Expired gases

An adult takes about 12 breaths per minute, inhaling roughly 500 mL of air with each breath. The molar compositions of the inspired and expired gases are as follows ... 

For the last application an indication of the kind of solvent used can speed up the treatment and save valuable time. However, this demand requires another type of sensor, eg, an IR sensor which consists of an adjustable dispersive optical element to select specific absorption bands and compare the intensities with spectra stored in a built-in memory [27]. Figure 23-29 presents a prototype of a tunable IR sensor , Isolde, which can be used for the detection of solvents in expired gases. This sensor has been clinically evaluated as a prototype but has not yet been offered commercially. 

Respiratory exchange measurements, namely, oxygen consumption ( 02) and the concentration of oxygen and carbon dioxide in expired gases, were monitored throughout rest, exercise, and recovery. Blood samples taken at the end of the rest, exercise, and recovery periods, were analyzed for glucose, lactate, and pyruvate. Blood samples were obtained during the exercise sessions only in study 2. 

The types of analyte can vary from expired gases to high relative molecular mass proteins but considerable differences in the type of mass spectrometer used for such analyses means that no single instrument will cover the whole range. Table 2 lists some typical analytes and the kind of mass spectrometric analyses that would be used to characterize them. 

Lan and Mottola [14] have presented two continuous-flow-sensing strategies for the determination of C02 in gas mixtures using a special reaction cell. Both approaches are based on the effect of the complex of Co(II) with phthalocyanine as a rate modifier of the CL emission generated by luminol in the absence of an added oxidant agent, which is enhanced by the presence of C02 in the system. This enhancement allows the fast and simple determination of carbon dioxide at ppm levels (v/v) in atmospheric air and in human breath. In the first case, a continuous monitoring system was applied however, because the flow of expired gas is not constant, a discrete sample introduction approach was used in the analysis of C02 in breath. 

It is calculated by measuring the nitrogen concentration in expired gas after a single breath of 100% oxygen. The nitrogen wash-out test is the same method used to measure anatomical dead space. Closing volume increases with age and reaches the standing FRC at 70 years and the supine FRC at 40 years. 

There are two techniques used to measure diffiision capacity. In one procedure, the subject takes a single vital capacity inspiration of a dilute mixture of CO and holds his breath for 10 seconds. In the second, the subject breathes a low concentration of CO (about 0.1%) for 30 seconds until a steady state has been reached. In both methods, the rate of disappearance of the CO from the alveolar gas is calculated by measuring the concentrations of CO in the inspired and expired air with an infrared analyzer. The larger the diffiising capacity (DlCO), the more CO enters the blood and the lower the amount of CO measured in the expired gas. 

Monitoring of gaseous NO and NO2 levels is an increasingly complex issue that is only briefly described here. At the outset we must state that we believe any acceptable monitoring system must reliably measure NO and NO2 in a gas mixture with 50-90% oxygen characterized by cyclic pressure variations and at both 100% (expired gas) and 0% humidity (inspired gas immediately following the ventilator). 

The cumulative amounts of generated radiolabeled by-products were detected in the expired gas, urine, and feces of the rats as depicted in Figure 5.4. The data in Figure 5.4 indicate that ... 

In a typical test, the subject would breathe in room air and exhale into a collapsed (Douglas) bag. The test is continued for 3 min or more, and the number of breaths is counted in that period. An arterial blood sample is withdrawn during the collection period. The PCO2 in the expired gas is measured, and... 

The equipment needed to calculate the DIXX) includes either a spirometer or a flow smsor to measure the inspired volume and gas analyzers to measure the concentrations of CO and the tracer gas. In some systems, the sample of expired alveolar gas is collected in a bag for analysis in other systems with rapidly responding analyzers, the expired gas is sampled continuously for calculation. It is worth noting that using a flow sensor for this test requires that the flow sensor be calibrated with the gases to be used, as described above. 

The total volume of exhaled N2 may be calculated by collecting all the expired gas in a very large spirometer and making a single measurement of its nitrogen concentration, or the expired gas may be analyzed continuously for N2 contem with simultaneous use of a flow sensor. Even when the expired gas is collected separately, a continuous N2 signal is helpful to detect leaks in the system that will interfere with accuracy and to determine when the test is completed. 

The simplest method for measuring carbon dioxide production (Vco,) is to collect a timed sample of expir gas in a balloon or spirometer, measuring the total volume of gas collected and its CO2 concentration. If the inspired gas is assumed to contain no CO2 (a reasonable assumption for most measurement purposes), then all of the CO2 contained within the expired gas came from the C02> which may be calculated as... 

At the end of inspiration, the conducting airways (trachea, bronchi etc.) are full of gas similar in composition to air, except that the gas is saturated with water vapour. Since this gas does not take part in gaseous exchange with the blood, it is called the dead space. During expiration, gas is forced out of the lungs. The first gas to leave via nose and mouth is this dead space gas and it is followed by alveolar gas. This gas mixture can be collected and is known as mixed expired gas. Its composition is between that of air and alveolar gas, since it is a mixture of the two. 

C. The rate of excretion of carbon dioxide in expired gas is lower than the rate of CO2 production in the tissues of the body. 

B. the concentration of oxygen in expired gas at one atmosphere (760 mmHg), the oxygen partial pressure being 120 mmHg. (express your answer as the fractional concentration and as a percentage of total) ... 

B. the amount of carbon dioxide excreted per minute in the expired gas rises ... 

Expired carbon dioxide partial pressure is important because it measures the adequacy of ventilation and provides a measure of blood pH this is because expired gas from the lungs is in equilibrium with blood passing through the lungs. (Note that blood serves to carry CO2, produced from aerobic metabolism, to the lungs in the form of carbonic acid, H2CO3.) Since deviations of only a few tenths of a pH unit in blood pH can be either the cause or the effect of serious disease, you can imagine how this is useful information to... 

Expired minute ventilation, V, defines the gas volume inspired or expired in 1 minute and is given by... 

Forced vital capacity (FVC) quantifies the maximum air volume expired following a maximal inspiration and is one of the basic measures of analyzing flow changes such as reduced airway patency observed in asthma. To measure FVC, an individual inhales maximally and then exhales as rapidly and completely as possible. FVC primarily reflects the elastic properties of the respiratory tract. The gas volume forcibly expired within a given time interval, FEV (where t is typically one second, FEVj q)... 

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