Neurovascular coupling on trial: How the number of trials completed impacts the accuracy and precision of temporally derived neurovascular coupling estimates

Abstract

Standard practices for quantifying neurovascular coupling (NVC) with transcranial Doppler ultrasound (TCD) require participants to complete one-to-ten repetitive trials. However, limited empirical evidence exists regarding how the number of trials completed influences the validity and reliability of temporally derived NVC metrics. Secondary analyses was performed on 60 young healthy participants (30 females/30 males) who completed eight cyclical eyes-closed (20-seconds), eyes-open (40-seconds) NVC trials, using the “Where’s Waldo?” visual paradigm. TCD data was obtained in posterior and middle cerebral arteries (PCA and MCA, respectively). The within-day (n = 11) and between-day ( n = 17) reliability were assessed at seven- and three-time points, respectively. Repeat testing from the reliability aims were also used for the concurrent validity analysis ( n = 160). PCA metrics (i.e., baseline, peak, percent increase, and area-under-the-curve) demonstrated five trials produced excellent intraclass correlation coefficient (ICC) 95% confidence intervals for validity and within-day reliability (>0.900), whereas between-day reliability was good-to-excellent (>0.750). Likewise, 95% confidence intervals for coefficient of variation (CoV) measures ranged from acceptable (<20%) to excellent (<5%) with five-or-more trials. Employing fewer than five trials produced poor/unacceptable ICC and CoV metrics. Future NVC, TCD-based research should therefore have participants complete a minimum of five trials when quantifying the NVC response with TCD via a “ Where’s Waldo?” paradigm.

Cerebral blood flow regulation is not acutely altered after a typical number of headers in women footballers

“…Thus, each visual search challenge lasted the full 40 s, and this approach is understood to be highly engaging compared to other visual stimuli ( 43 ). This process was repeated 5 times in total, which has been shown to provide excellent reproducibility ( 44 ).…”

“…The PCAv and MAP response to each 40 s eyes open transition was scrutinized prior to ensemble averaging the 5 attempts. In line with others (9,42,44,45), data are presented as the averaged, absolute and percentage increase in PCAv in the first 30 s of each search attempt above the last 5 sec of averaged eyes closed baseline. The time to peak PCAv was noted, and the total hyperaemic response was calculated as the area under the PCAv curve vs. time, adjusted to the eyes closed baseline.…”

Cerebral blood velocity during concurrent supine cycling, lower body negative pressure, and head-up tilt challenges: implications for concussion rehabilitation

“…Females and males differ in body weight and mass, and therefore these regressions were stratified by sex to control for both potential modifying factors of sex and body weight. While R 2 estimates have no agreed-upon thresholds as these will vary depending upon the field of study, a priori cut-offs consistent with previous literature were used: <0.10 (negligible), 0.10-0.30 (small), 0.30-0.50 (moderate), 0.50-0.80 (large), and 0.80-1.00 (very large) (Burma et al 2022). Variability between baseline physiological variables was assessed through coefficient of variation (CoV) estimates (Hopkins 2000).…”

Validity and reliability of deriving the autoregulatory plateau through projection pursuit regression from driven methods

“…The associated 95% CI for the CoV estimates were calculated in accordance with published recommendations (Hartmann et al., 2023 ). CoV thresholds consisted of 0%–5% (excellent), 5%–10% (good), 10%–20% (moderate), and >20% (poor) (Burma et al., 2022 ). Giavarina ( 2015 ) has extensively shown the inability of Bland–Altman analysis to be completed on non‐normally distributed data, due to artificial bias.…”