The photoplethysmographic (PPG) waveform contains hemodynamic information in its oscillations. We provide a new method for quantitative study of the waveform morphology and its relationship to the hemodynamics. A data adaptive modeling of the waveform shape is used to describe the PPG waveforms recorded from ear and finger. Several indices, based on the phase and amplitude information of different harmonics, are proposed to describe the PPG morphology. The proposed approach is illustrated by analyzing PPG waveforms recorded during a lower body negative pressure (LBNP) experiment. Different phase and amplitude dynamics are observed during the LBNP experiment. Specifically, we observe that the phase difference between the high order harmonics and fundamental components change more significantly when the PPG signal is recorded from the ear than the finger at the beginning of the study. In contrast, the finger PPG amplitude changes more when compared to the ear PPG during the recovery period. A more complete harmonic analysis of the PPG appears to provide new hemodynamic information when used during a LBNP experiment. We encourage other investigators who possess modulated clinical waveform data (e.g. PPG, arterial pressure, respiratory, and autonomic) to re-examine their data, using phase information and higher harmonics as a potential source of new insights into underlying physiologic mechanisms.

光电容积脉搏波 (PPG) 波形在其振荡中包含血液动力学信息。我们为定量研究波形形态及其与血流动力学的关系提供了一种新方法。波形形状的数据自适应建模用于描述从耳朵和手指记录的 PPG 波形。基于不同谐波的相位和幅度信息，提出了几个指标来描述 PPG 形态。通过分析在下半身负压 (LBNP) 实验期间记录的 PPG 波形来说明所提出的方法。在 LBNP 实验期间观察到不同的相位和振幅动力学。具体来说，我们观察到，在研究开始时，从耳朵记录 PPG 信号比从手指记录时，高次谐波和基波分量之间的相位差变化更显着。相反，在恢复期间，与耳朵 PPG 相比，手指 PPG 振幅变化更大。在 LBNP 实验中使用时，对 PPG 进行更完整的谐波分析似乎可以提供新的血液动力学信息。我们鼓励拥有调制临床波形数据（例如 PPG、动脉压、呼吸和自主神经）的其他研究人员重新检查他们的数据，使用相位信息和高次谐波作为对潜在生理机制的新见解的潜在来源。在恢复期间，与耳朵 PPG 相比，手指 PPG 振幅变化更大。在 LBNP 实验中使用时，对 PPG 进行更完整的谐波分析似乎可以提供新的血液动力学信息。我们鼓励拥有调制临床波形数据（例如 PPG、动脉压、呼吸和自主神经）的其他研究人员重新检查他们的数据，使用相位信息和高次谐波作为对潜在生理机制的新见解的潜在来源。在恢复期间，与耳朵 PPG 相比，手指 PPG 振幅变化更大。在 LBNP 实验中使用时，对 PPG 进行更完整的谐波分析似乎可以提供新的血液动力学信息。我们鼓励拥有调制临床波形数据（例如 PPG、动脉压、呼吸和自主神经）的其他研究人员重新检查他们的数据，使用相位信息和高次谐波作为对潜在生理机制的新见解的潜在来源。