Hypovolemic shock nursing NCLEX review for students!
In this review, you will learn about hypovolemic shock.
After reviewing these notes, don’t forget to take the quiz that contains hypovolemic shock NCLEX Questions and to watch the lecture.
Lecture on Hypovolemic Shock
Hypovolemic Shock NCLEX Review
What is hypovolemic shock? It occurs when there is LOW fluid volume in the intravascular system.
“low blood volume”
The intravascular system is the space that contains the volume of blood in a person’s circulatory system. Therefore, if there is a decrease in the volume of blood in a person’s circulatory system, what does the heart have to pump? Hardly anything at all!
If the amount of blood the heart pumps to the organ/tissues DECREASES, the cardiac output decreases. This will lead to decreased tissue perfusion, which will alter the function of cells. It will limit their access to oxygen and signs and symptoms of shock will occur.
A person needs to lose about 15% or MORE of their intravascular volume for hypovolemic shock to occur.
The average human blood volume is 5 L (exact amount depends on the person’s size). So, if a person who has a blood volume of 5 L and loses 1 L of blood volume (1,000 mL), that would be 20% of their blood volume. This person would start showing signs and symptoms of hypovolemic shock.
Causes of Hypovolemic Shock
What can lead to a loss of fluid volume in the intravascular system?
Any condition that leads to fluid leaving the body externally or there is shifting of fluid within the body that leaves the intravascular space.
Relative hypovolemic shock: this is an INSIDE fluid shift from the intravascular system (this tends to be more concealed than absolute)
- Fluids or blood collecting or leaking inside the body from internal bleeding, third-spacing of fluid (severe burns due to increased capillary permeability), fracture of long bones, damage to organs like the pancreas…example: Cullen or Turner’s Sign.
- Massive vasodilation from septic shock
Absolute hypovolemic shock: this is an OUTSIDE fluid shift from the intravascular system that leaves the body (this tends to be more noticeable compared to relative)
- Massive bleeding from injury or surgery
- Excessive fluid loss from oral (vomiting), GI (diarrhea), GU (urine), integumentary (sweating)…..many times this is caused by a disease process (diabetes or endocrine disorders) or illnesses
Pathophysiology of Hypovolemic Shock
What is happening in hypovolemic shock?
There’s major depletion of volume in the intravascular system (relative or absolute cause) -> this decreases the amount of venous return to the heart (this is the amount of blood draining back to the heart) -> this DECREASES preload (the amount the ventricles stretch once their filled with blood)…they won’t be stretching very much because there isn’t much fluid to fill them -> this decreases stroke volume (the amount of blood pumped by the left ventricle with each beat -> this DECREASES CARDIAC OUTPUT (this is the amount of blood the heart pumps per minute….4-8 Liters per minute…CO = HR x SV)
-If cardiac output falls too low, the amount of blood that should be going to the organs/tissues cells per minute will drastically fall.
And guess what important substance is in the blood that the cells of the organs and tissues rely on to survive? OXYGEN!
But since the amount of blood that reaches them is low, the cells won’t receive enough oxygen to function and hypoxic injury to the cell can occur.
The body will attempt to compensate by activating the sympathetic nervous system, which will trigger the body’s built-in survival system.
Now, based on the percentage of fluid volume that is lost will determine the signs and symptoms the patient may present with and what stage the patient is likely in.
Hypovolemic shock can be divided into four stages or classes, and these are like the stages of shock we just reviewed in this series, but these stages are based on the percentage of fluid volume loss.
Remember the numbers: 15, 15-30, 30-40, 40% and what is happening to the blood pressure, heart rate, urinary output, mental status, and the skin.
Class I : <15% of volume loss….up to 750 mL in an adult
The body can maintain cardiac output with this volume loss. Patient is mainly asymptomatic with this class.
- Heart rate within normal limits (less than 100 bpm)
- Blood pressure, respiratory rate, within normal limits
- Skin pink, warm, and capillary refill normal (<2 seconds)
- Normal urinary output (greater than 30 mL/hr)
- Mental status: normal…may be a little anxious
Class II: 15-30% of volume loss….750-1500 mL in an adult
Cardiac output is starting to fall due to the volume loss. There is major body system compensation via the sympathetic nervous system, renin-angiotensin system, and the shunting of blood to vital organs.
- Heart rate will increase….tachycardia (greater than 100 bpm)….due to the effects of the SNS
- Blood pressure decreases but within normal limits (for now due to vasoconstriction)
- Respirations increase (mild)…due to low oxygen level in the body
- Urinary output will start to lower (20-30 mL/hr)….blood flow is shunted and body will start to keep water from aldosterone and ADH being released due to angiotensin II
- Skin: cool, clammy, increased capillary refill >2 seconds…blood flow diverted to vital organs
- Diminished peripheral pulses
- Mental status: mild anxiety
Class II: 30-40% of volume loss….1,500-2000 mL in an adult
The body can’t compensate anymore….it’s exhausted! Therefore, cardiac output falls so low that tissue perfusion is altered, which causes the cells that make up the organs to malfunction….heart, liver, lungs, kidneys, brain etc.
