The effect of the volumetric flow rate and endotracheal tube diameter on the pressure distribution in human airways.

The comprehension of the fluid flow in the upper airways is of paramount importance when treating patients under clinical conditions that demand mechanical ventilation. Barotrauma and overdistension are related to undesirable pressures and might be responsible for morbidity and mortality. In the current work we use computational fluid dynamics to investigate the pressure field in the upper respiratory airways. We performed a set of simulations varying the volumetric flow rate of mechanical ventilators and we have shown that the pressure profile can be calculated by means of the volumetric flow rate in accordance with a mathematical expression given by Pav=aV˙2, where Pav is the average pressure at selected sections of the upper airways and V˙ is the volumetric flow rate. Numerical findings provide evidence that the constant a varies with the location of the plane in the upper airways. We also show that some particular diameters of endotracheal tubes (ETT) must be used with care for a given range of volumetric flow rates. Overall, we document an important relationship among pressure, volumetric flow rate and selected internal diameters from ETT.

Cardiac protein changes in rats after soybean oil treatment: a proteomic study.

BACKGROUND: Several studies show that the consumption of vegetable oils, such as soybean oil, rich in polyunsaturated fatty acids (PUFAs) has beneficial health effects by preventing or reducing the risk factors of cardiovascular diseases. While the demonstration of beneficial effects of the consumption of unsaturated fatty acids on the cardiovascular system has been proven in a macroscopic level, the molecular/cellular mechanisms responsible for this phenomenon are poorly understood. METHODS: In this work, a comparative proteomic approach, two-dimensional gel electrophoresis (2-DE) coupled to mass spectrometry (MALDI-TOF/TOF), was applied to investigate proteome differences in the left ventricle (LV) of rats that received 0.1 mL of soybean oil intramuscularly for 15 days (treated group-TR) and rats that had not (control group-CT). RESULTS: Soybean oil treatment improved left ventricular function, TR animals presented lower value of LVEDP and significantly changed LV proteome. The protein profile of VE revealed differences in the expression of 60 protein spots (p<0.05) between the experimental groups (CT and TR), 14 of those were identified by MS and MS/MS, and 12 of the 14 being non-redundant proteins. Robust changes were detected in proteins involved in cellular structure and antioxidant system and muscular contraction. CONCLUSIONS: The TR group presented an increase in the intensity of proteins involved in muscle contraction (myosin light chain-3 (3-MCL), creatine kinase M (CKM)) and thireodoxin, an antioxidant enzyme. Low intensity cytoskeletal protein, desmin, was also detected in TR animals. The results suggest that soybean oil induces changes in the levels of heart proteins which may partially account for the underlying mechanisms involved in the benefits provided by oils rich in polyunsaturated fatty acids.