FEV1\FVC

1. OBSTRUCTIVE AND
RESTRICTIVE OF LUNG
DISEASE
HAMAD EMAD H. DHUHAYR

2. VALUES MEANING DESCRIPTION INTERPETITION
VC Vital Capacity Volume of air displaced by maximal exhalation or maximal inhalation maneuver Typically preserved in obstruction, but reduced in restriction.
FVC Forced vital capacity Volume forcefully exhaled from maximal inhalation (TLC) to maximal exhalation (RV), the
FEVC maneuver
Pattern similar to VC, although more likely to be reduced in
obstruction than VC. Used to grade severity of restriction.
FEV1 Forced expiratory volume in one
second
Volume exhaled in 1st second of FEVC maneuver Reduction typical of medium to large airways obstruction.
Used to grade severity of obstruction
FEV1/FVC Ratio of FEV1 to FVC Reductions indicative of airway obstruction
FEF25–75 Forced expiratory flow (25–75%) Mean expiratory flow rate in the middle half of FEVC
maneuver
Sensitive but nonspecific indicator of small airways
obstruction. Poorly reproducible, varies with effort and time of
expiration.
MVV Maximum voluntary ventilation Estimate of one minute’s maximal air displacement extrapolated from repeated inspiratory
and expiratory efforts
Disproportionate reductions relative to FEV1 may indicate
upper airways obstruction, muscle weakness, or poor
performance.
PEF Peak expiratory flow Maximal sustained airflow achieved during the FEVC
maneuver
Worsening may correlate with asthma exacerbations.
Sometimes helpful in assessing subject effort.

3. OBSTRUCTIVE AND RESTRICTIVE DISEASES:

4. OVERVIEW
• THE MAXIMUM INSPIRATORY FORCE: IS LIMITED AT TOTAL LUNG CAPACITY THAT
CAN BE APPLIED BY THE INTERCOSTAL MUSCLES AND DIAPHRAGM
• IS OPPOSED EQUALLY BY:
THE INCREASING RECOIL FORCE OF THE LUNGS AS THEY ARE DISTENDED TO HIGHER
VOLUMES
• SO, TLC IS LIMITED PRIMARILY BY THE ELASTIC PROPERTIES OF THE LUNGS, BECAUSE
VARIATIONS IN MUSCLE STRENGTH HAVE ONLY A SMALL EFFECT ON TOTAL CHEST
EXPANSION UNTIL WEAKNESS BECOMES QUITE MARKED.

6. • FACTORS THAT AFFECT TLS:
• 1-PARENCHYMAL RESTRICTIVE DISEASES REDUCE LUNG COMPLIANCE,
SO GREATER DISTENDING PRESSURE IS REQUIRED TO ACHIEVE ANY
VOLUME CHANGE AND, EVENTUALLY, LOWER TLC.
• 2-THE DISPLACEMENT OF INTRATHORACIC GAS VOLUME BY EFFUSIONS,
EDEMA, INTRAVASCULAR VOLUME, AND INFLAMMATORY CELLS ALSO
CONTRIBUTES TO A REDUCTION IN MEASURED LUNG GAS VOLUMES.
• * EXCEPT FOR PLEURAL EFFUSIONS, THESE QUANTITIES ARE RELATIVELY
SMALL AND ARE OUTWEIGHED BY THE FREQUENTLY ASSOCIATED
CHANGES IN LUNG ELASTIC PROPERTIES. THE MINIMUM LUNG VOLUME,
OR RV, IS DETERMINED BY A COMBINATION OF TWO FACTORS. THE
FIRST IS THE AMOUNT OF SQUEEZE THE CHEST WALL AND ABDOMINAL

7. • RESTRICTIVE DISEASE
RESTRICTIVE LUNG DISEASES ARE: THE DISEASES THAT CAUSE A
SIGNIFICANT DECREASE IN TLC.
• THE CHARACTERISTIC OF R.D:
• 1- PARALLEL DECREMENTS IN FRC, RV, AND VC, ALTHOUGH A
REDUCTION IN ONLY RV MAY BE SEEN IN EARLY STAGES OF DISEASE.
• 2- INCREASED TISSUE RECOIL DELAYS AIRWAY CLOSURE.

8. • *OBESITY SHOWS A DIFFERENT PATTERN, IN THAT THE PRIMARY
EFFECT IS ON THE RELAXED END-EXPIRATORY VOLUME OR FRC.
WHY??
THE LARGE ABDOMEN AND HEAVY CHEST WALL REDUCE THE
OUTWARD RECOIL OF THE THORACIC CAGE, WHICH OPPOSES THE
INWARD RECOIL OF THE LUNG PARENCHYMA AND MAINTAINS
NORMAL FRC.
• HOWEVER, RV IS DETERMINED BY AIRWAY CLOSURE AND IS LITTLE
AFFECTED, AND THE TLC ACHIEVABLE BY USE OF MAXIMUM
INSPIRATORY FORCE IS ONLY MINIMALLY REDUCED UNTIL OBESITY
BECOMES EXTREME.

10. OBSTRUCTIVE DISEASE
• OBSTRUCTIVE DISEASES CAUSE AIRWAY CLOSURE THAT STOPS
EXHALATION AT A HIGHER LUNG VOLUME BECAUSE OF THE
COMBINED EFFECTS OF AIRWAY INFLAMMATION AND LOSS OF
TISSUE RECOIL ON LUMINAL CALIBER.

11. • THE CHARACTERISTIC OF R.D:
1- A PROGRESSIVE INCREASE IN RV, BECAUSE INCREASING AMOUNTS
OF GAS ARE TRAPPED BEHIND CLOSED AIRWAYS.
2-THESE PATIENTS BREATHE AT AN INCREASED FRC
3- A DECREASE IN LUNG RECOIL FORCE FROM EMPHYSEMA
4- INCREASE LUMINAL CALIBER TO MINIMIZE THE RESISTIVE WORK OF
AIRFLOW.
• ** THE TLC IS NORMAL TO HIGH, WHICH AGAIN REFLECTS THE LOSS
OF LUNG RECOIL FORCES. BECAUSE RV INCREASES TO A GREATER
EXTENT THAN DOES TLC, THE VC DECREASES WITH SEVERE AIRWAY
OBSTRUCTION.