Document k9rq168nw34Be9YXOwk3RavNb

CHAPTER 7 It is generally , reported .that dry-bulb temperatures of:76 to 78 F with .55^ percent relative humidity not only furnished comfort for the operating room?1.; workers, but apparently prevented exhaustion of patients as evidenced by?w rapid convalescence in the recovery ward. Additional heat may biefff furnished to patients locally or by suitable covering, according to bodyrj^,' temperature in individual cases. : In the control of airborne infection in the operating room, the prevention'll of dispersal of infectious materials into the air, control of dust, and proper^ ventilation supersede attempts to remove or kill pathogenic organisms/^,! The bacterial content of conditioned operating rooms is generally lower5.1,) than that of non-conditioned rooms. Bacterial counts aboard an air-conditioned submarine were found to exceptionally low and not cumulative with time, although all of the air was recirculated for more than 12 hours88 without replenishment. The;j? removal of bacteria by the process of air cooling and condensation of mois-'Ji ture out of air, merits further study.38 The degree of air contamination can be reduced by proper ventilation^ if velocity of air over the floor does not exceed 50 fpih. Research isin^jj progress on the use of. filtered air flowing through a system of mechanical?.'? cleaners .which protect .the patient against infection from attendants, and'jS from bacteria-containing air in the corridor or ward?40 ' Operations are frequently postponed on allergic patients during asthmatic' manifestations through fear of complications. The removal of airborne*!? allergens, therefore, is in some cases an important function of the air coi&ll ditioning system in preparing patients for operation. ,.f'i The best practice in air conditioning hospital operating rooms is the use;;! of all outside air with arrangements for preheat, reheat, And the control of?;; humidity, coupled with a mechanical exhaust system that removes fhe air->; from both the high and low levels of the operating room. However, there?; is some evidence regarding the lack of any cumulative effect on bacteria:?5? count through the recirculation of air through an air conditioning unit iiiA; operating rooms. This consideration and the fact that relief cooling fre:V-, quently provides improved, if not ideal conditions, has lead to the use oL> central systems employing 50 percent recirculated air. Also, perhaps as'a|t recognition of practice, the NBFU Pamphlet No. 56 outlines the conditions'.? under which room air conditioners may be used in operating rooms. The*-', conditions are so written in the pamphlet that the recommendation of sep;i;i arate mechanical ventilation of such rooms is clearly inferred. Stated in the reverse order, room air conditioners for relief cooling of;;: mechanically ventilated rooms are now considered permissible when used`s with the necessary precautions. These precautions are not generally asj|. sured by the use of standard room air conditioners as produced by tK||| manufacturers, and are frequently costly of accomplishment in the fieldSI The use of larger systems employing 50 percent recirculated air is a recogm! nized practice. It is certain that such a system must have the necessar^f precautions (regarding the electrical and air moving equipment) against^: the hazard of gross spillage of the anesthetics. Systems using 100 percent'! outside air and adequate air removal means are regarded as following th best practice. The choice between the systems is usually made on tH& basis of first costs. As compared with the other daily usage costs of Wjgj operating room, the differences between the operating costs of the various!! systems is not a significant item. ?|j Good thermal construction of the operating rooms is a recommended, practice. Much can be gained by thermal insulation of sterilizing equip; -Air Conditioning in Prevention and Treatment of Disease 141 ment, and by through exhaust ventilation of sterilizing rooms adjoining the operating rooms. Glass surface should be kept to a minimiuh, particu larly in walls exposed to the sun. Double windows are desirable and often necessary to prevent condensation on the glass in cold weather. The equipment capacity and control methods must be properly selected for the type of system employed, and for the thermal loads encountered. The resulting air flow rates are usually in the range of 8 to 12 changes per hour. The method of air introduction should be selected to keep air movement in the operating area under 50 fpm. Where all outside air or a large per centage of outside air is used, the air introduction and exhaust arrange ments should be designed to provide a thorough air change in all parts of the room. This may be accomplished by introducing the air at one side and exhausting it from the other side of a small room or by introducing the air at the center and exhausting from the sides of a large room. ; The supply and exhaust arrangements can be exchanged in the case of large rooms. An air conditioned recovery ward in connection with the air con ditioned operating room, is of great value in stabilizing peripheral circula tion, and in reducing excessive loss of fluids on hot humid days. NURSERIES FOR PREMATURE INFANTS . One of the most important requirements in the care of premature infants is the stabilization of body temperature. This is necessary because the infant's heat regulatory system is not fully developed, with the resultant tendency for environmental temperature to influence body temperature. The younger the premature infant, the greater is the tendency. As the infant's metabolism is low, heat production is not adequate to maintain a normal body temperature in a cool environment. The resistance to in fection is low, and the mortality rate is high. In general, the younger the age of the premature infant, the higher the mortality rate. Nurseries constructed for metabolic research should be air conditioned so that conditions are reproducible. Results of such studies may be in valid if environmental conditions are not identical, since fluid and electro lyte loss may vary greatly with change in environmental conditions. Air Conditioning Requirements. The optimum air conditions for growth and development of premature infants were determined by extensive research41 at the Children's Hospital, Boston, Mass., using four valid criteria, namely, stability of body tempera te*!' jam *n welght, incidence of digestive syndromes, and mortality. Individual temperature requirements varied widely (from 72 to 100 F) according to the constitutional state of the infants and body weights. ne optimum relative humidity was about 65 percent, and the air move ment less than 20 fpm. . . , ^ _single nursery conditioned to 77 F and 65 percent relative humidity lound to fulfill satisfactorily the requirements of the majority of prer V1 mfants. Additional heat for weak (or debilitated) infants may be rnn^veCl!? cr*^s or by means of electric incubators placed inside the reauirne+nUrTer^' an<* temperature adjusted according to individual annarof16 - ' . - t*1is way multiplicity of chambers and of air conditioning of hrpntk' 1S 0 ,lated; the infants iii the heated beds derive the benefit tthhepmmsceolvimesn?to00e0xtrebmume idcoanidr,itiaonnds. the nurses and doctors need hot expose in the^rn^t6 humidity: Although external heat is an important factor i amtenance of normal body temperature, humidity appears to be