IPFT | IPFT indices | Unit | Physiological interpretation |
TBFVL | Inspiratory time (tI), expiratory time (tE), total respiratory time (ttot), time to peak tidal inspiratory or expiratory flow (tPTIF or tPTEF) | s | Time taken to complete individual manoeuvres |
Tidal volume (VT), inspiratory or expiratory tidal volume (VI or VE) | mL | Tidal lung volume | |
Peak tidal inspiratory or expiratory flow (PTIF or PTEF) Mid tidal inspiratory or expiratory flow (MTIF or MTEF) Tidal expiratory flow (TEF) at 75, 50, 25 or 10% of tidal expiratory volume still have to be expired (TEF75, TEF50, TEF25 or TEF10) | mL/s | Flow rate | |
Ratio of inspiratory or expiratory time to total respiratory time (tI/ttot or tE/ttot), inspiratory to expiratory time (tI/tE), Peak ratio: time to PTEF to tE(tPTEF/tE) Ratio of exhaled volume to PTEF to tidal expiratory volume (VPTEF/VE) Ratio of TEF75,TEF50, TEF25 or TEF10 to peaked tidal expiratory flow (PTEF) | % | Represent airway resistance | |
RTC | Maximum expiratory flow at functional residual capacity (Vʹmax,FRC) Maximum expiratory flow at 50% or 70% of expiration (Vʹ50 or Vʹ70) | mL/s | Flow rate |
Volume to peak expiratory flow (VPEF) | mL | Lung volume at partial expiratory flow—airway resistance | |
RVRTC | Forced expiratory volume (FEV), FEV at 0.5, 0.75 or 1.0 s of the forced expiration (FEV0.5/FEV0.75/FEV1.0) | mL | Forced lung volume at given period |
Maximum expiratory flow at 25% or 10% of FVC (MEF25 or MEF10) Forced expiratory flow between 25% and 75% of FVC (FEF25–75) Peak expiratory flow (PEF) | mL/s | Forced flow rate representing airway resistance. | |
Ratio of forced expiratory volume at 0.5 s to total forced expiratory volume (FEV0.5/FEV) | % | Airway obstruction |
IPFT, infant pulmonary function testing; RTC, rapid thoracoabdominal compression; RVRTC, raised volume rapid thoracoabdominal compression; TBFVL, tidal breathing flow-volume loop.