title: Comparison of noninvasive pulse transit time estimates as markers of blood pressure using invasive pulse transit time measurements as a reference.
abstract: Pulse transit time (PTT) measured as the time delay between invasive proximal and distal blood pressure (BP) or flow waveforms (invasive PTT [I-PTT]) tightly correlates with BP PTT estimated as the time delay between noninvasive proximal and distal arterial waveforms could therefore permit cuff-less BP monitoring. A popular noninvasive PTT estimate for this application is the time delay between ECG and photoplethysmography (PPG) waveforms (pulse arrival time [PAT]). Another estimate is the time delay between proximal and distal PPG waveforms (PPG-PTT). PAT and PPG-PTT were assessed as markers of BP over a wide physiologic range using I-PTT as a reference. Waveforms for determining I-PTT, PAT, and PPG-PTT through central arteries were measured from swine during baseline conditions and infusions of various hemodynamic drugs. Diastolic, mean, and systolic BP varied widely in each subject (group average (mean ± SE) standard deviation between 25 ± 2 and 36 ± 2 mmHg). I-PTT correlated well with all BP levels (group average R(2) values between 0.86 ± 0.03 and 0.91 ± 0.03). PPG-PTT also correlated well with all BP levels (group average R(2) values between 0.81 ± 0.03 and 0.85 ± 0.02), and its R(2) values were not significantly different from those of I-PTT PAT correlated best with systolic BP (group average R(2) value of 0.70 ± 0.04), but its R(2) values for all BP levels were significantly lower than those of I-PTT (P < 0.005) and PPG-PTT (P < 0.02). The pre-ejection period component of PAT was responsible for its inferior correlation with BP In sum, PPG-PTT was not different from I-PTT and superior to the popular PAT as a marker of BP.
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan.
authors.forename: Mingwu
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, Michigan.
authors.forename: N Bari
authors.initials: NB
authors.lastname: Olivier
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan rama@egr.msu.edu.
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Mukkamala
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods / Q000592:standards; D063177:Pulse Wave Analysis / Q000379:methods* / Q000592:standards*; D013552:Swine; D013997:Time Factors
keywords: Cuff‐less blood pressure; PPG; pulse arrival time; pulse transit time; pulse wave velocity