Hypoxemia and Hypoxia

Samuel, Jacob; Franklin, Cory

doi:10.1007/978-0-387-75246-4_97

Cited by 39 publications

(21 citation statements)

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“…Tissue hypoxia resulting from an inadequate uptake of ambient oxygen or an increase in cellular oxygen demand is one of the key features of the critically ill patient 7 . Since hypoxaemia, defined as a decrease in arterial oxygen tension 8 , is also a predominant feature of the high-altitude environment, research on the pathophysiologic processes behind hypoxia was significantly facilitated with the advent of altitude simulation tests 9 . On the cellular level, hypoxic stress initiates a transcriptional response by hypoxia inducible factors (HIF; during intermittent hypoxia predominately HIF-1α [10][11][12], which leads to a reduction of cellular energy consumption, a secretion of pro-angiogenic and survival factors 10 , and qualitative changes in mitochondrial function 13 , which in turn results in alterations of the cardiovascular, haematological and even urinary physiology 14,15 .…”

Section: Llsmentioning

confidence: 99%

Exposure to acute normobaric hypoxia results in adaptions of both the macro- and microcirculatory system

Mirna

Bimpong-Buta

Hoffmann

et al. 2020

Sci Rep

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Although acute hypoxia is of utmost pathophysiologic relevance in health and disease, studies on its effects on both the macro- and microcirculation are scarce. Herein, we provide a comprehensive analysis of the effects of acute normobaric hypoxia on human macro- and microcirculation. 20 healthy participants were enrolled in this study. Hypoxia was induced in a normobaric hypoxia chamber by decreasing the partial pressure of oxygen in inhaled air stepwisely (pO2; 21.25 kPa (0 k), 16.42 kPa (2 k), 12.63 kPa (4 k) and 9.64 kPa (6 k)). Macrocirculatory effects were assessed by cardiac output measurements, microcirculatory changes were investigated by sidestream dark-field imaging in the sublingual capillary bed and videocapillaroscopy at the nailfold. Exposure to hypoxia resulted in a decrease of systemic vascular resistance (p < 0.0001) and diastolic blood pressure (p = 0.014). Concomitantly, we observed an increase in heart rate (p < 0.0001) and an increase of cardiac output (p < 0.0001). In the sublingual microcirculation, exposure to hypoxia resulted in an increase of total vessel density, proportion of perfused vessels and perfused vessel density. Furthermore, we observed an increase in peripheral capillary density. Exposure to acute hypoxia results in vasodilatation of resistance arteries, as well as recruitment of microvessels of the central and peripheral microcirculation. The observed macro- and microcirculatory effects are most likely a result from compensatory mechanisms to ensure adequate tissue oxygenation.

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Section: Llsmentioning

confidence: 99%

Exposure to acute normobaric hypoxia results in adaptions of both the macro- and microcirculatory system

Mirna

Bimpong-Buta

Hoffmann

et al. 2020

Sci Rep

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“…Hypoxemia is defined as arterial oxygen tension (PaO2) below normal (normal PaO2=80–100 mmHg) [ 4 ]. Severe hypoxemia is also a characteristic of ARDS [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Autopsy and Histologic Findings of Patients with New Coronavirus Pneumonia: The Pathologic Associations with Hypoxemia

et al. 2021

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Background Coronavirus 2 (SARS-CoV-2) was declared a pandemic by the World Health Organization (WHO) in March 2020. To further reveal the pathologic associations between coronavirus and hypoxemia, we report the findings of 4 complete systematic autopsies of severe acute respiratory syndrome coronavirus 2-positive individuals who died of multiple organ failure caused by severe hypoxemia. Material/Methods We examined the donated corpses of 4 deceased patients who had been diagnosed with severe acute respiratory syndrome coronavirus 2. A complete post-mortem examination was carried out on each corpse, and multiple organs were macroscopically examined. Results The 4 corpses were 2 males and 2 females, with an average age of 69 years. Bilateral lungs showed various degrees of atrophy and consolidation, with diffusely tough and solid texture in the sections. A thromboembolism was found in the main pulmonary artery extending into the atrium in 1 corpse, and significant atherosclerotic plaques tagged in the inner wall of the aortic arch were found in 2 corpses. Two corpses were found to have slightly atrophied bilateral renal parenchyma. Atrophic changes in the spleen were found in 2 corpses. Notably, there were significantly expanded alveolar septa and prominent fibroblastic proliferation. Conclusions The laboratory data of these corpses showed a progressive decrease in blood oxygen saturation, followed by refractory and irreversible hypoxemia. Clinical and laboratory information and autopsy and histologic presentations of multiple organs showed insufficient air exchange due to abnormalities in the respiratory system, and reduced erythropoiesis in bone marrow may play a role.

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“…In particular, cells located deep inside the tissue construct will experience a hypoxic environment (Samuel & Franklin, 2008), a condition that contributes to apoptosis after prolonged exposure in vivo by inducing stress-related pathways because oxidative phosphorylation is no longer possible and anaerobic respiration is insufficient to meet the metabolic demand. Mesenchymal stem cells (MSCs), for example, have been shown to be resilient to transient hypoxia for up to 48 hr through anaerobic metabolic pathways, yet mitochondrial stress leading to increased caspase-3 activation, together with the build-up of lactic acid and the resulting low pH, will eventually induce apoptosis (Das, Jahr, van Osch, et al, 2009;Potier et al, 2007).…”

Section: Oxygen Supply Hypoxia and Hyperoxiamentioning

confidence: 99%

Oxygen and nutrient delivery in tissue engineering: Approaches to graft vascularization

Rademakers

Horvath

Blitterswijk

et al. 2019

J Tissue Eng Regen Med

113

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The field of tissue engineering is making great strides in developing replacement tissue grafts for clinical use, marked by the rapid development of novel biomaterials, their improved integration with cells, better‐directed growth and differentiation of cells, and improved three‐dimensional tissue mass culturing. One major obstacle that remains, however, is the lack of graft vascularization, which in turn renders many grafts to fail upon clinical application. With that, graft vascularization has turned into one of the holy grails of tissue engineering, and for the majority of tissues, it will be imperative to achieve adequate vascularization if tissue graft implantation is to succeed. Many different approaches have been developed to induce or augment graft vascularization, both in vitro and in vivo. In this review, we highlight the importance of vascularization in tissue engineering and outline various approaches inspired by both biology and engineering to achieve and augment graft vascularization.

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Hypoxemia and Hypoxia

Cited by 39 publications

References 0 publications

Exposure to acute normobaric hypoxia results in adaptions of both the macro- and microcirculatory system

Exposure to acute normobaric hypoxia results in adaptions of both the macro- and microcirculatory system

Autopsy and Histologic Findings of Patients with New Coronavirus Pneumonia: The Pathologic Associations with Hypoxemia

Oxygen and nutrient delivery in tissue engineering: Approaches to graft vascularization

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