Effect of high flow oxygen on exertional dyspnea in cancer patients: A double-blind randomized clinical trial.

Abstract

11600 Background: High flow oxygen therapy is effective for hypoxemic respiratory failure. However, its effect on dyspnea in non-hypoxemic patients is unknown. In this 2x2 factorial, double-blind randomized clinical trial, we assessed the effect of flow rate (high vs. low) and gas (oxygen vs. air) on exertional dyspnea in cancer patients. Methods: Non-hypoxemic patients with cancer completed two structured cycle ergometer exercise tests with Low Flow Air [LFAir] at 2 L/min. They were then randomized to receive High Flow Oxygen [HFOx] with up to 60 L/min, High Flow Air [HFAir], Low Flow Oxygen [LFOx] or LFAir during a constant work rate exercise test at 80% maximum. Dyspnea intensity was assessed with the modified 0-10 Borg scale. The primary outcome was difference in the slope of dyspnea intensity vs. time during the third test. Secondary outcomes included difference in exercise time, vital signs, and adverse events. We estimated that 10 patients per arm will provide 86% power to detect a 1-standard deviation main effect and 86% power to detect a 2-SD interaction effect with an alpha of 5%. A linear mixed effects model was used to assess the impact of flow rate and gas on study outcomes. Results: 45 patients were randomized and 44 completed the study (10, 11, 12, 11 patients on HFOx, HFAir, LFOx, LFAir, respectively). The mean age was 63 (range 47-77); 18 (41%) were female; 34 (44%) had lung cancer; and 20 (46%) had metastatic disease. In mixed effects model, the association between the change in dyspnea intensity over time with flow rate differed significantly between oxygen and air (P = 0.04). Specifically, HFOx (slope difference -0.20, P < 0.001) and LFOx (-0.14, P = 0.01) were significantly better than LFAir, but not HFAir (+0.09, P = 0.09). Exercise time also significantly increased with HFOx (difference +2.5 min, P = 0.009) compared to LFAir, but not HFAir (+0.63 min, P = 0.48) or LFOx (+0.39 min, P = 0.65). HFOx was well tolerated without significant adverse effects. Conclusions: The combination of high flow rate and oxygen improved dyspnea and exercise duration during constant work exercise test in non-hypoxemic cancer patients. Larger trials are needed to confirm the benefits of HFOx during exercises. Clinical trial information: NCT02357134.