Since the concept of hyperventilation on neurosurgical and neurotraumatological patients has been contested, our analysis was aimed at its scrutiny on the basis of easily accessible parameters of perisurgical monitoring. Furthermore, the influence of an improved oxygen supply was tested on hyperventilationally induced cerebral changes and to what extent recommendations ...

The purpose of this study was to determine the effects of a 1-h exposure to 2.0 atm abs (202.6 kPa) and 100% oxygen on subsequent maximal O2 consumption (VO2max), ventilation threshold (VT), lactate threshold (LT), and muscle oxygenation (%Mox) during incremental exercise to maximum on a cycle ergometer. Two baseline ...

Long hyperbaric exposures of humans, at pressures in excess of 2.5 atmospheres, require that the oxygen concentration of the breathing gas be maintained at levels less than atmospheric air, in order to prevent pulmonary oxygen toxicity. Carbon dioxide produced by humans must be removed from the breathing gas of closed ...

Two aerobic microorganisms,Saccharomycopsis lipolytica andBrevibacterium lactofermentum, have been used in a study of mass transfer and oxygen uptake from a global perspective, using a closed gas system. Oxygen concentrations in the gas and liquid were followed using oxygen electrodes; the results allowed for easy calculation of in situ oxygen transport. ...

OBJECTIVE: To evaluate the ratio of peak oxygen consumption to peak heart rate (peak oxygen pulse) as a predictor of long term prognosis in chronic heart failure. PATIENTS AND SETTING: 178 consecutive heart failure patients recruited to the cardiology department of a tertiary referral centre between 1986 and 1993. DESIGN: ...

The present study deals with a species of enteropneust, Glossobalanus crozieri, focusing on two aspects of its respiration: a) oxygen consumption and body mass, and b) the influence of environmental oxygen tension on the respiratory rate. Preliminarily, the body water content was shown to be 85% of the whole body ...

Sympathetic and angiotensinergic activation reduce splanchnic oxygen delivery during hypovolemia, which may lead to failure of the intestinal mucosal barrier and eventually multiple organ dysfunction. This study integrates sympathetic and angiotensinergic responses with splanchnic hemodynamics and duodenal mucosal function during hypovolemia and evaluates pharmacologic blockade of either system to ameliorate ...

PURPOSE: This study measured the effect of hyperbaric oxygen (HBO) treatment on transmucosal oxygen tension in irradiated human oral mucosa. PATIENTS AND METHODS: Ten patients received 30 dives of HBO as part of their treatment for mandibular osteoradionecrosis. A noninvasive, nonheated oxygen electrode was used to measure the tissue surface ...

OBJECTIVE: The effects of varying oxygen tensions on tissue metabolic behavior are not well understood, yet many intracellular pathways are influenced by them. In the placenta, optimal in vivo oxygen tension at the villous level is unknown. The purpose of this study was to determine effects of varying oxygen tensions ...

We measured oxygen consumption in the exercising lower limb by using noninvasive tissue oximetry with the near-infrared spectra of hemoglobin in the quadriceps muscle during bicycle ergometer exercise in four normal controls and three patients with chronic progressive external ophthalmoplegia (CPEO) as well as one patient with mitochondrial myopathy, encephalopathy, ...

Mixed venous oxygen saturation (SvO2) and physical activity (PhyAc) are practical candidates as parameters of total artificial heart (TAH) control because SvO2 can be measured through a transparent blood pump housing with infrared rays and PhyAc can be calculated from signals of an accelerometer used for rate response pacemakers. Although ...

The dynamics of oxygen delivery and utilization are examined in a variety of mitochondrial disorders during rest, exercise and post exercise. We used a non-invasive optical technique to measure the oxygen consumption in the exercising limb in normal subjects and 5 patients with cytochrome c oxidase deficiency. We also examined ...

At early stages of germination, a special lipoxygenase is expressed in cotyledons of cucumber and several other plants. This enzyme is localized at the lipid storage organelles and oxygenates their storage triacylglycerols. We have isolated this lipid body lipoxygenase from cucumber seedlings and found that it is capable of oxygenating ...

