30 Questions
What is the recommended timing method for conducting the single-breath DLCO maneuver?
Jones and Meade method
What is the acceptable timeframe for rapid inspiration to TLC from RV during the DLCO maneuver?
< 4 seconds
How much volume should be inspired during the DLCO maneuver relative to VC?
~85% of VC
What is the recommended dead space washout volume during the DLCO maneuver?
0.75 - 1.0 L
What is the acceptable timeframe for collecting the alveolar gas sample during the DLCO maneuver?
< 3 seconds
How much time should be allowed between DLCO tests?
4 minutes
What is the formula to calculate % decrease in FEV1?
(X-Y)/X * 100
What is an indicator to stop the test during bronchial challenge testing?
35%-45% decrease in sGaw
Which value is used to calculate the fraction of medication delivered to the lower airways?
SVN output per minute
What should be monitored if FEV1 is not sensitive in some asthmatics?
sGaw
Which parameter requires knowledge of TI/Ttot for its calculation?
sGaw
What does a decrease in sGaw of 35%-45% indicate during a test?
Patient has large airway changes
How is the FRC calculated in the Open Circuit Multiple Breath N2 Washout test?
FRC = FEN2final x (Expired Volume – N2tissue)
What is the purpose of correcting for 'N2tissue' in the FRC calculation?
To adjust for the volume of nitrogen washed out of blood and tissues
What assumption is made in the Closed-Circuit/Multiple-Breath Helium (He) Dilution test?
Equilibration of helium can occur between the spirometer and the lungs
What is added to the spirometer initially in the Closed-Circuit/Multiple-Breath Helium (He) Dilution test?
Air and then helium
Why is oxygen added to the system in the Closed-Circuit/Multiple-Breath Helium (He) Dilution test?
To maintain FiO2 near or above 0.21
How long does it usually take for equilibration of helium concentration between the lungs and rebreathing system in the Closed-Circuit/Multiple-Breath Helium (He) Dilution test?
~3 minutes
What can cause an overestimation of FRC using dilutional techniques?
Leakage in breathing circuits
Which element is crucial for accurately measuring FRC using dilutional techniques?
End expiratory level
In pulmonary function testing, which value indicates the severity of obstruction?
FEV1/FVC ratio
Which step is recommended in the evaluation process of pulmonary function testing following the review of graphs?
Evaluate FEV1/FVC ratio
What can a 20% - 30% increase in FEF25%-75% indicate during pulmonary function testing?
Positive response
What is the significance of a decrease in FEV1/FVC ratio?
Suggestive of severe obstruction
In obstructive lung diseases affecting medium and smaller airways, what shape does the expiratory limb of the flow volume loop take?
Concave
Which type of obstruction is characterized by decreased flow rates on both inhalation and exhalation with a square-like appearance in the flow volume loop?
Fixed obstruction
What causes the intrathoracic variable obstruction to have normal inspiratory flows but flattened expiratory flows?
High pleural pressures during expiration
Which condition is an example of a fixed obstruction?
Tracheal stenosis
What mnemonic is used to differentiate variable extrathoracic and variable intrathoracic obstruction?
"What's in is out, and what's out is in."
What effect does obstructive lung disease have on expiratory flow rates?
Decreases them
Test your knowledge on calculating percentage decrease in FEV1 levels using the formulas provided for control FEV1 and current FEV1 after inhalation. Explore concepts like Provocative Concentration (PC20), Provocative Dose (PD20), and the indications for stopping the test based on sGaw decrease percentage. Content based on Mottram 12th edition, Figure 9.3.
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