Page 23 - JSOM Summer 2018

of presentations, which are generally more progressive, with that tension pneumothorax was responsible for only 0.2% of
slower decompensation.” In a review of 183 tension pneu- deaths among US combat fatalities in the Afghanistan and Iraq
31
mothorax patients (86 breathing unassisted and 97 receiving conflicts, a decrease of greater than 90% in preventable deaths
assisted ventilation), 50% of spontaneously breathing patients from this cause compared with the estimated 3% o 4% re-
were hypoxic in contrast to 92% of assisted ventilation pa- ported by McPherson in the Vietnam conflict. 1,33
tients. The incidence of subsequent hypotension and cardiac
28
arrest was 12.6 and 17.7 times greater, respectively, among A Chronology of Suspected Tension Pneumothorax
patients receiving assisted ventilation than in spontaneously Management Recommendations in TCCC
breathing patients. 28
The original TCCC Guidelines, published in 1996, recom-
There is also no single definitive animal model for tension mended NDC (not a chest tube, as was being taught to Special
pneumothorax. Different studies show variation in methods Operations medics at the time) as the initial treatment for sus-
and definitions. 5,7,8,11,35 pected tension pneumothorax. There were no specific rec-
45
ommendations made at that time regarding the length of the
Hypoxemia has been observed to reliably precede the onset of catheter to be used for this purpose. The recommended cathe-
shock in animal models of tension pneumothorax. 29,35 Hypox- ter length for NDC before 2007 was 5 cm (2 in). 12
emia alone, however, does not typically cause the subjective
experience of dyspnea or “air hunger.” A review of 27 cases of US combat operations in Afghanistan began in October 2001
hypobaric hypoxia reported during aviation operations found as a result of the al-Qaeda terrorist attacks on 9/11. It was
that the symptoms of hypoxia were “subtle and often involved reported in 2007 that in two US combat-related fatalities, 2-in
cognitive impairment or light-headedness.” Hypoxia-related needles failed to penetrate the chest wall and the casualties died
36
closed-circuit mixed-gas diving accidents that are caused by in- with an unrelieved tension pneumothorax. A subsequent se-
12
terruption of the oxygen supply may progress to hypoxic loss ries of virtual autopsy CT scans in 100 military fatalities done
of consciousness without producing the sensation of dyspnea. to examine chest wall thickness in US Servicemembers who had
37
Hypercapnia (carbon dioxide buildup), in contrast, is a potent died found that the mean chest wall thickness was 5.36 cm.
12
stimulator of ventilation and does cause increased depth and The authors recommended use of a 3.25-in (8 cm) needle/
frequency of respirations and the subjective sensation of dys- catheter unit for NDC in order to achieve a 99% assurance of
pnea or “air hunger.” Hypoxemia and hypercapnia may both reaching the pleural space. As a result of this work and the two
37
be present with impaired alveolar ventilation, as would occur observed preventable deaths associated with using needles of
with respiratory compromise from a tension pneumothorax. insufficient length, both the US Army and the CoTCCC recom-
mended that a 3.25-in needle be used for NDC instead of the
If tension pneumothorax is not treated quickly enough, the previously used 2-in needle. 46,47 The need for an NDC device
intrapleural pressure may rise to a level sufficient to cause longer than 2 inches has also been reported in other studies. 48–50
life-threatening shock as a result of compression of the heart
and great vessels. Once shock is present, it may be difficult to No published reports were identified in this review that de-
determine whether it has resulted from noncompressible hem- scribed deaths in US combat forces due solely to tension
orrhage or tension pneumothorax. NDC will be effective only pneumothorax as a result of failed NDC after the US military
in treating shock resulting from tension pneumothorax. If the began aggressively treating suspected tension pneumothorax
tension is not relieved by NDC or other means, the hypoxemia with 14-gauge, 3.25-in (8-cm) needles. The TCCC Guide lines
and shock may result in a traumatic cardiac arrest. prior to this change still recommended treatment of suspected
tension pneumothorax with this device. 51,52
One of the pioneers of needle decompression for tension pneu-
mothorax was the late Dr Norman McSwain, who published a Another change to the management of suspected tension pneu-
report on a new device developed for this purpose, the McSwain mothorax in TCCC oc curred in 2011. A polytrauma casualty
Dart, in 1982. Treatment of tension pneumothorax with NDC presented on the Joint Trauma System (JTS) weekly trauma
38
is one of the relatively few interventions that has been shown to teleconference arrived at a medical treat ment facility with no
improve survival in victims of traumatic cardiac arrest. 39–43 vital signs and CPR in progress. NDC had not been attempted
during the prehospital phase of his care. He was successfully
resuscitated with bilateral NDC in the Emergency Depart-
Tension Pneumothorax in Combat Casualties
ment. The TCCC Guidelines were subsequently changed to
In the Vietnam conflict, tension pneumothorax was reported recommend bilateral NDC for casualties with torso trauma
to have been a leading cause of preventable death in combat or polytrauma who develop a prehospital cardiopulmonary
casualties. 33,44 Needle decompression was not routinely used to arrest. 4
treat tension pneumothorax during this conflict. 33
The most recent change to the TCCC Guidelines regarding
Two factors have helped to reduce deaths from tension pneu- needle decompression was made in 2012 and established the
mothorax in combat casualties sustained during recent com- fourth or fifth intercostal space at the mid-axillary line as an
bat actions. One is the widespread use of personal protective alternate site to the previously recommended second inter-
equipment in the US military that includes protection for costal space at the midclavicular line. This recommendation
24
the anterior and posterior aspects of the thorax. Second, for for NDC sites was still in place at the time this change was
more than two decades, combat medical personnel trained in undertaken. 3,52
TCCC have been taught to treat suspected tension pneumo-
thorax aggressively with NDC. Largely as a result of these Since 2012, the TCCC guidelines have recommended the fol-
two innovations, the 2012 study by Eastridge et al. reported lowing management for suspected tension pneumothorax:

TCCC Guidelines Change 17-02 | 21