Document ExwM9XY2qy7B8kGGgmMk2nZEb

HEATING VENTILATINC AIR CONDITIONING GUIDE 1940 days. Satisfactory conditions in the recovery ward not only hasten convalescence, but dispel the fear frequently found in patients who must undergo operations during the hot seasons*. , Sterilization of Air in Operating Room Of considerable significance to operating rooms and contagious wards is the use of ultra-violet radiation for sterilizing the air4. Results reported4 would indicate that the post-operative temperature rise of patients during the.first few days is in most instances caused more by bacterial contamination of the operative wound, than by the absorption of blood and'traumatized tissues.' Operating room infections, which were quite frequent.before the installation of special ultra-violet lamps, are ap parently, being reduced,, NURSERIES FOR PREMATURE INFANTS One of the most important requirements in the care of premature infants is the stabilization of body temperature. This is because their heat regulating systems are not fully developed, the metabolism is low arid the irifants generally exhibit marked inability to maintain norinal .body, temperatures. The resistance to infection is low and mortality .rate high. 'Air Conditioning Requirements * The optimum air conditions for the growth and development of these infants were determined by extensive research7 at the Infants Hospital, Boston, Mass., .using four valid criteria, namely, stability of body temperature, gain in weight, incidence of digestive syndromes, and mor tality. Individual temperature requirements varied widely (from 72 to 100 F) according to the constitutional state of the infants and body weights. The optirnum relative humidity was about 65 per'cent, and the air movement less than 20 fpm. A single nursery conditioned to 77 F and 65 per cent.relative humidity was found to fulfill satisfactorily the requirements of the rnajority of premature'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 arid - 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 r 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. Wien the premature nurseries at the Infants Hospital were kept at relative humidity between 25 and 50 Report of the Committee on Air Conditioning (The American Hospital Association, 1937, p. 2). Air-Borne Infection and Sanitary Air Control, by W. F. Wells (Journal Industrial Hygiene, 17:253, 1925). Sterilization of the Air in the Operating Room by Special Bactericidal Radiant Energy, by Deryl Hart (Journal Thoracic Surgery, 6:45, 1936). The Premature Infant: A Study of the Effects of Atmospheric Conditions on Growth and on Develop ment. by K. D. Blackfan, C. P. Yaglou and K. McKenzie (American Journal Diseases of Children, 46: CHAPTER 3Z AlR CONDITIONING IN THE TREATMENT OF DISEASE 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: exposure to air conditions with 55 to 65 per cent relative humidity gave satisfactory results over a period of years. The effect of humidity on mortality is shown in Table 2. 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 humidity it aver aged 12.4 per cent of the birth weight; in the conditioned nurseries it was 8.9 per cent with 25 to 49 per cent relative humidity, and 6.0 per cent with 50 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 Table 2. Net Mortality of Premature Infants According to Humidity2 _Infants Hospital, Boston, Mass. Unconditioned Nubseriks (1923-1925) Conditioned Nurserum (1926-1929) Cause or Death Natural Huumn-r Relative Huwditt 25-49 Per Cent 50-75 Per Cent Per Cent Mortality Per Cent Mortality Per Cent Mortality Acute and chronic infections._ Congenital deformities............... Unclassified........... ...................... 26.5 1.2 1.2 9.7 0.0 0.0 0.7 4.8 0.0 All causes.. .28!.9 - r14.5 0.7 ^Excluding cases with multiple congenital-anomalies incompatible with life, and also deaths occurring1 within 4$ hours after admission to the hospital. .. <- 5 lb..''The gains were less.under low humidjty (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, persistent vomiting, diminishing' gain or loss of body weight, and other usynmdeprtohmigsh, whuerme igdeitnye. rally from two to three times as high under low than 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 Most of the installations now in use are of the central system type' providing, for filtration, for humidification and heating in cold weather,, 577: