1
Q
What is the primary function of a pneumotachograph?
A
Measures flow by detecting pressure difference across a resistive element.
2
Q
What type of flow sensor uses temperature change to measure flow?
A
Heated wire anemometer.
3
Q
What is the standard calibration syringe volume for spirometers?
A
3 liters.
4
Q
What is the acceptable accuracy range for spirometer calibration with a 3-L syringe?
A
±3.5%.
5
Q
Which gas is used to calibrate a nitrogen analyzer?
A
100% oxygen.
6
Q
Which gas is used to calibrate a helium analyzer?
A
Known helium-air mixture.
7
Q
What is the purpose of a water seal spirometer?
A
Measures lung volume by water displacement.
8
Q
Which device measures gas volume by detecting pressure changes in a closed system?
A
Body plethysmograph.
9
Q
What type of analyzer measures CO in a DLCO test?
A
Infrared analyzer.
10
Q
What is the typical response time for a gas analyzer used in DLCO testing?
A
Less than 0.5 seconds.
11
Q
What does BTPS correction account for?
A
Body temperature, ambient pressure, and water vapor saturation.
12
Q
What is the recommended leak rate during plethysmography testing?
A
Less than 30 mL per minute.
13
Q
What is the recommended calibration frequency for spirometers?
A
Daily before testing.
14
Q
What is the main hazard of using water-seal spirometers?
A
Risk of microbial contamination.
15
Q
What type of transducer converts pressure to electrical signal?
A
Pressure transducer (strain gauge).
16
Q
What gas is used to test for leaks in a helium dilution system?
A
100% helium.
17
Q
What is the acceptable accuracy range for volume-displacement spirometers?
A
±1% of full scale or ±25 mL.
18
Q
What is the effect of temperature increase on gas volume in spirometry?
A
Increases measured volume.
19
Q
What is the purpose of an absorber in a closed-circuit helium system?
A
Removes carbon dioxide.
20
Q
What is the expected temperature inside a body plethysmograph?
A
Room temperature (ambient).
21
Q
What is the calibration gas mixture for DLCO testing?
A
0.3% CO, 10% He, balance air.
22
Q
What is the function of a barometer in a PFT lab?
A
Measures ambient pressure for BTPS correction.
23
Q
What is the most common error in spirometer calibration?
A
Leaks in the system.
24
Q
What component maintains constant flow in a pneumotachograph?
A
Laminar flow element.
25
What factor affects accuracy of a hot-wire anemometer?
Temperature and humidity changes.
26
What is the minimum exhalation time for a valid FVC maneuver?
6 seconds in adults.
27
What is the required repeatability for FEV1 and FVC in spirometry?
Within 150 mL.
28
What is the minimum number of acceptable FVC maneuvers?
Three.
29
What is the primary criterion for acceptability of a flow-volume loop?
Good start, no cough, and full exhalation.
30
What is the significance of a concave flow-volume loop?
Indicates obstructive disease.
31
What does a restrictive pattern show on spirometry?
Reduced FVC, normal or increased FEV1/FVC ratio.
32
What is the main purpose of performing a pre- and post-bronchodilator test?
Assess reversibility of airway obstruction.
33
What percent improvement in FEV1 indicates significant bronchodilator response?
≥12% and ≥200 mL increase.
34
What causes a sudden spike on the flow-volume loop?
Cough or glottic closure.
35
What is the definition of FVC?
Forced Vital Capacity, maximum exhaled volume after full inspiration.
36
What is FEF25–75% used to assess?
Small airway function.
37
What is the primary cause of early termination in spirometry?
Poor coaching or fatigue.
38
What artifact can cause falsely high FVC?
Mouthpiece leak or hesitation.
39
What is the normal FEV1/FVC ratio in adults?
75–80%.
40
What is the minimum exhalation time for children under 10?
3 seconds.
41
What does FEF200–1200 measure?
Effort and large airway patency.
42
What is the acceptable variation in PEFR reproducibility?
Within 10%.
43
What is the most common error in flow-volume testing?
Poor effort or incomplete exhalation.
44
What should you do if the patient coughs in the first second of exhalation?
Repeat the maneuver.
45
What is the role of the RT during spirometry?
Coach and ensure patient effort and technique.
46
What causes flattening of the inspiratory loop?
Variable extrathoracic obstruction.
47
What causes flattening of the expiratory loop?
Variable intrathoracic obstruction.
48
What causes both inspiratory and expiratory flattening?
Fixed large airway obstruction.
49
What is the purpose of a slow vital capacity test?
Determine true vital capacity without forced effort.
50
What is the expected FEV1 in a normal healthy adult?
About 80% of predicted.
51
What is the normal TLC compared to predicted?
80–120% of predicted.
52
What is the normal RV/TLC ratio in adults?
20–35%.
53
What is a common method to measure RV?
Body plethysmography or gas dilution.
54
What is the gas used in helium dilution testing?
Helium.
55
What is the gas used in nitrogen washout testing?
Nitrogen.
56
How long should nitrogen washout testing continue?
Until end-tidal nitrogen is less than 1.5% for 3 breaths.
57
What does an elevated RV indicate?
Air trapping or obstruction.
58
What does decreased TLC indicate?
Restrictive lung disease.
59
What is the definition of FRC?
Functional Residual Capacity, volume remaining after normal exhalation.
60
What is the most accurate method for lung volume measurement?
Body plethysmography.
61
What is the Boyle’s Law equation used in plethysmography?
P1V1 = P2V2.
62
What does a high airway resistance value indicate?
Obstructive lung disease.
63
What are normal airway resistance values?
0.6–2.4 cmH2O/L/sec.
64
What is the unit for specific airway conductance?
L/sec/cmH2O per liter of lung volume.
65
What does specific airway conductance correct for?
