Document LJRxVG2jv4yOEXveLk7LmoOnw

606 HEINZ SPECHT and humid atmosphere. This practice is based on the fact that peri] circulation is practically occluded. by vasomotor response to lowering'? temperature, and thus desaturation of the skin and adjacent tissues is pri, with the unpleasant results of bends, itching, and similar sequelae. ^ As suggested above, the desaturation procedures described here?! proceed without occasional symptoms of decompression sickness, -ao debility may appear for some hours after decompression because ofo;j from improperly desaturated nitrogen reservoirs. The subsequent lodfi such bubbles in a critical point of the circulation will bring about tn$ symptoms as mentioned above and in the same range of severity. TSfijf' necessary to keep decompressed individuals within reach of recom equipment and to apply pressure and ventilative breathing of oxyg'i remission of symptoms is complete.67 The re-solution of bubbles is;|| recompression conditions because of the decreased bubble surface "pre during recompression.66 Unfortunately, these procedures often have beei out on the worker's time, thus introducing a deterrent factor, and therefofj cases have been prolonged unnecessarily. In large part, the blame foriS compression technique falls on the workers themselves, since theyvii reckless in their baste to decompress and get off the job; and man^lS ill-conceived notion that they have tough constitutions that will enabld||l absorb such abrupt changes without permanent effects.48 . Repeated exposure to bends symptoms, and perhaps even the mer#ifj| of decompression wi_thout_discernible_symptoms, will_in time prodvid'eff those regions where bubble formation usually takes place.63 In gebb^ chronic lesions are situated in the joints and in other tissues with pooler They are thought to be the result of bubble trauma and repeated acutet! low-grade anoxia of the local tissues. They include: simulated arthriticpeff.eut of hip and knee joints; ankylosis of the incus, malleus, and stapc3 of thdijiiidTh ear; thickening of the drum; and so forth.68 / "'""iKfSBf IV. Effects of Reduced Atmospheric Pressure on the jViwfef Ascent into the atmosphere simulates physically the conditionV-'Tittcndin' decompression from increased atmospheric pressures. It will be seen, how,evi+;;t the ratio of pressure change permissible for the diver cannot be at taiijcrl.'lyjjt, aviator. Thus, divers can work at 10 atm., a ninefold differi 1 ; natural environment, yet at V* atm. there is serious disturbance' for and few, even hardened and acclimated, men have ever attained more than passing intervals.6 The difference in range is mainly duo tcfdhcjj ' --thAt4he^de6r^ewb-#ar-om'etr-io-pesSuF`6-on-^scent-to-sMtadd^Hl?es:atd:I component of the body's energy-liberating mechanism that it is unable' to any reasonable extent: oxygen. The following sections will deal wifhVMhS''' * other limiting factors in a manner comparable to that of the preceding.sejetto positive pressures. 'Sfi EFFECTS OF ABNORMAL ATMOSPHERIC PRESSURE 607 ^A. DISCHARGE OF GASES FROM THE BODY: DECOMPRESSION |n decompression from positive pressures, the reduction in environmental li'causes a differential pressure to exist between the gases dissolved in the Incbthe ambient atmosphere. In this case, however, the body is usually in P?equilibrium with the.inert gases and thus will be supersaturated as Igny ascent is begun. Obviously, the body will lose part of all the gases etUffit, even oxygen if the rate of ascent is abrupt enough, and this efflux lij'regulated by the access that the various parts of the body have to the ^hjis, the fatty tissues and those with poor vascularization will maintain Inferential pressure as compared with others more favorably endowed. 1. Bate of Ascent he present writing, the physical possibilities of rates of ascent can hardly gtimated. Given a suitable initial change of acceleration, the practical for the newer type of aircraft are actually beyond the capacity of the Upping with the changes in the environment; for example, the little |rocket-propelled "viper" developed by the Germans for use against nf>ers made a practically vertical ascent to over 30,000 feet in somewhat Ipo minutes, and it is probable that this is not the maximum that can gdjfor piloted aircraft. In any case, this rate of ascent induces a pressure si. of nitrogen of about 368 mm. Hg in a matter of minutes, discounting SjHnent the loss of nitrogen in this time from some of the tissues. Thus, seen below, ascents can be made in such time'ihtervals that the normal gcijgffis transfer cannot handle the amount of gas that tends to be freed ltlipn. aw and Gersh69 have shown that for rabbits the critical rate of somewhere near 7000 to 8000 f.p.m., even though the animals are ||gen during ascent. At 4500 f.p.m., survivals^at 45,000 feet for 30 icated that serious effects were not incurred at this rate. In human |s?dhs to altitude more conservative estimates must be made, first, If#bfcthe difference in size and vascularization as compared with those of |Mnals and, second, because of factors other thaii bubble formation. In asSm for experimental purposes.^where bends are to be avoided it has ^^^^?5er{oJascen3^arAbb^r^608i'an<i"',S6W(r"fjprmrTn''inclo'cfen'ati6h 'ffitfere, the rate of ascent has been set as high as 5000 f.p.m. In the latter %do occur in some instances and this routine has been used to assist ISm' air crews. The experience of the Army Air Corps79* shows that ^^Iffltin-feMtlLeaafeaiQf'-i&limbiiabout :50QQrf-.p:m.,-at-the4-time,mf:t,his fees a bends syndrome only above 18,000 feet, and the severity is contributing factors of exercise, cold, length of stay, and so forth... cWhpole and I. Gersh, Naval Med. Research Inst., Research Project X-ZS/,;' VS'i'/l.CJ946). Also in J. Cellular Comp. Physiol., 27, 15 (1946). Teeh' Manval 1-705 G941), 1