Pulmonary Function Tests
PFT
Spirometry:
Dynamic Lung Volumes
Static lung volumes
Diffusion Capacity
Arterial Blood Gases
(ABG)
Exercise Capacity
(CPX)
FVC,FEV1
FEV1/FVC
FEF25-75,PEF
MVV
TLC,VC,RV
RV/TLC
FRC,IC
IRV,ERV
DLCO
VA
DLCO/VA
pH
PaO2, PaCO2
P(A-a)O2
SAT
VE
VO2
VCO2
HR, SpO2,ABG
Other tests of lung function:1. Lung mechanics -Resistance
-Compliance
2. Distribution of Ventilation
(N2 delta)
3. Maximal Respiratory Pressures
(MIP, MEP)
V/Q ratio
V/Q mismatch (3-compartment model)
Lung volumes and capacities
How to measure FRC?
• Nitrogen washout method
• Inert gas dilution technique
• Plethysmography
Resistance
Volume dependence of airway resistance
(Raw)
RV
SRaw (cmH2O/L/sec)
4
3
2
1
TLC
0
2
4
6
Lung Volume (liters)
8
Compliance
Compliance
Ventilatory Mechanics: Healthy
100
% VC
Pcw
80
PRS
60
40
20
PL
0
-60
-40
-20
0
Pressure (cmH2O)
20
40
60
Ventilatory Mechanics: Healthy
100
ΔV
ΔP
% VC
ΔP
80
ΔV
 elastic
WOB
60
RV
4
elastic and resistive
work
of breathing is
minimized when tidal breathing occurs
3
within the compliant portion of the
respiratory systems 2P-V curve
ΔP
20
SRaw (cmH2O/L/sec)
40
ΔV
1
TLC
 resistive WOB
0
-40
-20
0
20
40
4
6
Lung Volume (liters)
0
-60
2
60
Pressure (cmH2O)
SRaw  as lung volume  because the airways distend as the lungs inflate, and bigger airways have
lower resistance (*Poiseuilles’ Law*). The opposite is also true, of course!
8
Ventilatory Mechanics: Healthy
Begin Exercise
IC
IC
VT
Ventilatory Mechanics: Healthy
8
TLC
Volume (liters)
 EILV
6
4
EELV

VT

EELV
2
0

IRV
R
V
- 0 10 20 30 40 50
40 30 20 10
Pressure (cmH20)
 IC
Dynamic hyperinflation during exercise
IRV
IRV
Diffusion capacity (DLCO, DLCO/VA, Tco, Kco)
Mechanism of hypoxaemia
Hypoxaemia, hypercapnia in clinical cases
Respiratory and metabolic shifts
chronic
acute
acute
chronic
Exercise tests in lung diseases
1. Exercise-induced asthma (EIA) - FEV1
2. Interstitial lung disease (ILD) - SAT
3. Exercise tolerance in rehabilitation (COPD) cardiopulmonary exercise (CPX). Important
variables: - work rate (watts), SpO2, ABG
- VO2, VCO2, RQ, VE
- lactate threshold (LT)
- breathing reserve (1-VEmax/MVV)
- heart rate reserve (1-HRmax/220-age)
Mechanism of
exercise-induced
hypoxaemia
Noninvasive determination of lactate threshold by the
V-slope method
Respiration during exercise
( Wasserman K, 1999 )