piece in the body that plays a role in
It’s where the heart can NOT pump tissue perfusion, and everything in the
enough blood to meet the perfusion body depends on the heart for its
needs of the body. survival. If the heart can’t pump blood
efficiently, the organs don’t receive fresh
Therefore, the heart does not pump
oxygenated blood and the cells that
enough blood throughout the body,
make up that organ start to die.
which will decrease cardiac output and
this leads to a decrease in tissue Therefore in a nutshell, when the heart
perfusion and oxygen supply to the can’t pump, cardiac output falls,
organs/tissue’s cells. which decreases tissue perfusion and
the cells that make up our organs don’t
Note: In cardiogenic shock, there is receive enough oxygen to work. They
NOT an issue with a loss of blood start to panic and eventually die.
volume like in some of the other types of
shock. Blood volume is normal. When cardiac output falls (hence the
However, because the heart has blood pressure drops), the patient
experienced a decrease in its ability to begins to enter the stages of shock (we
function properly, that blood volume talked about the stages of shock in the
starts to back up and leads to previous lecture: initial, compensatory,
congestion in the lungs and the right progressive, and refractory).
side of the body (keep this in mind for
when we review the signs and
symptoms).
Let’s break down the heart’s role:
The heart is the PUMP of the body. It
takes blood to the right side of the heart
that has been used and depleted of
oxygen by the cells of the body and
pumps it to the lungs. The lungs
oxygenate and remove carbon dioxide
from the blood and sends it back to the
heart via its left side.
The left side is very strong, especially
the left ventricle, which is the main Cardiac Output and
pumping chamber of the heart. The left Cardiogenic Shock
side shoots the fresh oxygenated blood
into the aorta. The aorta branches off First, let’s talk about cardiac output
into many arteries that go into this because it’s a very important term you
complex network of vessels to feed the should know when taking care of a
organs oxygenated blood. patient with cardiogenic shock:
, Cardiac output is the amount of blood medications that will affect preload,
the heart pumps per minute. The heart’s afterload, and contractility via drugs like
cardiac output should be anywhere vasopressors, inotropes,
from 4-8 liters of blood per minute. vasodilators, and diuretics.
Cardiac output is determined by the Examples:
person’s heart rate times the stroke
volume. if afterload is decreased (which is
the resistance the heart must
Stroke volume is the amount of blood pump against to get blood out of
pumped from the left ventricle each beat the heart….if you decrease this, it
(50-100 ml). Stroke volume is makes it easier for the heart to
determined by the preload, afterload, pump blood forward) the stroke
and contractility of the heart. volume will increase hence
delivering a higher cardiac
Preload is the amount the ventricle output….vasodilators can achieve
stretches at the end of diastole (hence this.
it’s the amount the ventricles stretch
once their filled with blood….so it’s if contractility is increased (whic
the end-diastolic volume). Remember h is how strong the muscle cell
diastole is the relaxation/filling phase of contracts) it will increase stroke
the heart. volume and cardiac
output….positive inotropic
Afterload is the pressure the ventricle medications can achieve this.
must pump against to squeeze blood if preload is increased (which is
out. Therefore, it’s the force the heart the amount the ventricle stretches
has to pump against to get blood out of at the end of diastole) the stroke
the ventricle. volume will increase hence
delivering a higher cardiac
Contractility is how well the muscle output… vasopressors can
cells are contracting. Therefore, it’s how achieve this by causing
well the heart is contracting to pump vasoconstriction, which will
blood. increase venous return to the
heart.
If the stroke volume falls (meaning the
heart muscle is NOT pumping blood Another term you may see, especially
very well), the cardiac output decreases when talking about cardiogenic shock,
and this leads to a fall in tissue is Cardiac Index.
perfusion.
This is a more specific cardiac output
So, in other words, cardiac output tells measurement based on the patient’s
us how well the heart is pumping and body size. It’s calculated by taking the
perfusing the cells that make up our cardiac output and dividing it by the
organs. patient’s body surface area.
When we talk about treatment for
cardiogenic shock it will include