scholarly journals Correlation and spectral analysis of microcirculatory changes in symmetric areas of human head in short-term hypoxic exposure

2022 ◽  
Vol 20 (4) ◽  
pp. 62-69
Author(s):  
L. V. Mezentseva ◽  
E. N. Dudnik ◽  
E. V. Nikenina ◽  
M. A. Zapara ◽  
V. G. Samartseva ◽  
...  
Keyword(s):  
Vascular Tone ◽  
Human Head ◽  
Test Method ◽  
Hypoxic Exposure ◽  
Circulation System ◽  
Short Term ◽  
Doppler Flowmetry ◽  
Left And Right ◽  
Correlation And Spectral Analysis ◽  
Areas Of Interest

Purpose. To study the effect of short-term hypoxic exposure on correlation between microcirculatory parameters (MCR) of symmetric areas of the human head. Materials and methods. MCR parameters of 10 healthy male volunteer were measured by laser Doppler flowmetry method. Short-term hypoxic exposure was produced according to the hypoxic test method using the ReOxy Cardio unit (S. A. Aimediq). We assessed the perfusion metrics left and right areas of interest, neurogenic, myogenic, respiratory and cardiac contributors to vascular tone and correlations between baseline parameters and after hypoxic exposure. Results. We revealed the specificity of regional circulation system rearranging induced by hypoxic load. The specificity is caused by functional asymmetry of correlations between different vascular tone contributors in symmetrical head areas. Strong correlation declining under the hypoxic loads between baseline perfusion on left/right was found. The perfusion changes of symmetrical temporal areas under the hypoxic loads correlate negatively with the baseline perfusion of both the same and the opposite side. Conclusion. Short-term hypoxic load rearranges the balance of different vascular tone contributors regulatory role in MCR of symmetric head areas to maintain the sustainable activity of the whole MRC.

scholarly journals Research of adaptation mechanisms of regulation of microcirculatory beds in patients with hemophilia

2019 ◽  
Vol 6 (3) ◽  
pp. 54-58
Author(s):  
I. L. Davydkin ◽  
Yu. A. Gergel ◽  
D. A. Kudlay ◽  
I. V. Kurtov ◽  
E. O. Danilova ◽  
...  
Keyword(s):  
Vascular Tone ◽  
Tissue Perfusion ◽  
Severe Form ◽  
Stress Factor ◽  
Control Group ◽  
Short Term ◽  
Doppler Flowmetry ◽  
Cardiovascular Pathology ◽  
Adaptation Mechanisms

Introduction. Frequent bleeding with hemophilia significantly worsens the quality of life of patients. The pathogenesis of hemorrhage in hemophilia has not been studied enough, especially at the vascular level, so it is necessary to study microcirculation in this disease. The purpose of the study is to assess the mechanisms of regulation of blood tissue perfusion and the adaptive reserves of the microcirculation system in patients with hemophilia. Materials and methods. Total microcirculation was assessed by laser Doppler flowmetry in 44 patients with hemophilia A between the ages of 14 and 20 years. Severe form of the disease was in 59 % of patients, the average – in 32 %, light – in 9 % of patients. The control group included 26 healthy men aged 14 to 19 years. The sensors recorded blood flow in the index fingers on both sides. In 20 patients with hemophilia А, an occlusion test was performed. The results of the study. In patients with hemophilia, asymmetric changes in microcirculation parameters were detected when measured in the area of the index fingers. At rest in patients with hemophilia, the prevalence of vasospasm was revealed: a decrease in the perfusion index M, an increased blood bypass due to the predominance of myogenic tone. However, neurogenic tone indicators tended to decrease. During occlusive ischemia, vasospasm is slowed down in the first seconds after the onset of exposure to the stress factor. Conclusion. The study revealed a dysregulation of the vascular tone of the microvasculature in young hemophilia patients at rest and under the influence of a stress factor in the form of short-term ischemia. Therefore, with hemophilia from a young age, control of microcirculation is necessary for the timely prevention of both bleeding and cardiovascular pathology associated with vasospasm.

scholarly journals WALANT–Epinephrine injection may lead to short term, reversible episodes of critical oxygen saturation in the fingertips

2021 ◽  
Vol 141 (3) ◽  
pp. 527-533
Author(s):  
P. Moog ◽  
M. Dozan ◽  
J. Betzl ◽  
I. Sukhova ◽  
H. Kükrek ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Saturation ◽  
Substantial Reduction ◽  
Tissue Perfusion ◽  
Critical Levels ◽  
Short Term ◽  
Doppler Flowmetry ◽  
Epinephrine Injection ◽  
Venous Oxygen Saturation

