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Properties of the Arterial Wall
Published in Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos, McDonald's Blood Flow in Arteries, 2022
Venous occlusion plethysmography is used to measure blood flow into a limb. The limb is enclosed by an airtight box within which pressure can be measured and calibrated to volume change. Venous efflux is prevented by inflation of the limb cuff just proximal to the seal, while arterial flow is not significantly impaired and can be measured by the increase in mean pressure within the box. Pulsations within the box are caused by arterial blood entry, and these become progressively more prominent with increase of pressure in the box. Such increase in pulsation is due to compression of arteries within. Increase in box pressure reduces arterial transmural pressure. Increase box pulsation is not caused by increased blood entry into the box but by greater volume change of arteries when mean pressure within is decreased. Validity of the instrument depends on separating the increase in mean pressure from the increasing pressure pulsations within the box.
Indirect noninvasive venous testing
Published in Joseph A. Zygmunt, Venous Ultrasound, 2020
There are four basic types of plethysmography that each work on slightly different principles. With each of these devices, venous determinations typically involve placing a measuring device on the calf (leg). With some of these techniques, there is often a cuff placed over the thigh to occlude the deep system for a period of time. Over the course of time, with or without specific maneuvers, the lower portion of the device measures changes in volume from which interpretations are made, and measurements of different venous flow parameters can be determined: venous volume (VV), venous refilling times (VRT), maximum venous outflow (MVO), segmental venous capacitance (SVC), and the ejection fraction (EF) can be determined [3,4].
Methods of Recording Tumor Blood Flow
Published in Hans-Inge Peterson, Tumor Blood Circulation: Angiogenesis, Vascular Morphology and Blood Flow of Experimental and Human Tumors, 2020
Plethysmography can be looked upon as an arterial inflow method. The venous outflow is stopped momentarily and the tumor volume increase by arterial inflow is registered for a few seconds. The procedure is assumed not to change the circulatory state of the tumor. The volume-change registration places certain demands on the localization of the tumor, the two present possibilties being the s.c. tissue of the paws or the tail of small animals.79 Plethysmography has been applied to the measurement of tumor blood flow in a rat 20-methylcholanthrene-induced sarcoma implanted into the dorsum of the hindpaw of the rat10 (see Figure 2, upper panel). Venous occlusion was achieved by small rubber cuffs which could be rapidly inflated above venous pres-sure by opening a line to a pressure reservoir. The paw were placed in thermostat-controlled, water-filled, plexiglass cylinders. The change of the paws volume was measured by the precalibrated pressure change of a small air bubble in the cylinder. The volume of the tumor and the tumor blood flow were calculated as the differences of volume and change of volume per time unit between the tumor-bearing and the normal hindpaw. The toes were temporarily ligated to diminish the flow of normal tissue within the cylinders. This difference calculation did not account for differences in paw flow due to inflammatory and edematous changes in the skin adjacent to the tumor or to the displacement of the skin by the tumor.
Changes in vascular function and autonomic balance during the first trimester of pregnancy and its relationship with the new-born weight
Published in Journal of Obstetrics and Gynaecology, 2022
Silvia Benvenuto, Claudio Joo Turoni, Rodrigo O. Marañón, Rossana Chahla, María Peral de Bruno
EF was evaluated through plethysmography, as we previously described (Joo Turoni et al. 2013, 2016). To record and measure the waveforms, we used a plethysmograph connected to an electrocardiograph (Dong Jiang 32A; Chine). Also, to standardise the chart recording, the equipment was calibrated as follows: 1 mm = 0.1 mV velocity: 25 mm/s. The hyperaemic response was obtained by flow-mediated vasodilatation (Joo Turoni et al. 2013). Briefly, a photoelectric transducer was placed on the index finger of the left hand. Previously to the recording phase, women hold their breath for 10 seconds (pre-occlusion phase). Then, the sphygmomanometer cuff was insufflated until 50 mmHg above SBP by five minutes (occlusion phase). Subsequently, the sphygmomanometer cuff was deflated, and after two minutes, another 10 seconds of apnoea was required (post-occlusion phase). The record obtained was scanned to measure the pulse wave amplitude (valley/peak size) using Image J 1.52a (Bethesda, MD). Ten consecutive waves were averaged from each phase to compare pre-occlusion vs. post-occlusion phases.
Blunted Pain Modulation Response to Induced Stress in Women with Fibromyalgia with and without Posttraumatic Stress Disorder Comorbidity: New Evidence of Hypo-Reactivity to Stress in Fibromyalgia?
Published in Behavioral Medicine, 2021
A. López-López, B. Matías-Pompa, J. Fernández-Carnero, A. Gil-Martínez, M. Alonso-Fernández, J. L. Alonso Pérez, J. L. González Gutierrez
Pressure pain threshold (PPT) and pressure-induced intolerance threshold (PPTo) were measured at three points over time: baseline (after a rest period), stress (during the maintenance of stress) and recovery (after a recovery period) with an electronic algometer calibrated in kPa (Somedic ©). Two types of measurement were made in the right epicondyle.37 Since plethysmography was located on the left side of the participants’ body, we decided to measure only on the right side in order to avoid possible biases. To assess the PPT, three measurements were made, with an interval of at least 10 seconds.38 For the evaluation of the PPTo, two measurements were taken, with an interval of at least 30 seconds38 As a safety measure, the pressure would stop if a pressure of 1300 KPa was reached.39 Due to their non-normal distribution, and prior to any statistical analysis, both PPT and PPTo scores were transformed by applying the reciprocal function.40
Association between lipid profile and endothelial dysfunction as assessed by the reactive hyperemia index
Published in Clinical and Experimental Hypertension, 2021
Kenji Norimatsu, Koki Gondo, Takaaki Kusumoto, Kota Motozato, Yasunori Suematsu, Yusuke Fukuda, Takashi Kuwano, Shin-Ichiro Miura
This study has several limitations. First, the sample size was relatively small, which limited our ability to determine significance. Furthermore, we were not able to observe the changes in RHI and L/H over time. A large-scale prospective study will be needed to prove the utility of L/H-targeting therapy. Third, EndoPAT2000® is not a gold standard for the evaluation of ED. Plethysmography has been the gold standard for measuring vascular endothelial function. There is a noninvasive method for observing the increase in blood flow after the release of avascularized blood and an invasive method for administering acetylcholine to coronary arteries. However, plethysmography is not widely used in clinical practice because it is invasive or too complicated. Therefore, in this study, we used EndoPAT2000®, which is both noninvasive and simple.