Effects of occlusion pressure on hemodynamic responses recorded by near-infrared spectroscopy across two visits

Abstract

Ischemic Preconditioning (IPC) has emerged as a promising approach to mitigate the impact of hypoxia on physiological functions. However, the heterogeneity of occlusion pressures for inducing arterial occlusion has led to inconsistent hemodynamic outcomes across studies. This study aims to evaluate the peripheral hemodynamic responses to partial and total blood-flow occlusions on the left arm at rest, using absolute or individualized pressures, on two occasions. Thirty-five young males volunteered to participate in this study. IPC procedure (3 × 7-min) was performed on the left upper arm with cuff pressures at 50 mmHg (G1), 50 mmHg over the systolic blood pressure (SBP + 50 mmHg) (G2) or 250 mmHg (G3). NIRS-derived parameters were assessed for each occlusion and reperfusion phase in the brachioradialis. Results showed a significantly lower magnitude of deoxygenation (TSIAUC) for G1 compared to G2 (-1959.2 ± 1417.4 vs. -10908.1 ± 1607.5, P < 0.001) and G3 -1959.2 ± 1417.4 vs. -11079.3 ± 1828.1, P < 0.001), without differences between G2 and G3. However, G3 showed a significantly faster reoxygenation only for tissue saturation index (TSI_slope) compared to G2 (1.3 ± 0.1 vs. 1.0 ± 0.2, P = 0.010), but without differences in the speed of recovery of deoxyhemoglobin [(HHb) slope], or in the magnitude of post-occlusive hyperemia (PORH). Besides TSI reoxygenation speed, G2 and G3 elicit comparable resting hemodynamic responses measured by NIRS. Thus, this study highlights the practicality and effectiveness of using relative occlusion pressures based on systolic blood pressure (SBP) rather than relying on excessively high absolute pressures.

Keywords: NIRS; arterial occlusion; blood flow restriction; muscle ischemia; muscle oxygenation; remote ischemic preconditioning.

FIGURE 1

Flowchart of the study design. During the protocol, the participant was supine on a medical couch, with the arm at the level of the heart. The baseline consisted of 15 min of rest, without any occlusion, to establish resting values.

FIGURE 2

Illustration of the NIRS device placement. Reproduced with permission from Desanlis et al. (2022).

FIGURE 3

Example of tissue saturation index (TSI%), oxyhemoglobin concentration [(O₂Hb)] and deoxyhemoglobin concentration [(HHb)] responses during the protocol for a single participant in group 3 (G3: 250 mmHg). The dashed rectangle represents the last minute at baseline, which is averaged to provide the baseline value of each parameter. When the cuff is inflated during occlusion phases (O1, O2, O3; in grey on the graph), both TSI% and [O₂Hb] decrease until their minimum, whereas [HHb] increases to its maximum. When the cuff is deflated at the beginning of reperfusions phases (R1, R2, R3), TSI% and [O₂Hb] rise until their maximum above the baseline value (hyperemia spike), whereas [HHb] reach its minimum. During occlusion phases and post-occlusive reactive hyperemia phases, the area under the curve (AUC) is calculated.

FIGURE 4

Lineplot of [HHb] response during the protocol in S1. Values are aggregate over participants of each group to plot the mean (in bold) and 95% confidence interval using seaborn library for python (Waskom, 2021).

FIGURE 5

Raincloud plots of TSI_AUC during PORH. The plot highlights the lack of differences between group 2 (G2, n = 12) and group 3 (G3, n = 12) during PORH. The values from S1 and S2 are displayed. Generated using JASP 0.17.1.0 (JASP Team, 2023).