Breath gases

Breath alcohol testing, 72 96 Breathing gases, noble gases as, 77 376-378... 

The gas is also used to fill balloons, in gas discharge lamps, and as an additive in the breathing gases of astronauts and scuba divers. The rarer stable isotope of helium (3He) is produced by the decay of radioactive tritium, and is used in resonance imaging and in the attainment of very low temperatures, about 0.010 kelvin, via a process known as dilution refrigeration. see also Noble Gases Nuclear Fusion. 

Zeolites have also been used as absorbers for perfluorocarbons (PFC), which are applied in the treatment of respiratory diseases, to control the PFC content in breathing gases. [53] By preventing water condensation in the zeolite and PFC condensation, the weight gain of the zeolite absorber over time allows precise measurements with volume errors less than 1 % for PFC volumes grater than 1 ml. 

Many bioactive molecules have absorption bands in the infrared, which are accessible by existing infrared lasers or OPOs (Fig. 10.50). When enhancement cavities and cavity ringdown or cavity leak out spectroscopy are used detection sensitivities down into the ppb or even ppt range can be achieved [1545], This is important for sensitive measurements of breathing gases, where the composition of the exhaled gas gives information about possible diseases. One famous example is the presence of the bacteria Helicobacter pylori in the stomach, which can cause gastritis or even stomach cancer. Their presence and concentration can be monitored by the spec-... 

In Fig. 10.51 a possible experimental arrangement for breath analysis is shown [1547, 1548]. The breathing gases are dried, mixed with a buffer gas and injected into the multipath absorption cell. 

Fig. 10.51 Setup for real-time analysis of breathing gases [1547]...

Figure 14 The SIFT spectrum obtained following the introduction of breath from a diabetic patient with end-stage renal failure who smokes cigarettes (see the text). The concentrations of the major breath gases are given in ppb in parentheses. u= mass, c/s = counts per second.

To consider whether exposure of the surgical team to anesthetic could still be an issue in modem operating rooms, consider isoflurane (CH2CIF5O), whose release to the air can occur both directly from breathing gases and via diffusion through the patient s skin. 

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