Question

Cardiac parameters:

-what is cardiac parameters?

-explain each: preload, after load, cardiac output and index, etc

-what are the physiology related to IABP? Including indications, nursing care, weaning

-and what are treatment and relationship to IABP?

Answer 1

CARDIAC PARAMETERS

The physiological parameters which are used to study the activity and regulation of cardiovascular systems are known as Cardiac Parameters. The main parameters include Ventricular End Diastolic Volume (VEDV), Ventricular End Systolic Volume (VESV), cardiac output (CO), cardiac index (CI) and stroke volume (SV)

Ventricular End Diastolic Volume (VEDV): It is is the total amount of blood within a ventricle at the end of Diastole. That means, it is the volume of the ventricle when maximally filled, immediately prior to the onset of a cardiac contraction.

Ventricular End Systolic Volume (VESV): It is the total volume of blood within a ventricle after completion of systole. That means, it is the volume of the ventricle when minimally filled immediately after systolic ejection of blood.

Stroke Volume : It is the total volume of blood that is ejected by the heart in a single contraction. The stroke volume for a typical heart at rest is approximately 70 ml.

Stroke Volume = VEDV – VESV

Cardiac Output: It is the total volume of blood ejected from the heart in one minute (ml/min). In a resting individual the average cardiac output is approximately 5000 ml/min. Cardiac Output is calculated as follows;

Cardiac Output = Stroke Volume x Heart Rate

Heart Rate: It is the number of contractions the heart undergoes in one minute (Beats/min)

The normal heart rate is between 60-100 beats/min

Cardiac Index: It is a parameter that relates the Cardiac Output from left ventricle in one minute to body surface area (BSA) and thus shows the performance of the heart in relation to the size of the individual. To find the cardiac index, divide the cardiac output by the person's body surface area (BSA). The normal range for CI is 2.5 to 4 L/min/m².

Cardiac Index = (Stroke Volume x Heart Rate)/BSA or Cardiac Output/BSA

Preload: It is the initial stretching of the cardiac muscle cells (cardiac myocytes) prior to contraction. It is related to ventricular filling.

Afterload: It is the force or load against which the heart has to contract to eject the blood.

Physiology of Intra-aortic balloon pump (IABP)

An intra-aortic balloon pump is a long, skinny balloon that controls the flow of blood through the aorta. The device gets smaller when the heart pumps so blood can flow out to the rest of the body. Then it gets bigger when the heart relaxes to keep more blood in the heart and coronary system. IABP increases myocardial oxygen perfusion and indirectly increases cardiac output through afterload reduction. It helps the heart to pump more blood. If the heart is unable to pump enough blood for the body, IABP is inserted.

Indications of IABP:

1) Heart problems which can cause Cardiogenic Shock, where the heart isn’t getting enough blood or isn’t sending enough to the rest of the body as in the following cases;

• Unstable angina
• Heart attack
• Certain abnormal heart rhythms
• Heart failure
• Heart defects

2) Myocarditis where an infection inflames the heart muscle

3) To reopen or bypass a blocked artery near the heart. A percutaneous coronary intervention which opens a blocked artery in the heart might need an IABP.

Nursing Care:

Educate the patient about the procedure and clarify any doubts or concerns. Explain that an IABP is attached to a tube called a catheter. Doctor will put the catheter and balloon into an artery in one of the legs and use an X-ray camera to move it up to the aorta. The device is hooked up to a machine that tells the balloon when to get bigger and when to get smaller. It uses helium to blow up the balloon because helium won’t cause problems in the body if it leaks.

Obtain a written consent for the procedure. Observe for any symptoms of complications after the procedure and instruct to report if any chest pain, breathlessness etc. Explain the patient to stay in the bed and to keep the leg straight. Explain that there may have some bleeding in the area where the device was put in, but observe for excessive bleeding. Observe for serious issues, like trouble with the blood flow in the arms or legs or signs of gas leaking from the balloon etc.

Observe for the signs and symptoms of following complications ;

• Damage from the lack of blood flow to a limb (ischemia)
• Injury to an artery
• Rupture of the balloon
• Incorrect position of the balloon, which might cause injury to the kidneys or other problems
• Low platelet count, which might cause excess bleeding because your blood doesn’t clot as well
• Infection
• Stroke

Weaning: It may need to stay in the aorta for several days. When it’s time to take it out, explain the procedure to the patient like, the doctor will give medicine to relax and then pull out the catheter, and close the cut where it came out.