Cardiogenic Shock Pathophysiology

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1. Cardiogenic Shock Pathophysiology
2. Functions of the Heart
3. Blood Flow
4. Cardiogenic Shock Nursing Interventions

Shock has many types, and the manifestations are different for every type. We’ll be talking about cardiogenic shock pathophysiology, what it really is, and how it differs from the other types of shock.

The important detail you must remember with cardiogenic shock is this: low pressure equals low perfusion.

For those unfamiliar with perfusion, it’s the amount of oxygen being distributed around the body. Therefore, cardiogenic shock is decreased oxygen perfusion in the body.

Cardiogenic Shock Pathophysiology

Knowing about cardiac output, stroke volume, and blood pressure will better understand what happens in cardiogenic shock. Basically, cardiogenic shock is decreased pressure which equates to reduced perfusion.

Therefore, decreased cardiac output will result in decreased blood pressure. Instead of the normal cardiac output of four to eight liters per minute, there would be two liters per minute. And anything that’s less than two liters per minute can be categorized as cardiogenic shock.

Remember that shock, in any form, is decreased pressure influencing perfusion. If there is decreased perfusion, there will be decreased oxygen. A body with decreased oxygen will become anxious and hypoxic, and the client will have faint pulses.

Aside from those basic signs and symptoms, there are other manifestations that a client with cardiogenic shock will present. 

Functions of the Heart

To fully understand what is happening with cardiogenic shock, you have to understand the heart’s main function and how blood is pumped effectively in and out of the organ.

The heart’s primary function is to pump blood throughout the body. Blood is composed of many components, one of which is hemoglobin. Hemoglobin is a protein that holds oxygen and is responsible for transporting oxygen to different parts of the body.

Hematocrit is another blood component that is basically the liquid portion of the blood which helps hemoglobin to move around every system.

Decreased Hemoglobin and Hematocrit (H&H)

If there is decreased hemoglobin and hematocrit (H&H), there will be decreased perfusion since these two components are primarily tasked with transporting oxygen to all parts of the body. Insufficient hemoglobin and hematocrit are directly correlated with cardiac output.

H&H Ratio

If there is a decrease in hemoglobin, the hematocrit will also decrease because the two are intertwined with each other. If they go down, they go down together. 

The ratio is 1:3. One hemoglobin is equivalent to three hematocrits. 

For example, in your client’s laboratory values, if the hemoglobin is 8, the hematocrit will be 24.

Borderline H&H

If the hemoglobin value is eight or less, the client will immediately need a blood transfusion; therefore, the borderline value for hemoglobin is around 10 g/dl.

Stroke Volume

Now that we have a clearer picture of hemoglobin and hematocrit, the next thing that you have to know is the stroke volume. The stroke volume refers to the amount of blood that comes from the left ventricle in one pump. Stroke volume is composed of the preload and the afterload.

Question: How much blood is normally pushed out of the left ventricle?

Answer: About an ounce or two of fluid per stroke.

Preload and Afterload

Preload and afterload are phases of stroke volume. Preload refers to the time it takes for the left ventricle to be filled with blood, while afterload is the blood pumping out of the left ventricle. 

You can think of the preload and afterload as a slingshot. Preload is the pull, while the release is the afterload. So, preload and afterload are equivalent to the stroke volume.

Cardiac Output

Cardiac output is simply the amount of blood being pumped out in 60 seconds or one minute. The normal cardiac output is between four to eight liters per minute. Cardiac output is also influenced by a client’s body build.

Blood Pressure in Cardiogenic Shock

Blood pressure is a mixture of cardiac output (the amount of blood coming out of the heart in a minute) and heart rate (how hard the heart pumps blood to get out of the heart).

Blood Flow

So, this is what happens with proper blood flow inside the heart and lungs:

The right side of the heart will push unoxygenated blood to the lungs to get oxygenated. Then, oxygenated blood will get pushed into the left atrium, to the bicuspid valve, and into the left ventricle. 

The left ventricle is the area of the heart that pumps out all the blood to the rest of the body through the aorta. This is also called the preload and afterload.

Cardiogenic Shock Nursing Interventions

• Monitor vital signs, including blood pressure, heart rate, respiratory rate, and oxygen saturation, and report any changes immediately.
• Administer medications as prescribed, such as inotropic agents to improve cardiac function, vasopressors to increase blood pressure, and diuretics to reduce fluid overload.
• Assist with invasive monitoring, such as arterial lines, central venous lines, and pulmonary artery catheters, to continuously monitor hemodynamic status.
• Position the patient in a semi-Fowler’s position to reduce venous congestion and improve oxygenation.
• Collaborate with the healthcare team to develop a plan of care that addresses the patient’s specific needs and goals, and adjust the plan as needed based on the patient’s response to treatment.

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