Pulmonary Artery Pressures

Definition:
Pulmonary artery catheterization is a diagnostic procedure in which a small catheter is inserted through a neck, arm, chest, or thigh vein and maneuvered into the right side of the heart, in order to measure pressures at different spots in the heart.
Purpose:
Pulmonary artery catheterization is performed to:
evaluate heart failure
monitor therapy after a heart attack
check the fluid balance of a patient with serious burns, kidney disease, or after heart surgery
check the effect of medications on the heart
Precautions:
Pulmonary artery catheterization is a potentially complicated and invasive procedure. The doctor must decide if the value of the information obtained will outweigh the risk of catheterization.
Description:
Pulmonary artery catheterization, sometimes called Swan-Ganz catheterization, is usually performed at the bedside of a patient in the intensive care unit. A catheter is threaded through a vein in the arm, thigh, chest, or neck until it passes through the right side of the heart. This procedure takes about 30 minutes. Local anesthesia is given to reduce discomfort.
Once the catheter is in place, the doctor briefly inflates a tiny balloon at its end. This temporarily blocks the blood flow and allows the doctor to make a pressure measurement in the pulmonary artery system. Pressure measurements are usually recorded for the next 48-72 hours in different parts of the heart. During this time, the patient must stay in bed so the catheter stays in place. Once the pressure measurements are no longer needed, the catheter is removed.
Preparation:
Before and during the test, the patient will be connected to an electrocardiograph, which makes a recording of the electrical stimuli that cause the heart to contract. The insertion site is sterilized and prepared. The catheter is often sutured to the skin to prevent dislodgment.
Aftercare:
The patient is observed for any sign of infection or complications from the procedure.
Risks:
Pulmonary artery catheterization is not without risks. Possible complications from the procedure include:

1. infection at the site where the catheter was inserted
2. pulmonary artery perforation
3. blood clots in the lungs
4. irregular heartbeat

Normal results:
Normal pressures reflect a normally functioning heart with no fluid accumulation. These normal pressure readings are:

right atrium: 1-6 mm of mercury (mm Hg)
right ventricle during contraction (systolic): 20-30 mm Hg
right ventricle at the end of relaxation (end diastolic): less than 5 mm Hg
pulmonary artery during contraction (systolic): 20-30 mm Hg
pulmonary artery during relaxation (diastolic): about 10 mm Hg
mean pulmonary artery: less than 20 mm Hg
pulmonary artery wedge pressure: 6-12 mm Hg
left atrium: about 10 mm Hg

Abnormal results:
Abnormally high right atrium pressure can indicate:
pulmonary disease
right side heart failure
fluid accumulation
compression of the heart after hemorrhage (cardiac tamponade)
right heart valve abnormalities
pulmonary hypertension (high blood pressure)
Abnormally high right ventricle pressure may indicate:
pulmonary hypertension (high blood pressure)
pulmonary valve abnormalities
right ventricle failure
defects in the wall between the right and left ventricle
congestive heart failure
serious heart inflammation

Abnormally high pulmonary artery pressure may indicate:
diversion of blood from a left-to-right cardiac shunt
pulmonary artery hypertension
chronic obstructive pulmonary disease or emphysema
blood clots in the lungs
fluid accumulation in the lungs
left ventricle failure

Abnormally high pulmonary artery wedge pressure may indicate:
left ventricle failure
mitral valve abnormalities
cardiac insufficiency
compression of the heart after hemorrhage

Key Terms
Cardiac shunt
A defect in the wall of the heart that allows blood from different chambers to mix.

EKG Waves

Heart Auscultation

Aortic area: Right sternal border, 2nd intercostal space. S2 is louder than S1.

Pulmonic area: Left sternal border, 2nd intercostal space.

Erb's point: Left sternal border, 3rd intercostal space.

Tricuspid area: Left lower sternal border, 4th intercostal space, not always audible.

Mitral (Apex) area: Left midclavicular line, 5th intercostal space. The S1 is loudest in this area. S3 and S4 are heard here.

Multiple Organ Dysfunction Syndrome

MODS. . .results from perfusion abnormalities and/or altered oxygen uptake by cells during sepsis and SIRS. MODS is considered a syndrome because the s/s are multiple and progressive. Organ systems are considered dysfunctional when they cannot maintain homeostasis or when they require supportive therapies to maintain homeostasis. The degree of organ dysfunction is a continuum that includes the possibility of return to normal function. The major organ systems affected in MODS are the pulmonary, renal, hepatic, cardiovascular, and CNS.

Disseminated Intravascular Coagulation

DIC. . .a result of unregulated clotting and thrombolysis stimulated by cytokine and/or pathogen toxin injury to the vascular endothelium during sepsis and SIRS.

Septic Shock

Affect on hemodynamic variables:

1. HR: Tachycardia in response to fever and hypermetabolism and as a compensatory response for the low SVR and low preload.
2. BP: Hypotension is related to low SVR, low intravascular volume, and/or inadequate EF. The degree of diastolic hypotension correlates with the low SVR.
3. Preload: Cardiac filling pressures, CVP and PAOP are low before IV fluid resuscitation because of vasodilation, peripheral vascular shunt formation, and the increased third spacing of intravascular fluid secondary to severe capillary leak.
4. CO: Typically elevated to compensate for low SVR and increased metabolic needs related to sepsis. Occasionally, patients with septic shock present with low CO and biventricular hypokinesis on echocardiogram. This low-CO state is thought to be caused by thy cytokine myocardial depressant factor, which is released during sepsis. This type of cardiac dysfunction is completely reversible and usually lasts 2 to 4 days.
5. SVR: Low because of vasodilation and increased peripheral vascular shunt formation casued by the cytokine and inflammatory response.

Cosyntropin Stim Test

Cosyntropin Stimulation. . .Detects adrenal insufficiency after cortisone stimulation. Cosyntropin and Cortrosyn are synthetic subunits of Adrenocorticotropin Hormone (ACTH) that exhibits the full corticosteroid-stimulating effect of ACTH in healthy persons. Failure to respond is an indication of adrenal insufficiency.

Normal value: Cortisol: >20 ug/dL (>552 nmol/L) rise after Cosyntropin/Cortrosyn administration.

4mL fasting venous blood sample before administration of stim drug. 4mL sample at 30 and 60 minutes after administration.

Absence or blunted response to stim: Addison's dis, hypopituitarism, adrenal ca, adrenal insufficiency - possible sepsis picture.
Response to stim: adrenal hyperplasma.