Document k98RkdOj0BZ8bBZM4ekYdMLJ0

220 CHAPTER 13 ' . ; . : 1948 Guide Frequently from 50-to 75 per cent of personnel aboard-naval vessels operating in tropical waters-are afflicted with heat rash to a degree that interferes with rest and sleep. In carefully controlled experiments ir- it was possible to produce a fulminating type of rash in all men living continuously'at an effective temperature of 85 (90 F dry-bulb and 83 F wet-bulb). In the control group, 12 out of 24 hr were spent in a relatively cool atmosphere of 75 ET (80 F dry-bulb, and 70 F wet-bulb). These men either remained`free from heat rash or occasionally developed a mild" form. Thus, intermittent cooling to a degree which prevented sweating in men at rest eliminated a serious handicap to good performance of duty. In both laboratory tests and aboard hospital ships a relatively cool living environment of 76 to 78 ET provided an atmosphere conducive to rest and . sleep without sweating. Berthing spaces tended to have extremely low odor levels. Motivation, initiative and alertness, in con trast to the usual irritability and lack of incentive incident to residence in tropical climate, were maintained 1S. Little has been done, however, to obtain practical methods for appli cation of air conditioning under heavy heat loads and on the enormous scale that would be needed to modify life in the tropics. It is not im probable that cooled houses in a tropical climate, if used consistently for one generation, might modify the whole character of a population. The obvious advantages of part time cooling on personnel to promote rest and sleep in tropical areas would provide a prophylactic measure of great potential importance. TREATMENT OF DISEASE In the past few years considerable progress has been made in using air conditioning as an adjunct in the treatment of various diseases. Among the important applications are those in operating rooms, nurseries for premature infants, maternity and delivery rooms, children's wards, clinics for arthritic patients, heat therapy, cold therapy, oxygen therapy, X-ray rooms, the control of allergic disorders, and for the physiological effects in industry. OPERATING ROOMS The widest application of air conditioning in hospitals is in operating rooms. Complete air conditioning of operating wards is important because winter humidification helps reduce the danger of anesthetic gases; summer cooling with some dehumidification is needed to eliminate excessive fatigue and to protect the patient and operating personnel; and finally, filtering aids the removal of allergens from the operating room air. Reducing Explosion Hazard , Explosion hazards in operating rooms began with the introduction of modern anesthetic gases and apparatus. ' Ether administered by the old drop method gives rise to an explosive mixture, but in practice this -method is still regarded as comparatively safe. When ether is mixed with pure oxygen, or nitrous oxide in certain concentrations, the explosion hazard may be as great as with ethylene-oxygen, or cyclopropaneoxygen mixtures. Of the anesthetic gases nitrous oxide alone does not explode but sup ports combustion; Ether, vinyl ether, ethylene, and cyclopropane are as potentially dangerous as gasoline or illuminating gas in the home Air Conditioning in the Prevention and Treatment of Disease 221 Chloroform.does not explode violently in contact with flame but decom poses to liberate phosgene. All of the anesthetic gases and vapors except ethylene are heavier than air. Although the incidence of injury or death from explosion is negligible compared with other hazards in the operating room, the dramatic features surrounding an explosion justify continued investigation to"eliminate the hazard. -. During the course of ethylene anesthesia, the mixture, usually 80 per cent ethylene and 20 per cent oxygen, is so rich that the danger-of explosion is slight in the immediate vicinity of the face mask, but leakage .of ethylene into the air may.accumulate to any lower concentration, and thus introduce a serious hazard. . The.most- dangerous period is at the end of the operation when the patient's lungs and the anesthesia apparatus are customarily washed out with oxygen with or without the addition of carbon dioxide. Even.when this procedure is omitted, it is difficult in ;practice to avoid dilution of the anesthetic gas with air during the normal course of breathing following the administration. In either case the mixture would pass through the explosion range and extraordinary precaution is necessary for the safety of the patient and operating personnel. In a study u of 230 anesthetic explosions and fires, 70 per cent of the explosions and 60 per cent of the deaths were caused by igniting agents other then static sparks. In 1941 the National Fire Protection Associa tion 16 made certain recommendations for. safe practice based on available information. Some of these recommendations are: Windows should be kept closed so that the air conditioning system can prevent'pooling of-explosive anesthetic gases. Twelve air changes per hour and a humidity of 55 per cent, are advised. If a higher humidity were compatible with the well being1 of the patient and personnel, it should be maintained. All. electrical installations should comply with the standards set by the: National Electrical Code for- use in explosive situations. Cautery equipment should not be used in hazardous locations: To ^prevent: static sparks, all bodies in an operating, room should be conduc tive or coupled. It is essential that adequate grounding be provided for the' floor and every object in the operating- room. Conductive rubber should be used, on shoes, leg tips,.operating table coverings and all rubber parts of the anesthesia equipment. All-furniture in contact with the floor should be.metal. In the absence of Complete grounding facilities, the simple method: of intercoupling patient, operating table,- anesthetist and gas machine at ground potential ifiay.be used. :: Experience has shown that neither high humidity nor intercoupling devices have eliminated the danger from static electric discharge. The removal of gas concentrations from the operating table area by means of specially devised exhaust ventilation should be thoroughly tested. Port able duct-systems as installed aboard ship should be acceptable. Serious explosions can occur in a closed system but proper precautions will reduce this hazard to a minimum. ' It should be realized that when a room and the occupants have been completely grounded there is always the possibility that the patient- or the operator might receive a dangerous shock if a short circuit developed in any of the electrical equipment. A comprehensive study of the explosion problem and of the general causes and prevention of operating room hazards by the University of Pittsburgh, the A.S.H.V.E. Research Laboratory, and the U. S. Bureau of Mines has led to a fruitful, attempt to eliminate the explosive range of