Overview of Fluid Management
Managing fluids is very important when looking after patients in hospital settings. Each patient has different needs and there isn’t a one-size-fits-all method for this. However, one common rule is to replace fluids when a patient’s body is running low. The amount and type of fluids a patient might lose can vary depending on their health conditions. For example, a patient with severe burns will lose more fluids than a healthy person who is not allowed to eat or drink before a procedure. A patient who is dehydrated due to severe diarrhea may need different fluids than a patient who has lost a significant amount of blood from an injury to their stomach (upper gastrointestinal bleed).
When giving fluids through an IV, or intravenous line, it’s important to think about how these fluids might affect the patient. Different fluids have different ingredients and can change the patient’s metabolism. Healthcare providers must make sure they are using the right fluids, for the right amount of time, in the right dose, for the right patient. This is known as the “Four Rights” of fluid stewardship.
The two main types of IV fluids are crystalloid and colloid solutions. Crystalloid solutions, like normal saline and lactated Ringer solution, are generally the first choice for replacing fluids. Colloid solutions, like albumin, are not usually the first choice for replacing fluids lost to non-bleeding conditions, like vomiting or burns. But they might be used if the patient doesn’t respond to crystalloid solutions or if they have a condition called hypoalbuminemia that contributes to shock. However, care must be taken to avoid a certain type of colloid solution called hypertonic starch in patients with low blood volume (hypovolemia) as it can cause acute kidney injury.
Maintenance fluids are given to replace fluid losses from normal body functions like urination, defecation, sweating, and breathing. They may also be needed in unusual conditions like vomiting, diarrhea or severe burns. Hypotonic IV fluids are not suitable for hospitalized patients for maintenance, due to the risk of having low sodium levels (hyponatremia). Using isotonic IV maintenance fluids reduces this risk and is a better choice. Healthcare providers should be careful to avoid giving too much fluids as it can cause fluid overload and lead to negative outcomes for the patient.
Why do People Need Fluid Management
Doctors use fluids for different purposes such as helping the body to stabilize after shock or severe injury, getting a patient hydrated, or providing the necessary amount of fluid and essential substances the body needs daily if the patient can’t get them through drinking or eating food. Sometimes, even if someone can take food and fluid orally, they might need additional amounts given to them directly into their blood vessels, and this can be done using an IV fluid or a drip.
Sometimes a doctor needs to understand how well the patient’s body is controlling the amount of fluid in its system. This is called the patient’s volume status. There are different ways of doing this: observing the person, measuring their vital signs like heart rate, blood pressure, and checking laboratory test results. There’s a system called the National Early Warning Score (NEWS) which doctors use to predict if a patient might get worse, develop sepsis, or require fluids. It looks at different measurements like the rate of breathing, the level of oxygen in the blood, blood pressure, heart rate, alertness or confusion, and body temperature.
If a patient has a NEWS score of 5 or more, it could mean that the volume of fluids in their body is critically low, and they may need fluids given directly. However, the doctor needs to consider the whole picture, and not just this score, before deciding to add fluids.
There are several signs that help doctors to tell whether a patient is losing too much fluid or has too much:
In terms of vital signs, doctors can check:
- Body weight: This is a very sensitive indicator of changes in the fluid status of the body. If a person’s weight changes suddenly, it can be because of fluid loss or gain. For example, significant weight loss can be a sign of fluid loss, while weight gain can suggest that the body’s fluid level is too high.
- Heart rate: If the heart rate exceeds 90 beats per minute, it can be an early sign of shock from fluid loss, indicating that the person might need fluids.
- Blood pressure: If a person’s blood pressure goes below 100 mm Hg, that could be an alarming sign, suggesting that the cardiovascular system can no longer make up for the lack of fluid in the body. Conversely, a higher blood pressure may suggest that there is too much fluid in the body.
- Urine output: For adults, doctors expect a minimum urine output of more than 1 mL/kg/h. Certain clinical conditions might need higher urine output levels to reduce the risk of kidney toxicity, especially when using certain medications that might be harmful to the kidneys.
Doctors can also observe:
- Capillary refill: If a person is losing too much fluid, the small blood vessels in their fingertips and toes might refill more slowly than usual.
- Pulse: If a person is dehydrated, their pulse might be fast and weak.
- Skin appearance: Flaccid or tented skin, or eyes sinking back into the cavities, can be a sign of severe dehydration.
- Mucous membranes: Dry textures on the oral mucosa or tongue might indicate dehydration.
- Jugular vein appearance: A swollen jugular vein can be a sign of fluid overload.
By looking at these signs and interpreting laboratory results, the doctor can make a better decision about whether a patient needs more fluids, less fluids, or if the fluid status is just right.
Equipment used for Fluid Management
When someone isn’t able to take in enough fluids through drinking, the common solution is to supply fluids through an IV (intravenous) line. This means that fluid is put directly in your veins. If an IV line isn’t the best method, the fluids can still be given by a few other methods like inserting a tube under the skin, inside large bones, inside large veins, or through a feeding tube. Usually, this is done in a healthcare setting unless there are special circumstances that call for it to be done elsewhere. Below is a list of the equipment needed for an IV.
