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Flashcards in Spirometry and Mechanics Deck (16):
1

methods of measuring lung volume

helium-dilution, nitrogen washout, or body plethysmography

2

helium dilution

involves inhaling a known volume and concentration of helium for several minutes until stead state conditions are reached

by measuring the decrease in helium concentration casued by its larger volume of distribution, lung volume can be estimated

3

nitrogen washout technique

the patient breathes 100% oxygen until all the nitrogen in the lungs is washed out

the exhaled volume and nitrogen concentration in that volume are measured

the difference between the initial and final concentrations of nitrogen allows for calculation of lung volume

4

body plethysmography

requires patients to sit inside an air-tight box and breathe through a mouthpiece

lung volume is determined by measuring the change in box volume and pressure during a panying maneuver using Boyle's Law

5

expiratory obstructive diseases

ex. emphysema, chronic bronchitis, and asthma

may be hyperinflated and trap gas

6

restrictive lung diseases

ex. pulmonary fibrosis, asbestosis

characterized by low lung volumes

lung volume is decreased because of increased elastic recoil pressure

7

FRC

functional reserve capacity

resting lung volume

the volume in the lung at the end of a quiet tidal breath

determined by the inward elastic recoil of lung and the outward elastic recoil of the chest wall

8

IC

inspiratory capacity

IC = TLC - FRC

9

TLC

total lung capacity

the amount of air present within the lungs when they are maximally inflated

10

RV

residual volume

the amount of air present within the lungs when they are maximally deflated

11

ERV

expiratory reserve volume

ERV = FRC - RV

12

IRV

inspiratory reserve volume

IRV = IC - TV

13

TV

tidal volume

amount of air inspired during a quiet breath

14

equation for expiratory flow

Pel/Rus

Pel = elastic recoil pressure

Rus = resistance upstream to the equal pressure point

15

FEV1

the volume can exhale from FVC in the first second of trying

when airflow obstruction is present, this falls more than FVC, which lowers the FEV1/FVC ratio

16

What does normalization of FEV1 and FVC after albuterol in asthma patients mean?

it suggests that asthma patients can have normal pulmonary function when asymptomatic