SPIROMETRY (XVIII).
RECORDING OF THE FORCED VITAL CAPACITY (XIX).
Dep. of Physiology, Fac. of Medicine, MU 2015 © © Ksenia Budinskaya
Static lung volumes
V [l]
VT: Tidal volume – volume of air inspired during quite inspiration (after quite expiration)
IRV: Inspiratory reserve volume – the maximal volume of additional air that can be inspired by forced inspiration after normal inspiration
ERV: Expiratory reserve volume – the maximal volume of additional air that can be expired by forced expiration after normal expiration
RV: Residual volume – volume of air that remains in lungs after the maximal forced expiration
VT – 0.5 l
IRV – 2.5 l
ERV – 1.5 l
RV – 1.5 l
VT
IRV
ERV
RV
V [l]
Static lung volumes - capacities
Vital capacity [VC] = IVR + VT + ERV
Functional residual capacity [FRC] = ERV + RV
Total lung capacity [TLC] = IRV + VT + ERV + RV
VT
IRV
ERV
RV
Bradypnoea – decreased frequency
Tachypnoea – increased frequency
Eupnoea – normal (resting) breathing
Apnoea in inspiration
Apnoea in expiration
Normal (resting) breathing:
Frequency: 10 – 18 breaths/min
Tidal volume: 0.5 l
Minute ventilation: 5 – 9 l/min
Dynamic lung volumes
Changes of frequency
Recording of forced vital capacity
V [l]
Time [s]
1 s 2 s
6
5
4
3
2
1
0
RVFVC
FEV1
FEV1 – amount of air expired after the maximal inspiration with the maximal effort in 1 s (FEV1 ≥ 80% od VC)
FVC – forced vital capacity
FVC
Obstructive diseases (↓FEV1)
• Tracheal stenosis
• Asthma, bronchitis
• COPD
• Tumors in airways
0
1
2
3
4
5
1 s 2 s
V [l]
Time [s]
Restrictive diseases (↓FVC)
Pulmonary causes
• Pulmonary fibrosis
• Resection of lungs
• Pulmonary edema
• Pneumonia
Extrapulmonary causes
• Ascites
• Kyfoscoliosis
• Serious burn
0
1
2
3
4
5
1 s 2 s
V [l]
Time [s]
VCVC