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)
Metabolic alkalosis is usually associated with what electrolyte shift
Low potassium
And normal room air ABG you can evaluate the blood gas by adding PaO2 and PaCO2 and value should be in what range?
110-140 torr
Low values would indicate VQ mismatch shunting or venous blood
What types of blood gases look good but the patient feels bad and what do you do?
- Carbon monoxide poisoning, hundred percent oxygen and hyperbaric
- Anemia – give oxygen to support patient until transfusion is complete.
- Dead space issue-test for pulmonary embolism
What type of blood gas looks bad, but patient feels good. How can you tell?
Chronic obstructive lung disease
Fully compensated respiratory acidosis and hypoxemia. You should decrease FiO2 if patient ihypoventilating
A shift to the right in the O2-Hb dissociation curve indicates what?
decreased oxygen affinity
-Increased hydrogen ion
-Decreased pH
increased temperature.
-Increased PCO2
-Increased 2–3 DPG
What is an accurate spirometer used in pulmonary function testing to measure volumes and flows?
Pressure differential (Fleisch) pneumotachometer
What can negatively impact the accuracy of a peak flow meter?
Debris and moisture
How do you determine a personal best peak flow?
The single highest measurement recorded during a 2 to 3 week timeframe of peak flow testing every morning and afternoon
What is a typical peak value for a healthy adult?
10 L/sec or 600 L/min
What does a plelthysmograph, or body box, measure
Thoracic gas volume, which is the same as functional residual capacity
Airway resistance, or the difference in pressure between the mouth and the alveoli
What type of monometer consist of a sealed metal container with a gear or spring mechanism that responds to changes in pressure  and what type of equipment is it used in
Aneroid manometer
Blood pressure cuffs and ventilator displays
What is MIP used for and what is an abnormal measurement?
Determine a patient’s readiness to wean from a ventilator or assess for guillian- Barre or myasthenia gravis
Normal 80
Less than
20 cm H2O
What is MEP measuring useful for
Helpful in evaluating a patient’s ability to maintain an airway and generate a cough
Normal 160
< 40 indicates poor ability
What is an SVC important for?
Slow vital capacity.
provides the volumes used to identify restrictive disease
Why is an FVC important?
Force vital capacity
Provides the important flow rates used to identify obstructive disease
How would an FVC indicate obstructive disease?
If it was smaller than the SVC
If it cannot be completed in three seconds
In pulmonary function testing, what is the best indicator of obstructive disease?
The FEV1/FVC
Less than 70%
What indicates decreased values in the forced expiratory flow 200–1200 (FEF 200-1200) and what does it indicate?
A flow less than 6.0 L/sec indicates large airway obstruction (large airway tumors, vocal cord paralysis)
What does a decreased expiratory flow 25-75% indicate?
A flow less than 4.7 L per second indicate small airway obstruction (asthma, COPD)
What is the purpose of pre and post bronchodilator testing and what would indicate there is a reversible component?
Measure the reversibility of an obstructive pattern. An increase of 12% and 200 mL in the FEV1 is considered significant.
How long should bronchodilators be held prior to pre-post testing?
Eight hours
What does a flow volume loop measure?
Measures and displays the volumes and flow rates measured during an FVC. Flow rates in the vertical axis and volumes are in the X axis.
Describe what the different shapes diagnose in a flow volume loop
-Skinny and tall – restrictive
-Short and wide large airwave obstruction
-Reclining chair-small airway obstruction
What is P-50 express in the O2 - Hb dissociation curve?
When the PaO2 = 50% saturation
Normal is 27 torr
What volumes make up the vital capacity?
Inspiratory reserve volume
Tidal volume
expiratory reserve volume
What vines make up the functional reserve capacity
Expiratory reserve volume
Residual volume
What volumes make up the inspiratory capacity?
Inspiratory reserve volume
Tidal volume
What percent of predicted are the levels of disorder in a pulmonary function test (normal, mild, moderate and severe)
Normal= >80%
Mild=60-79%
Moderate =40-59%
Severe=<40%
What are the three main criteria for a vital capacity maneuver for acceptability?
3 acceptable tests that don’t differ by more than 5%, or 200 ml
Show good start
SVC of at least 6 seconds
Among multiple spirometry trials, what indicates the best trial.
The highest sum of the FVC plus FEV1 is the best trial
How long is the MVV typically performed for and what is the purpose?
12 seconds (multiply by 5)
Evaluate respiratory muscle reserve, endurance, and fatigue
What are the three ways you can obtain a functional residual capacity measurement in pulmonary function testing
Helium dilution (closed method)
Nitrogen wash out (open method)
Plethysmography ( Body Box)
What pulmonary function test is used to determine the diffusion of gas across the alveolar-capillary membrane and what is the normal range?
Gas diffusing capacity
25 mL CO/min/mm Hg
When performing a gas diffusing capacity, what do numbers below 25 mL CO/min/mm Hg indicate?
Decreased diffusion that occurs with thickened or damaged alveolar/capillary membrane. Pulmonary fibrosis, sarcoidosis, ARDS, pulmonary edema.
What is the only obstructive disease that impacts the DLCO?
Emphysema as it damages the alveolar lining
What type of bronchoscopy is preferred for therapeutic indications?
Rigid bronchoscopy
What procedure provides real time ultrasound guidance for trans bronchial needle aspiration (TBNA)
Endobronchial ultrasound (EBUS)-has an ultrasound probe attached to the distal end
What procedure would you recommend for obtaining biopsy samples from peripheral pulmonary nodules?
Electromagnetic navigational bronchoscopy that uses low frequency electromagnetic waves to create a three-dimensional map
What are contraindications for bronchoscopy?
Refractory hypoxia
Bleeding disorders
Cardiovascular instability
Status Asthmaticus
Marked hypercapnea
The most common complication of bronchoscopy is nasal bleeding. What steps should you take to address serious bleeding?
Lovage w saline
Install epinephrine
Compress the site with the scope.
Insert a Fogerty catheter
What is the minimum endotracheal tube size for a flexible bronchoscopy
8.0
What type of adapter allows a patient to continue to receive positive positive pressure ventilation during bronchoscopy
Bodai adapter
