Goya-Pulmonary Function Testing

Front 1

Describe spirometry

Back 1

physiological test that measures how an individual inhales or exhales volume of air as a function of time
Primary measurements in spirometry are volume or flow
most common function test used; differentiates b/t obstruction and restrictiion
3 primary spirometric indices:
1. Forced Vital Capacity (FVC)
2. Forced Expiratory volume in 1 sec (FEV1)
3.Ratio FEV1/FVC

Front 2

Describe the indications for spirometry

Back 2

A. recommended as gold standard for diagnosis of obstructive lung disease; adults w/ new diagnosis or newly active COPD need spirometry to confirm diagnosis
B. Detecting & quantifying pulmonary impairment
C. Following evolution of diseases & monitoring response to therapy
D. Assess preoperative risk
E. Assessing disability & impairment

Front 3

Describe the FVC test

Back 3

performed by having patient inhale to total lung capacity (TLC) & make maximally forced exhalation into spirometer
Exhaled volume is measured as function of time (volume-time curve)
Flow also measured & displayed as function of exhaled volume (flow-volume loop)

Front 4

Describe the pathophysiologic correlation w/ spirometry

Back 4

Spirometry classifies patients in 3 patterns:
1. Normal
2. Airflow obstruction
3. Restriction
Specific diagnoses cannot be made with spirometry alone; spirometry patterns must be interpreted according to clinical presentation

Front 5

Describe an obstructive ventilatory defect

Back 5

characterized by decreased expiratory flows compared wi/ healthy persons
obstruction begins in small airways & tends to reduce flows at lower lung volumes
Progressive slowing of expiratory flow is reflected in concave shape on flow-volume curve
Primary marker for presence of airway obstruction is FEV1/FVC ratio (<70% predicts obstruction)
severity of obstruction is classified by using FEV1%

Front 6

Describe the FEF 25-75

Back 6

average forced expiratory flow rate over mid 50% of FVC; can be helpful in diagnosing obstruction, but dependent on FVC
reduced FEF25-75 <60% & FEV1/FVC in low-normal range can confirm airflow obstruction
first value to be affected and last to improve in lung diseases

Front 7

Describe the severity of obstructive defect

Back 7

degree of severity is classified by FEV1% predicted:
1. mild: FEV1>70%
2. moderate: 60-70%
3. moderately severe: 50-60
4. severe: 35-50
5. very severe: <35

Front 8

Describe the bronchodilator response

Back 8

in patients w/ obstructive defect, performing spirometry before & after inhaling a short acting B agonist (SABA) can be beneficial:
obtain baseline spirometry; administer SABA, (wait 15 mins); repeat spirometry
An improvement in FEV1 or FVC of 12% & 200ml from baseline is considered a positive response; lack of response doesn't preclude clinical response
Asthma-responds to beta agonists
Emphysema-doesn't respond to beta agonists

Front 9

Describe a restrictive ventilatory defect

Back 9

Restrictive patterns characterized by reduced FVC
Flows typically reduced because of smaller absolute lung volumes
FVC<80% predicted is suggestive of a restrictive defect
If airway obstruction is present & FVC is low, restrictive defect maybe present; obtain lung volumes to confirm restrictive defect

Front 10

Describe the appearance of the flow volume loop normally and how it appears in various obstructive and restrictive diseases

Back 10

A. normal-looks like shield w/ top right part broken off; area above line shows exhalation;area below line shows inhalation
B. restrictive disorder-right side of entire loop is truncated (decreased volume in both exhalation and inhalation)
C. small airway obstruction-concave curve in 2nd half of exhalation; slight truncation of top, right, and bottom parts of loop (slight decreased volume and flow)
D. fixed large airway obstruction-large truncations on top and bottom of loop (decreased flow, but not volume)
E. intrathoracic variable large airway obstruction-large truncation in exhalation flow, very slight trunction in inhalation flow, no change in volume

Front 11

Describe lung volume testing and its indications

Back 11

volume of gas w/in lungs; measured by body plethysmography, gas dilution or washout
Major indication is to diagnose restrictive lung disease & to determine severity of impairment
Restrictive lung disease-reduced lung volumes (VC & TLC)
Helps to clarify whether decrease in FVC is due to restriction or a consequence of air trapping due to airflow obstruction

Front 12

Describe typical lung volume patterns

Back 12

TLC Normal Range is 80-120% predicted
Restrictive Defect-TLC<80% predicted
Obstructive Defect-TLC>120%
Airway narrowing & destructive changes that occur in COPD enhance airway compression during expiration-->increases RV & reduces FVC
Advanced emphysema-proportionate increase in RV & FRC are usually greater than increase in TLC

Front 13

Describe diffusion capacity (DLCO)

Back 13

Measures ability of lungs to transport inhaled gas from alveoli to pulmonary capillaries
Depends on:
a. alveolar-capillary membrane
b. hemoglobin concentration
c. cardiac output

Front 14

What are the indications for diffusion capacity?

Back 14

A. To help differentiate asthma from emphysema
B. To help in evaluation & determine severity of interstitial lung disease or restrictive lung disease
C. Evaluate cardiovascular disease

Front 15

Describe diseases predicted by increased and decreased DLCO

Back 15

A. Increased DLCO (>120% predicted)
1. pulmonary hemorrhage
2. Asthma (may also be normal)
3. Polycythemia
4. Left to Right Shunt
B. Decreased DLCO (<80% Predicted)
1. Obstructive Lung Disease
2. Parenchymal Lung Disease
3. Pulmonary Vascular Disease
4. Anemia (decreased RBCs)
note-anything that destroys lung will decrease diffusion capacity

Front 16

Describe the systematic way to interpretation of PFTs

Back 16

1. Look at Force Vital Capacity (FVC) to see if its w/in normal limits; look at FEV1 & determine if it is w/in normal limits; if both FVC & FEV1 are normal, then no need to go further
2. FEV1/FVC <70%-indicates obstructive defect (severity determined by FEV1)
FEV1/FVC>88% and/or FVC<80%-indicates restrictive defect; consider obtaining lung volumes and/or diffusion capacity
3. TLC
a. TLC<80%-restrictive ventilatory defect
b. TLC>80% but FVC<80%-no restrictive defect
c. TLC>120%-obstructive ventilatory defect