Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 2008
A measure of confidence in Bland-Altman analysis for the interchangeability of two methods of measurement.
Bland-Altman (B-A) analysis has largely replaced the correlation coefficient as the predominant tool for evaluating the interchangeability of two methods of clinical measurement. However, we contend that B-A analysis might lead to erroneous conclusions when the data range is small. We provide an example to illustrate this and explore a possible analysis technique to address this limitation.
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J Clin Monit Comput · Aug 2008
Noninvasive detection of the hemodynamic stress of exercise using the photoplethysmogram.
Exercise induced hemodynamic stress has been studied extensively using a wide range of physiological sensors. While athletes can modulate their training intensity using EKG-based heart rate monitors, there are currently no noninvasive monitors that can be used to ascertain with a high degree of certainty the hemodynamic stress an individual is experiencing because of fatigue or an underlying pathology. We propose that cardiac stress will result in detectable changes in skin blood flow. ⋯ As volitional fatigue approached, the low frequency (f = 0.05-0.2 Hz) amplitude modulation observed in the PPG became more pronounced; then, within several seconds of the cessa- tion of the protocol, they disappeared. Using a software-based detector, these distinct waves are reliably detected, with a low incidence of false positives, in all subjects before the onset of volitional fatigue. We hypothesize that the low frequency waves observed in the PPG of individuals exercising to volitional fatigue provide a mechanism for noninvasively detecting hemodynamic stress to the human vascular system.