scholarly journals Modeling lung perfusion abnormalities to explain early COVID-19 hypoxemia

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jacob Herrmann ◽  
Vitor Mori ◽  
Jason H. T. Bates ◽  
Béla Suki
Keyword(s):  
Mathematical Model ◽  
Pulmonary Embolism ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Lung Perfusion ◽  
The Novel ◽  
Venous Admixture ◽  
Pulmonary Vasoconstriction ◽  
Injured Lung ◽  
Perfusion Defects ◽  
Novel Coronavirus

Abstract Early stages of the novel coronavirus disease (COVID-19) are associated with silent hypoxia and poor oxygenation despite relatively minor parenchymal involvement. Although speculated that such paradoxical findings may be explained by impaired hypoxic pulmonary vasoconstriction in infected lung regions, no studies have determined whether such extreme degrees of perfusion redistribution are physiologically plausible, and increasing attention is directed towards thrombotic microembolism as the underlying cause of hypoxemia. Herein, a mathematical model demonstrates that the large amount of pulmonary venous admixture observed in patients with early COVID-19 can be reasonably explained by a combination of pulmonary embolism, ventilation-perfusion mismatching in the noninjured lung, and normal perfusion of the relatively small fraction of injured lung. Although underlying perfusion heterogeneity exacerbates existing shunt and ventilation-perfusion mismatch in the model, the reported hypoxemia severity in early COVID-19 patients is not replicated without either extensive perfusion defects, severe ventilation-perfusion mismatch, or hyperperfusion of nonoxygenated regions.

scholarly journals Can Hyperperfusion of Nonaerated Lung Explain COVID-19 Hypoxia?

2020 ◽  
Author(s):  
Jacob Herrmann ◽  
Vitor Mori ◽  
Jason H.T. Bates ◽  
Béla Suki
Keyword(s):  
Mathematical Model ◽  
Vascular Resistance ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Considerable Reduction ◽  
The Novel ◽  
Pulmonary Emboli ◽  
Pulmonary Shunt ◽  
Pulmonary Vasoconstriction ◽  
Injured Lung ◽  
Novel Coronavirus

Abstract Early stages of the novel coronavirus disease (COVID-19) have been associated with ‘silent hypoxia’ and poor oxygenation despite relatively small fractions of afflicted lung. Although it has been speculated that such paradoxical findings may be explained by impairment of hypoxic pulmonary vasoconstriction in infected lungs regions, no studies have confirmed this hypothesis nor determined whether such extreme degrees of perfusion redistribution are physiologically plausible. Here, we present a mathematical model which provides evidence that the extreme amount of pulmonary shunt observed in patients with early COVID-19 is not plausible without hyperperfusion of the relatively small fraction of injured lung, with three-fold increases in regional perfusion to afflicted regions. Although underlying perfusion heterogeneity (e.g., due to gravity or pulmonary emboli) exacerbated existing shunt in the model, the reported severity of hypoxia in early COVID-19 patients could not be replicated without considerable reduction of vascular resistance in nonoxygenated regions.

scholarly journals Web Application for Statistical Tracking and Predicting the Evolution of Active Cases with the Novel Coronavirus (SARS-CoV-2)

2021 ◽  
pp. 70-74
Author(s):  
Iulia Clitan ◽  
◽  
Adela Puscasiu ◽  
Vlad Muresan ◽  
Mihaela Ligia Unguresan ◽  
...  
Keyword(s):  
Neural Network ◽  
Mathematical Model ◽  
Web Application ◽  
Point Of View ◽  
The Novel ◽  
End User ◽  
First Case ◽  
Novel Coronavirus ◽  
Second Wave ◽  
Over Time

Since February 2020, when the first case of infection with SARS COV-2 virus appeared in Romania, the evolution of COVID-19 pandemic continues to have an ascending allure, reaching in September 2020 a second wave of infections as expected. In order to understand the evolution and spread of this disease over time and space, more and more research is focused on obtaining mathematical models that are able to predict the evolution of active cases based on different scenarios and taking into account the numerous inputs that influence the spread of this infection. This paper presents a web responsive application that allows the end user to analyze the evolution of the pandemic in Romania, graphically, and that incorporates, unlike other COVID-19 statistical applications, a prediction of active cases evolution. The prediction is based on a neural network mathematical model, described from the architectural point of view.

Pulmonary hypoxic vasoconstriction: not affected by chemical sympathectomy

1979 ◽  
Vol 46 (3) ◽  
pp. 529-533 ◽  
Author(s):  
C. A. Hales ◽  
D. M. Westphal
Keyword(s):  
Hypoxic Pulmonary Vasoconstriction ◽  
Systemic Blood Pressure ◽  
Lung Perfusion ◽  
Chemical Sympathectomy ◽  
Test Lung ◽  
Systemic Blood ◽  
Pulmonary Vasoconstriction ◽  
Hypoxic Vasoconstriction ◽  
Alveolar Hypoxia ◽  
6 Hydroxydopamine