BACKGROUND: Nitric oxide (NO) is present in the exhaled air of animals and humans. In isolated animal lungs the amount of exhaled NO is decreased during hypoxia. A study was undertaken to determine whether changes in arterial oxygen tension affect levels of exhaled NO in humans. METHODS: Sixteen healthy subjects ...

An oxygen economizer tube is attached to draw-over vaporizers and acts as a reservoir of supplemental oxygen. The clinical importance of the presence or absence of the economizer tube (volume 130 ml) has not been adequately studied in manually ventilated patients using ether from an Ohmeda Cyprane Portable Anesthesia Complete ...

OBJECTIVE: To review the literature addressing use of the pulmonary artery catheter (PAC) to augment oxygen delivery to supranormal levels in critical illness. DATA SOURCE: All pertinent English language articles dealing with use of the PAC to augment oxygen delivery to supranormal levels in critical illness were retrieved from 1988 ...

Singlet oxygen (1O2), a highly reactive and toxic intermediate, may play a role in photo-induced aging. We examined singlet oxygen generation from hematoporphyrin (HP) with UV-A, by monitoring the emission at 1,268 nm corresponding to 1O2 --> 3O2. Singlet oxygen was formed HP-dose-dependently in this system. We then investigated the ...

The aim of this study was to evaluate which parameters of preoperative spirometry and cardiopulmonary exercise test are the best predictors of postoperative morbidity and mortality in patients with bronchogenic carcinoma. Ninety seven patients were prospectively and consecutively examined. All patients had preoperative maximal exercise test and dynamic spirometry. Postoperative ...

STUDY OBJECTIVES: To confirm that a newly drafted treadmill exercise protocol designed on a theoretical basis to span a range of 0 to 200 W with approximately 25-W increments by alteration of either speed or grade from one stage to the next should correspond to a standard bicycle protocol consisting ...

Yellowfin tuna Thunnus albacares (1400-2175 g) instrumented with electrocardiogram electrodes and pre- and post-branchial catheters were subjected to incremental swimming velocity tests. Increasing velocity, from a minimal speed of 1.0 FLs-1, where FL is fork length, resulted in a 1.4-fold increase in heart rate (from 61.4 to 84.6 beats min-1), ...

The surface of polypropylene hollow fiber was successfully coated with a very thin (0.2 micron) silicone layer. Experimental studies were performed in long-term (6 h) normothermic cardiopulmonary bypass (CPB) using 10 goats. A conventional membrane oxygenator (Mera Excelung HPO-15H, MERA, Tokyo, Japan) was used for 5 goats as a control ...

Haemophilus influenzae type b, a causative agent of bacterial sepsis and meningitis in young children, contains a single superoxide dismutase (SOD), a cytoplasmic MnSOD. To study the role of this enzyme, a chromosomal sodA::lacZ mutant (M-2) was constructed. M-2 had an increased sensitivity towards oxygen and the redox-active agent paraquat. ...

Variations in the levels of muscle hemoglobin and of myoglobin oxygen saturation can be detected non-invasively with near-infrared spectroscopy. This technique could be applied to the diagnosis of chronic compartment syndrome, in which invasive testing has shown increased intramuscular pressure associated with ischemia and pain during exercise. We simulated chronic ...

The purpose of this study was to examine the effects of breathing dry or humidified hyperbaric oxygen on pulmonary function. Pulmonary function tests were performed before and after each of 10 hyperbaric oxygen exposures at 2.5 atmospheres absolute (ATA) for 95 min in a group of 13 patients treated daily ...

Near-infrared spectroscopy (NIRS) is a noninvasive optical technique to monitor cerebral oxygen saturation at the bedside. Despite its applicability, NIRS has had limited clinical use because of concerns about accuracy, noted by intersubject variability in slope and intercept of the line between NIRS- and weighted-average arterial-cerebrovenous saturation (SMO2). This study ...

