1. Disciplina de Pneumologia, Universidade Federal de São Paulo, São Paulo (SP) Brasil. Tissues obtain energy primarily from oxygen. Adequate oxygen levels in the inhaled air and a preserved ventilation/ perfusion ratio (V • /Q) are the major determinants of oxygen supply to the blood. However, peripheral supply depends on effective oxygen transport to the tissue mitochondria, a critical task t...

We have developed a new quantitative single-photon-emission computed tomography (SPECT) method that uses (113m)In-labeled albumin macroaggregates and Technegas ((99m)Tc) to estimate the distributions of regional ventilation and perfusion for the whole lung. The multiple inert-gas elimination technique (MIGET) and whole lung respiratory gas exchange were used as physiological evaluations of the ...

During discontinuous gas exchange cycles in insects, spiracular opening follows a typical prolonged period of spiracle closure. Gas exchange with the environment occurs mostly during the period of full spiracular opening. In this study we tested the hypothesis that recently reported ventilatory movements during the spiracle closure period serve to mix the tracheal system gaseous contents, and s...

AMONG THE PROBLEMS presented by the chronic uraemie patient, the anaesthetist is particularly concerned with anaemia, a-3 acid-base and electrolyte upsets, and impaired renal excretion of drugs. When such patients are on chronic haemodialysis programs, they frequently present for surgical creation or revision of arteriovenous shunts and fistulae. Usually, these procedures are done under local o...

[1] Rain has been shown to significantly enhance the rate of air-water gas exchange in fresh water environments, and the mechanism behind this enhancement has been studied in laboratory experiments. In the ocean, the effects of rain are complicated by the potential influence of density stratification at the water surface. Since it is difficult to perform controlled rain-induced gas exchange exp...

To investigate the effects of bilateral intrathoracic vagotomy on the establishment of continuous breathing and effective gas exchange at birth, we studied 8 chronically instrumented, unanesthetized, sham-operated and 14 vagotomized newborn lambs after a spontaneous, unassisted vaginal delivery. Fetal lambs were instrumented in utero to record sleep states, diaphragmatic electromyogram, blood p...

Concepts of continuous ventilation and perfusion have founded mathematical models of lung gas mixing and cardiopulmonary blood±gas exchange, whether for anaesthetic vapour uptake or for cardiorespiratory measurement, for several decades now. 28 37 42 The beauty of continuousventilation and perfusion models is that they allow mathematical expressions that are readily soluble, and they describe b...

The alcohol breath test is reviewed with a focus on gas exchange factors affecting its accuracy. The basis of the alcohol breath test is the assumption that alveolar air reaches the mouth during exhalation with no change in alcohol concentration. Recent investigations have shown that alcohol concentration is altered during its transit to the mouth. The exhaled alcohol concentration is modified ...

Until the late 1960's there was a remarkable lack of information on the consequences of asthma on arterial oxygenation [1, 2). Since then, it has been known that arterial blood gas abnormalities can range from overt hypoxaemia, usually associated with hypocapnia and respiratory alkalosis, as shown in acute severe asthma, to mild increases in the alveolar-arterial 0 2 tension difference (AaPo,) ...