The influence of chemical sympathectomy with 6-hydroxydopamine (6-OHDA) on regional alveolar hypoxic vasconstriction and on global hypoxic pulmonary vasoconstriction was investigated. In eight dogs a double-lumened endotracheal tube allowed ventilation of one lung with nitrogen as an alveolar hypoxic challenge while ventilation of the other lung with 100% O2 maintained adequate systemic oxygenation. Distribution of perfusion to the two lungs was determined with 133Xe and external counters. Mean perfusion to the test lung was 50.9 +/- 4.9% of total lung perfusion on room air and decreased by 32.4% (P smaller than 0.01) during alveolar hypoxia. Following 6-OHDA the test lung continued to reduce perfusion during alveolar hypoxia by 27.3%. In five dogs global hypoxia induced a 106% increase in pulmonary vascular resistance (PVR) prior to 6-OHDA and a 90% increase in PVR after 6-OHDA. After 6-OHDA no rise in PRV or systemic blood pressure occurred in response to tyramine, confirming effective sympathectomy by the 6-OHDA. Thus, sympathectomy with 6-OHDA failed to substantially block regional alveolar hypoxic vasoconstriction or global hypoxic pulmonary vasconstriction.

scholarly journals Unusual presentation of COVID-19 in a child complicated by massive acute pulmonary embolism and lung infarction

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Tahani Bin Ali ◽  
Ghaleb Elyamany ◽  
Maha Nojoom ◽  
Mohamed Alfaki ◽  
Hassan Alahmari ◽  
...  
Keyword(s):  
Pulmonary Embolism ◽  
Respiratory Failure ◽  
Anticoagulant Therapy ◽  
Acute Pulmonary Embolism ◽  
Respiratory Illness ◽  
Unusual Presentation ◽  
The Novel ◽  
Limited Data ◽  
Progressive Respiratory Failure ◽  
Novel Coronavirus

The Novel Coronavirus 2019 (SARSCoV- 2), which was first reported on in Wuhan, China, in late December 2019, causes a respiratory illness called COVID- 19 Disease. COVID-19 is most likely causing a hypercoagulable state, however the prevalence of acute venothromboembolism is still unknown. Limited data suggest pulmonary microvascular thrombosis may play a role in progressive respiratory failure. Here, we report a case of a child with an unusual presentation of COVID-19 presented initially by dry cough without fever and complicated by massive acute pulmonary embolism and lung infarction and treated successfully by hydroxychloroquine and azithromycin, in addition to anticoagulant therapy.

scholarly journals A Note on COVID-19 Diagnosis Number Prediction Model in China

2021 ◽  
Author(s):  
Yi Li ◽  
Xianhong Yin ◽  
Meng Liang ◽  
Xiaoyu Liu ◽  
Meng Hao ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Future Trend ◽  
Disease Prediction ◽  
The Novel ◽  
Limited Impact ◽  
Infected People ◽  
Health Authorities ◽  
Novel Coronavirus ◽  
New Diagnosis ◽  
The Mathematical Model

Abstract Objective: In December 2019, pneumonia infected with the novel coronavirus burst in Wuhan, China. We aimed to use a mathematical model to predict number of diagnosed patients in future to ease anxiety on the emergent situation. Methods: According to all diagnosis number from WHO website and combining with the transmission mode of infectious diseases, the mathematical model was fitted to predict future trend of outbreak. Our model was based on the epidemic situation in China, which could provide referential significance for disease prediction in other countries, and provide clues for prevention and intervention of relevant health authorities. In this retrospective, all diagnosis number from Jan 21 to Feb 10, 2020 reported from China was included and downloaded from WHO website. We develop a simple but accurate formula to predict the next day diagnosis number: ，where N i is the total diagnosed patient till the i th day, and was estimated as 0.904 at Feb 10. Results: Based on this model, it is predicted that the rate of disease infection will decrease exponentially. The total number of infected people is limited; thus, the disease will have limited impact. However, new diagnosis will last to end of March. Conclusions: Through the establishment of our model, we can better predict the trend of the epidemic in China.

Hypoxic Pulmonary Vasoconstriction as a Contributor to Response in Acute Pulmonary Embolism

2014 ◽  
Vol 42 (8) ◽  
pp. 1631-1643 ◽  
Author(s):  
K. S. Burrowes ◽  
A. R. Clark ◽  
M. L. Wilsher ◽  
D. G. Milne ◽  
M. H. Tawhai
Keyword(s):  
Pulmonary Embolism ◽  
Acute Pulmonary Embolism ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Pulmonary Vasoconstriction

Stability of alveolar hypoxic vasoconstriction with intermittent hypoxia

1980 ◽  
Vol 49 (5) ◽  
pp. 846-850 ◽  
Author(s):  
M. A. Miller ◽  
C. A. Hales
Keyword(s):  
Hypoxic Pulmonary Vasoconstriction ◽  
Lung Perfusion ◽  
Double Lumen ◽  
Double Lumen Endotracheal Tube ◽  
Pulmonary Vasoconstriction ◽  
Group I ◽  
Hypoxic Vasoconstriction ◽  
Anesthetized Dogs ◽  
Alveolar Hypoxia ◽  
Group Ii

