Prefrontal hemodynamic changes measured using near-infrared spectroscopy during the Valsalva maneuver in patients with orthostatic intolerance

Abstract

The Valsalva maneuver (VM) with beat-to-beat blood pressure and heart rate monitoring are used to evaluate orthostatic intolerance (OI). However, they lack the ability to detect cerebral hemodynamic changes, which may be a cause of OI symptoms. Therefore, we utilized near-infrared spectroscopy during VM. Patients with OI symptoms and normal healthy subjects were recruited. Patients were subgrouped according to VM results: patients with normal VM (NVM) and abnormal VM (AbVM). Oxyhemoglobin (HbO), deoxyhemoglobin, and total hemoglobin changes were measured at four different source-detector distances (SD) (15, 30, 36, and 45 mm), and latency, amplitude, duration, and integrated total signal were calculated. Those parameters were compared between a normal healthy control (HC) group and the two OI patient subgroups. We found that HbO increment latency at 30-mm SD in the HC, NVM, and AbVM groups was as follows: [Formula: see text], [Formula: see text], and [Formula: see text], respectively ([Formula: see text]). Among the four parameters we evaluated, latency of HbO increment was the best marker for differentiating OI.

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

“…This method has been shown to be effective in removing sudden and drastic changes in time-series data induced by motion artifacts (Molavi and Dumont, 2012). A more detailed review of the NIRS methodology, principles, and terminology can be found in our previous article (Kim et al, 2018).…”

Cerebral hemodynamic monitoring of Parkinson’s disease patients with orthostatic intolerance during head-up tilt test

“…The system used in this study is the same as used in our previous studies. 1,15 In short, the probe was controlled by an 8 bit of microcontroller unit with 200 to 4095 resolution. The system alternated LED sources between wavelengths of 760 and 830 nm at a temporal frequency of 5 Hz for scanning the entire forehead.…”

“…The data preprocessing steps were similar to our previous publications, including a 2-Hz low pass filter. 1,15 In short, a wavelet-based denoising method (Daubechies 5) was applied to the time series data to remove large motion artifacts. This method has been shown to be effective in removing sudden and drastic changes in time series data induced by motion artifacts.…”

“…In our previous studies, we have shown the feasibility of direct cerebral perfusion monitoring with near-infrared spectroscopy (NIRS) during the HUTT and Valsalva maneuver (VM). 1,15 Specifically, patients with OH showed a delayed change in cerebral hemodynamics during the VM 15 and a later inflection point of blood volume restoration during the HUTT compared with those of healthy controls (HCs), 1 suggesting an impairment of the autonomic reflex, which maintains cerebral perfusion in patients with OH. These findings imply that direct monitoring of cerebral hemodynamics may provide additional information useful for the accurate diagnosis of OI symptoms.…”

Heart-Rate-Based Machine-Learning Algorithms for Screening Orthostatic Hypotension

“…11 Using near-infrared spectroscopy, monitoring the pattern of cerebral perfusion changes during the Valsalva maneuver (VM) was also found to be a useful tool for identifying patients with OI as an alternative to the HUTT. 12 In addition, a few studies have shown a relationship between BP responses during the VM and HUTT, implying that the VM might be a nonpostural method for supplementing the HUTT in detecting and differentiating OI. 13,14 Although the above-mentioned methods are valuable alternatives that can be applied to patients who are unable to perform the HUTT, those methods have the limitation that beat-to-beat BP measurements using special equipment are required to obtain reliable data.…”