Cerebral Perfusion Monitoring Using Near-Infrared Spectroscopy During Head-Up Tilt Table Test in Patients With Orthostatic Intolerance.

Yoo Hwan Kim,Beop-Min Kim,Nam-Joon Jeon,Seung-Ho Paik,Zephaniah Phillips V,Byung-Jo Kim

doi:10.3389/fnhum.2019.00055

Abstract

The head-up tilt table test (HUT) is one of the primary clinical examinations for evaluating orthostatic intolerance (OI). HUT can be divided into three phases: dynamic tilt phase (supine to tilt up), static tilt phase (remain tilted at 70°), and post tilt phase (tilt down back to supine position). Commonly, blood pressure (BP) and heart rate (HR) are monitored to observe for OI symptoms, but are indirect measurements of cerebral perfusion and can lead to inaccurate HUT evaluation. In this study, we implemented a 108-channel near-infrared spectroscopy (NIRS) probe to characterize HUT performance by monitoring cerebral hemodynamic changes for healthy controls (HCs), OI patients with normal HUT results, and OI patients with positive HUT results: vasovagal syncope (VS), postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension (OH), and orthostatic hypertension (OHT). By the end of the static tilt phase, OI patients typically did not show a complete recovery back to baseline cerebral oxygenation and total blood volume compared to HCs. We characterized the return to cerebral homeostasis by polynomial fitting total blood volume changes and determining the inflection point. The OI patients with normal HUT results, VS, OH, or OHT showed a delay in the return to cerebral homeostasis compared to the HC group during HUT.

Highlights

The autonomic nervous system (ANS) is essential for maintaining homeostasis in response to environmental changes, for example, maintaining cerebral hemodynamics by regulating blood pressure (BP) and heart rate (HR)
The patients with orthostatic intolerance (OI) symptoms were grouped according to the findings of the head-up tilt table test (HUT) as follows: (1) vasovagal syncope (VS) group (n = 4; median age 30.0; one male); (2) postural orthostatic tachycardia syndrome (POTS) group (n = 2; median age 31.0; one male); (3) orthostatic hypotension (OH) group (n = 7; median age 72.0; four males); (4) orthostatic hypertension (OHT) group (n = 5; median age 66.0; one male); (5) NOI group (n = 16; median age 54.0; five males); and (6) healthy controls (HCs) group (n = 8; median age 67.5; five males)
Our study demonstrates that additional near-infrared spectroscopy (NIRS) measurements during HUT can help detect OI symptoms in suspected OI patients

Summary

Introduction

The autonomic nervous system (ANS) is essential for maintaining homeostasis in response to environmental changes, for example, maintaining cerebral hemodynamics by regulating blood pressure (BP) and heart rate (HR). When the ANS is disturbed, various symptoms related to ANS dysregulation, such as dizziness, lightheadedness, blurred vision and palpitation are observed, including more severe symptoms such as fainting. The head-up tilt table test (HUT) is a validated, quantifiable autonomic function test that is widely used as a diagnostic tool to evaluate patients with orthostatic intolerance (OI). The HUT was initially introduced to diagnose vasovagal syncope (VS; Kenny et al, 1986). The use of the HUT has since expanded to demonstrate physiological events mediated by transient cerebral hypo-perfusion.

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