Pulse transit time by R-wave-gated infrared photoplethysmography: review of the literature and personal experience.
OBJECTIVE
Pulse transit time (PTT) is the time it takes a pulse wave to travel between two arterial sites. A rela tively short PTT is observed with high blood pressure (BP), aging, arteriosclerosis and diabetes mellitus. Most methods used for measuring the PTT are cumbersome and expensive. In contrast, the interval between the peak of the R-wave on the electrocardiogram and the onset of the corresponding pulse in the finger pad measured by photoplethysmography can be easily measured. We review herein the literature and impart the experience at our institution on clinical applications of R-wave-gated photo-plethysmography (RWPP) as measurement of PTT.


METHODS
The MEDLINE data base on clinical applications of RWPP was reviewed. In addition, studies performed in the author's institution are presented.


RESULTS
When used as a surrogate for beat-to-beat BP monitoring, RWPP did not meet the level of accuracy required for medical practice (two studies). RWPP produced accurate and reproducible signals when utilized as a surrogate for intra-thoracic pressure changes in obstructive sleep apnea, as well as BP arousals which accompany central sleep apnea (five studies). In estimation of arterial stiffness, RWPP was unsatisfactory (one study). In assessment of cardiovascular reactivity, abnormal values of RWPP were noted in autonomic failure (one study), while disease-specific reactivity patterns were identified utilizing a method involving RWPP (two studies).


CONCLUSIONS
In clinical practice, sleep-apnea may be accurately monitored by RWPP. RWPP seems to reflect autonomic influences and may be particularly well-suited for the study of vascular reactivity. Thus, further descriptions of disease-specific cardiovascular reactivity patterns may be possible with techniques based on RWPP. Other clinical uses of RWPP are investigational.
Naschitz
Jochanan E
JE
Departmentments of Internal Medicine A, Bnai-Zion Medical Center and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel. naschitz@tx.technion.ac.il
Bezobchuk
Stanislas
S
Mussafia-Priselac
Renata
R
Sundick
Scott
S
Dreyfuss
Daniel
D
Khorshidi
Igal
I
Karidis
Argyro
A
Manor
Hagit
H
Nagar
Mihael
M
Peck
Elisabeth Rubin
ER
Peck
Shannon
S
Storch
Shimon
S
Rosner
Itzhak
I
Gaitini
Luis
L
D001794:Blood Pressure; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D017156:Photoplethysmography / Q000379:methods; D011674:Pulse; D012891:Sleep Apnea Syndromes / Q000175:diagnosis; D014655:Vascular Resistance