purpose as a nasogastric tube.
- Gastric tube: This tube is also placed directly into the stomach, but by surgery. It’s used for long-term support or situations where nasal or oral tubes are not preferred.
- Gastrojejunal tube: This is a two-in-one tube that is inserted into the stomach and small intestine, typically used for feeding when the stomach cannot adequately empty itself.
The ideal level of sodium (a vital electrolyte) in the bloodstream is between 135 and 144 mEq/L.
Different fluid solutions contain different sodium concentrations. For example, ‘normal saline’ that doctors often use has a higher sodium content of 154 mEq/L. It also comes in half and quarter concentrations.
Another solution known as ‘Lactated Ringer’s’ contains a sodium concentration of 131 mEq/L, which is slightly lower than the ideal blood level. It is used in various situations including surgery, burns, trauma, and severe diarrhea.
How is Pediatric Fluid Management performed
Treating dehydration involves three steps:
1. Correcting fluid loss: This is necessary to bring your body’s fluid levels back up to normal.
2. Maintenance treatment: Regular intake of fluids and essential minerals (electrolytes) to prevent further dehydration.
3. Sustained replacement of fluids: Continuously keeping up fluid levels as they continue to be lost.
The amount of fluids required usually depends on a person’s weight change or symptoms. When taking oral fluids, it is recommended to drink 50 mL to 100 mL/kg within 2 to 4 hours. Oral rehydration solution is the optimal drink of choice over free water or commercial sports drinks. Sometimes, the rehydration solution is given through a nasogastric tube, which is a tube that goes through the nose to the stomach.
Isotonic solution is usually administered to replace lost fluids and electrolytes when someone is dehydrated (isotonic refers to fluids that have the same concentration of solutes as the cells in the human body). Doctors will keep checking the hydrated status and fluid balance of every child receiving an intravenous (IV) fluid. Ondansetron, a medication used to stop vomiting, may be given if the physical condition is otherwise normal. This can further reduce the need for intravenous therapy.
Fluids given intravenously (IV) have two rates – bolus and maintenance rate. Bolus rate refers to a large amount of fluid given in a quick span. In children with moderate dehydration, a fluid bolus is rapidly infused at 10 to 20 ml/kg of isotonic saline over 20 minutes. For severe dehydration, fluid administration should be as fast as possible. IV fluids can be repeated until signs of dehydration, like fast heart rate and dryness in the mouth, improve. If a child requires more than 60 ml/kg fluid without any improvement, it mostly signifies a severe issue such as septic shock or severe bleeding.
The rate of IV fluid is decided based on maintenance requirements, estimated fluid deficit, and ongoing losses. The maintenance requirement can be calculated using the Holiday-Segar method which is based on the child’s weight.
In the past, hypotonic fluids were used for IV administration. But, it has been found that their use can lead to a dangerous drop in sodium levels in the blood or hyponatremia. Therefore, the American Academy of Pediatrics in 2018 recommended the use of isotonic solutions with potassium chloride and dextrose which has a reduced risk of hyponatremia. But, potassium chloride should be avoided in cases of high potassium levels in blood or compromised kidney functions.
For patients with excessive sodium concentration in their blood (hypernatremia), it should be corrected slowly over 48 hours to prevent any brain complications. If corrected too quickly, a rapid fall in blood sodium might lead to cerebral edema (fluid build up in the brain) which can cause seizures.
Additionally, in 2018, a review concluded that the use of starches, dextrans, albumin, or gelatins compared to crystalloids has little to no effect on mortality. For children who can’t consume adequate calories due to inability to eat, 5% dextrose should be added to maintenance fluids. If there is low blood sugar (hypoglycemia), it should be treated promptly.
Possible Complications of Pediatric Fluid Management
When children are dehydrated due to sickness or improper fluid replacement, they might have an electrolyte imbalance, ruling in too little sodium (hyponatremia), too much sodium (hypernatremia), or low blood sugar (hypoglycemia).
Hyponatremia is where there’s less sodium than normal in the blood, measured below 135 mEq/L. It’s often seen in children who were given intravenous (IV) fluids in a hospital. This can happen if there’s a sodium shortage or too much water in the body. Sometimes, it’s because of certain hormones being released excessively in hospitalized kids. Doctors might need to adjust the fluid being given to correct it. Some IV solutions can also result in hyponatremia. Keep in mind that a normal sodium level doesn’t guarantee that the fluids in the body are balanced properly.
Another issue could be fluid overload. While kidneys normally keep our body’s water balance in check, receiving too many fluids can tip the scale. It’s really important to avoid too much fluid, especially in babies, as it could cause over-hydration. Signs to look out for include swelling or rapid weight gain. Some existing health conditions like liver or kidney diseases, heart failure, and kidney failure can make fluid overload more likely.
On the other hand, hypernatremia is when there’s too much sodium in the blood, measured above 145 mEq/L. This might hint at more water loss than sodium loss. Despite high sodium in blood, there’s a shortage of sodium in the body. But if the fluids given are balanced (isotonic), there’s a low chance of this happening. Babies in particular can encounter this risk if they’re not getting enough water, often due to diarrhea or insufficient breastfeeding. This might cause dehydration to be underestimated, because the body shifts water from inside cells to outside to maintain the balance. Traditional signs of dehydration like fast heartbeat or weak pulse might only appear when the dehydration is severe. Because the blood and fluid around cells still seem maintained, shock might not set until late and can happen suddenly.
What Else Should I Know About Pediatric Fluid Management?
Dehydration, or not having enough water in your body, often happens in children. Dehydration symptoms are signs that the body is losing water from spaces outside the body’s cells. Figuring out the problems caused by the lack of fluid and salts (electrolytes) in the body can be tricky. Knowing how to spot dehydration correctly is very important for taking care of it effectively.
The signs of dehydration are not always exact or reliable in telling us how dehydrated a child is. So, doctors need to be very careful and aware when checking children for dehydration. This is because diagnosing dehydration isn’t always straightforward and requires them to really be on the lookout for signs.
