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 a series of 6-min treadmill walking tests, with a progres...

Sensory receptor neurons match their dynamic range to ecologically relevant stimulus intensities. How this tuning is achieved is poorly understood in most receptors. We show that in the C. elegans URX O2 sensing neurons two putative molecular O2 sensors, a neuroglobin and O2-binding soluble guanylate cyclases, work antagonistically to sculpt a slowly rising sigmoidal O2 response curve tuned to ...

Measurement of cerebral tissue saturation during obstructive sleep apnoea (OSA) may provide additional information to conventional peripheral oxygen saturation. Thirteen subjects with OSA (mean apnoea/hypopnoea index 65.7+/-27.9) were monitored using full polysomnography and monitoring of near-infrared cerebral tissue oxygenation index (TOI). One-thousand and thirty-six apnoeas and hypopnoeas w...

The specific conductance (G) for O2 transfer by red blood cells (RBCs) of chicken and muscovy duck was measured using the experimental (stopped-flow) and analytical techniques (RBC model) previously applied to human RBC (Yamaguchi, Nguyen Phu, Scheid & Piiper, 1985). Avian RBCs behaved similarly to human RBCs: G values were of similar magnitude; G for O2 uptake decreased with time and increasin...

The effects of discontinuous hypoxia on cerebrovascular regulation in humans are unknown. We hypothesized that five nocturnal hypoxic exposures (8 h/day) at a simulated altitude of 4,300 m (inspired O2 fraction = approximately 13.8%) would elicit cerebrovascular responses that are similar to those that have been reported during chronic altitude exposures. Twelve male subjects (26.6 +/- 4.1 yr, ...

Tissue hypoxia is a common end product of circulatory shock and a primary target for resuscitation efforts. In this issue Podbregar and Mozina show that thenar tissue O2 saturation (StO2) and mixed venous O2 saturation (SvO2) co-vary in patients in left ventricular failure, but in patients with sepsis StO2 was higher than SvO2. Although StO2 may co-vary with SvO2 they have different determinant...

Because central venous O2 saturation (superior vena cava, ScvO2) can be monitored with less patient risk than mixed venous O2 saturation (pulmonary artery, SvO2), we examined the correlations between SvO2 and ScvO2 over a broad range of cardiorespiratory conditions, including hypoxia, hemorrhage, and resuscitation in anesthetized dogs. The correlation coefficient (r) between SvO2 and ScvO2 in 1...

High-resolution photoelectron spectroscopy using synchrotron radiation was applied for monitoring in real time the oxidation kinetics on the Ti(0001) surface at 405C with dry O2 gas. The time evolution of O 1s photoelectron intensity showed a linear uptake curve up to ~90 L followed by a sudden saturation up to ~160 L and then a restart of the linear increase, indicating that O2 adsorption obey...

To study the effect of genetic differences in the maternal oxyhemoglobin dissociation curve on fetal O2 supply, we compared eight pregnant ewes homozygous for high O2 affinity hemoglobin (A) with eight pregnant ewes homozygous for low O2 affinity hemoglobin (B). Each ewe carried a single fetus. Fetal weights were not significantly different (A, 3,000 +/- 170 g; B, 3,070 +/- 270 g). The A ewes h...

background: long surgery causes hypothermia and increased bleeding and can increase the arterial blood lactate levels during anesthesia. it causes cellular hypoxia and its complications. considering the core temperature of the patient during surgery it can prevent hypoxia. this study aimed to compare the effects of different temperatures on the core temperature and the concentrations of lactate...