PFT interpretation (General Review) Flashcards
1
Q
What counts as a good start for a FVC test?
A
BEV <150ml or 5% of FVC (whichever is larger)
- long enough Expiratory flow ->6 sec of plateau for 2 sec
2
Q
What can FVCs and FVLs be used for?
A
Identify level of upper airway obstruction
3
Q
If PEF falls with repeated efforts (or other expiratory flows), what can be suspected?
A
- suspect pt fatigue or
- hyperreactive airways (as pt tries more times, R may ⬆ and PEF = ⬇)
4
Q
A slow rise in PEF indicates what?
A
A large upper airway obstruction
5
Q
I or E curve squared indicates what?
A
Large upper airway obstruction
6
Q
Normal PEF criteria for women, men, and kids?
A
- Women: 340-550
- Men: 440-740
- Kids: 150-450
7
Q
How often should PEF be monitored?
A
2x daily; try to establish a personal best
8
Q
PEF green criteria indicates what treatment plan?
A
Green > 80% best -> Routine Tx
9
Q
PEF yellow criteria indicates what treatment plan??
A
yellow 50-80% best = increase meds
10
Q
PEF Red criteria indicates what treatment plan?
A
Red <50% best = SABA ASAP
11
Q
What does Body plethysmography measure?
A
FRC; determines ERV via spirometry
- FRC-ERV=RV
- TLC = FRC + IC
12
Q
What does nitrogen washout measure?
A
Measures FRC; only 1 good test needed
= if >1l should be change in 10% -> report mean
13
Q
What does Helium dilution measure?
A
Measures FRC
14
Q
What does single breath nitrogen washout measure?
A
Distribution of ventilation
- measures change in N2 during exp of VC breaths after single breath of 100% of O2
15
Q
What does P100 or P0.1 measure?
A
Measure airway hunger
- Insp against closed shutter. Pas at mouth recorded
- measures at 100ms after occlusion
16
Q
What does Resting Energy Expenditure (REE) greater than 10% above normal indicate?
A
Hypermetabolic State
17
Q
When to not smoke PFT
A
within 1hr (24hrs for DLCO)
18
Q
When not to have alcohol
A
within 4hrs of testing
19
Q
When not to have exercise
A
within 30 mins of testingW
20
Q
When to not have a large meal
A
within 2hrs of tesing
21
Q
Absolute contraindication to spirometry
A
1 month of MI
22
Q
Obstruction in spirometry?
A
- FEV1% is decreased
- FVC MAY be decreased
- FEV1/FVC is decreased
23
Q
Restriction spirometry results
A
- FEV1 is decreased
- FVC decreased
- FEV1/FVC normal
24
Q
obstructive AND restrictive spirometry results
A
- FEV1 decreased
- FVC decreased
- FEV1/FVC decreased
25
When to stop SABA before testing?
within 4hrs of testing
26
When to stop LABA and oral therapy before testing?
within 12hrs of testing
27
Pre test reversibility
3 accepctible FVC manoeuvres
28
How long to wait with SABA vs SAAC for PFT testing?
1. >10mins
2. 30 mins
29
Asthma dx reversibility
12-15% improvement in FEV1 OR FVC AND a 200ml increase in either.
30
negative bronchodilator response
<8% change in FVC and FEV1
31
Where can PEF be done
PF lab, in hospital or bedside,at home via FVL or peak flow meter
32
Test procedure in PEF
- rapid and maximum lung volume
- no hesitation in blow
- 1-3sec expiratory
33
Green zone PEF?
80-100% of PB
- routine tx
34
Yellow zone PEF?
50-50% of PB
- acute exacerbation, *increase in meds*
35
Red zone PEF
<50% bronchodilators should be taken immediately, and if no improvement, contact clinician
36
MVV
Maximum volume of air a subject can move in and out of the lungs in a specific period of time (12 seconds)
Not as good as FEV1
37
MVV procedure
Patient should be sitting and wearing nose clips.
- Breathe RAPID and as DEEP as possible for 12 seconds
- ideal rate 90-110br/min
38
Obstruction in MVV?
<75-80% of predicted
39
What is Thoracic Gas Volume (TGV)?
TGV is all the gas trapped in the thorax at time of airflow obstruction
40
What is FRC plethysmography?
Volume of intrathoracic gas when airflow occlusion happens at FRC
41
What is plethysmography used for?
Diagnosis of restrictive lung diseases (indicated when Spirometry not showing results or indicating restrictive)
- Evals obstructive diseases that usually produce lower results (bullous disease of CF)
- Determination of response to bronchodilators/methacholine (Raw,Sgaw)
- aka helps follow progression of disease
42
Contraindications of pleth
- Mental confusion
- IV pumps or O2
- Condition that interfere with pressure changes (chest tubes, ruptured eardrum, transtracheal O2 catheter)
43
Measurement technique pleth
Quiet breathing until stable Vt and FRC established
near FRC, shutter closed and **patient pants against closed shutter** around 60br/min for 2-3 seconds.
