| Long form | Unit | Short form | Definition |
| Tidal volume FRC | mL | V T,FRC | Tidal volume preceding FRCp. Average over the last 5 breaths pre-occlusion |
| tI prior to FRC | s | t I,FRC | Inspiratory time preceding FRCp. Average over the last 5 breaths pre-occlusion |
| tE prior to FRC | s | t E,FRC | Expiratory time preceding FRCp. Average over the last 5 breaths pre-occlusion |
| ttot prior to FRC | s | t T,FRC | Total breath time preceding FRCp. Calculated as tI+tE over 5 breaths pre-occlusion |
| RR prior to FRC | L·min−1 | RRFRC | Respiratory rate preceding FRCp. Calculated from the ttot-FRC parameter as RR=60/ttot |
| sd of EEL | mL | EELs | sd of EEL measured relative to the baseline EEL calculated over 5 breaths prior to each FRC occlusion manoeuvre |
| Stability of EEL prior to FRCp | % | EEEls% | Stability of EEL prior to FRCp, i.e. EELs expressed as a % of VT,FRC: EELs%=100×EELs/VT,FRC |
| % Change in EEL | % | ΔEEL% | Change in EEL post-preocclusion, expressed as % of mean VT prior to occlusion |
| Ambient pressure | kPa | P amb | Ambient pressure |
| Apparatus dead space | mL | DS app | Apparatus dead space including the mask |
| Occluded volume | mL | V occ | Volume inspired above EEL at moment of occlusion |
| Total occluded gas volume | mL | TOGV | Total occluded gas volume, including Vocc and DSapp (including the effective dead space of the mask) |
| FRCpleth | mL | FRCp | Mean functional residual capacity, i.e. (TOGV−DSapp−Vocc) |
| CV of FRCp | % | FRCpCV | Coefficient of variation (i.e. 100×(sd/mean)) of n accepted FRCp manoeuvres |
| No. of accepted FRCp | FRCp,n | Number of accepted FRCp manoeuvres | |
| Change in Pao,occ | kPa | ΔPao | Mean change in Pao during respiratory efforts against the airway occlusion measured between 5%–95% of troughs and peaks respectively |
| Change in Vpleth,occ | mL | ΔVpleth | Mean change in box volume during airway occlusion corresponding to ΔPao |
| Maximal inspiratory pressure | kPa | P I,max | Minimal absolute value in Pao during inspiratory effort against the occlusion |
| Maximal inspiratory pressure | kPa | P E,max | Maximal absolute value in Pao during expiratory effort against the occlusion |
| tI occluded | s | t I,occ | Duration of the first inspiratory effort during airway occlusion (for use if assessing the strength of the Hering Breuer reflex). This parameter is only measured during EE occlusions. tI,occ is measured from the start of inspiration (taken from the tidal volume trace) immediately before an EE occlusion until the end of the first inspiratory effort, when Pao starts to rise during the occluded effort |
| tE occluded | s | t E,occ | Duration of the first expiratory effort during airway occlusion. This parameter is only measured if EI occlusion is selected. The time is measured from the start of expiration (measured from the tidal volume trace) immediately before an EI occlusion, until Pao starts to fall during the airway occlusion |
| HBR-EE | % | HBR-EE | Strength of Hering Breuer Reflex calculated from end expiratory occlusion as 100×(tI,occ−tIFRC)/tIFRC |
| HBR-EI | % | HBR-EI | Strength of Hering Breuer Reflex calculated from end inspiratory occlusion as 100×(tE,occ−tEFRC)/tEFRC |
| Apparatus resistance | kPa·L·s−1 | R app | Apparatus resistance |
| Specific airway resistance | kPa·s−1 | sRaw | See definition in text, which includes correction for apparatus resistance |
| Specific airway conductance | 1/(kPa·s−1) | sGaw | Specific airway conductance. Calculated as sGaw=1/sRaw |
| V eff | mL | V eff | Lung volume used to convert specific effective airway resistance (see text) |
| V lv | mL | V lv | Volume to convert sRlv (see text) |
| V hv | mL | V hv | Volume to convert sRhv (see text) |
| Airway resistance | kPa·L·s−1 | R aw | Effective airway resistance. Calculated as: Reff=sReff/Veff (where Veff=effective volume above FRC at time of Reff analysis – see text) |
| Airway conductance | L·s·kPa−1 | G aw | Airway conductance. Calculated as: Gaw=1/Raw |
| sRlv | kPa·s−1 | sRlv | Specific airway resistance at low lung volume (i.e. end inspiratory and initial expiratory values – see text) |
| sRhv | kPa·s−1 | sRhv | Specific airway resistance at high lung volume (i.e. end inspiratory to initial expiratory values – see text) |
| PEF during resistance | mL·s−1 | PEF | Peak tidal expiratory flow during resistance measurement as weighted mean from all accepted breaths |
| PIF during resistance | mL·s−1 | PIF | Peak tidal inspiratory flow during resistance measurement as weighted mean from all accepted breaths |
| No. of Raw | R aw,n | Number of accepted Raw breaths | |
| CV of sRaw | % | sRawCV | Coefficient of variation of sRaw |
| Exp to ins sRaw ratio | sRE/I | Ratio of slope of end expiratory to initial inspiratory parts of the specific resistance loop, taken from above and below zero flow over a selected flow limit | |
| Flow limit sRI | % | %VR,I | Percentage of inspiratory peak flow, used for calculation of sRlv and sRhv |
| Flow limit sRE | % | %VR,E | Percentage of expiratory peak flow, used for calculation of sRlv and sRhv |
| RR during Raw | L·min−1 | RRRaw | Respiratory rate during the resistance manoeuvre. The average over all breaths used in the resistance calculation is taken. Best is calculated from 60×(1/mean tI+mean tE) |
| Tidal volume Raw | mL | V T,Raw |
Suggested suffixes to denote specific type of analysis etc. (particularly during Raw measurements when so many options are available): eff: effective (e.g. Raw,eff); E: expiratory; I: inspiratory; tot: total; hv: high volume; lv: low volume; X% assessment at specified pre cent of peak inspiratory or expiratory flow (e.g. R50%I=Raw measured at 50% PIF, whereas sG75%E would be sGaw at 75% PEF); EEL: end expiratory level.