Abstract Introduction Although the WALANT technique’s long-term safeness has been demonstrated in many studies, there are only few data investigating its short-term effects on tissue perfusion and oxygen levels. It was hypothesized that, temporarily, critical levels of tissue perfusion may occur. Methods Seventeen patients, who were scheduled for different procedures in WALANT technique, were injected with 5–7 ml of 1% Articain containing 1:200,000 epinephrine at the finger base. Capillary-venous oxygen saturation, hemoglobin volume in the capillaries, and relative blood flow in the fingertips were recorded once per second by white light spectrometry and laser Doppler flowmetry before, during and after injection for an average of 32 min. Results Clinically, no persistent tissue malperfusion was observed, and there were no postoperative complications. Capillary-venous oxygen saturation was reduced by ≥ 30% in seven patients. Critical levels of oxygen saturation were detected in four patients during 13 intervals, each lasting for 132.5 s on average. Oxygen saturation returned to noncritical values in all patients by the end of the observation period. Blood flow in the fingertips was reduced by more than 30% in nine patients, but no critical levels were observed, as with the hemoglobin. Three patients demonstrated a reactive increase in blood flow of more than 30% after injection. Conclusions Injection of tumescent local anesthesia containing epinephrine into finger base may temporarily cause a substantial reduction in blood flow and lead to critical levels of oxygen saturation in the fingertips. However, this was fully reversible within minutes and does not cause long-term complications.

scholarly journals Enhanced hepatic respiratory capacity and altered lipid metabolism support metabolic homeostasis during short-term hypoxic stress

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Katie A. O’Brien ◽  
Ben D. McNally ◽  
Alice P. Sowton ◽  
Antonio Murgia ◽  
James Armitage ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Respiratory Chain ◽  
Complex Iii ◽  
Whole Body ◽  
Hypoxic Exposure ◽  
Metabolic Homeostasis ◽  
Short Term ◽  
Respiratory Capacity ◽  
Alcoholic Fatty Liver ◽  
Hepatic Diseases

Abstract Background Tissue hypoxia is a key feature of several endemic hepatic diseases, including alcoholic and non-alcoholic fatty liver disease, and organ failure. Hypoxia imposes a severe metabolic challenge on the liver, potentially disrupting its capacity to carry out essential functions including fuel storage and the integration of lipid metabolism at the whole-body level. Mitochondrial respiratory function is understood to be critical in mediating the hepatic hypoxic response, yet the time-dependent nature of this response and the role of the respiratory chain in this remain unclear. Results Here, we report that hepatic respiratory capacity is enhanced following short-term exposure to hypoxia (2 days, 10% O2) and is associated with increased abundance of the respiratory chain supercomplex III2+IV and increased cardiolipin levels. Suppression of this enhanced respiratory capacity, achieved via mild inhibition of mitochondrial complex III, disrupted metabolic homeostasis. Hypoxic exposure for 2 days led to accumulation of plasma and hepatic long chain acyl-carnitines. This was observed alongside depletion of hepatic triacylglycerol species with total chain lengths of 39-53 carbons, containing palmitic, palmitoleic, stearic, and oleic acids, which are associated with de novo lipogenesis. The changes to hepatic respiratory capacity and lipid metabolism following 2 days hypoxic exposure were transient, becoming resolved after 14 days in line with systemic acclimation to hypoxia and elevated circulating haemoglobin concentrations. Conclusions The liver maintains metabolic homeostasis in response to shorter term hypoxic exposure through transient enhancement of respiratory chain capacity and alterations to lipid metabolism. These findings may have implications in understanding and treating hepatic pathologies associated with hypoxia.

Head Impact Modeling to Support a Rotational Combat Helmet Drop Test

2021 ◽  
Author(s):  
Ryan Terpsma ◽  
Rika Wright Carlsen ◽  
Ron Szalkowski ◽  
Sushant Malave ◽  
Alice Lux Fawzi ◽  
...  
Keyword(s):  
Human Head ◽  
Mechanical Stimulus ◽  
Scientific Basis ◽  
Test Method ◽  
Drop Test ◽  
Head Impacts ◽  
Digital Twin ◽  
Brain Deformation ◽  
Acceleration Time Histories ◽  
Hybrid Iii

ABSTRACT Introduction The Advanced Combat Helmet (ACH) military specification (mil-spec) provides blunt impact acceleration criteria that must be met before use by the U.S. warfighter. The specification, which requires a helmeted magnesium Department of Transportation (DOT) headform to be dropped onto a steel hemispherical target, results in a translational headform impact response. Relative to translations, rotations of the head generate higher brain tissue strains. Excessive strain has been implicated as a mechanical stimulus leading to traumatic brain injury (TBI). We hypothesized that the linear constrained drop test method of the ACH specification underreports the potential for TBI. Materials and Methods To establish a baseline of translational acceleration time histories, we conducted linear constrained drop tests based on the ACH specification and then performed simulations of the same to verify agreement between experiment and simulation. We then produced a high-fidelity human head digital twin and verified that biological tissue responses matched experimental results. Next, we altered the ACH experimental configuration to use a helmeted Hybrid III headform, a freefall cradle, and an inclined anvil target. This new, modified configuration allowed both a translational and a rotational headform response. We applied this experimental rotation response to the skull of our human digital twin and compared brain deformation relative to the translational baseline. Results The modified configuration produced brain strains that were 4.3 times the brain strains from the linear constrained configuration. Conclusions We provide a scientific basis to motivate revision of the ACH mil-spec to include a rotational component, which would enhance the test’s relevance to TBI arising from severe head impacts.

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