Background: SpO2 is a widely used estimation of oxygen saturation owing to its convenient usage and low cost. However, SpO2 determination under low perfusion condition is severely affected by noise.
Methods: In this paper, an autocorrelation modeling method for the oxygen saturation measurement during low perfusion is presented. The proposed method mainly contains two steps: calculating the autocorrelation of the photoplethysmography (PPG) signals and modeling for the parameter calculation. The autocorrelation of the PPG signals can suppress the noise and extract pulse waves from low perfusion signals. The model can realize the calculation of SpO2 with the autocorrelation signals.
Results: Experiments showed that the new method had a good accuracy and stability under low perfusion condition (perfusion index (PI)<=0.2%), and it was also motion-tolerant. Meanwhile, the new method showed a good performance for the oxygen saturation measurement under the condition of lower perfusion(PI=0.1%).
Conclusions: The new method could realize the calculation of SpO2 by little computation and high efficiency without extra hardware. It has strong potential in real-time clinical use.