Comparison of two different O₂-delivery systems during exercise in patients with chronic hypoxia

Abstract

Results from case studies using a high-flow oxygen delivery system (TNI®) suggest advantage regarding the oxygenation compared to conventional O₂-therapy (LTOT). Aim of the study was to verify the feasibility, safety and clinical significance of TNI® compared to LTOT.

Method: 14 patients (pts) with chronic hypoxia underwent standardized treadmill six-minute walk test (6MWT) in a prospective, randomized study. All pts completed 6MWT on room air (basis). Then, they underwent consecutive 6MWTs applying TNI® and LTOT in a random order (40% O₂-admixture each). Between 6MWTs, pts had a rest of 30 minutes. We measured walking distance (m), workload performance (Watt), energy expenditure (kcal), and collected data from Borg-dyspnoea-scale (BDS) and blood gas analysis (BGA) before 6MWT and at maximum workload (WLm). Primary outcome measures were ΔPaO₂ and ΔPaCO₂ from rest to WLm and their relation to walking distance (m/ΔPaO₂), exercise performance (Watt/ΔPaO₂) and energy expenditure (kJ/ΔPaO₂).

Results: BDS scores increased from rest to WLm by 5,58±2,15 (basis), 2,67±1,78 (TNI®) and 3,38±2,04 (LTOT) scores. Waking distances during basis, TNI® and LTOT were 182,14 m, 235,86 m and 232,86 m respectively. ΔPaO₂ from rest to WLm was higher during LTOT compared to TNI® (-10,19 mmHg vs. -7,80 mmHg respectively) at identical workload performance (43,21 Watt). Workload economy, performance- and energy efficacy was better during TNI® vs. LTOT (30,22 vs. 22,85 m/mmHg; 5,53 vs. 4,24 Watt/mmHg and 2.02 vs. 1,51 kJ/mmHg respectively).

Conclusion: TNI® compared to LTOT was safe to deliver O₂ for pts with hypoxia during exercise and superior in regard to workload economy, performance- and energy efficiency.