Successful application of anticancer therapy, and especially photodynamic therapy (PDT) mediated by type II (PDTII) processes, depends on the oxygen content within the tumor before, during and after treatment. The high consumption of oxygen during type II PDT imposes constraints on therapy strategies. Although rates of oxygen consumption and repletion ...

OBJECTIVES: The purpose of this study was to identify the determinants of exercise tolerance in patients with Ebstein's anomaly. BACKGROUND: Patients with Ebstein's anomaly of the tricuspid valve may have exercise limitation that improves after surgical repair. METHODS: One hundred seventeen patients performed cycle ergometry for a total of 124 ...

Helium is an inert gas with unique physical properties that allow it to be used for various respiratory emergencies. Because of its low specific gravity and low viscosity, the passage of helium through the respiratory tract is smoother, more laminar, and less turbulent than either air or oxygen. These properties ...

The present study focuses on reversible mitochondrial ultrastructural alterations in myocardial myocytes that correspond or accompany reversible metabolic depression observed after oxygen radical exposure. The myocytic mitochondrial membranes and matrix of isolated Langendorff-perfused rat hearts were examined by semiquantitative morphometry using the electron micrograph as unit. The hearts were exposed ...

Impairment of splanchnic and peripheral tissue perfusion during cardiopulmonary bypass (CPB) may be responsible for endotoxin-mediated systemic inflammation and acute phase responses. We examined the effects of dopexamine on hemodynamic parameters, creatinine clearance, systemic and splanchnic oxygenation, gastric mucosal pH (pHi), and mixed and hepatic venous plasma levels of endotoxin, ...

Ephemerality and prolongation of luteal function have been matters of great concern in reproduction for many years. However, their control mechanisms are very complex and differ among mammals. Recently, evidence has indicated that reactive oxygen species may play important roles in the regulation of luteal function. Reactive oxygen species are ...

Near infrared spectroscopy (NIRS) was used to investigate the effect of behavioural states on changes of oxygenated (O2Hb), deoxygenated haemoglobin (HHb) and total haemoglobin (tHb), during endotracheal suctioning. In an open prospective design, NIRS measurements have been done during 20 suctioning episodes in 13 preterm neonates. Heart rate, arterial oxygen ...

The influence of disturbance on a hot spring cyanobacterial mat community was investigated by physically removing the top 3.0 mm, which included the entire cyanobacterial layer. Changes in 16S rRNA-defined populations were monitored by denaturing gradient gel electrophoresis analysis of PCR-amplified 16S rRNA gene segments. Some previously absent cyanobacterial populations ...

OBJECTIVE: To evaluate the effects of dopexamine administration on hemodynamic variables and tissue oxygen tensions during crystalloid resuscitation from hemorrhagic shock. DESIGN: Randomized, control trial. SETTING: An animal laboratory at a university center. SUBJECTS: Twelve piglets, mean weight 22 kg. INTERVENTIONS: The animals were anesthetized and bled to a state ...

Acute hypoxemia (low PaO2) leads to changes in oxygen consumption and electrical responses of the outer retina of cats, but inner retinal ERG components and ganglion cell responses have been shown to be quite resistant to hypoxemia. The purpose of this study was to determine whether the resistance of the ...

To evaluate the magnitude of the stress on the aerobic and the anaerobic energy release systems during high intensity bicycle training, two commonly used protocols (IE1 and IE2) were examined during bicycling. IE1 consisted of one set of 6-7 bouts of 20-s exercise at an intensity of approximately 170% of ...

Using an end-tidal fractional oxygen concentration of 0.9 as an end point for pre-oxygenation, we have compared the time taken to achieve this end point and the safe duration of apnoea after induction of anaesthesia following pre-oxygenation in elderly patients and young adults. The times taken to reach the end ...

The aim of this study was to determine whether it is possible using ear-oximetry to prescribe the correct oxygen flow rates during exercise in chronic obstructive pulmonary disease (COPD) patients on long-term oxygen therapy (LTOT). Twenty COPD patients on LTOT, with exercise desaturation breathing oxygen at resting flow rates, performed ...

