Document YGN7OabJDwZmxKODdLgx4VnNO

HEATING VENTILATING AIR CONDITIONING GUIDE 1940 duals who react abnormally to' the offending substance. The reaction may be induced by inhalation, eating, or absorption (through the skin) of the allergens. Some of the clinical manifestations are hay fever, asthma, eczema, and contact dermatitis. Symptoms of Hay Fever and Asthma The respiratory tract is the site of probably the most usual allergic manifestations, the so-called hay fevers and asthma. In hay fevers, the nose and eyes are red and itchy, and there is considerable discharge. Nasal obstruction is the most common and most distressing symptom. The severity of the symptoms varies widely from day to day depending chiefly on the amount of pollen in the air. Seasonal asthma comes in attacks. The most popular theory concern ing the mechanism of action is that the offending substance irritates the nerve endings in mucous membranes of the respiratory tract, causing spasmodic contraction of the small bronchioles of the lungs, which interferes with breathing, particularly with expiration. Non-seasonal allergic disturbances are sometimes attributed to house or street dusts, fungi, odors, animal dander, irritating gases, and heat or cold, particu larly sudden temperature changes. It is often stated in the literature that heat regulation in asthmatic individuals is likely unstable, with a tendency toward the subnormal. Many allergic cases who are ap parently well, develop their attacks when cold weather appears, or upon changing from warm to cool outdoor air. Air Conditioning Apparatus In recent years considerable effort has been directed toward the elimi nation of the principal cause of allergy from the air of enclosures by filtration or other air conditioning processes capable of removing pollens, in the hope of providing relief to individuals who fail to respond to medical treatment (desensitization or immunization). Paper or cloth filters, mounted in inexpensive window or floor units, prove quite satisfactory, but since dust and smoke "frequently cause asthmatic attacks, it is necessary that an air filter, to be of full value in the treatment of asthma, must remove all dusts and pollens regardless of size or amount. An electrostatic cleaner has proved extremely efficient in removing particles of 15 to 20 microns and smaller, besides dusts and smoke17. Although the chief remedial factor in the treatment by conditioned air is the filtration of pollen, a certain amount.pf 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 satisfactory18. Direct drafts, overcooling or overheating are apt to initiate or aggrevate the symptoms. Limitations of Air Conditioning Methods The results obtained with air filtration or other air conditioning pro- *fAir Cleaning as an Aid in the Treatment of Hay Fever and Bronchial Asthma, by Leo H. Criep and M. A. Green (Journal of Allergy, 7: 120, January. 1936). .iThe Effect of Low Relative Humidity and Constant Temperature on Pollen Asthma, by B. Z. Rappaport, T. Nelson and W. H. Welker (Journal of-Allergy, 6: 111, 1935). :580 CHAPTER 32. AIR CONDITIONING IN THE TREATMENT OF DISEASE 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 desensitizatiori is preven tive and in a few instances curative for all practical purposes, filtration gives only temporary relief. With rare exceptions, the' symptoms recur on exposure to pollen laden air. Moreover the usefulness of air condi tioning methods is limited because all cases are not caused' by air-borne substances. Cases of bacterial asthma do not respond at all to the treat ment 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 fmiltoesrtedofatihr.eir symptoms within 1. to 3 hours after, exposure to properly A pollen-free atmosphere is especially valuable in cases where desensiti zation has given little or no relief, and where desensitization is not advis able owing to intercurrent illness. On the whole, conditioning'methods are considered to be a valuable adjunct in medical diagnosis and treat ment of allergic disorders. 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 imnfeannttasl. disturbances, asphyxia, asthma and atelectasis in new-born The ncessity 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 and oxygen chambers. The oxygen rich atmosphere in these enclo sures 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 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 TO lb per hour gives" satisfactory results in patients with fever in a medium size oxygen tent. Oxygen tents are somewhat confining to the patient; the restless type of person.is difficult to control, and the delirious, impossible to control. 581