Document wg9DXZDJp7yLE5p8o01YRBvqD

100 CHAPTER 8 1960 Guide (5) A double-chambered cabinet using dry ice has been constructed. (6) Electrical refrigerating apparatus, consisting of & com pact noiseless unit that pumps fluid to various types of ap plications, is available. The applicators may be in the form of blankets containing rubber tubes suitable for covering the entire body, or &U or part of a limb. Special applicators are available for insertion into various body cavities, and for in ducing dental anesthesia. (7) An air chamber at regulated temperature for treatments of frostbite and immersion foot, and amputation stumpa The electrical apparatus is costly, but has the advantages of thermostatic regulation, light weight, freedom of move ment, and permits prolonged treatments with heat, as well as cold over the range of temperatures therapeutically desirable. ALLERGIC DISORDERS Hay fever, asthma, eczema and contact dermatitis are classified as allergic disorders. The allergic individual re sponds to contact with a variety of substances, which are innocuous to a non-allergic person, with severe manifesta tions of hypersensitivity. These substances are known as allergens and consist of airborne irritants such as dusts, molds, feathers, pollens, animal dander and others; of food protein such as milk, wheat, eggs, etc., or of ample chemicals brought in contact with the skin. They may enter the body by various routes of which inhalation is the most common type. Ingestion of offending food substances is not infrequent. The offending substance reacts with the sensitized cells of the mucous membranes or skin. During this reaction, histamine or a histamine-like substance is released and causes (a) increased capillary permeability, (b) secretion of mucus and (c) muscular contraction. In the eyes and nose this produces itching, redness and lacrimation or rhinorrhea, in short, the symptoms of hay fever. In the lungs it causes, in addition to the secretory response, a contraction of the smooth muscles of the bronchi resulting in a bronchial asthma. It is commonly known that non-specific environmental factors such as dust, irritating gases, change of temperature and humidity may precipitate asthmatic attacks in allergic subjects, even in the absence of exposure to specific allergens. It is assumed that the presence of frequent allergic bronchial constriction renders the smooth muscles of the bronchi so sensitive to various non-specific stimuli that the threshold of their response to such irritation is considerably lower than that of a non-allergic individual. Air-Conditioning Apparatus Of all the measures to relieve a specifically sensitive in dividual, elimination of exposure to the responsible allergen is the most efficient, though not always a practical, form of treatment. In recent years considerable effort has been made to accomplish, such elimination by removal of respiratory allergens from enclosures by filtration or other air-condition ing processes. Paper or cloth filters, mounted in inexpensive window or floor units, prove quite satisfactory in many cases, but since dust and smoke frequently cause asthmatic attacks, it is desirable that an air filter, to be of full value in the treat ment of asthma, should remove all possible dusts and pollens regardless of size or amount. Electrostatic air cleaners are more efficient than most commonly used types for capturing very fine dust. Although the chief remedial factor in the treatment by conditioned air is the filtration of pollen, & certain amount of cooling and dehumidification appears to be desirable. A comfortable temperature between 70 and 75 F, and a rela tive humidity well below 50 percent has proved satisfactory." 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 con ditioning processes, in the control of allergic conditions, are fairly comparable to those obtained by desensitization treat ment, so long as the patients remain in the pollen-free at mosphere. For all practical purposes filtration gives only temporary relief. In mild cases deeping in as air-conditioned space may make it possible for the individual to pass more comfortable nights. With rare exceptions, the symptoms recur on exposure to pollen-laden air. Moreover, the useful ness of air-conditioning methods is limited, because all cases are not caused by airborne 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, con venience, and under certain conditions, almost immediate relief." Pollen cases are usually relieved of most of their symptoms within 1 to 3 hr after exposure to property filtered air. A pollen-free atmosphere is especially valuable when desensitis&tion has given little or no relief, and when desensitization is not advisable owing to intercurrent illness. OXYGEN THERAPY Oxygen therapy is used to prevent or relieve anoxia. Some of the more important clinical conditions in which oxygen treatment is beneficial include pneumonia, severe anemia, cardiac decompensation, pulmonary atelectasis, asphyxia and asthma. The effectiveness of oxygen therapy is dependent on the concentration of the oxygen in the inspired air, or the partial pressure of oxygen in the pulmonary alveoli. Oxygen is usually administered by nasal catheter, face mask or tent.- 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 and oxygen chambers. Air conditioning is applied to the oxygen tent or chamber through reconditioning of the atmosphere in a closed circuit. Excessive heat, moisture and carbon dioxide are removed. 