Diese Präsentation wurde erfolgreich gemeldet.
Wir verwenden Ihre LinkedIn Profilangaben und Informationen zu Ihren Aktivitäten, um Anzeigen zu personalisieren und Ihnen relevantere Inhalte anzuzeigen. Sie können Ihre Anzeigeneinstellungen jederzeit ändern.
Part 1
Spirometry 
“Spiro” – from the greek for breathing 
“Metry” – measurement 
“Spirometry” – The measurement of breathing
 Spirometry is a measure of air flow and lung 
volumes during a forced expiratory manouver 
from full inspiration 
 Spir...
What is Spirometry? 
 Spirometry is the measure of: 
How quickly the lung can be emptied and filled 
AND 
How much air ca...
Volume Measuring Spirometer
Flow Measuring Spirometer
Desktop Electronic Spirometers
Small Hand-held Spirometers
Measuring vital capacity and 
its subcomponents. 
 Use a spirometer. 
TLC 
VC 
RV 
IC 
FRC 
IRV 
ERV 
RV 
Can Use 
Spirom...
Lung Volume 
 By calculation: 
RV = TLC - VC 
by spirometry 
by body 
plethysmography 
TLC or helium dilution 
FRC = TLC ...
Measurement of Lung Volumes 
Recall that spirometry can only measure volume from RV to 
TLC. Volume below RV is not “seen”...
Spirometer 
 A spirometer measures the flow or rate at 
which lung volume changes as a function of 
time . 
 A spiromete...
 A spirometer can be used to measure the 
following: 
– FVC and its derivatives (such as FEV1, FEF 25- 
75%) 
– Peak expi...
Spirometric indices 
 FVC (forced vital capacity) 
 FEV1 (forced expiratory volume in 1 s) 
 FEV1/FVC 
 FEV6 (forced e...
 VC–vital capacity (L) 
 FVC–forced vital capacity (L) 
 FEV1–one-second forced expiratory volume (L) 
 FEV1/FVC 
 FE...
Common Uses of PFTs 
1. To evaluate respiratory symptoms 
2. To determine severity of impairment and disability in 
patien...
Why Perform Spirometry? 
 Diagnostic 
– Causes of symptoms (eg. breathlessness) 
Is breathlessness due to heart or lung d...
Why Perform Spirometry? 
 Objective Assessment 
– The patients subjective assessment is often 
misleading 
– Helps differ...
Why Perform Spirometry? 
 Monitoring 
– Assess response to bronchodilator therapy 
– Determine the minimum effective dose...
Why Perform Spirometry? 
 Evaluations for Disability / Impairment 
Assessment for: 
– Rehabilitation program - capacity f...
What can PFTs tell you about 
the patient 
 Normal or abnormal 
 What diseases can you diagnose? 
– Only asthma is defin...
What PFTs cannot tell you 
 Does the degree of abnormality explain the 
patients symptoms? 
 “Normality” does not exclud...
PFTs are really wonderful but… 
 They do not act alone. 
 They act only to support or exclude a diagnosis. 
 A combinat...
Contraindications 
 No absolute contraindications. 
 FVC manoeuvre raise intra-cranial, intra-thoracic 
and intra abdomi...
Contraindications 
Recent cerebrovascular haemorrhage or 
known cerebral or abdominal aneurysm. 
Pneumothorax. 
Haemoptysi...
Patient preparation 
Before the test 
Avoid: 
 Acohol 4h 
 Large meal 2h 
 Smoking 1h 
 Vigorous exercise 30 min 
 We...
 For bronchodilator reversibility testing 
withhold bronchodilators prior to the test: 
Short-acting inhaled B2 agonists ...
Prior to Spirometry 
 Gain verbal consent 
 Check for contraindications and that the patient 
has been properly prepared...
Prior to Spirometry 
 The patient should sit upright with their legs 
uncrossed 
 A drink of water should be made availa...
Spirometry Maneuver 
In single breath test 
 A few normal tidal respirations 
 Then deeeeep inspiration 
 Momentary bre...
American Thoracic Society (ATS) 
Spirometry Guidelines 
Minimum of 3 technically acceptable blows 
(may need to perform up...
 Conventionally, a spirometer is a device used to 
measure timed expired and inspired volumes, 
and from these we can cal...
Spirometric Curves 
 The Volume–Time Curve (The Spirogram) 
 The Expiratory Flow–Volume Curve (FV 
Curve) 
36
38
Volume Time Curve 
 The vertical scale 
indicates total volume (l) 
the patient has blown out 
 The horizontal scale 
in...
40 
Normal Spirogram
Volume-time spirogram
42 
Volume-time Spirogram
Volume-Time Spirogram 
1)Tidal volume respirations 
2) At end expiration, 
patient performs maximal 
inspiration to TLC, f...
44 
Normal spirogram
Measurements 
Abbreviation Characteristic measured 
FEV1 Forced expired volume in 1 second 
FVC Forced vital capacity 
FEV...
 Basic spirometry involves only the measurement 
of forced vital capacity (FVC) and the forced 
expired volume in the fir...
 PEFR is not reproducible enough measurement 
for accurate diagnosis, but may be used more 
for following progress with a...
48 
Normal spirogram
The Volume–Time Curve (The Spirogram) 
49
 FVC is the highest point in the curve 
 FEV 1 is plotted in the volume axis opposite to 
the point in the curve corresp...
51 
The Volume–Time Curve (The Spirogram)
 FEF 25,50,75 can be roughly determined by dividing 
the volume axis into four quarters and determining the 
correspondin...
53 
The Volume–Time Curve (The Spirogram)
 FEF 25–75 can be roughly determined by 
dividing the volume during the middle half of 
the FVC (c–a) by the correspondin...
55 
Normal spirogram
 This curve also provides an idea about the 
quality of the spirometry,as it shows the 
duration of the exhalation [the f...
The Volume–Time Curve (The Spirogram) 
 Is simply the FVC plotted as volume in liters 
against time in seconds 
 You can...
58
 If a post bronchodilator study is done, as in case 
of suspected bronchial asthma, then there will 
be two discrete curv...
There is a lot of data reported 
out on a PFT test 
The only numbers to be really concerned 
with are: 
– FVC 
– FEV1 
– F...
PFT Reports 
o When performing PFT’s three values are reported: 
o Actual – what the patient performed 
o Predicted – what...
