IV Fluid Resuscitation
The human body is composed of
different fluid compartments and each compartment is important in regards to
fluid resuscitation; however, each compartment must work in cohesion with the
other.
Our bodies are made up of mostly
water; and water is the key source of life. However, if the water in our bodies
is not distributed correctly it can have a detrimental impact on the patient’s
outcome.
The fluid compartments consist of the
Intracellular Fluid Compartment (ICF), the Extracellular Fluid Compartment
(ECF), the intravascular space, and the interstitial space.
The Intracellular Fluid Compartment
contains about two-thirds of the body’s total fluid or 66%
according to the manual of Critical
Care; whereas the Extracellular compartment consists of one-third or 33% our
total fluid. The Extracellular compartment may be broken down further into the
intravascular space and interstitial spaces. The intravascular space contains
approximately 25% and the interstitial space contains about 75% as seen in
the
When assessing the patient the
healthcare provider should use their critical thinking skills to determine the
fluid needs of the patient; which fluid compartments are or will be affected,
and what types of fluids would best be ordered to help achieve an optimal fluid
distribution. Distribution of fluids will depend on the solute order and the
concentration of said solute.
The human body’s serum osmolarity
typically ranges from 285-295 in order to maintain homeostasis in these fluid
compartments. The healthcare provider should assess the osmolarity of the
crystalloids or colloids in order to help determine where and how they want to
move the fluids from one compartment to another.
There has been a lot of debate over
this particular issue in the healthcare setting for quite some time.
Why choose a crystalloid or a colloid
or vice versa. “A critical review of the experimental and clinical studies
comparing crystalloid versus colloid resuscitation essentially shows no
physiologic difference in the two solutions.”
(Tranbaugh, & Lewis, 1983)
So, to answer our previous question; why a colloid versus a crystalloid; is not an easy one. The physician may choose to select a colloid for patients who are already deemed to be in pulmonary edema or have some type of cardiac issue that may hinder an effect fluid exchange at the capillary level. By given colloids the healthcare provider can limit the fluid intake; yet still achieve fluid resuscitation. On the flip side if the patient has not yet gone into full blown pulmonary edema and has good kidney function the provider may opt for the crystalloid as this is less expensive and research has determined that neither has an advantage over the other; except cost. Crystalloids are less expensive than colloids; so the healthcare provider should outweigh the benefits versus the risk as well as a simple cost analysis.
So, to answer our previous question; why a colloid versus a crystalloid; is not an easy one. The physician may choose to select a colloid for patients who are already deemed to be in pulmonary edema or have some type of cardiac issue that may hinder an effect fluid exchange at the capillary level. By given colloids the healthcare provider can limit the fluid intake; yet still achieve fluid resuscitation. On the flip side if the patient has not yet gone into full blown pulmonary edema and has good kidney function the provider may opt for the crystalloid as this is less expensive and research has determined that neither has an advantage over the other; except cost. Crystalloids are less expensive than colloids; so the healthcare provider should outweigh the benefits versus the risk as well as a simple cost analysis.
In order to be effective in managing
the redistribution of fluids the healthcare provider must understand what types
of fluids are either crystalloids and or colloids and how that may affect the
movement of fluids across the different compartment membranes.
Before selecting a colloid versus a
crystalloid the healthcare provider must paint an overall picture of the patient’s
condition and underlying disease process.
Crystalloids
Hetastarch is another
type of plasma expander and is similar in properties to Albumin. If given; it
can sometimes cause an increase in the serum Amylase; which may throw
healthcare professionals for a loop into thinking the patient may be suffering
from pancreatitis. Hetastarch is composed of 154 mEq’s of Sodium with a ph
level of 5.5 as well as an osmolarity of 310.
1. Raoof, S, George, L, Saleh, A, & Sung, A. (2008). Acp manual of critical care. New York:
http://www.ncbi.nlm.nih.gov/pubmed/6349305
According to the Tabers Medical Dictionary a Crystalloid is a
solution in which crystals can or may form; but is able to diffuse across
cellular membranes. Crystalloids are the most common fluids used in the
healthcare setting. The following are some examples of the most common
solutions in the crystalloid category.
Normal Saline
Lactate Ringers
Dextrose 5%
Normal Saline
Normal Saline is composed of 154 milliequivalents (mEq/L) of
Sodium and 154 milliequivalents of Chloride. The ph is 6.0 and the osmolarity
is approximately 308. Normal saline is the main solution of choice when
administering a blood product. (Raoof, George, Saleh, & Sung, 2008)
Lactate Ringers
Lactated Ringers is composed of 130 milliequivalents of Sodium,
4mEq of Potassium, 109 mEq’s of Chloride, and 28mEq’s of Lactate. The ph is
approximately 5.1 and the osmolarity is approximately 273. (Raoof, George,
Saleh, & Sung, 2008)
Dextrose 5%
Dextrose 5% is composed of 140 mEq’s of Sodium 5 mEq’s of
Potassium, 98 mEq’s of Chloride, and 50 grams of Dextrose. The ph is 4.0 and
the osmolarity is around 252. (Raoof, George, Saleh, & Sung, 2008)
Colloids
Again, according to Tabers Medical Dictionary a colloid is a “glue-like
substance, such as a protein or starch… or a substance used as a plasma
expander in place of blood.” (Wilbur, 2009) The following are some examples of
colloid solutions.
