The Pulmonary Sequelae Associated with Accidental Inhalation of ...

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Baseline 5 25 50
CUMULATIVE DOSE (Breath Units)
FIo:oIOF: 2. Percentage of Loll fromml baseline FE\’
0 )i)so-rved soit Io tiot- didn’t-s iateol mnoiihe’l to uline
airway challenge iii tie’ 13 o.xisoseol u-orkers
1 50 tested 12 vo’.ors tI’ter oxposuro to (-illo)rimoo’ gos.
One in’eatio ommoitis coma1 too0)3W illll;llatio)IIod 1
mug/mill of mnttilao’holino
those with po)siti\’e airway responses to) methacholine
(N = 5) tended to) be older (p 0.004) and demonstrated
airflow obstructio)n (p = 0.03) with more air
trapping (p = 0.03) on standard pulmonary function
tests obtained within 24 hours of the exposure (Table
5). After controlling for age, we found that the degree
of air trapping on initial pulmonary function testing
was directly associated with airway reactivity only
among those who) were at least 35 years of age at the
time of the exposure to chlorine gas (data not shown).
The limited number of sUl)jects precluded a formal
multivariate
analysis.
D1s1sS1oN
Our findings suggest that short-term exposure to)
high concentrations of chlorine gas may lead to longterm
respiratory complications. We found that accidental
exposure to chlorine gas acutely maiuifests as
air trap)i11g. However, during the 12-year period of
observatio)n, we noted a progressive decline in residual
volume with 67 percent of those tested at year 12
having a residual volume below 80 percent of their
predicted value. This finding should be contrasted
with an expected increase in residual volume of 20
mi/yr given the age and height characteristics of our
study population. ‘ In addition, we found that five of
13 subjects tested at year 12 had an increased airway
reactivity to) inhaled methacholine and that the risk of
having reactive airways was directly related to) the
degree o)fairflow obstruction and air trapping that ‘as
observed immediately following the exposure.
The loss of residual volume iii our chlorine-exposed
cohort represents an important o)hservatio)n that helps
us to) piece together the findings from the other studies
that have addressed this type of ouma6mi.mS In
Table 6, we review the six other case series that have
evaluated the short- and long-term (at least one year
of follow-up) pulmonary changes in individuals acci-
dentally’ eXI)osed to high co)ncent rationis of chlori no’
gas. Of the four reports that actually prestiit ptilinonar
function results,l,10I5 studies56 report lower
than expected values for residual volume at tho’ emid
of the follow-up period. However, the most comprehensive
sttidy’5 to) date has found minimal changes in
residual \‘O)ltlfllC ( - 1 mllvr) during the six-ear folloxx’-
up peno)d. The inconsistency ofour findings with this
pre’is repo)rt is difficult to) explain l)LIt mnay reflect
the different exposure conditio )ns of on r respective
cohoorts. 1mm the only study2 that systemnatically revie\Ved
1)atients with isolated redtictioiis in I’csi(lual
volunie, toxic iruhalatiomus (ho’drocarbomus, amnmiio)ilia,
Table 4-Relationship Between Residual Volume at Year 12
and Clinical Charaiteristics* Within 24 hours of Exposure
to Chlorine Gas
o-ategorio.- variables are exI)resseol as tue frt’oiue’no.- (1o’rco-mot of total
smobjeets).
i10Si(iu1al\olimmoot it loam’ 12