IV Equipment Basics
A “sterile spike”, in this case, is a gadget that connects the tube to the bag of IV fluid. The “drip chamber” helps doctors or nurses monitor the speed at which the fluids are entering the body, counting the drops per minute. A “backcheck valve” stops any fluid or medication from flowing back up the IV line.
“Access ports” are places on the IV line where doctors or nurses can give additional medications. An “extension set” is a piece of extra tubing that helps to alleviate movement at the site where the IV was put in and prevents exposure to blood and body fluids when changing the tubing. Small clamps called “slide clamps” open and close the device that pumps the fluid into the body. And of course, the familiar “IV pole” holds the bag of fluid and allows it to be adjusted to the right height.
Placing the IV
When a doctor or nurse puts in an IV line, they need a particular set of stuff: nonsterile gloves, a fabric band (tourniquet) to make the veins easier to see, disinfectant solution or wipes to clean the area, the IV needle, a small square of gauze, an adaptor, a little lock filled with saline to keep the IV line from clotting, saline solution, a see-through bandage, and paper tape.
Choosing the right fluids for an IV
The kind of fluid that goes into an IV bag depends on what the body needs specifically. Some people have lost a lot of body fluids or have imbalances in their electrolytes, which can throw off their body’s normal processes. Depending on those needs, various fluid options are available.
Doctors and nurses typically pick among these choices:
- A saltwater solution, either regular strength or half-strength, with or without an element called potassium
- A solution called Lactated Ringer, which has several electrolytes mimicking human blood plasma
- A sugar water solution, called Dextrose, that comes in either regular or half-strength saltwater, again, with or without potassium
The key is to choose the fluid that will help balance the specific needs of the patient’s body. For example, sugar water solutions are proper for children who need maintenance fluids, patients with low blood sugar, or patients dealing with specific conditions related to fasting or alcohol. This fluid isn’t best for patients with uncontrolled diabetes or low potassium levels as it can trigger insulin release which worsens these conditions.
For patients dealing with severe fluid loss or shock, lactated Ringer solution or half-strength saltwater solution might be a better fit. Large amounts of normal saline can cause an acid-base imbalance because it contains more chloride than human plasma does.
Feeding Tubes
Feeding tubes or “enteral tubes” are other ways to provide needed fluids and come in several types to fit different medical needs and patient conditions, including tubes that go in the nose, mouth, stomach, or small intestine.
Fluids for feeding tubes
The kind of fluid put into a feeding tube depends greatly on the medical needs. These fluids can range from hydration to nutrition for infants and electrolyte supplements for athletes. Options include commercially produced rehydration solutions like those recommended by the World Health Organization (WHO), breast milk or formula, and commercially available sports drinks.
Preparing for Fluid Management
In the case of kids, size plays a big part when figuring out the amount of fluids they need. For example, a 3-month-old baby’s fluid needs are much different from those of an 8-year-old. A simple rule called the 4-2-1 rule can help calculate how much fluid a child needs hourly based on their weight.
Here’s how the rule works:
* For the first 10 kilograms (kg) of body weight, a child needs 4 milliliters (mL) per kilogram per hour.
* For the next 10 to 20 kg, the child needs 2 mL per kilogram per hour.
* For any weight more than 20 kg, the child needs 1 mL per kilogram per hour.
Let’s take an example. If a child weighs 22 kg, their fluid needs would be:
* 4 mL per hour for the first 10 kg, which is 4 mL/kg/h x 10 kg = 40 mL/hour
* 2 mL per hour for the next 10 to 20 kg, which is 2 mL/kg/h x 10 kg = 20 mL/hour
* 1 mL per hour for the remaining 2 kg, which is 1 mL/kg/h x 2 kg = 2 mL/hour
In total, the child would need 62 mL of fluids per hour (40 + 20 + 2).
Another method calculates the fluid needs over 24 hours:
* For the first 10 kg: 100 mL per kg per day
* For the next 10 to 20 kg: An extra 50 mL per kg per day
* For any weight more than 20 kg: An extra 20 mL per kg per day
For example, let’s calculate the fluid needs for a 70 kg adult:
* 1000 mL per day for the first 10 kg (100 mL/kg/d x 10 kg)
* 500 mL per day for the next 10 to 20 kg (50 mL/kg/d x 10 kg)
* 1000 mL per day for the remaining 50 kg (20 mL/kg/d x 50 kg)
In total, the adult would need 2500 mL of fluids per day (1000 + 500 + 1000), or around 104 mL per hour (2500 divided by 24).
However, it’s important to be careful using these rules, especially with older patients or those who are obese. The right amount and type of fluid can depend on many factors and require a doctor’s judgment based on the person’s current and future fluid needs.
