Summary of dyspnoea outcomes
| Author [Ref.] | Dyspnoea parameter | Findings relating to dyspnoea |
| Babb [28] | 20 point BS | No change to work of breathing |
| Eves [29] | 10 point BS | Decreased dyspnoea* |
| Johnson [30] | PSQ | No change to BS; 55% (He group) reported increased PROs |
| Laude [31] | 10 point BS and VAS | Decreased dyspnoea (BS and VAS)*** (all gas mixes) |
| Marciniuk [32] | 10 point BS | No change Heliox compared to room air |
| Oelberg [33] | PROs | Decreased dyspnoea# |
| Palange [34] | 12 point VAS | Decreased dyspnoea# (Heliox isotime only) |
| Richardson [35] | 10 point BS | No change in dyspnoea |
BS: Borg scale; PSQ: Patient Satisfaction Questionnaire; PRO: patient-reported outcome; VAS: visual analogue score. * p<0.05; ***: p<0.001. #: reported only (no statistical analysis performed).