Repeated intermittent global hypoxia has been reported to markedly enhance hypoxic pulmonary vasoconstriction in dogs. We have reexamined this phenomenon but with intermittent unilateral alveolar hypoxia, avoiding complications of systemic hypoxemia. Fifteen anesthetized dogs were intubated with a double-lumen endotracheal tube, allowing separate ventilation of one lung with 100% N2 as a hypoxic challenge and the other lung with 100% O2 to maintain adequate systemic oxygenation. Distribution of lung perfusion was determined with intravenous 133Xe and external chest detectors. Each dog alternately breathed air or the unilateral alveolar hypoxia combination for 15 min each for a total of 12 hypoxic challenges or 6 h. Two groups emerged on the basis of the strength of their vasoconstrictor responses to successive hypoxic challenge. In group I (n = 6), perfusion to the hypoxic lung decreased 29% with the first challenge and decreased comparably with successive challenges. In group II, vasoconstriction was initially weak with perfusion decreasing only 5%, but perfusion decreased further with time alone (n = 5) or successive challenges (n = 4), falling 35% on the 12th challenge (comparable to group I). Delayed achievement of hypoxic vasoconstriction in group II may be secondary to a vasodilating prostanoid that disappears with time.

Hypoxic pulmonary vasoconstriction and gas exchange in acute canine pulmonary embolism

1996 ◽  
Vol 80 (4) ◽  
pp. 1240-1248 ◽  
Author(s):  
M. Delcroix ◽  
C. Melot ◽  
F. Vermeulen ◽  
R. Naeije
Keyword(s):  
Pulmonary Embolism ◽  
Gas Exchange ◽  
Sulfur Hexafluoride ◽  
Blood Clot ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Autologous Blood ◽  
Response Curves ◽  
Pulmonary Hemodynamics ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

Hypoxic pulmonary vasoconstriction (HPV) is inhibited in several models of acute lung injury. Whether HPV is preserved in pulmonary embolism is unknown. We investigated the effects of a reduction in the fraction of inspired O2 (FIO2) on pulmonary hemodynamics and gas exchange in anesthetized dogs before and after autologous blood clot pulmonary embolism. In a first group of 14 dogs, stimulus-response curves for HPV were constructed as pulmonary arterial pressure (Ppa) vs. FIO2 varied between 1.0 and 0.06 at a cardiac output (Q) kept constant at 3.5 l.min-1.m-2. Gas exchange was evaluated by using the multiple inert-gas elimination technique at FIO2 of 1.0, 0.4, and 0.1. Embolism decreased the relative magnitude of HPV, expressed as the gradient between Ppa and pulmonary arterial occluded pressure in hypoxia divided by (Ppa-pulmonary arterial occluded pressure) at FIO2 of 1.0, from 1.8 to 1.2 (P < 0.05). Retention minus excretion gradients for sulfur hexafluoride and ethane were increased by decreased FIO2 (P < 0.005 and P < 0.05, respectively) before but not after embolism. Hypoxia-induced deterioration in gas exchange before embolism was related to the amount of baseline very low ventilation-perfusion (VA/Q) ratios. Similar results were obtained in a second group of seven dogs with Q decreased to maintain Ppa at the same average value as before embolism. However, gas exchange was not affected by inspiratory hypoxia before as well as after embolism in this group, which presented with a lesser amount of baseline very low VA/Q. In both groups of dogs, increase in the FIO2 from 0.4 to 1.0 did not affect gas exchange. We conclude that 1) pulmonary embolism is associated with a partial inhibition of HPV, 2) HPV does not contribute to preserve gas exchange in pulmonary embolism, and 3) a strong HPV may deteriorate gas exchange in severe hypoxia in the presence of minor very low VA/Q inequality.

scholarly journals A Note on COVID-19 Diagnosis Number Prediction Model in China

2020 ◽  
Author(s):  
Yi Li ◽  
Xianhong Yin ◽  
Yi Wang ◽  
Meng Liang ◽  
Xiaoyu Liu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Prediction Model ◽  
Disease Prediction ◽  
The Novel ◽  
Prevention And Intervention ◽  
Limited Impact ◽  
Infected People ◽  
Health Authorities ◽  
Novel Coronavirus ◽  
New Diagnosis

Abstract In December 2019, pneumonia infected with the novel coronavirus burst in Wuhan, China. We aimed to use a mathematical model to predict number of diagnosed patients in future to ease anxiety on the emergent situation. Our model was based on the epidemic situation in China, which could provide referential significance for disease prediction in other countries, and provide clues for prevention and intervention of relevant health authorities. In this retrospective, all diagnosis number from Jan 21 to Feb 10, 2020 reported from China was included and downloaded from WHO website. We develop a simple but accurate formula to predict the next day diagnosis number: N_i/N_(i-1) =〖(N_(i-1)/N_(i-2) )〗^α，where Ni is the total diagnosed patient till the ith day, and α was estimated as 0.904 at Feb 10. Based on this model, it is predicted that the rate of disease infection will decrease exponentially. The total number of infected people is limited; thus, the disease will have limited impact. However, new diagnosis will last to end of March. Through the establishment of our model, we can better predict the trend of the epidemic in China.

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