PFT Reports 
 Example 
Actual Predicted %Predicted 
VC 4.0 5.0 80%
Spirometry : Percent Predicted 
 Absolute values can be compared for one subject at 
different times 
 Percent predicted...
Forced Vital capacity(FVC) 
Total volume of air that 
can be exhaled forcefully 
from TLC 
The majority of FVC can 
be exh...
65 
Forced Vital Capacity (FVC) 
 Following full inspiration, patient exhales as rapidly as 
possible, forcibly and compl...
Forced Vital capacity (FVC) 
 is the volume of gas expired when the forced 
expiratory manoeuvre is continued to full 
ex...
Forced vital capacity 
A measure of VOLUME 
– How much air that can be forcefully exhaled 
– Normally FVC = VC 
 Varies d...
FVC and SVC are compared with each other in a normal subject 
( a ) and in a patient with an obstructive disorder ( b ). I...
 In addition, due to dynamic compression 
the FVC is then less than some other 
estimates of vital capacity, including 
i...
Vital capacity: slow vital capacity or 
forced vital capacity? 
 In some patients with obstructive airways disease, the f...
Forced Vital Capacity
Vital capacity is reduced in both 
obstructive and restrictive diseases 
VC 
RV 
VC 
RV 
VC 
RV 
Obstructive Normal Restri...
Forced Vital Capacity 
TLC 
FEV1.0 FVC 
1 sec 
FEV1.0 = 4 L 
FVC = 5 L 
% = 80% 
RV 
Normal 
TLC 
FEV1.0 
FVC 
1 sec 
FEV1...
Indication for lung volume test : 
● Low FVC : 
-? Restrictive 
-? Obstructive with hyperinflation and air 
trapping 
-? M...
Measuring TLC 
 To measure TLC or FRC, which include RV, 
spirometry is insufficient 
 Techniques: 
– Gas dilution 
– Pl...
Assessing severity of restrictive defects 
 Without TLC measurement, base severity 
on the FVC 
– ≥80% is considered “nor...
FVC 
 Interpretation of % predicted: 
– 80-120% Normal 
– 70 – 80 % Mild reduction 
– 50% –70 % Moderate reduction 
– <50...
FEV1 : 
Volume of air which can be forcibly exhaled 
from the lungs in the first second of a forced 
expiratory maneuver.
Forced expiratory volume 
in 1 second: (FEV1) 
Volume of air forcefully 
expired from full inflation 
(TLC) in the first s...
80 
FEV1 
 FEV1 :Amount of air forcibly exhaled in the 1st 
second of the FVC maneuver (80% of FVC 
volume). 
 Volume o...
5 10 15 
8 
6 
4 
2 
Time (s) 
Volume (L) 
Normal spirogram: 
Volume / time 
Man 
176 cm 
76 kg 
FVC 
FEV1 
0 1
Forced expiratory volume 
in 1 second (FEV1) 
A measure of FLOW 
─ Reported in liters and % of predicted 
─ 80 – 120% of p...
FEV1 
 The FEV1 may be misleading if interpreted alone 
as it can be low in the face of a low FVC 
 Considered abnormal ...
84
To calculate % predicted 
Actual Measurement x100 
Predicted Value 
– e.g. Actual FEV1 = 4.0 litres 
Predicted FEV1 = 4.0 ...
Severity of any spirometric 
abnormalities based on the FEV1 
Degree of severity FEV1 % predicted 
 Mild >70 
 Moderate ...
FEV1 
 Interpretation of % predicted: 
― >75% Normal 
― 60%-75% Mild obstruction 
― 50-59% Moderate obstruction 
― <49% S...
FEV1/FVC 
• Forced expiratory 
volume in 1 second 
– 4.0 L 
• Forced vital capacity 
– 5.0 L 
– usually less than during 
...
To calculate the ratio of FEV1 to FVC 
(FEV1%, FEV1/FVC or FER) 
Actual FEV1 x100 
Actual FVC 
e.g. FEV1 = 3.0 litres 
FVC...
90 
FEV1/FVC 
 FEV1/FVC: Very important ratio; when reduced, 
helps identify presence of obstructive disease. 
 Percenta...
FEV1 / FVC ratio 
 The FEV1/FVC ratio is the ratio of the forced expiratory 
volume in the first one second to the forced...
 FEV1 expressed as a percentage of the VC is the 
standard index for assessing and quantifying 
airflow limitation. 
 FE...
FEV1% = (FEV1/FVC) × 100 
 Forced expired volume in 1 second as percentage 
of forced vital capacity. 
 FEV1% is used as...
FEV1% = (FEV1/FVC) × 100 
 FEV1%may be misinterpreted if vital capacity is 
affected by increased strength or weakness of...
Forced Vital Capacity 
TLC 
FEV1.0 FVC 
1 sec 
FEV1.0 = 4 L 
FVC = 5 L 
% = 80% 
RV 
Normal 
TLC 
FEV1.0 
FVC 
1 sec 
FEV1...
Normal Values 
 FEV1/FVC ratio is the percentage of FVC that 
can be expired in one second. 
– 75 – 80% is normal 
– 60 –...
Normal Trace Showing FEV1 and FVC 
5 FVC 
FEV1 = 4L 
FVC = 5L 
FEV1/FVC = 0.8 
1 
2 3 4 5 6 
4 
3 
2 
1 
Volume, liters 
T...
Spirometry: 
Obstructive Disease 
Volume, liters 
FEV1 = 1.8L 
FVC = 3.2L 
FEV1/FVC = 0.56 
Time, seconds 
5 
4 
3 
2 
1 
...
Spirometry: Restrictive Disease 
Volume, liters 
Time, seconds 
FEV1 = 1.9L 
FVC = 2.0L 
FEV1/FVC = 0.95 
1 2 3 4 5 6 
5 
...
Mixed Obstructive and Restrictive 
Volume, liters 
Obstructive - Restrictive 
Time, seconds 
Normal 
FEV1 = 0.5L 
FVC = 1....
Spirometry: Abnormal Patterns 
Obstructive Restrictive Mixed 
Time Time Time 
Volume 
Volume 
Volume 
Slow rise, reduced 
...
Classification Of Ventilatory Abnormalities 
by Spirometry 
10 
2
Terminology 
 Forced expiratory flow 
25-75% (FEF25-75) 
– Mean forced expiratory 
flow during middle half of 
FVC 
– Mea...
 FEF25-75% is the average expired flow over the 
middle half of the FVC manoeuvre and is 
regarded as a more sensitive me...
