Features of the non-contact carotid pressure waveform: Cardiac and vascular dynamics during rebreathing.
This report amplifies and extends prior descriptions of the use of laser Doppler vibrometry (LDV) as a method for assessing cardiovascular activity, on a non-contact basis. A rebreathing task (n = 35 healthy individuals) was used to elicit multiple effects associated with changes in autonomic drive as well as blood gases including hypercapnia. The LDV pulse was obtained from two sites overlying the carotid artery, separated by 40 mm. A robust pulse signal was obtained from both sites, in accord with the well-described changes in carotid diameter over the blood pressure cycle. Emphasis was placed on extracting timing measures from the LDV pulse, which could serve as surrogate measures of pulse wave velocity (PWV) and the associated arterial stiffness. For validation purposes, a standard measure of pulse transit time (PTT) to the radial artery was obtained using a tonometric sensor. Two key measures of timing were extracted from the LDV pulse. One involved the transit time along the 40 mm distance separating the two LDV measurement sites. A second measure involved the timing of a late feature of the LDV pulse contour, which was interpreted as reflection wave latency and thus a measure of round-trip travel time. Both LDV measures agreed with the conventional PTT measure, in disclosing increased PWV during periods of active rebreathing. These results thus provide additional evidence that measures based on the non-contact LDV technique might provide surrogate measures for those obtained using conventional, more obtrusive assessment methods that require attached sensors.
Department of Industrial Engineering and Mathematical Science, Università Politecnica delle Marche, Ancona, Italy.
S
S
Casaccia
Department of Psychiatry, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.
E J
EJ
Sirevaag
Preston M. Green Department of Electrical and Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130-4899, USA.
E J
EJ
Richter
Preston M. Green Department of Electrical and Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130-4899, USA.
J A
JA
O'Sullivan
Department of Industrial Engineering and Mathematical Science, Università Politecnica delle Marche, Ancona, Italy.
L
L
Scalise
Department of Psychiatry, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.
J W
JW
Rohrbaugh
D000328:Adult; D001794:Blood Pressure; D002339:Carotid Arteries / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D011674:Pulse; D063177:Pulse Wave Analysis