Key result
Warm temperatures significantly improved PPG signal quality compared to baseline and cold temperatures (median RMS 0.0289 V vs 0.0174 V and 0.0066 V; P<0.004).
Why the study?
Does hand temperature affect PPG signal quality and pulse oximeter accuracy in adult volunteers?
Does hand temperature affect PPG signal quality and pulse oximeter accuracy in adult volunteers?
Absolute Event Rate: 0.0289% vs 0.0174%
p-value: p=<0.004
Warming the hand significantly improves photoplethysmography signal quality and pulse oximeter accuracy compared to cold or baseline temperatures.
Hand warming may enhance PPG signal quality for SpO2; leaves open clinical validation before practice change.
Pulse oximetry is a commonly used technique to determine arterial oxygen saturation (SpO2) and heart rate. This method uses photoplethysmography (PPG) signals to estimate SpO2. However, pulse oximeters can be less accurate at cold temperatures. In this research, the effects of temperature on PPG signal quality was investigated for a group of 20 adult volunteers. Raw PPG data was obtained using a custom pulse oximeter (PO) system. Three tests were performed with the subject's hand maintained at baseline, cold, and warm temperatures. Analysis showed the median PPG signal RMS, as an indicator of signal-to-noise, for the warm test was 0.0289 V [IQR = 0.0262 - 0.0315 V] compared to the baseline test's 0.0174 V [IQR = 0.0104 - 0.0285 V] and the cold test's 0.0066 V [IQR = 0.0053 - 0.0106V]. This improvement of up to 4x in signal quality was associated with a closer match between the SpO2 values estimated by the PO system and a commercial pulse oximeter. Paired RMS value comparison between the three tests showed a statistically significant difference for all P-values (P < 0.004). Results indicate that warm temperatures improve PPG quality and thus pulse oximeter accuracy.
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Khan et al. (2015) studied this question. Warm temperatures vs. Baseline and cold temperatures was evaluated on PPG signal root mean square (RMS) (p=<0.004). Warm temperatures significantly improved PPG signal quality compared to baseline and cold temperatures (median RMS 0.0289 V vs 0.0174 V and 0.0066 V; P<0.004).
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