- Albumin
- Hetastarch
- Dextran
Albumin
Albumin is produced
in a couple of varieties; typically 5% and 25%. Albumin “is made from pooled human
plasma, which undergoes ethanol fractionation, ultrafiltration, and
pasteurization.” (Raoof, George, Saleh, & Sung, 2008) Albumin 5% contains
no preservative and is a clear, slightly viscous liquid; it is almost colorless
or slightly yellow tint. (FDA.gov, 2006) It is mainly used to expand the intravascular
volume whereas Albumin 25% is typically used for hypoproteinemia. Albumin 5% is
composed of 154 mEq’s of Sodium and 50 grams of Albumin and has a ph level of
6.6 as well as an osmolarity of 290.
Hetastarch
(Hespan)
Dextran
Dextran is also a
plasma expander; however, it is higher in molecular weight than Hespan. The
amount of expansion it provides to the vascular system depends on the amount
and rate of infusion. Just like with Albumin; Dextran is provided in a couple
strengths; typically 40 or 70. Dextran 40 is composed of 154 mEq’s Sodium, a ph
level of 6.7, as well as an osmolarity of 320. Whereas Dextran 70 is composed of
154 mEq’s Sodium, a ph level of 6.3, and an osmolarity of 310.
Crystalloids
versus Colloids
So, what is the best
choice for fluid resuscitation? Crystalloids or Colloids? The problem is it
takes a larger amount of crystalloids to resuscitate a patient fully; on the
other hand it only takes a small amount of colloids. Colloids however are more
expensive and can expand the intravascular space fairly rapidly. Depending on
what the patient’s medical condition is and the end goal of the fluid
resuscitation will depend on whether the healthcare provider administers a
crystalloid or colloid. For example if a patient arrives to the emergency room
or ICU and as in hypovolemic shock; the goal of fluid replacement would most
likely be attained by administering a crystalloid. On the other hand if the
patient is septic and has been diagnosed with septic shock the provider may
give a colloid or crystalloid.
Monitoring FluidStatus
In a normal healthy patient the
body’s blood volume is typically 70ml/kg or 4.9 liters for a patient who weighs
70kg. There are many methods to monitor and asses a patient’s fluid status;
however it is difficult to pinpoint the exact amount of fluid loss. Healthcare
providers may choose to perform a venipuncture and obtain a serum osmolarity or
the physician may opt to insert a central line a monitor the patients central
venous pressure (CVP) otherwise known as right atrium pressure. In a normal healthy
adult; the CVP should normally range from 6 to 8 cm of water. The lower the CVP
the more dehydrated the patient may be; whereas the higher the CVP the patient
will most likely present with fluid overload. If the healthcare provider is
using the serum osmolarity to judge the fluid status one must first remember
that early we stated the normal range usually falls between 285-295 mOsm/kg.
The higher the serum osmolarity the more dehydrated the patient may present;
whereas the higher the serum osmolarity the more likely the patient will
present with symptoms of fluid overload. Another option that healthcare
providers have at their disposal is the complete blood count (CBC). The
provider may assess the hematocrit. If the patient presents with a hematocrit
greater than 45 they may also be suffering from fluid overload.
Conclusion
The goal of fluid resuscitation
is to hydrate the cells in order to maintain a normal blood pressure and pulse
rate. Both crystalloids and colloids have their place in fluid resuscitation,
but the healthcare provider must look at the overall picture and use critical
thinking skills in order to administer the correct fluids, at the correct rate,
and the correct amount. The healthcare provider should assess the patient and determine
the goal of the fluid resuscitation needed and then make a decision on the
correct fluid to administer. The healthcare provider should also look at the
risk versus the benefits as well as the cost analysis.
References
McGraw-Hill Professional.
2. Wilbur, C. (2009). Taber's Cyclopedic Medical Dictionary. Philadelphia: F A Davis Co.
3. "Albumin 5%." Albumin 5%. FDA.gov, 02 Oct 2006. Web. 2 Apr 2011.
http://www.fda.gov/downloads/biologicsbloodvaccines/bloodbloodproducts/approvedproducts/li
censedproductsblas/fractionatedplasmaproducts/ucm056844.pdf
4. Nursing i.v. drug handbook. (2005). Philadelphia: Springhouse Pub Co.
5. Tranbaugh, RF, & Lewis, FR. (1983). Crystalloid versus colloid for fluid resuscitation of
hypovolemic patients.
Medline, 1-10(0195-878X), Retrieved from
http://www.ncbi.nlm.nih.gov/pubmed/6349305