Forced mid expiratory flow 
(FEF25-75%) 
 Sometimes termed the maximal mid expiratory 
flow rate (MMEF) 
A measure of FLO...
Forced mid expiratory flow 
(FEF25-75%) 
 It is less effort dependent compared to the FEV1 / 
FVC ratio 
 It may detect ...
FEF25-75 
 Interpretation of % predicted: 
– >60% Normal 
– 40-60% Mild obstruction 
– 20-40% Moderate obstruction 
– <10...
MMEF25-75% 
 Maximum Mid expiratory Flow rate 
 Max. Flow rate during the mid-expiratory part of FVC 
maneuver. 
 Effor...
 Forced expiratory flow (FEF25−75%fvc) was 
formerly maximal mid expiratory flow (MMEF). 
 This index is the average flo...
 MEFR – Mid-expiratory flow rates: 
(FEF25−75%), 
Derived from the mid portion of the flow 
volume curve but is not usefu...
FEV6 – Forced expired volume in six seconds: 
 Often approximates the FVC. FEV6 is the forced 
expiratory volume during t...
 FEV6 (the volume exhaled in the first 6 seconds) is 
sometimes used as an alternative measurement 
to the FVC if the spi...
FET (forced expiratory time) 
 Is the time required to perform the FVC 
manoeuvre (usually less than 5–6 seconds in 
adul...
FEV1, FVC and FER 
 Spirometry provides three basic 
measurements: 
1. The forced vital capacity (FVC) 
2. The forced exp...
 All three are needed to interpret spirometry. 
 A normal spirogram plots the total volume 
exhaled against time. 
 The...
11 
7 
The Volume–Time Curve (The Spirogram) 
Normal spirogram 
Approximately 80% of the total volume is exhaled in the fi...
 Approximately 80% of this volume (slightly lower 
in older people) is exhaled within 1 second, so 
the FEV1/FVC ratio is...
Obstructive pattern 
 In obstructive disorders (for example, asthma or 
chronic obstructive pulmonary disease), airflow 
...
Obstructive pattern 
 The FVC may also be reduced (because gas is 
trapped behind obstructed bronchi) but to a 
lesser ex...
12 
1 
Spirogram showing airways 
obstruction
 Although the FEV1/FVC ratio is very useful in 
diagnosing airflow obstruction, the absolute 
value of the FEV1 is the be...
 Patients with an FEV1 of less than 1 litre are likely 
to be limited by dyspnoea. 
 If the FEV1 is less than 0.5 litres...
Obstructive pattern 
 Both the FEV1 and the FVC may be reduced, but 
the FEV1 is reduced to a greater extent. The 
FEV1/F...
Restrictive pattern 
 Restrictive disorders can be caused by disease of 
the lung parenchyma (such as interstitial lung 
...
 Airflow may be normal or even increased 
because the stiffness of fibrotic lungs increases 
the expiratory pressure. 
 ...
Spirogram showing a Restrictive 
disorder 
12 
7
 Both the FEV1 and FVC may be reduced, but the 
FVC is reduced to the same or greater extent 
than the FEV1. 
 The FEV1/...
 A restrictive pattern on spirometry can be 
mimicked by a poor technique. 
 Often the FVC is underestimated because the...
Inadequate technique mimicking a 
restrictive disorder 
13 
0
 Inadequate technique mimicking a 
restrictive disorder 
 The patient stopped blowing too soon. 
 The FVC is underestim...
 Be cautious about diagnosing a restrictive 
disorder on spirometry alone, particularly if the 
FEV1 is in the normal ran...
FEF25–75%. 
 This is the forced expiratory flow between 25% and 
75% of the FVC (also called the maximum mid-expiratory 
...
13 
4
Quiz Practice 1 
A patient’s pulmonary function tests 
reveal the following: 
Actual Predicted %Predicted 
 FVC 4.01 L 4....
Quiz Practice 2 
A patient’s pulmonary function tests reveal the 
following: 
Actual Predicted %Predicted 
FVC 3.75 L 4.97...
Quiz Practice 3 
Predicted Actual Predicted% 
FVC 3.8 4.5 83 
FEV1 2.2 4.2 47 
FEV1/FVC 82 59 72 
FEF25-75 1.6 3.7 43 
Sur...
Quiz Practice 4 
Actual Predicted % Predicted 
FVC 2.9 4.5 64 
FEV1 2.5 4.2 59 
FEV1/FVC 89 82 113 
FEF25-75 3.7 3.5 102 
...
Quiz Practice 5 
Actual Predicted % Predicted 
FVC 4.0 4.5 88 
FEV1 2.6 4.2 57 
FEV1/FVC 65 82 71 
FEF25-75 1.7 3.6 47 
Be...
Quiz Practice 6 
Actual Predicted % Predicted 
FVC 4.0 4.5 88 
FEV1 3.6 4.2 89 
FEV1/FVC 90 82 112 
FEF25-75 3.1 3.4 95 
N...
Quiz Practice 7 
Actual Predicted % Predicted 
FVC 4.0 4.5 88 
FEV1 3.3 4.2 81 
FEV1/FVC 83 82 101 
FEF25-75 1.7 3.5 48 
S...
Quiz Practice 8 
Actual Predicted % Predicted 
FVC 3.5 5.3 68 
FEV1 3.1 4.6 68 
FEV1/FVC 93 82 117 
FEF25-75 3.7 3.3 120 
...
Quiz Practice 9 
Predicted 
Values 
Measured 
Values 
% Predicted 
FVC 6.00 liters 4.00 liters 67 % 
FEV1 5.00 liters 2.00...
Quiz Practice 10 
Predicted 
Values 
Measured 
Values 
% Predicted 
FVC 5.68 liters 4.43 liters 78 % 
FEV1 4.90 liters 3.5...
14 
5
Spirometry Basics
Spirometry Basics
Spirometry Basics
Spirometry Basics
Spirometry Basics
Nächste SlideShare
Wird geladen in …5
×

Spirometry Basics

. .

  • Als Erste(r) kommentieren

Spirometry Basics

  1. 1. Part 1
  2. 2. Spirometry “Spiro” – from the greek for breathing “Metry” – measurement “Spirometry” – The measurement of breathing
  3. 3.  Spirometry is a measure of air flow and lung volumes during a forced expiratory manouver from full inspiration  Spirometry is a method of assessing lung function by measuring the total volume of air the patient can expel from the lungs after a maximal inhalation. 5 What is a spirometry ??
