Document NN214xr4xpNNGLYG9gQ0KGXER
600 HEINZ SPECHT
by Behnke and Yarbrough82 and Case and Haldane88 that helium reduced
severity of a syndrome that attends exposure to high pressure atmospheresffii
10 atm., even though oxygen tensions were maintained at the normal leveijf
work resulted from an attempt to find a diluent for oxygen less solublg'ffcS'g!
nitrogen. According to. Behnke and Yarbrough82 argon and. nitrogen
narcotic, effect at high atmospheric pressures that is proportional to the m'$jj|
weight and oil/water solubility ratio. Recently it has been shown thatglel
helium, and argon have definite effects in man and lower animals-thalf
probably physicochemical in mechanism, but for which there is at prelsgn|
even a hypothetical basis for action.87'89 The correlation between th#l$p!2
responses of the inert gases and their oil/water solubility ratios, as is ;trS
narcotic substances generally, and the common property' of a lack o'fp!|
chemical effects lend substance to the claims of Behnke.
*lH
5. Effects of Temperature and Humidity
m
At the pressures existing in most caisson installations the incidjn|i
disturbances during maintained pressure is very low, but nevertheless afl
exposures some prostrations have been reported. At the level of pressure',exaitli!!
these instances there is no reason' to expect "oxygen poisoning," and
impossible to show such effects in experimental work on animals in
air.88 Disorientation, epileptiform seizures, and painful cramps of the^rr"
legs seem to be the most marked symptoms and are not readily differl from the syndrome'"appearing after decompressionrThere"is"thus_ffqH^^
that with complete saturation at even moderate pressures disturbancMpp
origin may be expected. It is possible that in actual practice other fa||gcf as heat and humidity, play , a role not fully recognized because the:-af|e
investigators is drawn by the hazards of compressed air as discusso'd*||k
The effects of temperature during positive pressure work shifts-. a|ej
to those at normal atmospheric pressure except for qualitative^aiM. brought about by the fact that humidity values are always high, and|^&
modes of heat loss are thus restricted to radiation and convection. Te^^iS
of 90.0 F. are often encountered in caisson work because of the lao||||
exchangers between the compressors and the inlet ports to the cai: exposed-situation-of some-equipment.-Irr-such-an-environmente:prosrrnm'n..{!
to excessive sweating and circulatory disorders are bound tor.ocgl^fflra^
that these reactions are subclinical but followed by uncritical1'dMoinpre-l
they may act as predisposing factors for the sequelae of bends and mon__^
responses. In all caisson work ventilation is effected in one..,way^onaannljb,Mg there are minimum rates set up by local authority that are designedh'tojK
the accumulation of C02 respired by the workers.42 In general :tmstve|r|i||
does not serve to lower the temperature of the caisson.
, >fu
"A. R. Behnke and O. D. Yarbrough, Am. J. Physiol., 126, 409 (1939).
:\
EFFECTS OF ABNORMAL ATMOSPHERIC PRESSURE
601
6. Other Effects and Subjective Responses
the attainment. of positive pressure levels seems to result in ration or euphoria, which has been thought to be reflected in an ^capacity for muscular work,88 but the effect soon gives way to a deitale. Disturbances of the senses of smell and taste may appear. Alteraf'voice are a constant feature of speech in compressed-air atmospheres. Ration for this phenomenon has not been established, despite attempts thtit density and its effects on the resonance chambers of the head and office similar changes. The same changes and difficulties of speech, nasal
fffea' sounds, and straining of the muscles of the larynx, can be elicited at |essure when breathing oxygen mixtures containing hydrogen or helium, cSnge back to the normal tone can be effected by increasing the
.-pressure of such mixtures. As far as can be ascertained these changes (impressed air are strictly reversible except perhaps for the soreness of the aipTurfaces and muscles produced by straining.
'CHARGE OF GASES FROM THE BODY FOLLOWING EXPOSURE TO INCREASED ATMOSPHERIC PRESSURE: DECOMPRESSION
Mechanical Effects
nssion of the mechanical effects of decreasing the pressure of the gases
ding the body may be arbitrarily limited to the condition that a discrete
.b.e_presen,t,^s.in..the.middle_ear, intestinal gases, etc. Although
ofquestion that gases freed from solution do exert a mechanical effect | and intravascularly, the latter will be considered separately.
^middle ear there is usually no serious effect unless complete closure of
fnian tube has occurred. Since this condition would have precluded en%6'sitive pressure, the incidence of middle ear troubles is low.-The same
ghe effects on the sinuses, and even though some blockage may occur,
Mat develop are mainly from displacement of tne tissues and ischemia
u|ous linings and are relatively minor. It is possible that movement of
Ipyindow separating middle and inner ear lumens',may permit injection
7of the capillaries in the inner ear. This eventuality has a more
Q^Qsis_than.similar..traiuna in.the .middle..ear-.becausnlt-maylresult in g* of the receptor tissues of the cochlea and consequent deafness to ^equencies of sound.
'"ugh the expansion of intestinal gases is a potential hazard in decom-
.ptle mention of it is made in the literature. This is gerhap_s due to the
^prroiwoiiFiSd-divtBr
hccom-
||qre the shift is over and also to the indoctrination of workers in dietary
that avoid gas-producing food. In any event the presence of intestinal
.ffe. _
.
,,
Gerbis and R. Koenig, Drucklufterkrankungen. Thieme, Leipzig, 1939.