Lung volume differences.
66
What is the typical inspiratory gas used in a DLCO test?
0.3% CO, 10% He, balance air.
67
What does the DLCO test measure?
Diffusion capacity of the alveolar-capillary membrane.
68
What is the normal DLCO value?
25 mL CO/min/mmHg.
69
What is the significance of a reduced DLCO?
Decreased alveolar surface area or membrane thickening.
70
What condition causes low DLCO with normal spirometry?
Pulmonary vascular disease.
71
What condition causes low DLCO and restriction?
Pulmonary fibrosis.
72
What condition causes high DLCO?
Polycythemia or alveolar hemorrhage.
73
What is the required breath-hold time in DLCO testing?
10 seconds.
74
What causes DLCO to increase falsely?
High altitude or supine position.
75
What causes DLCO to decrease falsely?
Poor inspiratory effort.
76
What is the minimum inspired volume for a valid DLCO maneuver?
At least 85% of vital capacity.
77
What is the required repeatability for DLCO?
Within 2 mL CO/min/mmHg.
78
What factor must be corrected for in DLCO reporting?
Hemoglobin concentration.
79
What gas analyzer measures CO concentration in DLCO testing?
Infrared analyzer.
80
What gas analyzer measures He concentration in DLCO testing?
Thermal conductivity analyzer.
81
What is the normal alveolar volume (VA) in DLCO?
Equal to or slightly less than TLC.
82
What ratio indicates poor test effort in DLCO?
VA/TLC less than 0.85.
83
What is the purpose of a gas calibration mixture for DLCO?
Ensures analyzer accuracy.
84
What is the normal range for arterial pH?
7.35–7.45.
85
What is the normal range for PaCO2?
35–45 mmHg.
86
What is the normal range for PaO2?
80–100 mmHg.
87
What is the normal range for HCO3–?
22–26 mEq/L.
88
What is the normal range for SaO2?
95–100%.
89
What causes respiratory acidosis?
Hypoventilation or CO2 retention.
90
What causes respiratory alkalosis?
Hyperventilation or excessive CO2 elimination.
91
What causes metabolic acidosis?
Decreased HCO3– or increased acid production.
92
What causes metabolic alkalosis?
Excess HCO3– or acid loss.
93
What does an elevated A–a gradient indicate?
Ventilation-perfusion mismatch or shunt.
94
What is the normal A–a gradient on room air?
Less than (age/4 + 4).
95
What is the normal dead space to tidal volume ratio (VD/VT)?
0.2–0.4.
96
What does an increased VD/VT ratio indicate?
Wasted ventilation or dead space.
97
What is the normal mixed expired CO2 (PECO2)?
25–30 mmHg.
98
What is the formula for dead space fraction?
(PaCO2 – PECO2) / PaCO2.
99
What is the normal alveolar-arterial oxygen difference?
5–15 mmHg on room air.
100
What does capnography measure?
End-tidal CO2 concentration.
101
What is the normal end-tidal CO2 (ETCO2)?
35–45 mmHg.
102
What causes ETCO2 to decrease?
Hyperventilation or pulmonary embolism.
103
What causes ETCO2 to increase?
Hypoventilation or rebreathing.
104
What is the purpose of co-oximetry?
Measures multiple hemoglobin species (O2Hb, COHb, MetHb).
105
What is normal carboxyhemoglobin level in non-smokers?
Less than 2%.
106
What is normal methemoglobin level?
Less than 1%.
107
What is the most accurate method to measure O2 saturation?
Co-oximetry.
108
What interferes with pulse oximetry accuracy?
Poor perfusion, motion, nail polish, or COHb.
109
What is the recommended daily calibration for gas analyzers?
Zero and span calibration.
110
What is the acceptable calibration error for analyzers?
Less than ±2% full scale.
111
What is the purpose of biological control testing?
Checks instrument performance using known subject values.
112
How often should biological control tests be performed?
Weekly.
113
What is the acceptable variation in biological control data?
Within ±2 standard deviations of mean.
114
What is the purpose of a 3-L syringe in QC?
Verifies volume accuracy of spirometers.
115
What should be done if biological control results exceed 2 SD?
Repeat test and check calibration.
116
What is the acceptable leak rate for plethysmograph QC?
Less than 30 mL/min.
117
What is the most common cause of analyzer drift?
Temperature fluctuation or sensor aging.
118
What is the main infection control concern in PFT labs?
Cross-contamination between patients.
119
What disinfectant is recommended for mouthpieces and tubing?
70% isopropyl alcohol or 1:10 bleach.
120
How often should breathing circuit filters be changed?
Daily or between patients.
121
What is the minimum contact time for disinfectants?
10 minutes.
122
What PPE is recommended during PFT testing?
Gloves, mask, and eye protection.
123
What should be done if a patient is coughing excessively during testing?
Stop the test and clean equipment.
124
What test should not be performed on patients with active TB?
Plethysmography or DLCO testing.
125
What is the appropriate room ventilation for PFT labs?
At least 6 air changes per hour.
126
What temperature should be maintained in a PFT lab?
18–26°C (65–78°F).
127
What is the humidity range recommended for testing rooms?
30–60% relative humidity.
128
What should be done after testing a patient with a known infection?
Full disinfection of all contact surfaces.
129
What is the correct order of PFT testing?
Spirometry, lung volumes, DLCO.
130
What is the maximum acceptable delay between calibration and testing?
24 hours.
131
What is the recommended warm-up time for gas analyzers?
30 minutes minimum.
132
What is the function of a biological control log?
Track stability of instrument performance over time.
133
What are the main causes of poor repeatability in spirometry?
Poor patient effort or leaks.
134
What is the clinical purpose of performing full PFTs?
Differentiate obstructive vs restrictive lung disease.
RPFT
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