  4. 4. What is Spirometry?  Spirometry is the measure of: How quickly the lung can be emptied and filled AND How much air can be blown out  Spirometry measures How much and How quickly air can be expelled following a deep breath .
  5. 5. Volume Measuring Spirometer
  6. 6. Flow Measuring Spirometer
  7. 7. Desktop Electronic Spirometers
  8. 8. Small Hand-held Spirometers
  9. 9. Measuring vital capacity and its subcomponents.  Use a spirometer. TLC VC RV IC FRC IRV ERV RV Can Use Spiromenter Can’t Use a Spirometer TV
  10. 10. Lung Volume  By calculation: RV = TLC - VC by spirometry by body plethysmography TLC or helium dilution FRC = TLC - IC
  11. 11. Measurement of Lung Volumes Recall that spirometry can only measure volume from RV to TLC. Volume below RV is not “seen” by spirometry.
  12. 12. Spirometer  A spirometer measures the flow or rate at which lung volume changes as a function of time .  A spirometer measures subdivisions of vital capacity .  A spirometer does NOT measure RV .
  13. 13.  A spirometer can be used to measure the following: – FVC and its derivatives (such as FEV1, FEF 25- 75%) – Peak expiratory flow rate – Maximum voluntary ventilation (MVV) – Slow VC – IC, IRV, and ERV – Pre and post bronchodilator studies
  14. 14. Spirometric indices  FVC (forced vital capacity)  FEV1 (forced expiratory volume in 1 s)  FEV1/FVC  FEV6 (forced expiratory volume in 6 s)  FEF25-75 (Maximum Mid Expiratory Flow)  PEF (peak expiratory flow)  MVV ( Maximal voluntary ventilation )
  15. 15.  VC–vital capacity (L)  FVC–forced vital capacity (L)  FEV1–one-second forced expiratory volume (L)  FEV1/FVC  FEF25-75%--forced expiratory flow (L/S)  PEF–peak expiratory flow (L/S or L/min) 18 Spirometric indices
  16. 16. Common Uses of PFTs 1. To evaluate respiratory symptoms 2. To determine severity of impairment and disability in patients with known respiratory disease 3. To follow the course of disease in a patient, including the response to therapy 4. To assess preoperative risk for predicting postoperative respiratory complications 5. To screen for subclinical disease
  17. 17. Why Perform Spirometry?  Diagnostic – Causes of symptoms (eg. breathlessness) Is breathlessness due to heart or lung disease? – Assess pre-operative risk. Fit for surgery? – Screen individuals at risk of lung disease (eg. smokers) – Measure severity of airway obstruction or restriction – Demonstrates to the patient, the presence and reversibility of airway obstruction. e.g. Asthma
  18. 18. Why Perform Spirometry?  Objective Assessment – The patients subjective assessment is often misleading – Helps differentiate organic and psychosomatic disorders – Provides objective feedback to the patient about the presence and severity of respiratory defect
  19. 19. Why Perform Spirometry?  Monitoring – Assess response to bronchodilator therapy – Determine the minimum effective dose of preventative medication – Tool used in the Asthma 3+ Plan
  20. 20. Why Perform Spirometry?  Evaluations for Disability / Impairment Assessment for: – Rehabilitation program - capacity for work? – Medico-legal reasons – Insurance evaluation -risk? – Fitness to dive
  21. 21. What can PFTs tell you about the patient  Normal or abnormal  What diseases can you diagnose? – Only asthma is defined by its PFTs  Estimation of impairment, or severity of disease  Response to therapy  Occupational surveillance
  22. 22. What PFTs cannot tell you  Does the degree of abnormality explain the patients symptoms?  “Normality” does not exclude the presence of disease  Abnormal test may not reflect loss of lung function
  23. 23. PFTs are really wonderful but…  They do not act alone.  They act only to support or exclude a diagnosis.  A combination of a thorough history and physical exam, as well as supporting laboratory data and imaging will help establish a diagnosis.
  24. 24. Contraindications  No absolute contraindications.  FVC manoeuvre raise intra-cranial, intra-thoracic and intra abdominal pressures so, relative contraindications may be: Recent eye, thoracic or abdominal surgery. Recent Myocardial Infarction (Last 3 months) Unstable cardiovascular status (uncontrolled hypertension or pulmonary embolism ).
  25. 25. Contraindications Recent cerebrovascular haemorrhage or known cerebral or abdominal aneurysm. Pneumothorax. Haemoptysis of unknown origin (FVC maneuver may aggravate underlying condition). Acute disorders affecting test performance (e.g. vomiting, nausea, vertigo).
  26. 26. Patient preparation Before the test Avoid:  Acohol 4h  Large meal 2h  Smoking 1h  Vigorous exercise 30 min  Wear loose, comfortable clothing.  Relaxed, and have time to visit the toilet.
  27. 27.  For bronchodilator reversibility testing withhold bronchodilators prior to the test: Short-acting inhaled B2 agonists for 12-24h. Long-acting inhaled anticholinergics for 24-36 h. Theophyllines for 12 h. Sustained release theophyllines for 24 h.
