Respiratory Function Test
Department of internal medicine
Chen Yu
Respiratory Function Test
 Lung
volumes
 Ventilation function
 Gas exchange
 Blood flow
 Respiratory motive force
Lung Volume and Subdivisions
IC
TLC
VC
IRV
VT
ERV
FRC
RV
RV
Basal Lung Volume
 VT
(tidal volume): 500ml
 IRV (inspiratory reserve volume)
 ERV (expiratory reserve volume)
 RV (residual volume)
Basal Lung Capacity
 IC
(inspiratory capacity): VT+ IRV
 FRC (functional residual capacity):
ERV + RV
 VC (vital capacity) : IC + ERV
normal men: 4217ml
women: 3105ml
 TLC (total lung capacity): VC + RV
Some Explanatory Points
 Lung
volume is to describe the changes of
the lung volume during one breathing at
static conditions, also called static lung
volume.
 VT, VC, TLC are used at clinical. VT and
VC are determined by Spirometric trace ,
but FRC and RV by indirect method:
Helium or Nitrogen analyses method.
Clinical Significance
 VC
depends on sex, age and height.
 VC% < 80% is abnormal.
 VC : restrictive ventilation disorder
severe obstructive ventilation disorder
Clinical Significance
 RV/TLC%
(residual air rate)
normal : < 35%
emphysema: > 40 %
old person can be 50%.
 FRC : emphysema
 FRC : interstitial pulmonary fibrosis
Ventilation Function Test
 It
is called as dynamic lung volumes.
 Fast
spirometric trace to illustrate timed
ventilation tests (air volume and air flow
during breathing).
Ventilation Function Test
 Lung
ventilation volume
VE and MVV
 Forced vital capacity (FVC)
 Maximal mid-expiratory flow (MMEF.
MMF)
·
 Alveolar ventilation (VA)
 VE
( minute ventilation):
= VT×RR/min
normal : 4—6 liter
< 3L : hypoventilation
>10L: hyperventilation
 MVV
( maximal voluntary ventilation):
ventilative volume at the most rate and
most breathing deep during a minute
Normal : 80—100L
abnormal: < 70L
 MVV%=(MVV—VE)/MVV %
Normal: >95%
ventilation storage : <86%
 FVC
(Forced Vital Capacity)
The volume that after full inspiration,
to expire with the most force and the most
rate.
 FEV1
(forced expiratory volume in the first
second)
 FEV1/FVC% ( the first rate)
FEV1/FVC%: 83%
FEV2/FVC%: 96%
FEV3/FVC%: 99%
Normal: > 80%
<70%: obstructive ventilation disorder
 MMEF (maximal
mid-expiratory flow)
The mean flow between 25% and 75%
forced expiration.
 Significance: to evaluate the small airway
obstruction in early stage
 VA (alveolar ventilation)
The air volume entered respiratory
bronchioli and the alveoli during a
minute.
 VD (dead space )=150ml
 VA = (VT –VD) ×RR/min
 Normal VD/VT=0.3-0.4
VD/VT : effective ventilation increased
VD/VT : effective ventilation decreased
Clinical Values of Ventilation Test
MVV active/predictive%
 Air
rate index =
VC active/predictive%
 Normal
: =1
Degrees of Lung Disfunction
VC or MVV act/pre%
Normal
>80
Mild reduce
80-71
Mediate reduce
70-51
Severe reduce
50-21
Respiratory failure <=20
FEV1%
>70
70-61
60-41
<=40
Classification of Ventilative Function Disorder
obstruction
FEV1/FVC
MVV
VC
N or
Rate index
<1.0
RV
TLC
N or
restriction
N or
or N
>1.0
N or
mix
=1.0
uncertain
uncertain
Degrees of Obstructive Emphysema
RV/TLC (%)
Normal
<=35%
Mild emphysema
36-45
Mediate emphysema
46-55
Severe emphysema
>=56
Bronchial Dilation Test
 Method:
to determine FEV1 and FEV1/FVC%
before and after ß2-agonist inhalation
After-before
× 100%
improved rate= before
Positive: >15%
 Reversible limitation:
asthma
>15% and improved volume>200ml
 Result:
PEF Variable Rate
 PEF
(peak expiratory flow): the most flow
during forced expiration. It indicates the
force of respiratory muscle and airway
obstruction.
PEFmax-PEFmin
× 100%
 PEF variability=
1/2 (PEFmax+PEFmin)
 PEF
variability≥20% : asthma
Bronchial Provocation Test
 Method
: to inhale histamine from low to
high concentration till the FEV1 decrease
≥20%. Calculate drug volume (PD20FEV1).
 Positive:
PD20FEV1<7.8umol
indicate airway hyperresponsiveness
asthma
Gas Exchange Test
 Gas
distribution: Nitrogen concentration
method
normal < 2.5%
· ·
 Ventilation/perfusion ratio (V/Q) : 0.4
P(A-a)O2: 5-15mmHg
 Diffusion capacity (DL): CO method
Small Airway Function Test
airway: diameter ≤2mm
 Closing volume (CV): N2 or He method
 Maximum expiratory flow-volume curve
(MEFV):
indicate disease from the curve shape
 Small
Thank you!