Cardiac output is the amount of blood being pumped by the heart per minute and measured in liters/minute. It is calculated by multiplying the stroke volume, which is the amount of blood pumped out of the left ventricle during each systolic cardiac contraction, and the heart rate. Cardiac output is affected by three other factors as well including: preload, afterload, and contractility. Decreased cardiac output is a state in which an inadequate amount of blood is being pumped by the heart to meet the body’s metabolic demands.
There are various reasons a person may experience a decreased cardiac output. Below is a brief list of potential causes:
- Coronary artery disease
- Genetic cardiac disease
- Myocardial ischemia/infarction
- Congestive heart failure
- Cardiac structural abnormalities
- Pericardial effusions
- Cardiac tamponade
This is not a comprehensive list as many different causes for decreased cardiac output exist. It is important to keep in mind that sometimes it may take a while for a patient to experience clinical signs and symptoms of decreased cardiac output due to these potential causes. Regardless though, it is important as the nurse to understand how other cardiac conditions can ultimately affect the patient’s cardiac output.
Signs and Symptoms
Signs and symptoms of decreased cardiac output can manifest in different ways. First, listed below are physiologic signs and symptoms a nurse may begin to notice.
- Cardiac arrhythmias
- Chest pain
- Poor tissue perfusion (diminished pulses)
- Clammy, cool skin
- Decreased urine output
In addition to these signs and symptoms, patients may also display psychological signs and symptoms such as:
- Altered mental status/confusion
- Patient will show adequate cardiac output as evidenced by blood pressure, heart rate, and rhythm within normal limits.
- Patient will be able to return to baseline activity level.
- Patient will display adequate breathing as evidenced by appropriate oxygen saturation level and absence of adventitious breath sounds.
- Patient will be able to verbalize future self-care activities to improve cardiac health.
Nursing Assessment for Decreased Cardiac Output
1. Monitor heart rate and blood pressure.
Low cardiac output can stimulate the sympathetic nervous system. This is done to compensate for the low cardiac output and can result in increased heart rates and initially an increased blood pressure. Later on, blood pressures may drop and patient can become hypotensive.
2. Monitor breath sounds, respiratory rate and pattern, and oxygen saturation.
Patient may experience an increase in shortness of breath as cardiac output decreases. Assessing oxygen saturation will allow for objective data regarding patient’s breathing status. Adventitious breath sounds are also common such as crackles.
3. Monitor heart rhythm.
Decreased cardiac output can result in cardiac arrhythmias. A common cardiac arrhythmia seen in these patients is atrial fibrillation.
4. Monitor heart sounds.
Normal heart sounds include S1 and S2. These may be diminished with poor heart function. In addition, heart sounds S3 and/or S4 may become audible which are signs of heart failure.
5. Assess peripheral pulses.
Decreased cardiac output can result in poor tissue prefusion and decreased or diminished pulses peripherally.
6. Assess skin color and temperature.
As the patient’s cardiac output decreases, tissue perfusion can worsen and patient’s skin may become cool, clammy, and pale due to decreased oxygen saturation in the body.
7. Assess patient’s mental status.
Due to decreased oxygen saturation, patients may have altered mental status and become confused.
8. Assess lab values and results of any imaging studies.
These can help to indicate potential causes or underlying conditions that may be contributing to the low cardiac output.
9. Monitor weight closely.
Decreased cardiac output could result in retention of fluid which can worsen the symptoms the patient is experiencing.
10. Monitor intake and output closely.
This will allow the nurse to maintain appropriate fluid balance.
11. Monitor patient’s activity level.
Patients may become fatigued more quickly when cardiac output is low.
Nursing Interventions for Decreased Cardiac Output
1. Administer supplemental oxygen as needed.
Patient’s oxygen saturation may be low and may require supplemental oxygen in order to maintain appropriate levels. Appropriate oxygenation is necessary to improve overall condition and bodily functions.
2. Administer prescribed medications as ordered.
Various medications may be ordered for patients with decreased cardiac output (i.e. ACE, ARBs, etc.). These will help to improve heart function and decrease patient’s symptoms and cardiac workload.
3. Elevate the head of the bed.
Elevating the head of the bed will allow the patient better positioning for breathing and be able to maintain an appropriate oxygenation level.
4. Maintain fluid restriction and/or sodium restriction.
Patients with low cardiac output are more prone to retaining additional fluids and can be very sensitive to sodium. A fluid and/or sodium restriction may be necessary to minimize fluid retention.
5. Initially allow for bedrest during acute phase. As patient’s status improves slowly begin activity to increase tolerance and stamina.
Patients with decreased cardiac output can become deconditioned quickly. Initially, bedrest is warranted until patient is able to reach a stable cardiac and respiratory state. Once stable, slowly increasing activity level will help to strengthen muscles including cardiac muscles.
6. Educate patient on home self-care.
Providing education for patients will allow them to understand the pathophysiology of what is occurring in regards to their health. Education will also assist patients in understanding measures they can take at home to improve their cardiac health and prevent further deterioration.
7. Place patient on cardiac monitor.
Cardiac arrhythmias are common with decreased cardiac output. It is important to be able to monitor for these and then treat as appropriate should an arrhythmia develop.
8. Educate patient to avoid Valsalva maneuvers.
These maneuvers can put extra strain on the cardiac muscle.
9. Implement a rehabilitation plan for activity (PT and/or cardiac rehab).
These types of programs can improve patient’s quality of life and decrease mortality.
References and Sources
- Bauldoff, G., Gubrud, P., & Carno, M. (2020). LeMone and Burke’s Medical-Surgical Nursing: Clinical Reasoning in Patient Care (7th ed). Pearson
- Bruss, Z. & Raja, A. (2021). Physiology, stroke volume. https://www.ncbi.nlm.nih.gov/books/NBK547686/
- King, J. & Lowery, D. (2021). Physiology, cardiac output. https://www.ncbi.nlm.nih.gov/books/NBK470455/
- RegisteredNursing.org (2021). Hemodynamics: NCLEX-RN https://www.registerednursing.org/nclex/hemodynamics/
- Vincent, JL. Understanding cardiac output. Crit Care 12, 174 (2008). https://doi.org/10.1186/cc6975