Search results for " Oxygenation"
showing 10 items of 123 documents
Optimal Pre-Oxygenation: The Nasoral-System
1994
The human body’s intra-and extrapulmonary O2 reserves, i.e. the oxygen stores of the functional residual capacity (FRC) and the blood, will be rapidly depleted during any kind of respiratory arrest (apnea). Application of oxygen prior to iatrogenic apnea (e.g. for endotracheal intubation procedures), therefore, commonly is discussed [e.g. Miller, 1990] as the proposed measure designed to achieve an increase in the human body’s oxygen stores sufficient to avoid hypoxemia. This prophylactic application of oxygen simply has become to be termed “pre-oxygenation”, regardless of the amount of increase in the O2 stores actually achieved. A myriad of different techniques and procedures are practica…
Tumor Oxygenation and Tumor Vascularity: Evidence for Their Clinical Relevance in Cancer of the Uterine Cervix and Considerations on Their Potential …
1996
Most solid malignancies are thought to be derived from a single neoplastic precursor cell having lost proliferation control and gained the ability to penetrate basement membranes and to invade into the stroma. During the disease course tumors increase their overall cell number by local expansion and the development of regional and distant metastases. Along with the increase in cell number the tumors loose hormonal or other external signal dependencies and acquire resistances towards radio— and chemotherapy. The progressing disease causes symptoms through impaired tissue/organ functions and complications, and finally kills the individual (unless other causes leading to death become manifest …
Predictive Power of the Tumor Oxygenation Status
1999
In most solid tumors the tissue pO2 status is poorer than in normal tissue at the site of tumor growth (for reviews see Vaupel et al., 1996, 1998; Vaupel and Hoeckel, 1998). Peculiarities of tumor tissue oxygenation can mainly be attributed to characteristic structural and functional abnormalities of the tumor microcirculation (perfusion-limited O2 delivery), to a deterioration of the diffusion-geometry (diffusion-limited O2 delivery), and—in some cases—to a reduced O2 carrying capacity of the blood due to tumor-associated anemia.
Climate Over the Ages; Is the Environment Stable?
2010
As described in Chaps. 3 and 4, the advent of oxygenic photosynthesis triggered worldwide environmental changes. A world that had been reductive passed over into a state in which free dioxygen was available in the oceans and the atmosphere. We have already described the likely catastrophic effects on an anaerobic biota, but the changes were much broader than that. Dioxygen in the seas led to major changes in seawater chemistry. Iron, which had previously been soluble as ferrous salts, was precipitated in the ferric form. Copper, which had been insoluble in the anaerobic ocean as cuprous sulphide (Cu+-state), now became moderately soluble in the cupric form (Cu++-state).
Hypoxie beim Zervixkarzinom: Pathogenese, Charakterisierung und biologische/klinische Konsequenzen 1
2001
Approximately 60% of locally advanced carcinomas of the uterine cervix exhibit hypoxic and/or anoxic tissue areas which are heterogeneously distributed within the tumor mass. Hypoxia is caused by structural and functional abnormalities of the newly formed tumor vessels arising from neovascularization, by a disturbed microcirculation, enlarged diffusion distances and by tumor- or therapy-associated anemia. The extent of pretherapeutically measured hypoxic tissue areas is independent of clinical size, FIGO stage and histopathological grade of squamous cell carcinomas of the uterine cervix. Anemia can intensify tumor hypoxia. O2-tensions in local recurrences are even lower than those in the pr…
Can Tumor Oxygenation be Improved by Reducing Cellular Oxygen Consumption?
1999
Tumor hypoxia, which can be found in many experimental and human tumors is an important factor influencing the therapeutic efficacy of standard radiotherapy, O2-dependent chemotherapy and photodynamic therapy (Hall, 1994) and might be responsible for the development of aggressive tumor cell subpopulations (Graeber et al., 1996). Since this oxygen deficiency results from a disparity between O2 supply to the tumor tissue and the oxygen demand of the cells, several attempts have been undertaken to improve tumor oxygenation primarily by increasing the arterial oxygen supply. The O2 supply to the tumor cells can be improved by (a) increasing the arterial O2 content (by breathing hyperoxic gases …
Lack of Association Between Tumor Oxygenation and Cell Cycle Distribution or Proliferation Kinetics in Experimental Sarcomas
2003
In tumor cells, pronounced hypoxia induces an arrest of cell cycle in the late G1phase1−3. Since hypoxia is a common phenomenon in experimental and human tumors the hypoxia-induced disturbance of the cell cycle may play a role in the reduced efficacy of non-surgical treatment modalities resulting in a reduced long-term prognosis and a higher rate of local recurrences in hypoxic tumors4,5. It has been shown that a cell cycle arrest reduces the efficacy of standard radiotherapy6,7 and may alter the cytotoxic effects of various chemotherapeutic agents such as cisplatin, alkylating agents, doxorubicin or taxols8−12 and of cytokines13. If tumor hypoxia plays a relevant role in affecting the cell…
Blood Flow and Oxygenation Status of Head and Neck Carcinomas
1997
Solid tumors contain a significant fraction of microregions which are chronically or transiently hypoxic. Experimental evidence is growing, showing that hypoxia may have a profound impact on malignant progression and on responsiveness to therapy [1–4].The clinical relevance of tumor oxygenation in human solid malignancies is under investigation (for a recent review see [5]). In this presentation, relevant clinical findings available to date on blood and oxygen supply of human head and neck carcinomas will be reviewed and emphasis will be given to the relevance of these factors in clinical oncology.
Respiratory support techniques to avoid desaturation in critically ill patients requiring endotracheal intubation: A systematic review and meta-analy…
2017
Abstract Purpose To evaluate which respiratory support method for critically ill patients undergoing endotracheal intubation (ETI) is associated with less desaturation. Methods We searched PubMed, Cochrane Library, Scopus and CINAHL databases. We included randomized (RCT) and non-randomized (non-RCT) studies investigating any method of respiratory support before/during ETI compared to a reference control. Results Apneic oxygenation (ApOx) was the most commonly investigated respiratory support technique for critically ill patients undergoing intubation (4 RCTs, 358 patients). Three of these studies investigated high-flow nasal cannula (HFNC) for ApOx while standard nasal cannula was used in …
An Atypical Case of Taravana Syndrome in Mediterraneo
2010
Dysbaric accidents are usually referred to compressed air-supplied diving. Nonetheless, diving accidents are known to have occurred among breath-hold divers also and some cases are reported in medical literature. A male professional breath hold diver (57 year old) presented neurological disorders as dizziness, sensory numbness, blurred vision and left phronto-parietal pain after many dives to a 30-35 meters seawater depth. He went home after the regression of the symptoms and runned 8 Km the following morning. Pain, sensory numbness and dizziness occurred after running. He went by himself to the hospital where he had a grand mal seizure and lost consciousness. A magnetic resonance imaging o…