Postprandial superior mesenteric artery (SMA) blood flow is associated with the caloric content of a meal. Whether spectral analysis of a peripheral pulse wave or heart rate can model postprandial SMA blood flow is unclear. We hypothesized that altering the caloric content of a meal would evoke dose-response increases in postprandial SMA hyperemia and distinct changes in the pulse wave harmonic spectrum and heart rate. Twenty healthy subjects (10 male, 26 ± 10 yr) completed a randomized cross-over trial, comparing three meals (280, 560, or 840 kcal) on SMA blood flow (Doppler ultrasound), heart rate, and the first to seventh harmonic amplitudes (derived from a finger pulse wave). Supine SMA diameter and blood velocity were collected at baseline and every 15 min throughout 2 h of postprandial recovery. SMA blood flow was smaller across all time points following meal 1 (280 kcal) compared with both meal 2 (560 kcal) and meal 3 (840 kcal) (all P < 0.001), while meal 2 had attenuated responses compared with meal 3 at 60, 90, 105, and 120 min postprandial (all P < 0.01). Distinct changes in heart rate and the amplitude of second to fifth harmonics were observed between meals (all P < 0.05). The changes in harmonic spectrum or heart rate explained 66-69% (adjusted r2) of the variance in postprandial SMA blood flow. These results provide proof-of-concept that easily obtained and noninvasive postprandial harmonic profiles or heart rate may be used to explain changes in SMA blood flow and exploited for the development of wearable technology to noninvasively track caloric intake.NEW & NOTEWORTHY We studied the superior mesenteric artery (SMA) blood flow responses to three meals of varying caloric value and examined whether these responses could be modeled using changes in heart rate or the peripheral pulse wave harmonic spectrum. We found that both inputs could explain 66-69% of the SMA blood flow variance over 2 h of postprandial recovery. Noninvasive methods may be able to predict SMA blood flow and thus used to measure caloric intake.
Keywords: Fourier analysis; blood flow; caloric intake; superior mesenteric artery.