In severe cases, like adults with sepsis or severe low blood volume, 30 mL/kg of fluid should be given in 500 mL amounts within the first few hours of treatment. For children with severe low blood volume without signs of fluid overload, it is recommended to give 10 to 20 mL/kg of fluid every 20 to 30 minutes, repeating 2 to 3 times. If fluid overload is evident, children should receive 5 to 10 mL/kg delivered slowly over a longer period.
How is Fluid Management performed
Doctors tailor a patient’s fluid management to their specific needs and health conditions. Whenever possible, they prefer that the patient drinks fluids orally. However, in some circumstances, drinking might not be possible or sufficient. In these cases, doctors might use feeding tubes or combine methods, delivering fluids orally and through an IV drip. This flexible approach allows the doctor to adjust how much is given through each method based on the patient’s capacity to drink.
To make these decisions, the health team will conduct a thorough assessment of the patient. They’ll monitor vital signs like heart rate and blood pressure, physically examine the patient, and use data from lab tests. These evaluations help them determine the most effective fluid management strategy.
Before and after giving a large quantity of fluids quickly (referred to as a fluid bolus), the medical team needs to closely monitor the patient. It’s essential to check vital signs and note how the patient reacts. It’s also important to check for fluid buildup in the lungs, a condition known as pulmonary edema. Taking all these into account, the healthcare team ensures the patient’s fluid levels are managed safely and effectively.
Possible Complications of Fluid Management
While managing the amount of fluids in a patient’s body is very important for good care, it can sometimes lead to complications that need careful attention and constant check-ups.
Electrolyte Derangements
Hyponatremia: This is a condition where the level of sodium in the blood is too low. Patients need to have their sodium level checked regularly, especially when given fluids that have a lower concentration of salt. Many patients in the hospital already have risks, like an increased release of a hormone called ADH that can make the body hold onto extra water, making hyponatremia worse. In patients that release too much ADH, it’s better to give fluids that have the same concentration of salt as in normal body fluids.
The dangers of hyponatremia include the risk of brain swelling, which can cause serious nerve problems, including seizures. If a patient’s sodium level gets too low, doctors need to be sure not to raise it too quickly to avoid more nerve damage, a condition known as osmotic demyelination syndrome.
Hypernatremia: This is the opposite of hyponatremia, it is a condition where the level of sodium in the blood is too high. It can happen if the patient is given highly salty saline or if the nutrient solutions they are being given are mixed up.
Hyperkalemia: This is a condition where the level of potassium in the blood is too high. It can be a big concern for patients with kidney problems who are given solutions that contain potassium. These patients might not be able to clear out the extra potassium effectively, which could cause dangerous heart rhythm disturbances.
Volume Overload
Doctors should also keep a close eye on patients for signs of too much fluid in their body, like swelling in the arms or legs, fluid in the lungs, or an enlarged liver. Healthcare providers should be aware of heart problems or kidney failure and adjust the amount of fluids being given based on these conditions. Sometimes, these patients might actually need less fluids than what might be expected based on their body weight.
Compartment Syndrome
Abdominal compartment syndrome is a potential complication that can occur when large amounts of fluids (greater than 5 L in 24 hours) are given to a patient. Usual symptoms include reduced urine output, a hard and bloated belly, and increased pressure in the airways.
Metabolic Acidosis
Normal saline, the fluid commonly used in hospitals, is actually a bit more acidic than the body’s natural pH level. This might potentially cause a condition called metabolic acidosis. Lactated Ringer solution is another type of fluid that is closer to the body’s natural pH, but choosing which of these two to use often depends on what’s available in the hospital, which is a topic currently being discussed broadly in the medical community.
Other Complications
Other complications connected with fluid management can include a buildup of blood outside blood vessels (hematoma), inflammation of veins (phlebitis and thrombophlebitis), a bubble of air trapped in blood vessels (air embolism), swelling due to fluid leaking from blood vessels (infiltration), injecting fluids outside blood vessels or into arteries, infection, and something like a catheter breaking off and traveling through blood vessels (device embolism).
What Else Should I Know About Fluid Management?
Keeping the right amount of fluid in your blood vessels is essential to making sure your organs get enough blood and to maintain a balance of electrolytes (minerals in your body that have an electric charge) and pH level (a measure of how acidic or alkaline, or non-acidic, your body is). How doctors manage these fluids can vary. It can be as simple as making sure you get enough water and electrolytes every day, or it can be a more complicated procedure if you’ve had a serious injury, surgery, burns, a severe illness, or infection.
Not having enough fluid in your blood vessels can lead to shock, stroke, heart attack, kidney and liver damage, organ failure, and even death. However, having too much fluid can cause heart failure, fluid buildup in your lungs, or abdominal compartment syndrome, a serious condition that occurs when there is increased pressure in your abdomen.
Doctors need to consider a lot of details, like a patient’s current health status and past medical history, when making a plan for managing fluids. This is important to avoid complications such as dehydration, fluid overload (too much fluid), electrolyte imbalances, and pH imbalances. Regularly checking on the patient’s health status, vital signs (heartbeat, breathing rate, temperature, and blood pressure), weight, and lab test results, along with effective communication among the healthcare team, can help prevent these possible problems.