  28. 28. Prior to Spirometry  Gain verbal consent  Check for contraindications and that the patient has been properly prepared for the test  Gain an accurate height  Make note of Ethnic Origin and Age  The room should be a comfortable temperature  The patient should be sat in a hard backed chair with their feet able to touch the floor
  29. 29. Prior to Spirometry  The patient should sit upright with their legs uncrossed  A drink of water should be made available  The technique and purpose of spirometry should be explained in full prior to the test  Spirometry should be performed in the patients own time and they should not feel hurried Reinforce and Reassure
  30. 30. Spirometry Maneuver In single breath test  A few normal tidal respirations  Then deeeeep inspiration  Momentary breath holding  Very forced and fast expiration – As hard and as fast as he/she can blow out  Then deep, quick and full inspiration  Repeat at least 3 times – take the best
  31. 31. American Thoracic Society (ATS) Spirometry Guidelines Minimum of 3 technically acceptable blows (may need to perform up to 8 or more blows) Rapid take-off with no hesitation, cough, leak, tongue occlusion, glottic closure, early termination, valsalva manoeuvre Reproducible: within 200 ml from 2 of 3 technically acceptable blows Blow out for at least 6 seconds A nose peg is encouraged Prefer to have patient sitting
  32. 32.  Conventionally, a spirometer is a device used to measure timed expired and inspired volumes, and from these we can calculate how effectively and how quickly the lungs can be emptied and filled.  Spirometry is usually recorded as either a spirogram (a plot of volume versus time) or flow-volume curve or loop (a plot of volume versus flow). 35
  33. 33. Spirometric Curves  The Volume–Time Curve (The Spirogram)  The Expiratory Flow–Volume Curve (FV Curve) 36
  34. 34. 38
  35. 35. Volume Time Curve  The vertical scale indicates total volume (l) the patient has blown out  The horizontal scale indicates the total time (s) the patient has been blowing out for  Note the initial part of the curve which is steep followed by a gradual flattening of the curve
  36. 36. 40 Normal Spirogram
  37. 37. Volume-time spirogram
  38. 38. 42 Volume-time Spirogram
  39. 39. Volume-Time Spirogram 1)Tidal volume respirations 2) At end expiration, patient performs maximal inspiration to TLC, followed by 3) Exhalation as hard and as fast as possible until “all the air is out” •The volume of air exhaled is the FVC •The remaining volume of air in the lungs is RV Volume (L ) FVC RV
  40. 40. 44 Normal spirogram
  41. 41. Measurements Abbreviation Characteristic measured FEV1 Forced expired volume in 1 second FVC Forced vital capacity FEV1 /FVC Ratio Ratio of the above PEFR Peak expiratory flow rate FEF 25-75% Forced expiratory flow between 25-75% of the vital capacity
  42. 42.  Basic spirometry involves only the measurement of forced vital capacity (FVC) and the forced expired volume in the first second (FEV1).  The ratio between the two is a self-controlled statistic which tells if obstruction is present.  FVC and FEV1 can be measured against predicted values. 46
  43. 43.  PEFR is not reproducible enough measurement for accurate diagnosis, but may be used more for following progress with asthma.  FEF 25-75% is a measurement of smaller airway function but this measurement is usually not clinically useful 47
  44. 44. 48 Normal spirogram
  45. 45. The Volume–Time Curve (The Spirogram) 49
  46. 46.  FVC is the highest point in the curve  FEV 1 is plotted in the volume axis opposite to the point in the curve corresponding to 1s  Duration of the study (the forced expiratory time or FET) can be determined from the time axis, 6 s in this curve. 50 The Volume–Time Curve (The Spirogram)
  47. 47. 51 The Volume–Time Curve (The Spirogram)
  48. 48.  FEF 25,50,75 can be roughly determined by dividing the volume axis into four quarters and determining the corresponding time for each quarter from the time axis.  Dividing the volumes (a, b, and c) by the corresponding time (A, B, and C) gives the value of each FEF (FEF 25 , FEF 50 ,FEF 75 , respectively).  Note that this method represents a rough determination of FEFs, as FEFs are actually measured instantaneously by the spirometer and not calculated. 52
  49. 49. 53 The Volume–Time Curve (The Spirogram)
  50. 50.  FEF 25–75 can be roughly determined by dividing the volume during the middle half of the FVC (c–a) by the corresponding time (C–A).  FEF 25–75 represents the slope of the curve at those two points . 54
  51. 51. 55 Normal spirogram
  52. 52.  This curve also provides an idea about the quality of the spirometry,as it shows the duration of the exhalation [the forced expiratory time (FET)], which needs to be at least 6 s for the study to be clinically reliable. 56 The Volume–Time Curve (The Spirogram)
  53. 53. The Volume–Time Curve (The Spirogram)  Is simply the FVC plotted as volume in liters against time in seconds  You can extract from this curve both the FVC and FEV1.  FEV 1 /FVC ratio can be estimated by looking at where the FEV 1 stands in relation to the FVC in the volume axis 57
  54. 54. 58
  55. 55.  If a post bronchodilator study is done, as in case of suspected bronchial asthma, then there will be two discrete curves.  One curve will represent the initial prebronchodilator study whereas the second will represent the post bronchodilator study.  Looking at how the two curves compare to each other gives an idea about the degree of the response to bronchodilator therapy, if any 59
  56. 56. There is a lot of data reported out on a PFT test The only numbers to be really concerned with are: – FVC – FEV1 – FVC / FEV1 ratio – FEF25-75%
  57. 57. PFT Reports o When performing PFT’s three values are reported: o Actual – what the patient performed o Predicted – what the patient should have performed based on Age, Height, Sex, Weight, and Ethnicity o % Predicted – a comparison of the actual value to the predicted value
  58. 58. PFT Reports  Example Actual Predicted %Predicted VC 4.0 5.0 80%
  59. 59. Spirometry : Percent Predicted  Absolute values can be compared for one subject at different times  Percent predicted values allow comparison to population norms based on: – Sex – Age – Height – Race** - typically Black, White, “Hispanic;” everything else refers back to White values – Weight  Percent predicted also can be compared for one subject over time, allows for growth
  60. 60. Forced Vital capacity(FVC) Total volume of air that can be exhaled forcefully from TLC The majority of FVC can be exhaled in <3 seconds in normal people, but often is much more prolonged in obstructive diseases Measured in liters (L)
  61. 61. 65 Forced Vital Capacity (FVC)  Following full inspiration, patient exhales as rapidly as possible, forcibly and completely- volume of air exhaled is measured; takes 5-6 seconds with majority in 1 second.  Volume obtained is expressed as a % of predicted normal. Normals are based on volumes obtained from thousands of healthy individuals of similar age, sex, ht and wt and race.  Normal 80% of predicted.
  62. 62. Forced Vital capacity (FVC)  is the volume of gas expired when the forced expiratory manoeuvre is continued to full expiration.  In most healthy persons this point is reached within 6 s (hence FEV6), but in the presence of airflow limitation from narrow or collapsible airways the expiration can continue for much longer (up to 15 s). In this circumstance the FEV6 is a poor guide to FVC.
