Biology subjects

Pipinos, I. I.

Publications and source records attributed to Pipinos, I. I..

4 recordsLinked to original sources

bioRxiv2025

Sympathetic vasomotion as an early marker of hemorrhage

Each year, over 1.8 million people die from hemorrhagic shock, and, since the median time from onset to death is only two hours, early recognition is the cornerstone of management. The sympathetic nervous system is the fastest physiological hemodynamic compensatory mechanism, and we have developed a novel measure of sympathetic vascular control called sympathetic vasomotion which could serve as an early marker of hemorrhage. We performed unilateral renal denervation on six rabbits and instrumented these rabbits with bilateral renal flow probes and arterial pressure telemeters to allow for measurement of sympathetic vasomotion in paired vascular beds that differed only by sympathetic innervation. After a two-week recovery period, conscious rabbits then underwent controlled blood withdrawal via an auricular arterial catheter to simulate hemorrhage. Vasomotion differences between innervated and denervated kidneys in admittance gain, phase shift, and coherence increased significantly prior to increases in heart rate or decreases in blood pressure. These data suggest that sympathetic vasomotion could be a useful physiologically based biomarker for the early detection of hemorrhage. Further studies are needed to evaluate the utility of monitoring the sympathetic nervous system in clinical settings. NEW & NOTEWORTHYSympathetic vasomotion, a novel marker of sympathetic outflow, increases prior to other hemodynamic changes. Sympathetic vasomotion could serve as an early detection tool for hemorrhage that facilitates prompt and precise resuscitation.

physiology↗

bioRxiv2020

Gait variability is affected more by peripheral artery disease than by vascular occlusion

BackgroundPatients with peripheral artery disease (PAD) have altered gait variability from the first step they take, well before the onset of claudication pain. The mechanisms underlying these gait alterations are poorly understood. AimsThis study sought to isolate the effect of reduced blood flow on gait variability by comparing healthy older controls and patients with PAD. We also determined the diagnostic value of gait variability parameters to identify the presence of PAD. MethodsThirty healthy older controls and thirty patients with PAD walked on a treadmill at their self-selected speed in rested (normal walking for controls; pain free for PAD) and reduced blood flow (post vascular occlusion with thigh tourniquet for controls; pain for PAD) conditions. Gait variability was assessed using the largest Lyapunov exponent, approximate entropy, standard deviation, and coefficient of variation of ankle, knee, and hip joints range of motion. Receiver operating characteristics curve analyses of the rested condition were performed to determine the optimal cut-off values for separating individuals with PAD from those without PAD. Results and DiscussionPatients with PAD have increased amount of variability for knee and hip ranges of motion compared with healthy older group. Comparing for conditions, reduced blood flow demonstrated increased amount of variability compared with rested blood flow. Significant interactions between group and condition occurred at the ankle for Lyapunov exponent, approximate entropy, and coefficient of variation. A combination of gait variability parameters correctly identifies PAD disease 70% of the time or more. ConclusionsGait variability is affected both by PAD and by the mechanical induction of reduced blood flow.

bioengineering↗

bioRxiv2018

Collateral development and arteriogenesis in hindlimbs of domestic swine after ligation of arterial inflow

IntroductionThe development of collateral vasculature is a key mechanism compensating for arterial occlusions in patients with peripheral artery disease (PAD). We aimed to examine the development of collateral pathways after ligation of native vessels in a porcine model of PAD. MethodsRight hindlimb Ischemia was induced in domestic swine (N=11, male, kg) using two different versions of arterial ligation. Version 1 (N=6) consisted of ligation/division of the right external iliac, profunda femoral (RPFA) and superficial femoral arteries (RSFA). Version 2 (N=5) consisted of the ligation of Version 1 with additional ligation/division of the right internal iliac artery (RIIA). Development of collateral pathways was evaluated with standard angiography at baseline (prior to arterial ligation) and at termination (4-8 weeks later). Relative luminal diameter of the arteries supplying the ischemic right hindlimb were determined by 2D angiography, as percent of the size of the distal aortic diameter. ResultsThe dominant collateral pathway that developed after version 1 ligation connected the RIIA to the RPFA and RSFA/popliteal artery. Mean luminal diameter ({+/-} standard error) of the RIIA at termination increased by 38% (P<0.05) compared to baseline. Two co-dominant collateral pathways developed in version: (i) from the common internal iliac trunk and left internal iliac artery to the reconstituted RIIA, which then supplied the RPFA and RSFA/popliteal arteries; and (ii) from left profunda artery to the reconstituted RPFA. Mean diameter of the common internal iliac trunk and left profunda artery both increased at termination in the range of 20% (p < 0.05). ConclusionTwo versions of hindlimb ischemia induction (right ilio-femoral artery ligation with and without right internal iliac artery ligation in swine produced differing collateral pathways, along with changes to the diameter of the inflow vessels (i.e., arteriogenesis). Radiographic and anatomical data of the collateral formation in this porcine model should have value in investigation of the pathophysiology of hindlimb ischemia, and assessment of angiogenic therapies as potential treatments for PAD.

physiology↗

bioRxiv2017

Fluid administration rate for uncontrolled intraabdominal hemorrhage in pigs

BackgroundWe hypothesized that slow crystalloid resuscitation would improve blood loss and hemoglobin compared to a rapid resuscitation during uncontrolled hemorrhage.\n\nMethodsAnesthetized, splenectomized domestic swine underwent hepatic lobar hemitransection. Lactated Ringers was given at 150 or 20 mL/min IV (rapid vs. slow, respectively, N = 12 per group; limit of 100 mL/kg). Vital sign monitoring and serum testing was done for up to 180 min, followed by necropsy.\n\nResultsSurvival was 7 vs. 8 out of 12 subjects, rapid vs. slow respectively (p>0.05). The slow group had a less blood loss (1.6 vs. 2.7 L, respectively) and a higher final hemoglobin concentration (6.0 vs. 3.4 g/dL).\n\nConclusionsUsing a fixed volume of crystalloid resuscitation in this porcine model of uncontrolled intraabdominal hemorrhage, a slow IV infusion rate produced less blood loss and a higher hemoglobin level compared to rapid infusion.

physiology↗