When it comes to IV therapy, colloids play an important role in maintaining hemodynamic stability and managing fluid balance. Because of that, understanding their properties is equally important for both patients and healthcare providers. So, let’s explain which types of colloid fluids are important in managing various health conditions in patients.
What Are Colloid Solutions?
Colloids are solutions that contain large molecular weight particles, including proteins or hydroxyethyl starches (HES). Such solutions contain macromolecules and particles that cannot pass through the semipermeable membrane. What’s more, they remain in the intravascular space for a longer period of time, unlike crystalloids.
The main characteristic of colloid solutions is their ability to exert oncotic pressure, which is particularly important for retaining fluids in blood vessels.
Types of Colloid Fluids
Colloid solutions used in medical practice in IV therapy can be categorized into two large groups – natural and artificial colloids.
Natural colloids
Natural colloids originate from biological sources and include substances such as albumins and blood products:
Albumin
Albumin is a natural protein found in human plasma with a molecular weight of 66.5 kDa. When it comes to using albumin in IV therapy, it is used as a colloidal solution to increase oncotic pressure and blood plasma volume. In addition, it may be used in conditions such as hypoalbuminemia, hypovolemia, and septic shock.
Blood products
Blood products may contain proteins and various cellular components derived from blood, such as clotting factors, plasma proteins, and red blood cells. Such products may be used when blood volume needs to be replaced, and coagulation abnormalities must be corrected.
Artificial colloids
Unlike natural colloids, artificial colloids are solutions synthetically designed to mimic the properties of natural solutions. The most famous artificial solutions are gelatin-based and hydroxyethyl starch solutions.
These artificial colloids serve to maintain hemodynamic stability and rapidly expand plasma volume.
Gelatin-based solutions
Such gelatin-based colloids are derived from hydrolyzed collagen and have smaller molecules than natural colloids such as albumins. Such solutions have a high molecular weight and are known to exert osmotic pressure to maintain intravascular volume.
When it comes to their use in IV therapy, gelatin-based solutions may be used in shock conditions and if volume expansion is needed in hypovolemia. However, when working with such solutions, attention should be paid to the amount and duration of use. Improper use may lead to side effects such as coagulopathy.
Hydroxyethyl starch
Hydroxyethyl starch solutions are synthetic colloids composed of starch molecules synthesized with hydroxyethyl groups. Such solutions have a high molecular weight and, like albumins, exert oncotic pressure. When it comes to their use in IV therapy, hydroxyethyl starch solutions are used as hemodynamic support and volume expansion, usually in critical care patients.
Just like other artificial colloids with hydroxyethyl starch solutions, attention should be paid to the amount administered and the duration of the therapy. If not administered correctly, such solutions may cause certain conditions, such as coagulopathies and kidney damage.
Osmolality and Osmotic Pressure
To better understand the function of IV colloid solutions, you should be familiar with the definition of osmolarity and tonicity. Let’s see their definition and function when it comes to administering colloid solutions:
Osmolality
Simply put, osmolality represents the total number of solute particles per liter. This value can be expressed in milliosmoles per liter (mOsm/L) or milliosmoles per milliliter (mOsm/mL).
Such values can help to understand solutions and their osmotic pressure exerted across the semipermeable membrane. Namely, while solutions with higher osmolarity may draw water out of cells through osmosis, solutions with lower osmolarity may allow water to enter cells.
So, colloids are gelatinous solutions that may maintain a high osmotic pressure in the blood. Such particles are too large to pass through a semipermeable membrane such as a capillary membrane. As mentioned above, colloids, unlike crystalloids, remain longer in intravascular spaces.
Tonicity
When it comes to tonicity, it is defined as the ability of a solution to cause water to pass through a semipermeable membrane. For example, if the solution on one side has a higher osmolarity than the solution on the other, water from the solution with lower osmolarity will flow through the membrane until the two solutions are equal.
However, care should be taken when administering such solutions and having knowledge of their osmolarity. Side effects may occur if the osmolarity is not within the acceptable range.
Clinical Applications and Considerations
Such solutions have multiple clinical applications in various medical settings where blood volume expansion and hemodynamic stability are required. However, regarding IV solutions, including colloid solutions, you should also consider potential adverse effects. These aspects are presented in more detail in the following:
Clinical applications of colloids
Colloid solutions may have applications in multiple clinical cases, such as volume expansion, hemodynamic stability, preoperative and intraoperative use, and dehydration treatment.
Volume expansion
Colloid solutions may increase blood volume in case of hypovolemia or low blood volume. This use is due to the ability of colloid solutions to increase intravascular volume by exerting an oncotic pressure that can help retain fluid and prevent its distribution into the interstitial spaces.
Hemodynamic stability
Colloidal solutions may help stabilize hemodynamics through tissue perfusion and improve cardiac output. By increasing blood volume, these solutions may improve hemodynamic properties such as central venous and blood pressure, which play a key role in managing shock conditions.
Preoperative and intraoperative use
In addition to increasing volume and improving hemodynamics, colloid solutions may be administered before and after surgery. Such solutions are administered so that hemodynamic stability may be maintained and intravascular volume optimized.
Such properties of colloid solutions may be applied to patients requiring fluid replacement during the procedure or patients at risk of significant blood loss.
Treatment of severe dehydration
Colloid solutions may be used in many cases where there is a severe form of dehydration. Such cases may refer to severe bleeding, burns, or diarrhea.
Potential side effects and disadvantages
Although IV therapy with colloid solutions is fairly safe, there are still some potential risks that you should consider. Side effects with such solutions are rare and usually occur if IV therapy is performed in non-sterile conditions or by unlicensed health care providers.
Here are some of the disadvantages and side effects that may occur when administering colloid solutions:
Fluid overload
Fluid overload may occur if the health care provider is not careful about the amount of colloid solution administered. The amount of colloidal solution administered should be especially monitored in patients with impaired renal or cardiac function.
If the body is overloaded with colloid solutions, oncotic pressure may lead to excessive fluid retention in blood vessels. This may increase the risk of worsening heart failure or pulmonary edema.
Infections
In rare cases, colloid solutions may be the cause of infections. Infections may happen if working in aseptic conditions or using non-sterile instruments. Namely, such contaminated solutions may introduce bacteria into the bloodstream and worsen the patient’s health.
Price and availability
Regarding the cost of these solutions, colloid solutions are generally more expensive than crystalloids. Colloidal solutions containing expensive components like human albumin are especially expensive. In addition to the price, you should also consider the availability of such solutions. Certain colloid solutions may not be available in all healthcare settings.
Hypersensitivity reactions
Although rare, allergic reactions to the components of the colloid solution may occur. Symptoms may range from mild itching and rashes to more severe reactions like shortness of breath.
To avoid these reactions, it is important to talk to your healthcare provider if you are allergic or have an allergic reaction to any of the components of the colloid solution. That way, your healthcare provider will prepare IV fluid that matches your medical condition.
Conclusion
Different types of colloid IV fluids, such as natural and artificial colloids, may help improve hemodynamic stability, as well as expand the volume of blood plasma. However, before administering such solutions, healthcare providers should be familiar with the principles of osmolarity and oncotic pressure to ensure safe administration and patient safety.
Furthermore, you should consider the potential risks that may occur during IV therapy. So, before undergoing it, you should familiarize your doctor with your history of diseases, allergic reactions, and medications you have taken or are currently taking. With this type of information, the healthcare provider will know which types of colloid fluids are suitable for your health condition.