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, in creasing 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 hr gives satisfactory results in patients with fever in a medium size oxygen tent. Oxygen tents are confining to the patient. They may -terrify the restless and delirious patient. Medical and muting Ajr Conditioning m Prevention ond Treatment of Disease 101 care is complicated, as the tent must be opened or removed with attendant loss of oxygen. Oxygen concentrations of 50 percent 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. Iu fact, during hot humid weather as oxygen tent may be very valuable in controlling a patient's temperature, since the upper part of the body within the cooled tent loses heat rapidly. Oxygen in Aviation An important application of the principle of oxygen ther apy is in aviation. High altitude military airplanes in this country are normally provided with gaseous oxygen equip ment, 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. Today all large passenger aircraft are pressurized to pro vide passenger comfort in flight at altitudes of 20,000 feet or more. Smaller civilian aircraft are usually not pressurized and must carry gaseous oxygen equipment where appreciable altitudes must be attained. GENERAL HOSPITAL AIR CONDITIONING Complete conditioning of a large hospital involves a capital investment and running expenses which may not be justified. In clean and quiet districts, the requirements of almost all general and private wards during the cod season of the year can be satisfactorily fulfilled by the use of con ventional heating equipment, in conjunction'with window air supply and gravity or mechanical exhaust. Insulation against heat and sound is much more important than humidi fication in winter; thermal insulation will also help-in keeping the building cool in warm weather. Excessive outside noise and dust may require the use of silencers and air filters in the openings. Cooling and dehumidification in warm weather are im portant, In new hospitals particularly, the desirability of cooling certain sections of the building should be given seri ous consideration. Financial reasons may preclude the cool-, ing of the entire building, .but the needs of the average hospital can be met by the use of built-in room coolers and a few portable units which can be wheeled from ward to ward when needed. In the North, and certain sections of the Pacific Coast, cooling is needed but a few days during-summer, while in the South, it can be used to advantage from May to October, and in tropical climates almost continuously throughout the year. F. L. Grocott of the Anglo-Iranian Oil Co. found that in Iran, the medical staff after 10 years' experience with air conditioning, demand a uniform environment of 75 F and 50 percent relative humidity under all summer outdoor conditions for general wards and treatment rooms, and 70 F with 30 to 50 percent relative humidity for winter condi tions. In the operating rooms, 70 F with 50 percent relative humidity is demanded all the year 'round, although the annual external range is 40 F to 120 F. No ill effects have been noted in the medical personnel, though they are ex posed to changes from external to internal conditions many times daily. Temperature shock in either direction seems to create discomfort for a short interval, but if the individual is in good health, no injury results - Aside from comfort and recuperative power of the pa tients, cooling is of great assistance in the treatment of fevers in the new-born and in post-operative cases, in enteric disorders, fevers, heat stroke, heart failure, thyroid crisis, and in a variety of other ailments which often ac company summer heat waves. Problem of Odors Experiences in the evacuation of battle casualties in air craft and their subsequent hospitalization have stimulated efforts to find ways of minimising odors anting from drain ing wounds, dd odorous casts, and gangrenous wounds. For aircraft, chemical sprays and vapored 'perfumes, ' oxidizing gases and simple exhaust methods are unsatisfactory. An ideal deodorant would purify the air by means of odor adsorption so that subsequently the air could be recirculated. Based upon the effectiveness of activated carbon commer cially and industrially to adsorb odors, individual adsorp tion units have been used successfully. In hospital wards the feasibility of adsorption methods over other methods for elimination of odors remains to be answered.* REFERENCES 1 The Effects of Atomic Weapons (D. S. Government Print ing Office, revised September 1950). *J. G. Townsend, Mb.: Investigation of the smog incident in Donors, Pa., and vicinity (American Journal of Public Health 40: 183, February 1950). *C. P. McCord, MX).: The physiologic aspects of atmos pheric pollution (Industrial Medicine and Surgery 19:97, March 1950). 4 R, B. Bourdillon, 0. M. Lidwell, and J. E. Lovelock with W. C. Cawston, L. Colebrook, F. P. Ellis, M. V. Ende, R. E. .Glover, A. M. Macfarian, A. A. Miles, W. F. Raymond. E. Schuster, and J, C. Thomas: Studies in Air Hygiene (Medical Research Council of Great Britain, 1943, Special Report Series No. 262). *H. E. Rouge: Ultraviolet Irradiation with Artificial Il lumination (Uppsala, Sweden, 1943). *P. A. Bumicsnd: L'Hygiene du Batiment per l/Ultrotriolet (Centre Scientific et Technique du Batiment, Paris, 1949). 'Council of Physical Therapy: Acceptance of ultraviolet lamps for disinfecting purposes (Journal of American Medical Association-122: 03,1943). 'J. E. Perkins: Evaluation of methods to control airborne infection (American Journal of Public Health 35:891, 1945).' 'Committee on Evaluation of Methods to Control Airborne Infections of the American Public Health Association: The present status of the control of airborne infections (American PuMic Health Association Journal 37:13, 1947). "Subcommittee on Air Sanitation: Progress in the control of airborne infections (American Public Health Association Yearbook 40:5, May 1950, p. 82). "S. M. Wheeler and T. D. Jones: Factors in the control of the spread of acute respiratory infections with reference to streptococcal illness ana acute rheumatic fever (AmericanJournal of the Medical Sciences 209:58, 1945). *C. G. Loosli: Dust control, report on suppressive measures for the control of dust to the Standards Methods Committee for the Examination of Germicides and Antibacterial Agents (.American Journal of Public Health, March 1948, p. 409). "A. P." Krueger et &1: Laboratory and field studies of gly cols and floor-oiling in the control of air-borne bacteria (U. B. Nat/al Medical Bulletin 42:1288, 1944). "E. W. Dunklin and T. T. Puck: The lethal effect of rela tive humidity on air-borne bacteria (Journal of Experimental Medicine 87:87, February 1948). "Quotation by William Lester. Jr. in Health on the Job No. 22 (Institute of Industrial Medicine, New York Univer sity, February 1949).