Hemodynamic
Monitoring Study Questions
1.
What does CVP measure and what is
a normal CVP? What would this mean in
the care of my clients?
~ CVP is a measure of blood volume and venous return. It reflects RIGHT-SIDED filling
pressures. It is primarily used to
monitor fluid volume status.
~ Normal range for CVP is 2-8 cm H20 or 2-6 mmHg
~ Hypovolemia and shock DECREASE the CVP.
Fluid overload,
vasoconstriction, and cardiac tamponade INCREASE CVP.
~ If CVP is decreased,
client needs fluid to increase preload.
If CVP is increased, client needs diuresis, vasodilation to decrease
afterload, or treatment for cardiac tamponade!
2.
What is a PA catheter; what does a
PA catheter measure, and where is it placed?
~ A PA catheter is a flow-directed, balloon-tipped
catheter, a.k.a. the Swan-Ganz. PA = pulmonary artery.
~ A PA catheter measures pressures in the right atrium, pulmonary artery, and left
ventricle. It is used to evaluate left ventricular and overall cardiac
function.
~ It is inserted into a central vein and threaded into the
right atrium. A small balloon allows the catheter to be
drawn into the right ventricle and
from there into the pulmonary artery. Once in place, the balloon is deflated and
the multiple lumens of the catheter allow measurement of pressures in the right atrium, pulmonary artery, and left
ventricle.
3. What is a normal PA pressure and under what conditions
would a PA pressure be increased? What
does it mean in the care of my clients?
~
~ Pulmonary artery pressure is increased in left-sided heart failure. Manifestations of left-sided heart failure
result from pulmonary congestion and decreased cardiac output. PA pressure measurement allows restoration of
fluid balance while avoiding overcorrection of the problem. Nursing interventions for heart failure would
be appropriate.
4. What is PAWP (PCWP or PWP); what does it measure and what
does this value mean? How does it relate
to the Left Ventricular End Diastolic Pressure (LVEDP)?
~ PAWP is pulmonary artery wedge pressure. It measures pressures generated by the left ventricle. It is used to assess left ventricular function.
Normal PAWP is 8-12 mmHg. PAWP is increased in left ventricular failure and pericardial
tamponade. It is decreased in hypovolemia.
~ PAWP reflects LVEDP under normal conditions, that is,
when LVEDP (ventricular preload) is increased,
PAWP is increased also.
5.
How is PAWP obtained?
The measurement of PAWP is obtained by slowly inflating
the balloon with 1.5 mL of air while observing the distal lumen pressure
tracing. As the line becomes “wedged,”
the tracing changes shape and amplitude.
When the tracing changes from arterial to atrial, the catheter is said
to be wedged and PAWP is measured at the end of expiration.
6.
What is cardiac output/cardiac
index and what do these values mean?
What is normal cardiac output/cardiac index?
~ Cardiac output/cardiac index are used to assess the
heart’s ability to meet the body’s oxygen demands. Because body size affects overall cardiac
output, the cardiac index is a more precise measurement of heart function.
~ The cardiac index is a calculation of cardiac output per
square meter of body surface area. The
normal cardiac index is 2.8-4.2 L/min/m2.
CO = SV x HR.
7.
What is SVR; How
is it determined? What is MAP?
~ SVR is systemic vascular resistance. SVR is primarily determined by vessel
diameter and distensibility (compliance.)
Factors such as SNS input, circulating hormones
(epinephrine, norepinephrine, atrial natriuretic hormone, and vasopressin) and
the renin-angiotensin system affect SVR.
~ SVR is calculated by:
SVR = (MAP – CVP) x 80/cardiac output
* MAP is
mean arterial pressure is the amount of arterial that is necessary to maintain
adequate perfusion of vital organs…usually 60 mmHg and is calculated by Systolic
BP + 2 (Diastolic BP) divided by 3