Document b5d6Kw6jDJVvaprYane6yRwyy

144 CHAPTER 7 1950 Guide mature infants. Additional heat for weak (or debilitated) infants may be furnished in the cribs or by means of electric incubators placed inside the conditioned nursery, and the temperature adjusted according to individual requirements. In this way multiplicity of chambers and of air conditioning apparatus is obviated; the infants in the heated beds derive the benefit of breathing cool humid air, and the nurses and doctors need not expose themselves to extreme conditions. Importance of Humidity: Although external heat is an important factor in the maintenance of normal body temperature, humidity appears to be of equal or greater importance. When the premature nurseries at the Children's Hospital were kept at relative humidity between 25 and 50 per cent for two weeks or longer, the body temperature became unstable, gain in weight diminished, the incidence of gastro-intestinal disturbances increased, and the mortality rose. On the other hand, continuous ex posure to air conditions with 55 to 65. per cent relative humidity gave satisfactory results over a period of years. The initial physiologic loss of body weight (loss occurring within first four days of life) was found to vary inversely with the humidity. In the old nurseries with natural humid ity it averaged 12.4 per cent of the birth weight; in.the conditioned nur series it was 8.9 per cent with 25 to 49 per cent relative humidity, and 6.0 per cent with 60 to 75 per cent relative humidity. The number of days required to regain the birth weight was correspondingly maximum in the old nursery, and minimum in the conditioned nurseries under high humidity. Maximum gains in body weight occurred in the conditioned nurseries under high humidity (55 to 65 per cent) in infants weighing less than 5 lb. The gains were less under low humidity (25 to 50 per cent) in the same nurseries, and in the old nurseries prior to the installation of air conditioning apparatus. The incidence and severity of digestive syndromes, with diarrhea, per sistent vomiting, diminishing gain or loss of body weight, and other symp toms, were generally from two to three times as high under low as under high humidity. Summarizing, the best chances for life in premature infants are created by maintaining a relative humidity of 65 per cent in the nursery, and by providing a uniform environmental temperature just sufficiently high to keep the body temperature within normal limits. Medical and nursing care are, of course, factors of equal and sometimes of greater importance. Air Conditioning Equipment Many of the installations now in use are of the central system type pro viding for filtration, for humidification and heating in cold weather, and for cooling and dehumidification in hot weather. A ventilation rate, be tween 8 and 12 air changes, is desirable to remove odors and maintain uni formity of temperatures in extremes of weather. Recirculation should not be used in these wards owing to odors and the possibility of infection. There should be a frequent change in spray water. Control of Airborne Infection The protection of the premature and older infant against infection is of the utmost importance. It was found in one installation equipped with air conditioning, germicidal lights and mechanical barriers that air con ditioning alone did not prevent the spread of respiratory cross-infections.31 Bacterial ultraviolet barriers, air-conditioning and mechanical barriers are Air Conditioning in Prevention and Treatment of Disease 145 efficient. However, infections are brought in by, and often spread by, ward personnel in spite of these measures. FEVER THERAPY Artificial production of high fever in man can be considered an imitation of nature's way of overcoming invading pathogenic organisms. The action may be direct and specific by (destruction of the invading organism within the safe limit of human temperatures, or indirect in the case of heat re sistant organisms, by general mobilization of the defensive mechanisms of the body. Although the action may be direct and specific by destruction of the invading organisms within the safe human limits, fever therapy exerts much of its benefit through the improvement of the mechanism of bodily defense. A serious challenge to the theory on which fever therapy is based comes from the demonstration that high fever causes a reduction in the concentration of circulating antibodies in experimental animals. Patients for fever therapy should be carefully selected. The most serious complications which may arise are heat stroke, heat exhaustion and cir culatory collapse. The chief minor complications are heat cramps, fever blisters and mild dehydration. The limits of induced systemic fever are usually between 104 and 107 F (rectal), and the duration from 3 to 8 hours at a time. The total period of fever treatment varies with the type of the organism involved. The diseases which respond favorably to artificial fever therapy are gonorrhea and its complications (which include arthritis, pelvic infections in women, and involvement of the eye), syphilis and chorea. The most striking results are seen in gonorrhea and syphilis, since the causative organisms can be destroyed at temperatures compatible with human life. However, the use of fever therapy has decreased since peni cillin has been found so effective in the treatment of gonorrhea and syphilis. Mild fever, up to 101 F for one hour has recently been used in the treatment of rheumatoid arthritis. This degree of fever is not bactericidal but is believed to stimulate the body defense mechanism. Equipment for Production of Fever r Artificial fever can be induced by injections of various crystalloid or colloid substances, bacterial products of typhoid and malarial organisms, or by physical methods using hot baths, radiant heat cabinets, hot humidi fied air cabinets, or by short wave diathermy in combination with a cabinet. The relative advantages of various methods have been evaluated clin ically.32 Among the devices for the production of fever by physical means, the one most widely used is the hot humid air or air conditioned cabinet. This apparatus was developed at the Kettering Institute for Medical Re search at Miami Valley Hospital in Dayton, Ohio. In the earlier studies of the Society, temperatures were elevated more easily using saturated atmospheres. A fever therapy apparatus33 using these same principles has proved efficient as a means of inducing and main taining fever in a body, with small likelihood of burns because of the com paratively low dry-bulb temperatures. When heat is necessary in treating legs or arms, such media as short or long wave diathermy, micro-waves, infrared, water baths, etc., have been