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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied the mode of ventilation and chemosentivity in 10 patients suffering from pulmonary fibrosis. The total lung capacity was on average 63.5 +/- 8% of the predicted. Their static compliance was 0.078 +/- 0.05 l.cm of water. The patients were studied in the prone position breathing ambient air then on hyperoxia. The response to CO2 was assessed according to the rebreathing method of Read. The results of these patients were compared with those of 11 normal subjects. The ventilation at rest was normal, with a shortened respiratory time and a Ti/Ttot ratio which was lowered. The occlusion pressure (P0.1) was very much higher than that in normal subjects. This rise was correlated with an increase in pulmonary elastance and a reduction in vital capacity. The correction of hypoxia was without effect on the respiratory parameters. In relation to normal subjects the ventilatory response to carbon dioxide in fibrotics was decreased whilst the response of the P0.1 was increased expressing central hyperactivity. In conclusion, fibrotic patients have normal ventilation in spite of an increase in inspiratory work. This normal ventilation results from hyperactivity of the respiratory centre, as in the hyperventilation induced by carbon dioxide when at rest.
Rev Mal Respir 1991
PMID:[The control of respiration in pulmonary fibrosis. The effect of O2 and CO2]. 190 51

Measurement of TcPO2 in arterial diseased patient is a reliable and reproductible method for evaluation in stages III and IV of the degree of tissue ischemia which can serve to establish the viable prognosis of the limb. One of the disadvantages of this technique is the relatively long time taken. By contrast the Doppler-laser, a more recently introduced technique, can be used to measure superficial cutaneous flow. One of its advantages is the rapidity of its instantaneous measurements. Before testing this technique in arterial disease sufferers it was felt to be of interest to determine the possible existence in the healthy subject of a correlation between TcPO2 and laser-Doppler flow. The study involved 15 healty subjects, 8 men and 7 women, with a mean age of 24.2 years. TcPO2 and laser-Doppler measurements were carried out in the fore-foot at 38 degrees and 44 degrees, under basal conditions and then after ischemia each time for 5 minutes, finally followed by a 10-minute 100% hyperoxia test. There was only a slight correlation at 38 degrees between the two methods and no correlation was found at 44 degrees. With oxygen therapy TcPO2 increased considerably and there was a nonsignificant decrease in laser-Doppler flow. In total, the two methods did not truly explore the same microcirculatory data and clinical studies would appear necessary to determine whether laser-Doppler flow measurements in the arterial disease patient may prove to be as useful as those of TcPO2.
J Mal Vasc 1988
PMID:[Comparative study of transcutaneous oxygen pressure and laser- Doppler flow in the feet of 15 healthy subjects]. 297 61

Respiratory function studies were carried out in 18 patients with diffuse and isolated pulmonary lymphangitis (LCP) diagnosed on radiological and cyto-histological grounds. Restrictive ventilatory defects were found in 17 out 18 cases CPT: 75,3% (DS = 5), CV: 56.7% (DS = 14,5). The Tiffeneau coefficient was less than 65% in 50% of cases but the DEM/CV was reduced in 77% of cases, evidence of the great frequency of airflow obstruction. The measure of the (formula; see text) was normal in 5 out of 17 cases, implying the absence of an alveolar neoplastic lesion or obliteration by arteritis or capillaritis in LCP. The alveolar-arterial oxygen gradient on hyperoxia was normal (less than 27 kPa) 14 times out of 18 and slightly increased in 4. Important hypoxaemia at rest was present 17 times out of 18; PaO2: 8 kPa (DS = 1). There was no patient with alveolar hyperventilation: PaCO2: 4.3 kPa (DS = 0.5). On exercise, hypoxaemia remained stable 4 times, improved 5 times and worsened 9 times. A pathophysiological interpretation was given for each disturbance of respiratory function. In conclusion, a characteristic respiratory function profile of LCP is proposed, with a restrictive ventilatory disturbance or moderate mixed picture, a DLCO/VA ratio generally normal, almost constant hypoxaemia at rest and improvement or worsening on exercise. CPT = Mean total lung capacity. CV = Mean vital capacity. DS = Standard deviation.
Rev Mal Respir 1984
PMID:[Diffuse pulmonary carcinomatous lymphangitis. Study of respiratory function in 18 cases]. 653 14

Pulmonary vascular response to the inhalation of various concentrations of oxygen (FIO2) was studied under basal conditions and after nicardipine in 10 patients with pulmonary hypertension secondary to chronic bronchitis. Hemodynamic data and blood gases were measured during inhalation of 3 gas mixtures: hypoxia (FIO2 = 0.15), normoxia (FIO2 = 0.21) and hyperoxia (FIO2 = 0.30). Each gas mixture was administered for 20 minutes, initially during an infusion of placebo and then of nicardipine giving a steady plasma concentration of 29 +/- 4 ng/ml. This was obtained by continuous I.V. infusion of 0.06 mg/kg/hour. Under basal conditions with placebo, the heart rate, cardiac output and pulmonary hypertension increased with decreasing concentrations of inhaled oxygen. The systemic blood pressure was unchanged with hypoxia but decreased during hyperoxia. Nicardipine increased the heart rate and the cardiac output but reduced the blood pressure with every inhaled oxygen mixture. The blood pressure was independent of FIO2 and the reduction observed during hyperoxia with placebo no longer occurred with nicardipine. However, the pulmonary hypertension was unaffected. At the dosage used in this study, nicardipine modified the systemic vascular response to oxygen but not the pulmonary vascular response. The vasodilation induced was much greater in the systemic than in the pulmonary circulation. In relation to the absence of significant pulmonary vasodilation, no changes in blood gases, due to a possible pulmonary shunting effect, were observed. At this dosage, nicardipine is ineffective in reducing pulmonary hypertension. However, its systemic hypotensive action may be used in patients with respiratory failure due to chronic bronchitis without deleterious effects on blood gases.
Arch Mal Coeur Vaiss 1993 Jun
PMID:[Acute effects of nicardipine on the vascular reactivity of oxygen in patients with respiratory insufficiency and pulmonary hypertension]. 827 62