  63. 63. Forced vital capacity A measure of VOLUME – How much air that can be forcefully exhaled – Normally FVC = VC  Varies directly with height and inversely with age  Reported in liters and % of predicted
  64. 64. FVC and SVC are compared with each other in a normal subject ( a ) and in a patient with an obstructive disorder ( b ). In case of airway obstruction, SVC is larger than FVC, indicating air trapping 68
  65. 65.  In addition, due to dynamic compression the FVC is then less than some other estimates of vital capacity, including inspiratory vital capacity (IVC) 69
  66. 66. Vital capacity: slow vital capacity or forced vital capacity?  In some patients with obstructive airways disease, the forced vital capacity (FVC) will underestimate the true vital capacity (VC). This is because the increase in intrathoracic pressure during the forced manoeuvre compresses airways, causing early airway closure and gas trapping. This does not happen in normal lungs.  If suspected, it can be detected by measuring the vital capacity (from full inspiration to full expiration) without trying to force the air out (sometimes called a slow or relaxed vital capacity, SVC).  Some pulmonary function equipment also allows the vital capacity to be measured as an inspiratory manoeuvre (inspiratory vital capacity, IVC). 70
  67. 67. Forced Vital Capacity
  68. 68. Vital capacity is reduced in both obstructive and restrictive diseases VC RV VC RV VC RV Obstructive Normal Restrictive
  69. 69. Forced Vital Capacity TLC FEV1.0 FVC 1 sec FEV1.0 = 4 L FVC = 5 L % = 80% RV Normal TLC FEV1.0 FVC 1 sec FEV1.0 = 1.2 L FVC = 3.0 L % = 40% RV Obstructive airway resist Restrictive lung recoil TLC FEV1.0 FVC 1 sec FEV1.0 = 2.7 L FVC = 3.0 L % = 90% RV
  70. 70. Indication for lung volume test : ● Low FVC : -? Restrictive -? Obstructive with hyperinflation and air trapping -? Mixed pattern -? Equivocal spirometry findings (FEV1&FVC at lower limit of normal)
  71. 71. Measuring TLC  To measure TLC or FRC, which include RV, spirometry is insufficient  Techniques: – Gas dilution – Plethysmography (body box)
  72. 72. Assessing severity of restrictive defects  Without TLC measurement, base severity on the FVC – ≥80% is considered “normal” – 70-80% is considered mild – 60-70%% is considered moderate – 60% is considered severe  When TLC is measured – Gold standard to define restrictive ventilatory defect
  73. 73. FVC  Interpretation of % predicted: – 80-120% Normal – 70 – 80 % Mild reduction – 50% –70 % Moderate reduction – <50% Severe reduction FVC
  74. 74. FEV1 : Volume of air which can be forcibly exhaled from the lungs in the first second of a forced expiratory maneuver.
  75. 75. Forced expiratory volume in 1 second: (FEV1) Volume of air forcefully expired from full inflation (TLC) in the first second Normal people can exhale more than 75-80% of their FVC in the first second Measured in liters (L)
  76. 76. 80 FEV1  FEV1 :Amount of air forcibly exhaled in the 1st second of the FVC maneuver (80% of FVC volume).  Volume obtained is expressed as a % of predicted normal. Normals are based on volumes obtained from thousands of healthy individuals of similar age, sex, ht and wt and race.  Normal  80% of predicted.
  77. 77. 5 10 15 8 6 4 2 Time (s) Volume (L) Normal spirogram: Volume / time Man 176 cm 76 kg FVC FEV1 0 1
  78. 78. Forced expiratory volume in 1 second (FEV1) A measure of FLOW ─ Reported in liters and % of predicted ─ 80 – 120% of predicted is a normal value
  79. 79. FEV1  The FEV1 may be misleading if interpreted alone as it can be low in the face of a low FVC  Considered abnormal if < 80% of predicted value  Dyspnea usually present if < 50% of predicted value
  80. 80. 84
  81. 81. To calculate % predicted Actual Measurement x100 Predicted Value – e.g. Actual FEV1 = 4.0 litres Predicted FEV1 = 4.0 litres 4 x 100 = 100% 4
  82. 82. Severity of any spirometric abnormalities based on the FEV1 Degree of severity FEV1 % predicted  Mild >70  Moderate 60-69  Mod severe 50-59  Severe 35-49  Very Severe < 35 based on ATS/ERS criteria
  83. 83. FEV1  Interpretation of % predicted: ― >75% Normal ― 60%-75% Mild obstruction ― 50-59% Moderate obstruction ― <49% Severe obstruction FEV1 FVC
  84. 84. FEV1/FVC • Forced expiratory volume in 1 second – 4.0 L • Forced vital capacity – 5.0 L – usually less than during a slower exhalation • FEV1/FVC = 80% FEV1 FVC
  85. 85. To calculate the ratio of FEV1 to FVC (FEV1%, FEV1/FVC or FER) Actual FEV1 x100 Actual FVC e.g. FEV1 = 3.0 litres FVC = 4.0 litres 3 x100 =75% 4
  86. 86. 90 FEV1/FVC  FEV1/FVC: Very important ratio; when reduced, helps identify presence of obstructive disease.  Percentage reduction correlates with severity of obstruction; normal is 75-80%.  Normal (or ) in patients with restrictive disease.
  87. 87. FEV1 / FVC ratio  The FEV1/FVC ratio is the ratio of the forced expiratory volume in the first one second to the forced vital capacity of the lungs.  The normal value for this ratio is above 75-80%, though this is age dependent. 1. Values less than 70% are suggestive of airflow limitation with an obstructive pattern 2. Restrictive lung diseases often produce a FEV1/FVC ratio which is either normal or high 91
  88. 88.  FEV1 expressed as a percentage of the VC is the standard index for assessing and quantifying airflow limitation.  FEV1%VC declines with age and height. As IVC > EVC > FVC in patients with obstructive lung disease, the VC should be specified when using the FEV1/VC ratio, hence FEV1%FVC (Forced Expiratory Ratio, FER) or FEV1%IVC. The Tiffeneau-index is FEV1%IVC 92
  89. 89. FEV1% = (FEV1/FVC) × 100  Forced expired volume in 1 second as percentage of forced vital capacity.  FEV1% is used as a guide to airway calibre and has the merit that, unlike FEV1 it is nearly independent of lung size, body size and stature.
  90. 90. FEV1% = (FEV1/FVC) × 100  FEV1%may be misinterpreted if vital capacity is affected by increased strength or weakness of the accessory muscles of respiration or by dynamic compression, or if residual volume varies semi-independently.  Thus, a reduced FEV1% should not be interpreted as evidence for airflow limitation unless FEV1 is itself reduced.
