(Scientific Session) Treatment Effect of Respiratory Therapy with Intermittent Hypoxic-Hyperoxic Training (IHHT) on Functional Capacity in Patients with Post COVID19 Conditions: A Controlled Clinical Trial

Background and/or Objectives: COVID-19 can cause long-term lung and systemic damage that will lead to increasing numbers of patients disabled by reduced functional capacity. Intermittent hypoxia-hyperoxia training (IHHT) is a new respiratory training method which has been suggested to improve exercise performance via controlled hypoxic conditioning. The purpose of the present study is to investigate the therapeutic effect of IHHT on the recovery process during inpatient rehabilitation in post-COVID conditions.

Design: A prospective, single-center controlled trial was conducted in 145 patients with post COVID19 conditions, who were admitted to an inpatient rehabilitation center. Patients were allocated to the HHT or control group, along with standard rehabilitation.

Setting: inpatient rehabilitation

Participants: patients with post COVID19 conditions

Interventions: The patients in IHHT group attended regular sessions of treatments of hypoxia-hyperoxia training (6-8 cycles for a total of 45 min).

Main Outcome Measures: The main objective of the trial was to evaluate the difference in walking distance, as measured by the six-minute walk test (6MWT), between the two groups. Secondary endpoints of the functional testing included the stair climbing test (SCT), patient global assessment, fatigue assessment scale (FAS), quality of life (QoL) using the EQ5-D analog scale as well as subjective perceived health evaluated by the Median Corona Recovery Score (MCRS).

Results: The IHHT group exhibited a significant improved primary endpoint compared to the control group (6MWT difference between IHHT group and controls: 91.7 vs. 32.5m, P< 0.001). Additionally, the IHHT group demonstrated improved stair climbing (SCT: -1.9 vs. -0.5 seconds, P< 0.001), improved quality of life (EQ5-D analog scale change: 31.3 vs. 2.9, P< 0.001), improved fatigue (FAS: -8.9 vs. 3.6, P< 0.001), and improved perceived health (MCRS: -10.3 vs. -2, P< 0.001).

Conclusions: Respiratory treatment by IHHT in patients with post COVID conditions resulted in enhanced functional capacity across multiple functional tests, as well as improvements in quality of life and subjective perceived health.