Abstract Rationale Respiratory rehabilitation is crucial in the treatment of chronic obstructive pulmonary disease (COPD). Detecting the anaerobic threshold (AT) is necessary to optimize exercise intensity, but this is typically done using expensive and difficult-to-operate expiratory gas analyzers. In contrast, sweat lactate sensors can monitor lactate in sweat simply and non-invasively. Previous reports have shown that the sweat lactate threshold (sLT) detected by sweat sensors correlates with the ventilation threshold (VT) in heart failure patients. However, its accuracy in respiratory diseases remains unproven. We investigated whether sweat lactate sensors accurately detect VT in COPD patients. Methods Forty-one patients with stable COPD (mean age 73.9 years, interquartile range 68.0-79.0) without exacerbations in the past 4 weeks were enrolled. A cardiopulmonary exercise test using an ergometer was performed while sweat lactate concentration was monitored with the sweat lactate sensor. sLT was defined as the first point of rapid increase in lactate concentration from baseline. VT was assessed using the V-slope method. Results The sweat lactate sensor failed to respond in 13 cases. A correlation coefficient of 0.49 (p = 0.008) was obtained in 28 cases. Although the Bland-Altman plot showed a tendency for sLT to be higher than VT, nearly all data points fell within the limits of agreement, indicating good agreement between the two measurement methods. No sweat sensor-related adverse events were observed in enrolled patients. Conclusion The sweat lactate sensor is safe and accurate for detecting AT in COPD patients and is considered useful for assessing their condition and prescribing rehabilitation. This abstract is funded by: Grace imaging, Inc.
Oshima et al. (Fri,) studied this question.