Document B8wRzeK0K8OG3KkZo1Kxkja7o

602 HEINZ SPECHT gas -during rapid decompression will cause .discomfort only in proportion^ expansion ratio effected in the routine followed. Since in most cases this Ml the Haldane or Bornstein stage method of decompressing to half pressure,14'58 the expansion will be some two times (greater by the .e|| water vapor10) the voluine at equilibrium. In most cases this is a n||j^ stimulus to the smooth muscles of the gastrointestinal tract and results,|feli expulsion of the gas. _v A more serious consequence of mechanical nature is the rupture of during even moderate decompressions because of the failure to. keep tory passages open.54 This rupture occurs mainly in cases of submarine',, .ges! where a tendency to hold the breath is the natural result of apprehcnsiiM^ unfamiliarity with the unusual environment. The incidence in caisson :wpsl?N and divers is undetermined, but the individual should be warned agaihsj|j holding during decompression. &. Bubble Formation 'I5* The rate of removal of a gas from a fluid must keep pace with theite;^ to desaturation resulting from a fall in total pressure if the formation*'^ gas phase, i.e. bubbes, is to be prevented. The physiology of bubble' torr^ may be best evaluated by a consideration of the mechanism based on the'^kM theory of gases. The molecules of a liquid may exist in the gaseous efat|' whfle_inthe_gasequs state they have a higher average energy eonten.ftt@ fellows irTthe liquid rtaterPresumably,"tTi'M7tEe'average energy < dissolved in a liquid composed of other molecules becomes equal to; tho;^er. energy of the liquid molecules. A bubble of gas will not form unlo^^ufll^ energy is applied to enough gas molecules in a restricted locus M?resu|_rJm|wlS| placement of the liquid molecules. The chances for the spontaneous" of such energy quantities are very slight and it is generally assumea''.th|fS? gas or vapor spaces large enough to permit initiation of bubbles ar&^^yjgj at liquid-solid interfaces under natural circumstances.55-57 These sp.i|^^ termed "gas nuclei." (Harvey58 has been instrumental in popularizihg%rn but it is probably less oonfusing to call the spaces bubble nuclei.y^-~AP The data gathered from many experiments on degassm||f|l: Ficcard,56 Harvey et of.,59 and Dean57TndicaTelhafa iree-gal'-^ytM "X. B. Polak and B. H. Adams, V. S. Naval Med. Bull., 30, 165 (1932);.'^"J. B. H. Kuper, Rept., Aviation Medicine Unit, Ind. Hyg. Research*-hah. Health, Bcthesda, Md. (1942). 1 __ ...'(s --''"t*$r^KCK&^P$ocr-&idjJ~M`eeiinffs-May'o^Qlinic,-16i-7.QQ-(A$&l).t^Z. "R, B. Dean, J. Applied Physics, 15, 446 (1944). ( fl_ , "E. N. Harvey, A. H. Whitely, W. D. McElroy, D. C. Pease, and D. K. Bainesfls lar Comp. Physiol., 24, 23 (1944). ` `" 68E. N. Harvey, D. K. Barnes, W. D. McElroy, A. H. Whitely, D. C Pmo/yi<> Cooper, J. Cellular Comp. Physiol., 24, 1 (1944). EFFECTS OF ABNORMAL. ATMOSPHERIC PRESSURE 603 g&pace is present into which the gas may diffuse. Relatively enormous ||||ations are possible in the absence of such bubble nuclei. It is probable ||normal life conditions nuclei exist in profusion, specifically at such ipn substances active in the transfer of gases, such as hemoglobin and ijratory pigments. The question of the ultimate locus of bubble formation m being actively investigated at this time, and until definitive evidence |K|||o-further analysis can profitably be made. joru^he work of Gerah60 it is indicated that a gross correlation of the jjftfMution. of bubbles with that of fat tissues is found in decompressions from ^^etMessure. It seems that these loci by virtue of their relatively high gas ``ifjajge at least the requisite condition for maintaining patent bubbles |||ji.ot they offer the highest incidence of nuclei among the various jffln& body. In point of time it is evident, however, from these data that ffifthe vessels appear in greater number than bubbles in fat, at least in "Mtages of this condition. afey,olution of gases from solution in the various tissues of the body on Jffsion gives rise to the main body of sequelae and forms the basis of the MeM disease of workers in compressed-air atmospheres. The essential ||nat on decompression the body fluids are supersaturated to a varying bfending on the pressure attained and the time of exposure. If the super- Fatjjohs-is great enough in the face of a continuous loss of the gas through ||||||||and respiration, then discrete gas phases will form, both intra- and Blarly. These accumulations of gas then act to disturb the normal tissues in which tney appear'in proportion to their number and Bin the vascular system bubbles are found to form largely in the venous |||they are carried to the right heart and lungs where they accumulate |||onsible for the symptoms known as the "chokes."61 This is a disability "ffdegree, depending upon the extent to which the circulation of the lungs pd.with. In general, it is considered a serious condition and recompres|j|nted as quickly as possible. The appearance of, bubbles in.the blood is Kcftompanied by appearance of bubbles in the various tissues, the fatty png most subject to bubble formation.62'68 While the cause of the ffiggjf "bends" and other peripheral symptoms, such as pruritus, tingling ||an|l joint and tendon pain, is still a moot point,(thereJs^little, doubt ffisraceJbffffiuBuBbles'constitutes'one' of^th'e'iiibst'rea'sbnabl^eMechanisms ' Wfc, j8$TM, G. E. Hawkinson, and E. H. Jenney, Naval Med. Research Inst., Research JM, Rept. No. V (1944). Also in J. Cellular Comp. Physiol., 26, 63,.(1945). SrljK, Naval Med. Research Inst., Research Project X-S84, Rept. f^'X '(i945). Also i|BC!omp,vg)n/stokH26i--10kCi945)...-.. ...... -- . ................. ................................ 1pb G. E. Hawkinson, E. N. Rathbun, and A. R. Behnke, Naval Med. Research Mfih Project X-S84, Rept. No. II (1944). Also in J. Cellular Comp. Physiol., 24, 35 Jfreh, Naval Med. Research Inst., Research Project X-S84, Rept. No. IX (1945).SjtSiytWd., Rept. No. IV (1944).