Shutter will open and perform SVC when ready
44
Repeatability of FRC
At least 3 FRCpleth values within 5% of eachother
45
P.01
100ms of a closed shutter
- big inspiration against and measures pressure change at mouth recorded.
46
Normal P.01
1.5-2
47
What does P.01 measure
Ventilatory drive
- may be useful in determining weaning from ventilator capability
48
Increased P100
Increased with hypercapnia and hypoxia.
- 0.5-0.6cmH2O/mmhg/PcO2 (20% variability)
- (0.5cmH2O per 1mmhg increase in PaCO2)
49
How can MIP/MEP be assessed
against occluded airway either on intubated patients or mouthpiece
50
What does MIP/MEP measure
Assess muscular strength and weaning/extubation potential
51
MIP procedure
Exhale to RV, then occlude mouthpiece to inspire maximally for 1-3sec
52
MEP procedure
inhale to TLC, mouthpiece occluded and patient is coached to expire maximally for 1-3seconds
53
Normal MIP
-80--100cmH2O
54
Normal MEP
>80-100cmH2O
55
critical MIP
>-20cmh2o = difficult to wean or extubate or impending respiratory failure.
56
Normal DLCO
25ml/min/mmhg
57
Tracer gases DLCO
He, Ne and CH4
58
Results of patient with emphysema, Pulmonary fibrosis, ILD..etc
DLCO decreased
DLCO/Va decreased
59
Results of patient with small lungs/lung resection/short person DLCO
DLCO decreased
DLCO/Va normal
60
Reporting DLCO
Mean of results
61
Repeatability DLCO
Two tests within 10% or 2ml
62
Acceptability DLCO
Inspired volume >90% in less than 4 seconds
No leak or valsalva maneuvres
Expiration <4 seconds with a washout volume
63
He dilution goal
To measure FRC
64
What does Va determine
Alveolar volume. If DLCO/Va is decreased, it is an indicator for increased thickness of the AC membrane
65
In Bronchoprovocation testing, what do PC20 values indicate?
Level of airway hyperresponsiveness
- PC20 > 16 mg/mL = normal responsiveness
- PC20 4.0-16 mg/mL = borderline bronchial hyper-responsiveness (BHR)
- PC20 1.0-4.0 mg/mL = mild BHR and indicates a positive test
- PC20 < 1.0 mg/mL = moderate to severe BHR
- PC20 of ≤ 8 mg/mL is common in patients with hyperactive airways
66
Normal FEV1% (FEV1/FVC) range?
>70% of predicted
- Remember, FVC and FEV normal are >80% of predicted
67
What lung volumes make up Inspiratory capacity (IC)?
IRV and VT
68
What lung volumes make up Functional residual capacity (FRC)
ERV and RV
69
What lung volumes make up VC?
IRV, Vt, and ERV
70
What could a TLC <80% of predicted indicate?
Restrictive lung disease
- If you look at RV and TLC alone; Decreased TLC and with a normal RV/TLC ratio indicate RLD
71
Normal Lung volumes?
80-120% of predicted
72
What does a TLC > 120% of predicted indicate?
Obstructive lung disorder
- If you look at the TLC and RV alone; Increased RV/TLC + increased TLC indicate OLD
73
Normal RL/TLC ratio?
Anything less than 35% is considered normal.
- Anything greater than 35% with normal TLC indicates acute air trapping aka asthma
- Anything greater than 35% with increased TLC indicates chronic hyperinflation
74
COPD vs Acute asthma lung volume comparison
- COPD = Increased TLC and RV as well
- Acute asthma = normal TLC
75
What tests for lungs volumes
1. **Nitrogen washout** aka open circuit test (alveolar volume aka gas in and out) --> gives 100% O2 to washout Nitrogen
2. Helium dilution aka closed circuit test (alveolar volume)
3. Body plethysmography measures thoracic gas volume (TGN)
76
If you had to choose between nitrogen washout and helium dilution, which would you choose to test lung volumes on a COPD patient with hypercapnia?
Helium dilution bc nitrogen washout uses 100% fiO2 which is dangerous for COPD pateints
77
What do diffusing capacities depend on (both corrected and non) that will lower the ratio?
Hb (g/dl)
- If the Hb is low, the predicted diffusing capacity will be lower, but the actual measures, the DLCO/Va ratio will raise up higher than it should
78
Normal DLCO ratio?
80-120% of predicted is normal
- take actual/predicted DlCO...always use the corrected value = DLCO/Va
- Tells us there is a problem somewhere diffusion defect
79
Normal hemoglobin levels
- For adult males: 13.8 to 17.2 grams per deciliter (g/dL)
- For adult females: 12.1 to 15.1 g/dL
80
How do you get your percentages for FVC, FEV1, RV, TLC, and DLCO/Va (corrected)
Always take the actual/predicted
81
How do you get FEV1%?
FEV1/FVC
82
FVC and FEV normal ranges?
<80% of predicted
83
Normal FEV1% or FEV1/FVC?
>70% of predicted is normal
- Normal/restrictive normal bc they're able to blow out
- Anything less than 70% = obstructive bc they can't blow out their the right amount in the first second (FEV1)
84