  91. 91. Forced Vital Capacity TLC FEV1.0 FVC 1 sec FEV1.0 = 4 L FVC = 5 L % = 80% RV Normal TLC FEV1.0 FVC 1 sec FEV1.0 = 1.2 L FVC = 3.0 L % = 40% RV Obstructive airway resist Restrictive lung recoil TLC FEV1.0 FVC 1 sec FEV1.0 = 2.7 L FVC = 3.0 L % = 90% RV
  92. 92. Normal Values  FEV1/FVC ratio is the percentage of FVC that can be expired in one second. – 75 – 80% is normal – 60 – 80% demonstrates mild obstruction – 50 – 60% demonstrates moderate obstruction – <50% demonstrates severe obstruction
  93. 93. Normal Trace Showing FEV1 and FVC 5 FVC FEV1 = 4L FVC = 5L FEV1/FVC = 0.8 1 2 3 4 5 6 4 3 2 1 Volume, liters Time, seconds
  94. 94. Spirometry: Obstructive Disease Volume, liters FEV1 = 1.8L FVC = 3.2L FEV1/FVC = 0.56 Time, seconds 5 4 3 2 1 1 2 3 4 5 6 Normal Obstructive
  95. 95. Spirometry: Restrictive Disease Volume, liters Time, seconds FEV1 = 1.9L FVC = 2.0L FEV1/FVC = 0.95 1 2 3 4 5 6 5 4 3 2 1 Normal Restrictive
  96. 96. Mixed Obstructive and Restrictive Volume, liters Obstructive - Restrictive Time, seconds Normal FEV1 = 0.5L FVC = 1.5L FEV1/FVC = 0.30 1. Restrictive and mixed obstructive-restrictive are difficult to diagnose by spirometry alone; full respiratory function tests are usually required 2. (e.g., body plethysmography, etc)
  97. 97. Spirometry: Abnormal Patterns Obstructive Restrictive Mixed Time Time Time Volume Volume Volume Slow rise, reduced volume expired; prolonged time to full expiration Fast rise to plateau at reduced maximum volume Slow rise to reduced maximum volume; measure static lung volumes and full PFT’s to confirm
  98. 98. Classification Of Ventilatory Abnormalities by Spirometry 10 2
  99. 99. Terminology  Forced expiratory flow 25-75% (FEF25-75) – Mean forced expiratory flow during middle half of FVC – Measured in L/sec – May reflect effort independent expiration and the status of the small airways – Highly variable
  100. 100.  FEF25-75% is the average expired flow over the middle half of the FVC manoeuvre and is regarded as a more sensitive measure of small airways narrowing than FEV1.  Unfortunately FEF25-75% has a wide range of normality, is less reproducible than FEV1, and is difficult to interpret if the VC (or FVC) is reduced or increased. 10 4
  101. 101. Forced mid expiratory flow (FEF25-75%)  Sometimes termed the maximal mid expiratory flow rate (MMEF) A measure of FLOW  Measures flow rate over the middle half of expiration  Should be reported as L/sec and as % of predicted
  102. 102. Forced mid expiratory flow (FEF25-75%)  It is less effort dependent compared to the FEV1 / FVC ratio  It may detect closure of small airways better than the FEV1 or FEV1 / FVC ratio  Normal values vary widely – Varies with age, ht, wt
  103. 103. FEF25-75  Interpretation of % predicted: – >60% Normal – 40-60% Mild obstruction – 20-40% Moderate obstruction – <10% Severe obstruction
  104. 104. MMEF25-75%  Maximum Mid expiratory Flow rate  Max. Flow rate during the mid-expiratory part of FVC maneuver.  Effort independent – N value – 4.5-5 l/sec. Or 300 l/min – It may detect closure (obstruction ) of small distal airways better than the FEV1 or FEV1 / FVC ratio – But if the FEV1 / FVC ratio is greater than about 75% of predicted, the FEF25-75% is usually normal
  105. 105.  Forced expiratory flow (FEF25−75%fvc) was formerly maximal mid expiratory flow (MMEF).  This index is the average flow over the middle half of the forced vital capacity during maximally forced expiration  It is used for detecting the early stages of airflow limitation, but not for clinical management of patients.
  106. 106.  MEFR – Mid-expiratory flow rates: (FEF25−75%), Derived from the mid portion of the flow volume curve but is not useful for COPD diagnosis 11 0
  107. 107. FEV6 – Forced expired volume in six seconds:  Often approximates the FVC. FEV6 is the forced expiratory volume during the first 6 seconds and is a surrogate of the FVC.  Easier to perform in older and COPD patients but role in COPD diagnosis remains under investigation 11 1
  108. 108.  FEV6 (the volume exhaled in the first 6 seconds) is sometimes used as an alternative measurement to the FVC if the spirometer is unable to record beyond 6 seconds, or if the patient finds prolonged expiratory manoeuvres exhausting.  The FEV6 may underestimate the FVC in obstructive disorders, but this is unlikely to significantly alter the interpretation of the results. 11 2
  109. 109. FET (forced expiratory time)  Is the time required to perform the FVC manoeuvre (usually less than 5–6 seconds in adults and 2–3 seconds in children).  The FET is increased in the presence of airflow limitation (often > 12 seconds). 11 3
  110. 110. FEV1, FVC and FER  Spirometry provides three basic measurements: 1. The forced vital capacity (FVC) 2. The forced expiratory volume in one second (FEV1) 3. The ratio of the FEV1/FVC (the forced expiratory ratio FER, also known as the FEV1%). 11 5
  111. 111.  All three are needed to interpret spirometry.  A normal spirogram plots the total volume exhaled against time.  The trace becomes flat after about 3–4 seconds because the total volume of air which can be exhaled (the FVC) is expelled within this time. 11 6
  112. 112. 11 7 The Volume–Time Curve (The Spirogram) Normal spirogram Approximately 80% of the total volume is exhaled in the first 1 second (the FEV1) and that the curve has reached a plateau by 6 seconds.
