A double-blind, randomised, controlled Phase II trial of Heliox28 gas mixture in lung cancer patients with dyspnoea on exertion

Abstract

Helium has a low density and the potential of reducing the work of breathing and improving alveolar ventilation when replacing nitrogen in air. A Phase II, double-blind, randomised, prospective, controlled trial was undertaken to assess whether Heliox28 (72% He/28% O(2)) compared with oxygen-enriched air (72% N(2)/28% O(2)) or medical air (78.9% N(2)/21.1% O(2)) could reduce dyspnoea and improve the exercise capability of patients with primary lung cancer and dyspnoea on exertion (Borg >3). A total of 12 patients (seven male, five female patients, age 53-78) breathed the test gases in randomised order via a facemask and inspiratory demand valve at rest and while performing 6-min walk tests. Pulse oximetry (SaO(2)) was recorded continuously. Respiratory rate and dyspnoea ratings (Borg and VAS) were taken before and immediately post-walk. Breathing Heliox28 at rest significantly increased SaO(2) compared to oxygen-enriched air (96+/-2 cf. 94+/-2, P<0.01). When compared to medical air, breathing Heliox28 but not oxygen-enriched air gave a significant improvement in the exercise capability (P<0.0001), SaO(2) (P<0.05) and dyspnoea scores (VAS, P<0.05) of lung cancer patients.

Figure 1

Dyspnoea scores recorded after 6-min walk test while breathing helium/oxygen (72% He/28% O₂), oxygen-enriched air (72% N₂/28% O₂) and medical air (78.9% N₂/21.1% O₂). Mean±s.e.m. (n=12) modified Borg: ; and VAS (0–10): □; #: P<0.01 cf. medical air.

Figure 2

Distance walked and time spent resting during 6-min walk test while breathing test gas mixtures, helium/oxygen (72% He/28% O₂), oxygen-enriched air (72% N₂/28% O₂) and medical air (78.9% N₂/21.1% O₂). Mean±s.e.m. (n=12), : distance walked; □: time resting; #: P<0.01 cf. medical air; ^*: P<0.05 cf. oxygen-enriched air.

Figure 3

Pulse oximetry readings breathing room air, after breathing the test gas mixture at rest for 5 min and minimum reading during 6-min walk test while breathing test gases: helium/oxygen (72% He/28% O₂), oxygen-enriched air (72% N₂/28% O₂) and medical air (78.9% N₂/21.1% O₂). ▪: initial SaO₂; : SaO₂ after breathing gas for 5 min; □: minimum SaO₂ during walk. Mean±s.e.m. (n=12) #: P<0.05 cf. medical air; ## : P<0.001 cf. medical air; ^*: P<0.01 cf. oxygen-enriched air.