Underwater diving is a widely practised leisure activity. As cardiac patients may wish to participate, cardiologists should be aware of potential changes of cardiac function during diving. Multiple factors may affect haemodynamics. Firstly, changes in pressure, secondary to ventilation of a high density gas mixture which increases afterload. Hyperoxia is the principal factor which slows the heart rate, a commonly observed phenomenon. Excitability and conduction speed may be modified by the increase in hydrostatic pressure. During decompression, gaseous pulmonary embolism may increase right heart pressures and cause a paradoxical embolism may increase right heart pressures and cause a paradoxical embolism in patients with a right-to-left shunt. Immersion increases the preload. Exposure to cold also plays a role increasing afterload and slowing the heart rate. These factors may disturb cardiac function and expose cardiac patients to accidents during underwater diving.
Arch Mal Coeur Vaiss 1997 Feb
PMID:[Changes in cardiac function during recreational diving]. 918 Oct 36

Drainage of the inferior vena cava into the left atrium during surgery for closure of an atrial septal defect is a rare complication. More common in low situated defects, it was more frequent when this type of surgery was performed without cardiopulmonary bypass. This diagnosis was made in a 45 year old woman with cyanosis operated 28 years previously. The right-to-left shunt was demonstrated by the hyperoxia test and confirmed by perfusion pulmonary scintigraphy and contrast echocardiography but only when the contrast was injected in the inferior vena cava territory, and by angiography. The surgeon confirmed the abnormality, closed the interatrial septum and reconnected the inferior vena cava to the right atrium.
Arch Mal Coeur Vaiss 1997 Jul
PMID:[Late discovery of inferior vena cava draining into the left atrium after surgical closure of atrial septal defect]. 933 62

Oxidants play a key role in disease processes, particularly in the detrimental mechanisms leading to tissue damage in certain forms of acute lung injury. A number of mediators contribute to the pathologic response in ARDS, SIRS or hyperoxia-induced pulmonary damage. One of the most important detrimental factors is the generation and activation of highly reactive oxygen species which are leading factors implicated in the process of tissue damage. N-acetylcysteine (NAC) is a free radical scavenger and might access the endothelial cell thus increasing intracellular glutathione (GSH) stores. Different studies have demonstrated that NAC might be a promising compound either for the prevention or the treatment of acute lung damages such as ARDS. However, the true beneficial effect so far reported in several clinical and experimental studies contrasts with some contradictory and intriguing aspects, probably because the significance of a direct in vivo antioxidative effect of this compound remains to be established in humans. Thus, the mode of action of NAC may not be the same in different pathologies and clinical situations. More research into the mechanisms of action of this unique xenobiotic substance may offer a clue for elucidating these controversies.
Rev Mal Respir 1999 Feb
PMID:[Therapeutic use of N-acetylcysteine in acute lung diseases]. 1009 Dec 58

The case of a right-to-left shunt-induced hypoxemia with an abnormal return of the inferior vena cava (AIVCR) into the left atrium (LA) is reported in a 30-year-old male with cyanosis and polycythemia. The chest X ray and the lung CT scan was normal. Spirometry was normal but the transfert-CO coefficient (KCO) was lowered. Hypoxemia was observed at rest and worsening during exercise. The alveolo-arterial oxygen tension difference under hyperoxia was increased (56 kPa). Contrast echocardiography (CEch) suggested the presence of an AIVCR with a right-to-left shunt only observed by the inferior route. The inferior vena cava (IVC) angiography and the magnetic resonance imaging demonstrated an AIVCR characterized by a direct drainage of IVC in the left atrium. The good tolerance can be explained by the association of AIVCR with an inter-auricular septal defect resulting in a left-to-right shunt which partially corrected the right-to-left shunt. After surgical treatment, arterial blood gases normalized, KCO remained low and CEch became negative.
Rev Mal Respir 2001 Dec
PMID:[Hypoxemia secondary to inferior vena cava return into left atrium]. 1192 87

Static lung hyperinflation is defined as the elevation of end- expiratory lung volume above its predicted value, with no increase in end-expiratory alveolar pressure, which remains equal to atmospheric pressure. Dynamic hyperinflation is the transient increase of this volume above the relaxation volume. In patients with COPD, dynamic hyperinflation is mainly determined by the mechanical properties of the respiratory system. Its measurement relies on plethysmography and, during exercise, inspiratory capacity. During exercise, dynamic hyperinflation attenuates expiratory flow limitation but increases the inspiratory loading and induces functional weakness of the diaphragm. It also has haemodynamic consequences and results in more rapid, shallow breathing and progressive reduction in dynamic lung compliance. These events explain exercise intolerance. Several approaches may help combat dynamic hyperinflation and its deleterious clinical effects: bronchodilators, hyperoxia, helium-oxygen mixtures, lung volume reduction surgery...
Rev Mal Respir 2008 Dec
PMID:[Dynamic lung hyperinflation and its clinical implication in COPD]. 1910 20