- Heart rate increased (significant tachycardia >120 bpm)
- Respiratory increased….progressing to respiratory failure
- Oliguria (<30 mL/hr)….renal failure…high BUN and creatinine
- Poor peripheral pulses
- Skin: very cool, mottled, capillary refill >2 seconds
- Mental status: very anxious and confused…..acidosis, low oxygen, and low perfusion to the brain
Class IV: >40% of volume loss……more than 2,000 mL in an adult
Death is very near….needs very dynamic treatment! The body is shutting down….the fluid loss is SEVERE!
- Significant tachycardia (>140 bpm), increase respiratory (respiratory failure), severe hypotension, anuria (no urine production), mental status: lifeless, coma
*Source: Class/Stage volume loss percentage and amount of volume loss modified from American College of Surgeons Guidelines
Signs and Symptoms of Hypovolemic Shock
Remember it depends on the percentage of volume loss, but in a nutshell: tachycardia, hypotension, cool/clammy skin, weak peripheral pulses, anxiety, decreased urinary output…..central venous pressure: low, PAWP/PCWP: low
Nursing Interventions for Hypovolemic Shock
Treatment goals: fluid resuscitation, correct underlying cause that is leading to the fluid loss….example: hemorrhaging: surgery (get the patient ready for surgery)
Monitor oxygenation and perfusion status of patient: place on oxygen, may need intubation and mechanical ventilation, what is the patient’s hemodynamic status? blood pressure, heart rate, rhythm, tissue perfusion to organs: mental status, urinary output (will need catheter insertion to closely monitor urinary output…UOP needs to be greater than 30 mL/hr)
If bleeding, hold firm, direct pressure.
If showing signs and symptoms of hypovolemic shock, place in modified Trendelenburg position (feet at 45’ and head flat….increases venous return to heart and cardiac output).
Obtain IV access (at least two IV sites that are large….18 gauge or bigger in a large vein like antecubital)…needed for rapid fluid delivery and other medications….many patients with severe hypovolemic shock (especially ones who are not responding to fluid treatment) will have a central line and hemodynamic monitoring to monitor cardiac output and fluid replacement.
Collect labs: hgb, hct (blood level), lactate level (status of cell’s metabolism), blood gases (acidosis?), electrolytes, bun, and creatinine
Severe hypovolemic shock: Central Venous Pressure (low) and PAWP/PCWP (low)
Fluids for Hypovolemic Shock
Crystalloids and colloids Solution are two types of volume expanders used in hypovolemic shock: varies depending on the patient’s status and volume loss
Normal Saline or Lactated Ringer’s: Isotonic fluids that will add more fluid to the intravascular system…increasing preload, stroke volume, and cardiac output
- most commonly started out on a crystalloid solution
- watch for fluid volume overload
- If in fluid overload, hemodynamic monitoring may show: elevated CVP or PWCP/PAWP
- Auscultate for fluid in the lungs…crackles
- Edema, jugular venous distention
Remember the 3:1 rule for crystalloid solutions: For every 1 mL of approximate blood loss, 3 mL of crystalloid solution is given.
**** Crystalloid solutions are able to diffuse through capillary wall, so there is less fluid that remains in the intravascular space compared to colloid solutions.
Albumin, Hetastarch: made up of large molecules (example: proteins) that can’t diffuse through the capillary wall so more fluid stays in the intravascular space for longer
- more expensive
- patient can have an anaphylactic reaction
- monitor for fluid overload
***If giving large amount of fluids, need to WARM them.
WHY? If not warmed, it can lead to hypothermia, and this will alter clotting enzymes. Keep the patient warm, but not to the point of sweating.
Blood and Blood Products: Packed Red Blood Cells, Platelets or Fresh Frozen Plasma (FFP):
PRBCS: helps replace fluid and provides the patient with hemoglobin, which will carry oxygen to deprived cells (crystalloids and colloids can’t do this)….these types of fluid may be used when the patient is not responding to crystalloid fluid challenge, experiencing severe bleeding/severe hypovolemic shock etc.
Platelets: for uncontrolled bleeding to help with thrombocytopenia
Fresh Frozen Plasma: for when the patient needs clotting factors
****monitor for transfusion reaction with these products
American College of Surgeons Division of Education. ACS/ASE Shock Medical Student Core Curriculum [Ebook] (p. 4). Retrieved from https://www.facs.org/~/media/files/education/core%20curriculum/shock.ashx
Hypovolemic shock: MedlinePlus Medical Encyclopedia. Retrieved from https://medlineplus.gov/ency/article/000167.htm