  113. 113.  Approximately 80% of this volume (slightly lower in older people) is exhaled within 1 second, so the FEV1/FVC ratio is normally 0.7–0.8 or 70–80%.  Spirometry can demonstrate two basic patterns of disorder 1. Obstructive 2. Restrictive. 11 8
  114. 114. Obstructive pattern  In obstructive disorders (for example, asthma or chronic obstructive pulmonary disease), airflow is reduced because the airways narrow and the FEV1 is reduced  The spirogram may continue to rise for more than 6 seconds because the lungs take longer to empty. 11 9
  115. 115. Obstructive pattern  The FVC may also be reduced (because gas is trapped behind obstructed bronchi) but to a lesser extent than the FEV1.  Thus the cardinal feature of an obstructive defect is a reduction in the FEV1/FVC ratio. 12 0
  116. 116. 12 1 Spirogram showing airways obstruction
  117. 117.  Although the FEV1/FVC ratio is very useful in diagnosing airflow obstruction, the absolute value of the FEV1 is the best measure of severity.  In general, a reduction in FEV1 to 60–80% of predicted indicates mild, 40–60% moderate and less than 40% severe obstruction. 12 2
  118. 118.  Patients with an FEV1 of less than 1 litre are likely to be limited by dyspnoea.  If the FEV1 is less than 0.5 litres, the patient is likely to be breathless at rest and in respiratory failure.  Conversely, a patient with an FEV1 of more than 2 litres is unlikely to be short of breath due to 12 airways disease except on vigorous exertion. 3
  119. 119. Obstructive pattern  Both the FEV1 and the FVC may be reduced, but the FEV1 is reduced to a greater extent. The FEV1/FVC ratio is therefore low.  In this patient, the forced expiratory time is prolonged and a convincing plateau has not been reached by 6 seconds.  Ideally, the patient should continue to blow until 12 a plateau has been reached. 4
  120. 120. Restrictive pattern  Restrictive disorders can be caused by disease of the lung parenchyma (such as interstitial lung fibrosis) or chest wall disease (such as kyphoscoliosis).  These prevent full expansion of the lungs and therefore the vital capacity (VC or FVC) is reduced. 12 5
  121. 121.  Airflow may be normal or even increased because the stiffness of fibrotic lungs increases the expiratory pressure.  Thus although the absolute value of the FEV1 may be reduced, the FEV1/FVC ratio is normal or high 12 6 Restrictive pattern
  122. 122. Spirogram showing a Restrictive disorder 12 7
  123. 123.  Both the FEV1 and FVC may be reduced, but the FVC is reduced to the same or greater extent than the FEV1.  The FEV1/FVC ratio is normal or high.  The plateau to the curve occurs early. 12 8 Restrictive pattern
  124. 124.  A restrictive pattern on spirometry can be mimicked by a poor technique.  Often the FVC is underestimated because the patient stops blowing too early.  This will produce a high FEV1/FVC ratio 12 9
  125. 125. Inadequate technique mimicking a restrictive disorder 13 0
  126. 126.  Inadequate technique mimicking a restrictive disorder  The patient stopped blowing too soon.  The FVC is underestimated and the FEV1/FVC ratio appears high, giving the impression of a restrictive disorder. 13 1
  127. 127.  Be cautious about diagnosing a restrictive disorder on spirometry alone, particularly if the FEV1 is in the normal range.  Clinical correlation is necessary and more detailed lung function tests are indicated.  Ideally, measurement of the total lung capacity (TLC) should be used to confirm the diagnosis 13 2
  128. 128. FEF25–75%.  This is the forced expiratory flow between 25% and 75% of the FVC (also called the maximum mid-expiratory flow, MMEF).  This represents the airflow in the medium and small airways. It is a sensitive but less reliable indicator of airflow obstruction than the FEV1.  It may indicate mild airways disease (for example, in an asthmatic who is currently stable) but has a wide range of normal values, and should be interpreted with caution if it is the sole abnormality. 13 3
  129. 129. 13 4
  130. 130. Quiz Practice 1 A patient’s pulmonary function tests reveal the following: Actual Predicted %Predicted  FVC 4.01 L 4.97 L 81  FEV1 2.58 L 3.67 L 56  FEV1% 51 >75 _ Select the correct interpretation a. Restrictive pattern b. Obstructive pattern c. Inconclusive d. Normal
  131. 131. Quiz Practice 2 A patient’s pulmonary function tests reveal the following: Actual Predicted %Predicted FVC 3.75 L 4.97 L 75 FEV1 2.80 L 3.67 L 76 FEV1% 75 >/=75 _ Select the correct interpretation a. Restrictive pattern b. Obstructive pattern c. Inconclusive d. Normal
  132. 132. Quiz Practice 3 Predicted Actual Predicted% FVC 3.8 4.5 83 FEV1 2.2 4.2 47 FEV1/FVC 82 59 72 FEF25-75 1.6 3.7 43 Survey says … COPD
  133. 133. Quiz Practice 4 Actual Predicted % Predicted FVC 2.9 4.5 64 FEV1 2.5 4.2 59 FEV1/FVC 89 82 113 FEF25-75 3.7 3.5 102 DLCO is decreased when measured Restrictive lung pattern from Amiodarone
  134. 134. Quiz Practice 5 Actual Predicted % Predicted FVC 4.0 4.5 88 FEV1 2.6 4.2 57 FEV1/FVC 65 82 71 FEF25-75 1.7 3.6 47 Beta agonist treatment Actual Predicted % Predicted FVC 4.1 4.5 91 FEV1 3.6 4.2 89 FEV1/FVC 90 82 112 FEF25-75 3.2 3.6 91 Reversible obstructive defect
  135. 135. Quiz Practice 6 Actual Predicted % Predicted FVC 4.0 4.5 88 FEV1 3.6 4.2 89 FEV1/FVC 90 82 112 FEF25-75 3.1 3.4 95 Normal 
  136. 136. Quiz Practice 7 Actual Predicted % Predicted FVC 4.0 4.5 88 FEV1 3.3 4.2 81 FEV1/FVC 83 82 101 FEF25-75 1.7 3.5 48 Small Airways Defect
  137. 137. Quiz Practice 8 Actual Predicted % Predicted FVC 3.5 5.3 68 FEV1 3.1 4.6 68 FEV1/FVC 93 82 117 FEF25-75 3.7 3.3 120 By the way, the patient’s BMI = 47 … Restrictive pattern in obese patient
  138. 138. Quiz Practice 9 Predicted Values Measured Values % Predicted FVC 6.00 liters 4.00 liters 67 % FEV1 5.00 liters 2.00 liters 40 % FEV1/FVC 38 % 50 % 60 % Decision : This person is obstructed
  139. 139. Quiz Practice 10 Predicted Values Measured Values % Predicted FVC 5.68 liters 4.43 liters 78 % FEV1 4.90 liters 3.52 liters 72 % FEV1/FVC 84 % 79 % 94 % Decision : This person is restricted
  140. 140. 14 5

×