Page 24 - JSOM Winter 2025

The pressure was observed until it reached 0mmHg or it through the Texas State Anatomical Board (Texas Funeral
stopped changing for 60s. The 60-second observation period Commission) and the University of Texas Southwestern
was not included in the measurement of tPTX decompression (UTSW) Willed Body Program for research and procedural
time; however, it was assumed that once pressure plateaued for training. This study was conducted in strict accordance with
60s, any further delay would have no additional clinical signif- ethical guidelines governing the use of human cadaveric tis-
icance. A closed stopcock was then placed on the established sues. All procedures complied with the ethical standards set
catheter, and the tPTX was redeveloped to a target pressure of forth by the U.S. Army for research involving human remains.
15mmHg for a subsequent procedure to be performed at the
alternate location.
Results
Study Population The baseline demographics of the cadavers are presented in
This study was conducted at the Center for Emergency Health Table 1. The mean age of cadavers at death was 84 years (SD
Sciences in Spring Branch, TX, between October 2022 and No- 7.8 y), with 20 females and 11 males. There was a total of four
vember 2023. The study capitalized on the facility’s capacity to cadavers with sternotomies and three with pacemakers. Four
procure fresh, recently deceased, non-frozen, non-embalmed, hemithoraces were excluded due to no lung sliding on sonog-
unaltered, adult male and female cadavers for scientific studies raphy, precluding the ability to create tPTX physiology; how-
and procedural courses. In order to maximize generalizability, ever, the other hemithoraces were used for experimentation.
no adult cadavers were excluded based on age, weight, his-
tory, sex, race, or comorbidities. Cadaver hemithoraces were TABLE 1A Baseline Patient Demographics and Characteristics
excluded if the ultrasound did not exhibit lung sliding during No. (%) of patients*;
the ventilation phase. Variable n = 31
Sex
No external funding was used or required for this study. The Female 20 (64.5)
center provided facilities, equipment, necessary staff, endotra-
cheal tubes, NDC kits, administrative support, and video re- Male 11 (35.5)
cording equipment. Age, y, mean (SD) 84 (7.8)
Comorbid conditions affecting the thorax
Study Outcomes Sternotomy 4 (12.9)
The primary outcomes were successful decompression and the Pacemaker 3 (9.7)
time to successful decompression of tPTX. Successful relief of Excluded due to lack of lung slide on 4/62 hemithoraces
the tPTX was defined as a decrease in intrathoracic pressure ventilation (6.5)
to <4mmHg; the transmural lung pressure at rest in normal
23
physiology. Failure was defined as post-intrathoracic pres- TABLE 1B Excluded Hemithoraces
sure ≥4mmHg for 1 minute. The secondary outcomes were Age Sex Sternotomy Pacemaker Comments
comparison of 10ga versus 14ga at the 5th ICS AAL and 2nd 83 F N N Crepitus on right hemithorax
ICS MCL, and audible air release when the needle is in the with broken ribs
catheter and then removed. 85 F N N Prior lung surgery on left
hemithorax with no lung
Statistical Analysis sliding
A pilot study was performed where preliminary data indicated 90 F Y Y Large pleural effusion in
a success rate of 93.8% for 10ga and 75.0% for 14ga to de- right hemithorax with no
compression of tPTX after 16 NDC were performed with each lung sliding
gauge. The power analysis was performed using a power of .8, 82 F N N Large pleural effusion in
alpha of .05, and the ability to detect a 20% difference between right hemithorax with no
lung sliding
the success rates of 10ga and 14ga. The sample size require-
ment determined was 116 decompressions, with 58 per group. *Unless otherwise specified.
N = no; Y = yes.
SAS 9.4 (SAS Institute, Cary, NC) was used to perform all The NDC outcomes are presented in Table 2. A total of 116
statistical analyses. Normality testing (Kolmogorov-Smirnov) NDC attempts were made, and 104 successful NDCs were
was applied where appropriate. Chi-square analysis (or Fisher completed. There were 58 10ga NDC and 58 14ga NDC at-
exact, if cell counts <5) was used to examine any difference in tempts. Four NDCs were performed on 27 of the cadavers
proportions of decompression success between needle/catheter (two per hemithorax), and four cadavers had two NDCs per-
units, as well as between sites (5th ICS AAL vs. 2nd ICS MCL). formed due to one hemithorax being excluded. Of the NDCs
Wilcoxon-Mann-Whitney U was used to evaluate: 1) time to performed, 58 NDCs were in the 5th ICS AAL, and 58 NDCs
successful decompression and 2) decompression audibility. Al- were in the 2nd ICS MCL. One trial in both the AAL and
pha was set at .05, two-tailed. Multiple comparisons adjust- MCL groups inadvertently employed the incorrect size needle,
ments were not applied given the exploratory nature of our resulting in the incongruent counts reported in Table 2 regard-
study and the lack of prior knowledge about our outcomes. 24 ing NDC location. There were 10 NDC failures due to the
inability to decompress to less than 4mmHg of intrathoracic
Ethical Considerations pressure, with five failures each in the 10ga and 14ga groups.
The Institutional Review Board for the University of Texas Table 3 details the characteristics of the NDC failures.
Health Science Center, San Antonio, reviewed and deter-
mined this study was non-human subject research (IRB No difference was found between 10ga and 14ga needle/
#20220492NHR). Specimens were requested and approved catheter units in NDC success rates (91.4% vs. 91.4%, P=1.00).

22 | JSOM Volume 25, Edition 4 / Winter 2025