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Physiology- Respiratory
Clinical Assessment of Lung Mechanics (T Pierce)
40
Medical
Post-Graduate
03/02/2009

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Cards

Term
Process of spirometry test
Definition
  1. breath normally into a small mouthpiece connected to a small radius tube
  2. inhale as much air as you can
  3. now blow all that air how as fast as you can
    1. causes floating drum to move
Term

Define TLC

Definition
amount of air in the lung after a maximal inhalation
Term

define vital capacity

Definition

total amount of air that we are able to move out of the lung (this excludes residual volume)

Term
Define forced vital capacity
Definition
volume of air that can be forcibly expired after maximal inspiration to fill the lungs as much as possible
Term
If airway resistance is normal, how long does it take to get the entire FVC?
Definition
three seconds
Term

Define maximum mid-expiratory flow rate/FEF25-75

Definition
forced expiratory flow over the middle half of FVC
Term
Define Peak Expiratory flow rate/FEF max
Definition
the highest expiratory flow achieved
Term
Define functional residual capacity
Definition
amount of air left in lung after a normal exhalation
Term
Normal FEV1/FVC %
Definition
about 80%
Term
Define tidal volume
Definition

exchange of air btw a normal exhalation/inhalation cycle

Term

General cause of airway obstruction

Definition
airway resistance is higher than normal (airway narrowed)
Term
Examples of obstructive disease
Definition

asthma

chronic obstructive bronchitis

bonchiectasis

emphysema

Term
Which of the diagnostic values in spirometry is thought to be influenced mainly by obstructive disease?
Definition
FEF25-75
Term
Define restrictive disease
Definition
lung volumes are affected by change in elastic recoil forces on either lung or chest wall
Term
Effect of restrictive disease on diagnostic values
Definition
  • generally smaller than normal lung volumes
  • decrease FVC
  • decrease FEV1
  • NORMAL FEV1/FVC
  • NORMAL FEF25-75
  • decrease RV
  • decrease TLC
  • NORMAL RV/TLC
Term
Examples of restrictive disease
Definition
  • fibrosis- increase recoil, so smaller resting lung size
  • kyphoscholiosis- increase recoil, so smaller resting size
  • pleural effusion- compress lung, so smaller resting size
Term
Variables that are considerin when thinking if somebody when looking at lung size
Definition
  • age (decrease values with age)
  • sex
  • height (taller people have larger lungs)
Term
Effect of obstructive disease on all diagnostic values
Definition
  • significant decreases in FEV1
  • decrease in FVC
  • decrease in FEF25-75
  • decrease FEV1/FVC ratio
  • increased RV
  • increase TLC
  • increase RV/TLC
Term
Why does obstruction not usually affect inspiration?
Definition

the airway is pulled open during inspiration, so those resistance values decrease

Term
What makes for maximal exhalation of volume?
Definition
driving pressure is maximal and airway resistance is minimal
Term
Effect of obstructive disease on flow volume loops
Definition
the graph is concave due to reduced flow
Term
Effect of restrictive disease on flow volume loops
Definition
significantly reduced lung volumes, especially vital capacity (more narrow shape curve)
Term
What mechanical lung property determines the resing lung size
Definition
elastic recoil forces of lung and chest wall
Term
Define inspiratory reserve volume
Definition
volume of air inspired above TV (max inhalation volume-tidal volume inhalation)
Term
Define lung capacity
Definition
combinations of more than one basic lung volume
Term
Define expiratory reserve volume
Definition

volume of air expired below TV

Term
Define residual volume
Definition

amount of air trapped within lung

Term
Equation for IC
Definition
TV + IRV
Term
Equation for FRC
Definition
ERV + RV
Term
Equation for vital capacity
Definition
IRV + TV + ERV
Term
Equation for TLC
Definition
VC + RV
Term
What volumes and capacities cannot be measured by spirometry
Definition
 RV and FRC (trapped gas)
Term
Method used to measure FRC
Definition
  • gas dilution methods (via Helium reservoir or Nitrogen washout methods)
  • body plethysmography (more precise on FRC)
Term
What differentiate asthma from emphysema?
Definition
  • asthma- normal TLC
  • emphysema- increase TLC
Term
Different types of obstructive diseases
Definition

upper airway disease

peripheral airway disease

pulmonary parenchymal disease

Term
Examples of peripheral airway disease
Definition

asthma

chronic bronchitis

bronchiectasis

cystic fibrosis

Term
Example of pulmonary parenchymal disease
Definition
emphysema
Term
Example different causes of restrictive lung disease
Definition
  • neurological loss of muscle control
  • chest wall disease
  • interstitial lung disease
  • pleural disease
  • space occupying intrathoracic lesion
  • extra-thoracic conditions
    • obesity
    • ascites
    • pregnancy
Term
Why can a low ERV be caused by being overweight?
Definition
  • active exhalation requires stomach muscles (accessory muscles)
  • if you have stomach fat, it is more difficult because you lack stomach muscles
Term
What characteristics reduce DLCO
Definition

increase thickness

decrease surface area

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