Corrigendum: The use of near-infrared spectroscopy for the evaluation of a 4-week rehabilitation program in patients with COPD.

Background: Near-infrared spectroscopy (NIRS) technology can evaluate muscle metabolism and oxygenation. NIRS-based oximeters can measure skeletal muscle oxygen delivery and utilization during static and dynamic work non-invasively. Our goal was to assess the value and usability of NIRS technology in chronic obstructive pulmonary disease (COPD) rehabilitation program. Methods: Forty patients with COPD participated in a 4-week inpatient rehabilitation program that included breathing exercises and personalized cycle/treadmill training adjusted to the functional capacity, physical activity and comorbidities of the patients. A NIRS muscle oxygen monitor was used to measure tissue oxygenation and hemoglobin were recorded before and after the rehabilitation program. Results: Rehabilitation resulted improvement in 6 min walking distance (6MWD:335.3 +/- 110. vs. 398.3 +/- 126.2 m; P < 0.01), maximal inspiratory 4.00 +/- 1.76 cm; P < 0.01), breath hold time (BHT: 25.8 +/- 10.6 vs. 29.2 +/- 11.6 s; P < 0.01) and grip strength (GS: 24.9 +/- 11.9 vs. 27.0 +/- 11.4 kg; P < 0.01). Quality of life improvement was monitored by COPD Assessment Test (CAT: 17.00 +/- 8.49 vs. 11.89 +/- 7.3, P < 0.05). Total hemoglobin index (tHb: 12.8 +/- 1.3% vs. 12.8 +/- 1.4), average muscle oxygenation (SmO2: 67.5 +/- 14.4% vs. 65.2 +/- 20.4%) showed a tendency for improvement. Maximal muscle oxygenation decreased (SmO2 max: 98.0 +/- 20.5% vs. 90.1 +/- 14.3%; P < 0.01). Minimal muscle oxygenation increased (SmO2 min: 42.6 +/- 12.6% vs. 54.8 +/- 14.3%; P < 0.01). Conclusions: NIRS results showed that muscle oxygenation and microcirculation can be described as a high-risk factor in COPD patients. The 4-week rehabilitation improves functional parameters, quality of life and tissue oxygenation levels in COPD patients.