Background: Pulsatile Perfusion Therapy (PPT) is a method we have developed to induce 0.1 Hz hemodynamic oscillations. PPT protects cerebral blood flow and tissue oxygenation during simulated hemorrhage in humans, and also protects arterial pressure and cerebral blood flow following actual hemorrhage in rats, leading to improved survival. However, it is unknown whether vital organ injury is also reduced with PPT in rats following severe hemorrhage. We hypothesized that PPT would reduce vital organ injury following severe hemorrhage in rats, which would be associated with increased survival time. Methods: Seven adult Sprague-Dawley rats were anesthetized with isoflurane and hemorrhaged to 50% of their estimated blood volume over 30 min. Rats were then randomly assigned to the PPT condition (n = 4; 2F/2M) or the control condition (CON; n = 3; 2F/1M). PPT was administered via inflatable cuffs attached to both hind limbs, oscillating between 0–250 mmHg every 5-s (10-s cycles; 0.1 Hz) for 30 min immediately following hemorrhage. For the CON condition, cuffs were attached but not inflated. Animals were monitored for an additional 150-min recovery period, or until death (defined as the absence of ventricular function detected on the ECG), and survival time was calculated from the end of hemorrhage. Following death, brains, hearts, and left kidneys were immediately extracted and cut into 2-mm slices - brains were cut into coronal slices to focus on the hippocampus, hearts were cut into short-axis slices to focus on both ventricles, and kidneys were cut into axial slices to focus on the medulla. Two slices from each organ were stained with 2,3,5-triphenyltetrazolium chloride (TTC) for differentiation of infarcted vs. viable tissue via ImageJ (assessed as an average of the two slices). Results: PPT increased survival time following severe hemorrhage (PPT: 109.7 ± 77.0 min vs. CON: 5.6 ± 2.8 min; P = 0.07). PPT decreased infarct size in cerebral tissue (PPT: 24.8 ± 15.1 % infarct vs. CON: 57.8 ± 21.0 % infarct; P = 0.06) and renal tissue (PPT: 9.6 ± 2.1 % infarct vs. CON: 57.4 ± 36.8 % infarct; P = 0.04), but there were no differences between conditions in cardiac tissue (PPT: 17.2 ± 14.1 % infarct vs. CON: 19.9 ± 14.9 % infarct; P = 0.81). Conclusions: PPT decreased vital organ injury and increased survival time in rats following severe hemorrhage. These data add further evidence for the use of 0.1 Hz hemodynamic oscillations as a potential intervention for the treatment of hemorrhage. 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.
Dinh et al. (Fri,) studied this question.