What Is the Best Site for Measuring the Effect of Ventilation on the Pulse Oximeter Waveform?

Abstract

The cardiac pulse is the predominant feature of the pulse oximeter (plethysmographic) waveform. Less obvious is the effect of ventilation on the waveform. There have been efforts to measure the effect of ventilation on the waveform to determine respiratory rate, tidal volume, and blood volume. We measured the relative strength of the effect of ventilation on the reflective plethysmographic waveform at three different sites: the finger, ear, and forehead. The plethysmographic waveforms from 18 patients undergoing positive pressure ventilation during surgery and 10 patients spontaneously breathing during renal dialysis were collected. The respiratory signal was isolated from the waveform using spectral analysis. It was found that the respiratory signal in the pulse oximeter waveform was more than 10 times stronger in the region of the head when compared with the finger. This was true with both controlled positive pressure ventilation and spontaneous breathing. A significant correlation was demonstrated between the estimated blood loss from surgical procedures and the impact of ventilation on ear plethysmographic data (r(s) = 0.624, P = 0.006).

Reliable monitoring of oxygen saturation via pulse oximetry: Which site to choose?

“…This is in agreement with previous studies which highlighted the earlobe to be the most reliable site for SpO 2 measurement regardless the change of temperature [19][20].…”

Finger and forehead photoplethysmography-derived pulse-pressure variation and the benefits of baseline correction

“…In the present work, we demonstrated, by computing and comparing BV, that the baseline modulation in the ABP signal was much weaker than that in the PPG signals. Furthermore, we showed that the baseline modulation manifested itself more strongly in the forehead than in the finger, which is in line with the finding by Shelley et al [17]. In fact, the increase in BV from the ABP signal to the finger and forehead PPG signals might be caused by the presence of venous component in the PPG signals [17,28].…”

“…The presence of baseline modulations in the PPG signal has been described by Shelley et al [17,25]. Moreover, its impact on PAV was discussed recently in a simulation by Høiseth et al [27].…”

“…One suggestion was that PPG sensors placed in the cephalic region might improve the relationship between PPV and PAV as this area is less sensitive to changes in vasomotor tone and allow a stronger expression of ventilation effects [17][18][19].…”

Real-Time Driver’s Biological Signal Monitoring System

“…The amount of reflected light depends on the volume change of the blood vessels induced by the pressure pulse of the cardiac cycle. (10) The signal derived from the PPG sensor is then processed to obtain information on the HR and HRV. In the proposed monitoring system, the PPG sensor is attached to the steering wheel (Fig.…”