Key result
NIRS correlates with TCD for cerebral autoregulation but lacks agreement for individual clinical use.
Why the study?
The criterion validity of cerebral autoregulation measures derived from near-infrared spectroscopy as an alternative to transcranial Doppler was uncertain in patients with controlled hypertension, cognitive impairment, and controls.
Observational (n=202)
Yes
Effect estimate: ρ = 0.22-0.30 (supine rest) and 0.46-0.61 (sit-to-stand transitions); Limits of agreement separation 87°-112° (supine) and 65°-77° (transitions)
p-value: p=<0.05
Does not support NIRS for individual clinical autoregulation assessment; leaves open its research utility pending better agreement.
Purpose Cerebral autoregulation (CA) aims to attenuate the effects of blood pressure variation on cerebral blood flow. This study assessed the criterion validity of CA derived from near-infrared spectroscopy (NIRS) as an alternative for Transcranial Doppler (TCD). Methods Measurements of continuous blood pressure (BP), oxygenated hemoglobin (O 2 Hb) using NIRS and cerebral blood flow velocity (CBFV) using TCD (gold standard) were performed in 82 controls, 27 patients with hypertension and 94 cognitively impaired patients during supine rest (all individuals) and repeated sit to stand transitions (cognitively impaired patients). The BP-CBFV and BP-O 2 Hb transfer function phase shifts (TF φ ) were computed as CA measures. Spearman correlations ( ρ ) and Bland Altman limits of agreement (BAloa) between NIRS- and TCD-derived CA measures were computed. BAloa separation < 50° was considered a high absolute agreement. Results NIRS- and TCD-derived CA estimates were significantly correlated during supine rest ( ρ = 0.22–0.30, N = 111–120) and repeated sit-to-stand transitions ( ρ = 0.46–0.61, N = 19–32). BAloa separation ranged between 87° and 112° (supine rest) and 65°–77° (repeated sit to stand transitions). Conclusion Criterion validity of NIRS-derived CA measures allows for comparison between groups but was insufficient for clinical application in individuals.
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Mol et al. (2021) conducted an observational in Hypertension, Mild Cognitive Impairment, Alzheimer's Dementia (n=202). Near-infrared spectroscopy (NIRS) to assess cerebral autoregulation vs. Transcranial Doppler (TCD) to assess cerebral autoregulation was evaluated on Spearman correlation and Bland Altman limits of agreement between NIRS- and TCD-derived cerebral autoregulation measures (ρ = 0.22-0.30 (supine rest) and 0.46-0.61 (sit-to-stand transitions); Limits of agreement separation 87°-112° (supine) and 65°-77° (transitions), p=<0.05). Near-infrared spectroscopy-derived cerebral autoregulation estimates correlated significantly with transcranial Doppler measures but lacked sufficient absolute agreement for clinical application in individuals.
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