Breathing mixtures

The narcotic potency and solubiUty in oHve oil of several metabohcaHy inert gases are Hsted in Table 10. The narcotic potency, ED q, is expressed as the partial pressure of the gas in breathing mixtures requited to produce a certain degree of anesthesia in 50% of the test animals. The solubiUties are expressed as Bunsen coefficients, the volume of atmospheric pressure gas dissolved by an equal volume of Hquid. The Hpid solubiHty of xenon is about the same as that of nitrous oxide, a commonly used light anesthetic, and its narcotic potency is also about the same. As an anesthetic, xenon has the virtues of reasonable potency, nonflammability, chemical inertness, and easy elimination by the body, but its scarcity and great cost preclude its wide use for this purpose (see Anesthetics). 

ED q, narcotic potency, is expressed as the partial pressure of a gas in breathing mixtures requited to produce a certain degree of anesthesia in 50% of the test animals. 

C02-0082. One breathing mixture for deep-sea divers contains 25% moiecuiar oxygen and 75% heiium. Draw a moiecuiar picture of a sampie of this mixture that contains three moiecuies of oxygen. 

Helium None known Used to replace nitrogen as an 02 diluent in breathing mixtures to prevent the bends in high-pressure work. 

Two types of studies were carried out the first, reported on a preliminary basis (8), involves the use of an endpoint—death—and is oriented towards the articulation of the receptor sites for bubble nucleation. The second study, reported here for the first time, involves a measurement of the fast inert gas exchange constants of the animal model. Both studies utilized air as a breathing mixture and were begun with the animal assumed to be in equilibrium with air at 1 atm (Pn2 = 0-79 ata). 

The nitrogen washout data consist of F, the fraction of nitrogen in exhaled air, measured as a discrete function of time after shifting to an 80-20 He-02 breathing mixture. When plotted as log F vs. time, the data fall along one line. Only the first one or two data points are above this best line. These presumably are caused by pulmonary and breathing loop dead spaces and are neglected hereafter. 

Oxygen analyzers for monitoring patient breathing mixtures — Safety requirements ISO Standard ISO 7767 first edition, 1988. 

Another problem for high pressure environments involves inert gases used in breathing mixtures. At high pressures, nitrogen creates narcotic effects. Examples are euphoria, drowsiness, and muscular weakness. Nitrogen narcosis is the name for these narcotic effects. 

Contaminant gases in breathing mixtures may add other dangers. That is why there is special equipment for supplying breathing gas to divers. Regular compressors introduce contaminants that may create breathing hazards. 

Decompression table A profile or set of profiles of depth-time relationships for ascent rates and breathing mixtures to be followed after a specific depth-time exposure or exposures. 

For any dive outside the no-decompression limits, deeper than 100 fsw or using mixed gas as a breathing mixture, the employer shall instruct the diver to remain awake and in the vicinity of the decompression chamber which is at the dive location for at least one hour after the dive (Including decompression or treatment as appropriate). 

Divers must be concerned about increasing pressures on their ears and lungs when they dive below the surface of the ocean. Because water is more dense than air, the pressure on a diver increases rapidly as the diver descends. At a depth of 33 ft below the surface of the ocean, an additional 1 atm of pressure is exerted by the water on a diver, which gives a total pressure of 2 atm. At 100 ft, there is a total pressure of 4 atm on a diver. The regulator that a diver uses continuously adjusts the pressure of the breathing mixture to match the increase in pressure. 

A scuba tank is filled with Trimix, a breathing gas mixture for deep scuba diving. The tank contains oxygen with a partial pressure of 20. atm, nitrogen with a partial pressure of 40. atm, and helium with a partial pressure of 140. atm. What is the total pressure of the breathing mixture, in atmospheres ... 

A Hehox breathing mixture of oxygen and hehum is prepared for a scuba diver who is going to descend 200 ft below the ocean surface. At that depth, the diver breathes a gas mixture that has a total pressure of 7.00 atm. If the partial pressure of the oxygen in the tank at that depth is 1140 mmHg, what is the partial pressure, in atmospheres, of the helium in the breathing mixture ... 

Similarly, if a scuba diver does not decompress slowly, a condition called the bends may occur. While below the surface of the ocean, a diver uses a breathing mixture with higher pressures. If there is nitrogen in the mixture, higher quantities of nitrogen gas... 

UPDATED Chemistry Link to Health boxes, Brachy-therapy, Polycyclic Aromatic Hydrocarbons (PAHs), and Breathing Mixtures for Scuba, have been added. 

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