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to identify patients with a preoperative diagnosis of sub-
glottic stenosis. Clinical records were then further screened
to select patients who met the inclusion criteria. All data
points, to include demographic, clinical, operative, labora-
tory, radiographic, and pulmonary functional data, were
entered in a Microsoft Excel spreadsheet. Data were
imported into and analyzed via SPSS version 20.0 (SPSS
Inc, Chicago, Illinois, USA). A
P
value < .05 was consid-
ered to be significant.
As we could not assume a normal distribution for our small
sample size, a Wilcoxon signed rank test was used to look for
differences in the pre-dilation and post-dilation differences in
pulmonary function data. Subsequently, a Kruskal-Wallis test
was performed on those PFT parameters that improved sig-
nificantly to determine the contribution of dilation size on the
change. For those measures that changed significantly, post-
operative PFT values were plotted as a function of time to
assess the rate of change after intervention.
Results
Clinical Presentation and Evaluation of Stenosis
A total of 25 new patients with iSGS were seen between
2006 and 2011 at our clinic. As anticipated, all patients were
female. Ninety-two percent (N = 23) were white and 8% (n =
2) Hispanic. The median age at the time of the first surgical
intervention was 45.3 years (interquartile range [IQR],
38.5-67.0), with a median body mass index of 28.7 kg/m
2
(IQR, 23.5-32.1) (Table 1).
A total of 45 procedures were performed. Twelve patients
had 1 procedure, 9 patients had 2 procedures, 2 patients had 3
procedures, 1 patient had 4 procedures, and 1 patient had a
total of 7 procedures (median = 2).At the time of initial presen-
tation, the typical stenosis was described as beginning 15 mm
below the true vocal folds and measuring 12 mm long. Fifteen
patients had preoperative computed tomography (CT) scans.
The median degree of stenosis as determined by CTwas 56.8%
(Cotton-Myer grade 2). Four patients had grade 1 stenosis at
presentation and 4 patients had grade 3 stenosis.
Median follow-up after surgery was 21.4 months (IQR,
5.1-43.1). For the 11 patients receiving at least 2 dilations,
the median time between the first and second procedures
was 23.7 months. Three patients ultimately proceeded to
definitive cricotracheal resection.
Preoperative Versus Postoperative PFT
Assessment
Seventeen of the 25 patients had a preoperative PFT in addi-
tion to at least 1 postoperative PFT performed within 8
weeks of surgery. Four parameters demonstrated a statisti-
cally significant improvement after intervention: (1) PEF
(absolute change = 2.54 L/s), (2) PIF (absolute change =
1.57 L/s), (3) FEV1/PEF (absolute change = 0.44), and (4)
FIF50% (absolute change = 1.71 L/s). FEV1, FVC,
FEF25%-75%, and PEF/PIF did not change significantly
(Table 2). Preoperative and postoperative PFT values were
then examined in the context of balloon size. Improvement
in the PIF was the only parameter that was affected by the
size of dilation, with rank-order testing indicating a greater
degree of improvement with use of a larger balloon (
P
=
.047) (Table 3).
Changes in PFT Over Time
Seven patients of the 25 in this sample had at least 3 PFTs
taken following the initial dilation. PEF, PIF, FEV1/PEF,
and FIF50% from these samples were plotted as a function
of time. There is a linear relationship between time and both
PEF and FEV1/PEF (
P
= .0307 and
P
< .001, respectively).
The slope of the line was unique to each patient (Figures 1
and 2). PIF and FIF50% generally decrease as the time from
surgery increases, but a linear relationship could not be
established (data not shown). Five of the 7 patients did have
a second procedure but had not accumulated a sufficient
number of subsequent PFTs during the study period for
analysis. (The patients represented by a star and hexagon
had only 1 procedure.)
Discussion
Not all patients are ideal candidates for endoscopic man-
agement of subglottic stenosis. Historically, previous failed
dilations, stenosis length greater than 1 cm, circumferential
stenosis, evidence of cartilage loss/damage, a history of
severe bacterial infection with tracheotomy, posterior glot-
tic stenosis with arytenoid fixation, and involvement of the
inferior margin of the vocal folds were considered poor
Table 1.
Clinical Presentation.
Median
Interquartile Range
Race
Caucasian
23
Latina
2
Age at surgery, mo
45.3
38.5-67.0
Weight, kg
70
61.5-85.5
Height, m
1.6
1.55-1.65
Body mass index, kg/m
2
28.7
23.5-32.1
Stenosis, %
58.60
38.9-78.4
Cotton-Myer grade
2
1-3
Distance below cords, mm 15
11.0-16.5
Length of stenosis, mm
12
9.0-17.0
Follow-up, mo
21.4
5.1-43.1
No. of procedures
2
1-3
Time between first &
second surgeries, mo
23.7
15.6-31.8
175