Background: We developed a novel therapeutic approach called Pulsatile Perfusion Therapy (PPT) to protect tissues from ischemia by inducing hemodynamic oscillations at 0.1 Hz. We have demonstrated that 10 minutes of PPT during simulated hemorrhage protects internal carotid artery (ICA) blood flow and cerebral tissue oxygenation (ScO2), without affecting mean arterial pressure (MAP) and middle cerebral artery blood velocity (MCAv) responses. Positive physiological effects from a shorter duration of PPT could potentially minimize the extent of irreversible tissue damage from ischemia. We hypothesized that just 5 minutes of PPT would be sufficient to 1) increase 0.1 Hz hemodynamic oscillations, and; 2) protect ICA blood flow and ScO2, similar to the 10-minute protocol. Methods: Twelve healthy human participants (6M/6F; aged 25.8 ± 5.1 y) completed two simulated hemorrhage protocols (via -60 mmHg lower body negative pressure, LBNP) for up to 10 min each. In the PPT condition, intermittent inflation and deflation of bilateral thigh cuffs (0-230 mmHg) were applied every 5-s to induce 0.1 Hz hemodynamic oscillations. In the control condition (CON), thigh cuffs were placed but remained inactive. The order of PPT and CON were randomized. Measurements of beat-to-beat arterial pressure (via finger photoplethysmography), ICA blood flow (via duplex Doppler ultrasound), MCAv (via transcranial Doppler ultrasound), and ScO2 (via near-infrared spectroscopy) were made continuously. The amplitudes of 0.1 Hz oscillations in MAP and MCAv were assessed via Fast Fourier transform analysis. Only data from the first 5-min of LBNP were analyzed to address the hypothesis. Results: All results are presented relative to baseline within condition. By design, PPT induced greater 0.1 Hz oscillations in MAP (PPT: 55.6 ± 69.2 fold vs. CON: 4.1 ± 6.6 fold; P=0.0005) and MCAv (PPT: 9.2 ± 8.2 fold vs. CON: 1.8 ± 1.7 fold; P=0.02) compared to CON. PPT attenuated reductions in ICA blood flow (PPT: -18.1 ± 6.8% vs. CON: -30.3 ± 7.7%; P=0.03) compared to CON, but did not affect MAP (PPT: -8.2 ± 4.3% vs. CON: -8.9 ± 4.0%; P=0.72), MCAv (PPT: -16.1 ± 12.7% vs. CON: -13.7 ± 10.5%; P=0.67), or ScO2 (PPT: -4.6 ± 2.5% vs. CON: -6.3 ± 2.9%; P=0.10) responses. Conclusions: Just 5 minutes of PPT applied during simulated hemorrhage is effective in inducing 0.1 Hz oscillations in MAP and MCAv, and protecting cerebral blood flow responses (indexed by ICA blood flow, but not MCAv). In contrast to 10 minutes of PPT, however, ScO2 responses were not protected with 5 minutes of this therapy. Although 5 minutes of PPT is adequate to elicit protection of cerebral blood flow, a minimum of 10 minutes is recommended to further protect cerebral tissue oxygenation. These data add to our understanding of the time it may take for PPT to exert protective effects when used as a therapeutic intervention for the treatment of hemorrhage and other conditions of cerebral ischemia. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Vu et al. (Fri,) studied this question.