Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: Mar 01, 2010

Garbage In; Garbage Out—Identify Blood Volume Pulse (BVP) Artifacts Before Analyzing and Interpreting BVP, Blood Volume Pulse Amplitude, and Heart Rate/Respiratory Sinus Arrhythmia Data

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Page Range: 19 – 23
DOI: 10.5298/1081-5937-38.1.19
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Abstract

Blood volume pulse is a popular method for monitoring the relative changes in peripheral blood flow, heart rate, and heart rate variability. This article stresses the danger of blindly interpreting measures like heart rate, which are derived from blood volume pulse, without close inspection of the raw blood volume pulse signal. The authors identify common sources of signal contamination and recommend practical precautions and treatment of artifacts.

Keywords: artifacts; photoplethysmography; blood volume pulse (BVP); heart rate variability (HRV); respiratory sinus arrhythmia (RSA)
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Copyright: Association for Applied Psychophysiology & Biofeedback
Figure 1
Figure 1

Heart rate is derived from blood volume pulse by measuring the interbeat interval and then transforming this information into beats per minute. For example, the interbeat interval of .80 seconds is equal to a heart rate of 75 beats per minute, whereas the interbeat interval of .93 seconds is equal to a heart rate of 64.5. Reprinted with permission from Peper et al. (2008).

Figure 2
Figure 2

Recording of the heart rate derived from the raw blood volume pulse during the baseline period. The average heart rate included a segment of very rapid heartbeats due to movement artifact rather than to a true increase in average heart rate. Reprinted with permission from Peper et al. (2008).

Figure 3
Figure 3

When movement artifact was excluded from the signal shown in Figure 4, the actual heart rate was 61.05 beats per minute. Reprinted with permission from Peper et al. (2008).

Figure 4
Figure 4

Recording of changes in blood volume pulse during a research study. It seemed that blood volume pulse amplitude significantly increased during the neutral and anger imagery conditions.

Figure 5
Figure 5

The same recording as Figure 4 except that the time scale was changed to display 10 seconds of data. Visual inspection showed an absence of blood volume pulse waveforms (see the middle blood volume pulse raw tracing) in the anger condition. The blood volume pulse amplitude measure was most likely produced by movement artifact.

Figure 6
Figure 6

Effects of different amplification range settings (appropriate, too small, and too large) on the blood volume pulse raw signal.

Figure 7
Figure 7

The effect of temperature on blood volume pulse signal recorded from the left index finger. The amplitude of the blood volume pulse signal decreases as the finger is colder. If the signal is too low, heart rate cannot be derived from the interbeat intervals.

Figure 8
Figure 8

The effect of wrapping the tape loosely, snugly, or very tightly around the photoplethysmograph sensor and index finger. When taped loosely, the blood volume pulse amplitude is decreased and prone to movement artifacts. When taped very tightly, blood flow is occluded and the blood volume pulse signal cannot be recorded. Optimum signal is recorded when sensor is taped snugly.

Figure 9
Figure 9

Blood volume pulse and heart rate recording and statistics before excluding the premature ventricular contractions. Note the high blood volume pulse amplitudes and heart rate variability.

Figure 10
Figure 10

Recalculated BVP and heart rate statistics after two contaminated premature ventricular contractions segments were identified and excluded for statistical analysis. Note the lower blood volume pulse amplitudes and the lower heart rate variability.

Contributor Notes

Correspondence: Erik Peper, PhD, Institute for Holistic Healing Studies/Department of Health Education, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, e-mail: epeper@sfsu.edu.