Document 8pkNe9mnYGbY2Zo5wX3E574y

252 CHAPTER 13 . 1946 Guide and pollens regardless of size or amount. Electrostatic air cleaners are more efficient than most commonly used types for capturing very fine dust M. Although the chief remedial factor in the treatment by conditioned air is the filtration of pollen, a certain amount of cooling and dehumidification appears to be desirable. A comfortable temperature between 70 and 75 F ' and a relative humidity well below 50 per cent proved satisfactoryM. Direct drafts, overcooling or overheating are apt to initiate or aggravate the symptoms. Limitations of Air Conditioning'Methods The results obtained with air filtration or other air conditioning pro cesses in the control of allergic conditions are fairly comparable to those ' obtained by desensitization treatment so long as the patients remain in the pollen free atmosphere. But while specific desensitization is preven tive and in a few instances curative, for all practical purposes filtration gives only, temporary relief. In mild cases sleeping in an air conditioned space may make it possible for the individual to pass more comfortable days. _With rare exceptions, the symptoms recur on exposure-to pollen laden air. Moreover the usefulness of air conditioning methods is limited because all cases are not caused by air-borne substances. Cases of bacterial asthma do not respond to treatment with filtered air. Despite these limitations air conditioning methods possess definite advantages in the simplicity of treatment, convenience, and under certain conditions almost immediate relief ". Pollen cases are usually relieved of jnost of their symptoms within 1 to 3 hr.after exposure to properly filtered air. A pollen-free atmosphere is especially .valuable when desensitization has given little or no relief, and when desensitization is not. advisable owing to intercurrent illness. OXYGEN THERAPY Oxygen, therapy is the principal measure employed for preventing and relieving the distressing symptoms of anoxemia, which is a deficiency in the oxygen content of the blood. Some of the more important conditions in which oxygen treatment is believed to .be beneficial are pneumonias, anemia, heart affections, post-operative pulmonary disturbances, certain mental. disturbances, asphyxia, asthma and atelectasis in new-born infants. The effectiveness of oxygen therapy depends upon the'manner of ad ministration. Three common methods, catheter, face mask, or tent"8:39 , are employed. . ., The necessity of air conditioning in oxygen therapy arises from the fact that oxygen is too expensive a gas to waste in the ventilation of oxygen tents arid oxygen chambers. The oxygen rich atmosphere in these enclosures- is therefore reconditioned in a, closed circuit by removal, of excess heat, moisture, and carbon dioxide given off from the occupants being treated.. Oxygen Tents In oxygen tents .the air enriched with oxygen is usually circulated by means of a small motor blower which sends the air over soda lime to remove carbon dioxide and then over ice to remove excess heat and moisture. The concentration of oxygen in the tent is regulated by means Air Conditioning in the Prevention and Treatment of Disease 253 of a pressure reducing valve and flow' meter. In an inadequately cooled tent, high temperatures and humidities are inevitable, increasing the discomfort of the patient and imposing an added strain on an already overburdened heart. Oxygen therapy under such conditions may do more harm than good. An ice melting rate of approximately 10 lb per. hour gives satisfactory results -in patients with fever in a medium size oxygen tent. Oxygen tents are confining to the patient. They may terrify the. rest less and delirious patient. Medical and nursing care is complicated, as the tent must be opened or. removed with attendant loss of oxygen. Oxygen concentrations of 50 per. cent or more are difficult to maintain, and it is a problem to keep the temperature and humidity low enough in hot weather. However, with attention to details, the patient can be made quite comfortable.. Oxygen Chambers The conventional oxygen chamber is an air-tight sheet metal enclosure of fire-proof construction, large enough to accommodate one or two patients. Trap doors or curtains are provided for the personnel, food and service, to avoid loss of oxygen, Glass windows in the ceiling and walls admit light from outside the chamber. The air conditioning system may be of. the gravity type, or of the fan type using mechanical refrig eration or air drying agents. The temperature and humidity requirement in oxygen therapy depends primarily upon the physical condition of the patient, and secondarily upon the type of disease. In pneumonias40 prescribed conditions should be an effective temperature of 66 to 68 F, humidity of 50 per cent, air movement of not less than 50 linear feet per minute, oxygen concentra tion of 50 per cent, arid carbon dioxide of less than one per cent. / .Oxygen in Aviation . ... An important application`of`the principle of oxygen therapy is in aviation. At the present tinie ajl high, altitude military airplanes in this country are'provided with gaseous oxygen equipment and military personnel are required to utilize oxygen at all times while in flight above 15,000 ft, or-between 12,000 to 15,000 ft for longer than two hours, or between 10,000 to 12,000 ft for longer than six hours. The use of oxygen in commercial aviation .will .depend-on .the height and duration of the flights as well as the! state of health of the passengers. The necessity for portable, comfortable equipment, the possible fire hazards due to smoking, and the use of oxygen on sleeper planes are some of the difficulties facing civil airline operators. The pressure cabin airplane is a solution to the problem. AIR EVACUATION OF THE SICK AND WOUNDED Between November 1942 and June 1945, some 510,000 wounded orsick 1 soldiers were transported by air. So efficient was the service that- in the Normandy campaign men wounded in France in the morning could be given operative treatment- iri English hospitals the same evening. A major problem encountered in this type of service is the removal of odors in the hospital space. The ideal deodorant method for use in aircraft, should effect complete removal of unpleasant odors without vitiating cabin air with other odors or irritants in the form of vapor sprays or ^