OBJECTIVE: To investigate the influence of the neuromuscular blocking agent vecuronium on oxygen delivery (DO2), oxygen consumption (VO2), oxygen extraction ratio, and gastric intramucosal pH in heavily sedated patients with severe sepsis or septic shock. DESIGN: Prospective, randomized, placebo-controlled, cross-over trial. SETTING: University hospital intensive care unit. PATIENTS: Eighteen mechanically ...

To establish whether the indicators of oxygen metabolism reflects the improvement in tissue oxygenation during therapy, twelve rabbits subjected to progressive hemorrhage followed by retransfusion were studied. The changes in oxygen delivery (DO2), oxygen consumption (QO2), oxygen extraction ratio (O2ER), arterial lactate concentration, venous-arterial difference in PcO2 (v-aDPcO2) and arterio-venous ...

Mutants of Saccharomyces cerevisiae accumulating uroporphyrin (UP) or protoporphyrin (PP) were used as a model for the in vivo phototoxic effect of porphyrins observed in the human skin photosensitivity associated with porphyrias (porphyria cutanea tarda and erythropoietic protoporphyria). We have found that UP is localized in vacuoles and PP is ...

The effect of different inspiratory oxygen levels (FiO2) on cortical oxygenation (pO2) during and after recovery from apnea, was investigated in 18 anesthetized, paralyzed, and mechanically ventilated newborn piglets. Heart rate (HR) and mean arterial blood pressure (MABP) were continuously monitored as the piglets were subjected to repeated episodes of ...

Technically, open systems are more suited than closed systems for the measurement of oxygen uptake by bacteria present at high cell densities as in dental plaque. Moreover, measurements are easier to perform and can be done faster and continuously. However, quantifications is more difficult and, except for steady-state conditions, has ...

OBJECTIVE: To determine the accuracy of reflection pulse oximetry and visual on-line signal identification during the second stage of labor. STUDY DESIGN: The reflection pulse oximetry system used allows visual on-line identification of valid signals by showing the original red and infrared signals. With this system oxygen saturation measurements are ...

Imidazole compounds have been shown to be beneficial in systemic sepsis and inflammation. The purpose of this study was to delineate the effects of fluconazole on systemic hemodynamics and on microanatomy of the heart, lung, liver, and kidney parenchyma of swine during graded bacteremia. Eighteen adult swine were studied in ...

Oxygen consumption across the retina of a mammal with a naturally avascular retina has not previously been investigated. The oxygen consumption across the avascular retina of the guinea pig was measured in vivo by spatial analysis of the intraretinal oxygen profile. The avascular nature of the guinea pig retina allows ...

We report four cases in which oxygen intake abruptly decreased during a graded exercise test. In all these cases, there was an acute event (arrhythmia, mitral regurgitation) that had very likely resulted in a decrease in cardiac output. These studies provide new evidence of oxygen intake dependence on oxygen transport, ...

The hypothesis that the distribution of oxygen demand in relation to oxygen supply (dO2/qO2) effects oxygen extraction in peripheral tissues was tested. By using a simple theoretical model, realistic biphasic oxygen consumption-delivery relationships were predicted from dO2/qO2 distributions. Increasing width (relative dispersion) of the dO2/qO2 distribution, indicating mismatch between oxygen ...

The purpose of the study reported here was to explore a new strategy for the aerobic preservation of transplants using stable concentrated fluorocarbon emulsions as an oxygen delivery system. Fluorocarbons (FCs) are synthetic molecules, chemically and biologically inert, with a high oxygen-dissolving capacity. As they do not mix with water, ...

Fifteen neonates were studied to determine whether beclomethasone could be safely administered with a metered-dose inhaler to subjects with an endotracheal tube in place. Oxygen saturations and transcutaneous carbon dioxide values were monitored before, during, and after administration. We found significantly more episodes of desaturation to less than 85% before ...