Respiratory oscillations in alveolar oxygen tension measured in arterial blood.

Arterial oxygen partial pressure can increase during inspiration and decrease during expiration in the presence of a variable shunt fraction, such as with cyclical atelectasis, but it is generally presumed to remain constant within a respiratory cycle in the healthy lung. We measured arterial oxygen partial pressure continuously with a fast intra-vascular sensor in the carotid artery of anaesthetized, mechanically ventilated pigs, without lung injury. Here we demonstrate that arterial oxygen partial pressure shows respiratory oscillations in the uninjured pig lung, in the absence of cyclical atelectasis (as determined with dynamic computed tomography), with oscillation amplitudes that exceeded 50 mmHg, depending on the conditions of mechanical ventilation.

Experimental investigation of the effect of polymer matrices on polymer fibre optic oxygen sensors and their time response characteristics using a vacuum testing chamber and a liquid flow apparatus.

Very fast sensors that are able to track rapid changes in oxygen partial pressure (PO) in the gas and liquid phases are increasingly required in scientific research - particularly in the life sciences. Recent interest in monitoring very fast changes in the PO of arterial blood in some respiratory failure conditions is one such example. Previous attempts to design fast intravascular electrochemical oxygen sensors for use in physiology and medicine have failed to meet the criteria that are now required in modern investigations.

Intra-breath arterial oxygen oscillations detected by a fast oxygen sensor in an animal model of acute respiratory distress syndrome.

Background: There is considerable interest in oxygen partial pressure (Po2) monitoring in physiology, and in tracking Po2 changes dynamically when it varies rapidly. For example, arterial Po2 ([Formula: see text]) can vary within the respiratory cycle in cyclical atelectasis (CA), where [Formula: see text] is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these [Formula: see text] oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS).

A fibre optic oxygen sensor that detects rapid PO2 changes under simulated conditions of cyclical atelectasis in vitro.

Two challenges in the management of Acute Respiratory Distress Syndrome are the difficulty in diagnosing cyclical atelectasis, and in individualising mechanical ventilation therapy in real-time. Commercial optical oxygen sensors can detect [Formula: see text] oscillations associated with cyclical atelectasis, but are not accurate at saturation levels below 90%, and contain a toxic fluorophore. We present a computer-controlled test rig, together with an in-house constructed ultra-rapid sensor to test the limitations of these sensors when exposed to rapidly changing [Formula: see text] in blood in vitro.

Developing and implementing health and sustainability guidelines for institutional food service.

Health and sustainability guidelines for institutional food service are directed at improving dietary intake and increasing the ecological benefits of the food system. The development and implementation of institutional food service guidelines, such as the Health and Human Services (HHS) and General Services Administration (GSA) Health and Sustainability Guidelines for Federal Concessions and Vending Operations (HHS/GSA Guidelines), have the potential to improve the health and sustainability of the food system. Institutional guidelines assist staff, managers, and vendors in aligning the food environment at food service venues with healthier and more sustainable choices and practices.