IntroductionLong COVID‐19 illness is a severely disabling disease with shortness of breath, weakness and fatigue as leading symptoms, resulting in poor quality of life and substantial delay in return to work.No specific respiratory therapy has been validated for patients with long COVID. The intermittent hypoxia–hyperoxia training (IHHT) is a respiratory therapeutic modality to improve exercise performance via controlled respiratory conditioning. The purpose of the present study is to investigate the therapeutic effect of IHHT on functional and symptomatic recovery of patients with long COVID syndrome.MethodsA prospective, controlled, open‐treatment interventional study was conducted in patients with long COVID who were admitted to an inpatient rehabilitation programme. Patients were assigned nonrandomized to receive IHHT in addition to the standardized rehabilitation programme (IHHT group) or standard rehabilitation alone (control group). The IHHT group received supervised sessions of intermittent hypoxic (10–12% O2) and hyperoxic (30–35% O2) breathing three times per week throughout the rehabilitation period. Primary endpoint was improved walking distance in a 6‐min walk test (6MWT) between study groups. Secondary endpoints were change in stair climbing power, dyspnoea (Borg dyspnoea Scale), fatigue assessment scale (FAS) and change in health‐related quality of life (HRQoL) assessed by patient global assessment (PGA), EQ‐5D analogue scale and the MEDIAN Corona Recovery Score (MCRS). Further assessments included maximum handgrip strength, nine hole peg test, timed up‐and‐go, respiratory function and functional ambulation category (FAC), serum analyses and safety of the intervention.ResultsA total of 145 patients were included in the study (74% female, mean age 53 ± 12 years) and assigned to IHHT (n = 70) or standard care (n = 75). The 6MWT distance improved 2.8‐fold in the IHHT group compared to the control group (91.7 ± 50.1 m vs. 32.6 ± 54.2 m, ANCOVA p < 0.001). Stair climbing power improved 3.7‐fold in the IHHT group compared to controls (−1.91 ± 2.23 s vs. −0.51 ± 1.93 s, p < 0.001). Secondary endpoints on dyspnoea, fatigue and HRQoL (PGA, EQ‐5D and MCRS) improved significantly in the IHHT group compared to controls. The IHHT group exhibited a significant decrease in blood pressure, heart rate and increase in haemoglobin levels that was not observed in the control group. No adverse events were observed.ConclusionRespiratory treatment with IHHT in addition to a multidisciplinary rehabilitation programme improves functional capacity, symptomatic status and quality of life in patients with disabling long COVID. IHHT has been demonstrated to be safe, well tolerated and feasible to be integrated in an inpatient rehabilitation programme to improve outcome in long COVID.

中文翻译：

---

住院康复期间的间歇性低氧-高氧训练可改善长期 Covid 患者的运动能力和功能结果：对照临床试点试验的结果


简介长期 COVID-19 疾病是一种严重致残性疾病，以呼吸急促、虚弱和疲劳为主要症状，导致生活质量差和重返工作岗位的严重延迟。尚无针对长期 COVID 患者的特异性呼吸疗法得到验证。间歇性缺氧-高氧训练 （IHHT） 是一种呼吸治疗方式，通过受控呼吸调节来改善运动表现。本研究的目的是探讨 IHHT 对长期 COVID 综合征患者功能和症状恢复的治疗效果。方法在住院康复计划收治的长期 COVID 患者中进行了一项前瞻性、对照、开放性治疗干预研究。患者被非随机分配接受 IHHT 和标准化康复计划 （IHHT 组） 或单独标准康复 （对照组）。在整个康复期间，IHHT 组接受每周 3 次间歇性低氧 （10-12% O2） 和高氧 （30-35% O2） 呼吸的监督课程。主要终点是研究组之间 6 分钟步行测试 （6MWT） 中步行距离的改善。次要终点是通过患者整体评估 （PGA） 、EQ-5D 模拟量表和中位冠状病毒恢复评分 （MCRS） 评估爬楼梯能力的变化、呼吸困难 （Borg 呼吸困难量表） 、疲劳评估量表 （FAS） 和健康相关生活质量 （HRQoL） 的变化。进一步的评估包括最大握力、九孔钉测试、定时起跳、呼吸功能和功能行走类别 （FAC）、血清分析和干预安全性。结果共有 145 名患者被纳入研究 （74% 为女性，平均年龄 53 ± 12 岁） 并被分配到 IHHT （n = 70） 或标准护理 （n = 75）。与对照组相比，IHHT 组的 6MWT 距离提高了 2.8 倍 （91.7 ± 50.1 m vs. 32.6 ± 54.2 m，ANCOVA p < 0.001）。与对照组相比，IHHT 组的爬楼梯能力提高了 3.7 倍 （-1.91 ± 2.23 s vs. -0.51 ± 1.93 s，p < 0.001）。与对照组相比，IHHT 组呼吸困难、疲劳和 HRQoL （PGA、EQ-5D 和 MCRS） 的次要终点显著改善。IHHT 组血压、心率和血红蛋白水平升高，这在对照组中没有观察到。未观察到不良事件。结论除了多学科康复计划外，IHHT 呼吸治疗可改善致残性长期 COVID 患者的功能能力、症状状态和生活质量。IHHT 已被证明是安全的、耐受性良好的，并且可以整合到住院康复计划中以改善长期 COVID 的预后。