Pulmonary Diagnostic Testing Flashcards
What are the three access sites for narrow blood gas in the order from best to worst?
Radial due to collateral circulation
Brachial
Femoral
How would too much liquid heparin impact a blood gas sample?
The same as an air bubble. It would decrease PCO2, increase PO2 and increase pH.
How do you arterial realize a capillary sample in an infant?
Apply the site in a warm wet cloth at 45° for 5 to 7 minutes
What important value in a capillary blood gas does not correlate well with an actual arterial blood
PO2
What are the advantages of an umbilical artery catheter (UAC)?
Continuous monitoring of blood pressure
Arterial samples for ABG and lab analysis.
Blood transfusions
What is the sampling technique using an arterial line?
Withdraw approximately 3 to 5 mL of waste solution.
Attached blood gas syringe and collect blood sample.
Return waste solution to patient
Close stopcock and flush catheter and tubing.
Blood gas analyzers directly measure which values?
PO2- Clark electrode
PC02- severinghouse electrode
pH- Sanz electrode
When the blood gas machine is functioning correctly, the measure control values will have what characteristics
Within two standard deviations of the mean
A common set of rules developed to differentiate between random areas and true out of control?
Westgard rules
What are the out of control situations in the Westgard rules?
One control observation exceeds three standard deviations of the mean
Two consecutive control observations exceed two standard deviations of the mean
The difference between consecutive control runs exceeds four standard deviations
Other than Westgard rules, what are the other quality control methods for blood gas calibration?
Proficiency testing
Multiple machine analysis.
Gas exchange validation device or tonometry
What quality control method is the method of choice for precise control of the PO2 electrode?
Gas exchange validation device, or tonometry= device allows precision gas mixtures to be equilibrated with whole blood or buffer solution
When unknown blood gas control samples are sent to different laboratories using the same brand of model of analyzer, what is this control method called?
Proficiency testing
What is the alveolar air equation formula
PAO2=(Pb-PH2O) FiO2 - PaCO2/0.8
What is the formula for the A-a gradient and what is normal)
PAO2-PaO2
25-65 torr
What is the shortcut for the alveolar air equation?
(FiO2 x7) - PaCO2 + 10
What does a A-a gradient of 66-300 indicate and how would you treat?
how about >300
V/Q Mismatch-give O2
Shunt-CPAP and/or PEEP
What is the P/F ratio useful for?
Used in determining acute lung injury or acute respiratory distress syndrome
what is the normal value for the PaO2/FiO2 ratio?
Less than 300?
Less than 200
380 or greater
Acute lung injury
ARDS
What calculation is helpful in evaluating therapies to improve distribution of ventilation
A-a Gradient
What is the formula for mixed venous oxygen content (CvO2) and what is the normal range?
CVO2=(Hbx1.34xSVO2) + (PvO2x0.003)
14 vol% (12-16 vol%)
What is the formula for arterial oxygen content (CAO2) and why is it useful?
CAO2= (Hbx1.34xSaO2)+(PaO2x0.003)
Is the best measurement of oxygen delivered to the tissues or the best index of oxygen transport?
What is the normal value for a human shunt and how do you easily calculate changes?
Qs/Qt
3-5%
Start with 5 and add 5 for every 100 of the A-a gradient (I.e. 300 = 20% shunt). Round the number down
What could a large difference between the calculated and measured values of arterial oxygen saturation indicate?
Elevated carbon monoxide levels
The SaO2 in a blood gases calculated. How can it directly be measured?
Hemoximeter or co-oximeter
What does the oxygenation index (OI) measure and what is the formula and normal value?
The amount of ventilators support required to provide the level of oxygenation
(Paw x FiO2/PaO2) x 100
5, higher than 40 ECMO should be considered
What is the formula for dead space to tidal volume ratio (VD/VT) and what is the normal value?
(PaCO2-PeCO2/PaCO2) X 100
20-40%, but up to 60% with ventilator patients
What is the formula for desired minute volume?
(Current VE x Current PaCO2) = (Desired VE x Desired PaCO2)