Flashcards in Pulmonary Diagnostic Testing Deck (55):
What is the calculation for the partial pressure oxygen (PO2) in the alveoli?
What is the purpose of A-aDO2 (the A-a Gradient)?
This equation measures the difference between alveolar and arterial PO2
What is the formula to the A-a Gradient?
What is the interpretation of an A-a Gradient of 25-65 mm Hg on 100%?
What is the interpretation of an A-a Gradient of 66-300 mm Hg?
What is the interpretation of an A-a Gradient greater than 300 mm Hg?
What is the difference between the P/F Ratio and the A-a Gradient?
P(A-a)O2 : 300 means Shunting
Which Pulmonary Diagnostic Testing of 300 signifies ALI?
Which Pulmonary Diagnostic Testing of 300 signifies V/Q Mismatch?
What is CaO2?
Arterial Oxygen Content
What does measuring CaO2 mean?
It is the best measurement of oxygen delivered to the tissues, or the best index of oxygen transport; oxygen carried by the hemoglobin and dissolved in the plasma.
What is the formula for CaO2?
CaO2= (Hb x 1.34 x SaO2) + (PaO2 x .003)
What is the normal value for CaO2?
17-20 vol% or 19 vol%
What is CvO2?
Mixed venous oxygen content
What does the CvO2 mean?
It tells about the total amount of oxygen carried in the mixed venous blood
How is the CvO2 measured?
The blood is drawn from the Pulmonary Artery via the balloon-tip, flow directed (Swanz-Ganz) catheter
What is the formula for CvO2?
CvO2= (Hb x 1.34 x SvO2) + (PvO2 x .003)
What is the normal value for CvO2?
14 vol% (12-16 vol%)
When cardiac output decreases , what else decreases?
CvO2 and SvO2
Normally, what is the pressure on the left ventricle?
What is the mean arterial pressure (MAP) in the systemic arteries?
90 mm Hg (120/80)
What is the normal value for the Central Venous Pressure (CVP)?
2-6 mm Hg (<10)
What are the normal values of the Pulmonary Artery Pressure (PAP)?
25/8 mm Hg (teens)
What are the normal values for the Pulmonary Capillary Wedge Pressure (PCWP)?
8 mm Hg
What is the normal values for Cardiac Output (QT)?
What is Cardiac Index?
Cardiac Output divided by the Body Surface Area
What is the Cardiac Output divided by the Body Surface Area?
What is a normal adult cardiac index (CI)?
If the PCWP is high, where is the problem?
In the left heart
What pressures will be affected if there is a problem in the capillaries?
Mean Arterial Pressure (systemic)
If CVPs are high, where is the problem?
In the right heart
What pressures will be affected if the problem is in the lungs?
Pulmonary Artery Pressures (PAP)
What is the C(a-v)O2 (or arterial-venous oxygen content difference)?
It is CvO2 subtracted from CaO2, and measures the oxygen consumption of the tissues
What indicates a decreasing cardiac output when referring to the C(a-v)O2?
An increase in the C(a-v)O2; which means a decreasing CvO2
What P/F ratio signifies ALI?
A ratio less than 300 torr
What P/F ratio signifies ARDS?
A ratio less than 200 torr
If O2 Consumption (VO2) and O2 Content Difference (C(a-v)O2) are known, what equation will be used?
QT (Cardiac Output)
What is the QT (Cardiac Output) equation formula?
What is the normal value for QT (Cardiac Output)?
4-8 L/min (5)
What is QS/QT?
The shunt equation
What does the QS/QT (shunt equation) mean?
It is the portion of the cardiac output (QT) that is shunted (QS)
What is the QS/QT (shunt equation) formula?
(A-aDO2).003 + C(a-v)O2
Calculate the percent (%) shunt when A-aDO2 is 300 torr and the C(a-v)O2 is 3.6 vol%
.20 or 20% shunt
What are the normal values for the QS/QT (shunt equation)?
How can the PaO2 value be estimated from the SaO2?
Subtract 30 from the SaO2
If SaO2 values are 70, 80, or 90, what are the estimated PaO2 values?
40, 50, and 60 PaO2
What is the Deadspace to Tidal Volume Ratio?
It is the percentage of tidal volume that is deadspace (areas of the lung that do not participate in gas exchange) ventilation without perfusion
What are normal values for the VD/VT (deadspace to tidal volume ratio)?
20-40%, (up to 60% for ventilator patients).
What is PaCO2-PECO2 x 100/
The VD/VT (deadspace to tidal volume ratio) formula
What indicates a deadspace producing disease (pulmonary embolism) when it comes to the deadspace to tidal volume ratio?
An INCREASE in the VD/VT ratio
Calculate the VD/VT ratio for a patient who has a PaCO2 of 40 torr and a PECO2 of 30 torr.
.25 or 25%
What is the formula for the Desired Minute Volume equation?
(Current VE x Current PaCO2) = (Desired VE x Desired PaCO2)
With a minute volume of 8 L/min, the patient has a PaCO2 of 50 torr. What minute volume is required to achieve a PaCO2 of 40 torr?
VE = 10 L/min
What is the formula for the Desired PaO2 equation?
FIO2 x Desired PaO2/