Normal | Normal | Increasing air movement - VT should at least double
- VT increases up to 70% of resting IC
| No significant change with exercise - O2Sat >96% at rest, decreases <3% w/exercise
- Peak A-a O2 difference <35
| Normal ventilatory efficiency - Ventilatory reserve ≥30%
- VE-VCO2 slope <32
- VE/VCO2 nadir <34
- PETCO2 >36 at rest and at anaerobic threshold
- VD/VT <0.4 at rest, falls with exercise
| Normal | RR increases smoothly at low workloads; max RR usually <50/min |
Obstructive disease | Obstructed - Typically normal/↓FEV1
- ↓FEV1/FVC
| Exercise flow limitation - Decrease in IC
- Flow limitation in expiration
- Suboptimal VT increase
| Possible exertional hypoxemia - O2Sat may decrease at rest and w/exercise
- Peak A-a gradient may be >35
- Oxygenation deficits more likely w/emphysema
| Reduced ventilatory efficiency - Ventilatory reserve <30%
- VE-VCO2 slope >32
- VE/VCO2 nadir >34
- PETCO2 may be <36 at rest
- PETCO2 may increase more than normal w/exercise
- VD/VT may not decrease with exercise
| Decrease by >10 to 15% indicates EIB | Wheezing; RR may plateau early in exercise |
Restrictive disease | Restricted - ↓FEV1, ↓FVC
- Nl FEV1/FVC, ↓TLC
| Impaired increase in tidal volume - Suboptimal VT increase
- VT ≥85% of resting IC
| Possible exertional hypoxemia - O2Sat may decrease at rest and w/exercise
- Peak A-a O2 difference may be >35
- Oxygenation deficits more likely with ILD than neuromuscular disease
| Reduced ventilatory efficiency - Ventilatory reserve <30%
- VE-VCO2 slope >32
- VE/VCO2 nadir >34
- PETCO2 may be <36 at rest and at anaerobic threshold
- VD/VT may not decrease with exercise
| Close to baseline | Often highly increased max RR (>55/min); high RR early (with low workload) |
Abnormal breathing pattern (hyperventilation) | Normal | Variable - VT increase may be suboptimal
| No significant change with exercise - O2Sat >96% at rest, decreases <3% w/exercise
- Peak A-a O2 difference <35
| Reduced ventilatory efficiency - Ventilatory reserve <30%
- VE-VCO2 slope >32
- VE/VCO2 nadir >34
- PETCO2 often <36 at rest
- PETCO2 <36 at anaerobic threshold
- VD/VT may not decrease with exercise
| Normal | Often highly increased max RR (>55/min); high RR early (with low workload) |