Page 22 - JSOM Summer 2018

Proximate Reasons for This Proposed Change NDC attempts (as many as 14) have been performed because
the symptoms of respiratory distress have not been relieved by
A 2008 report from the Canadian military discussing oppor- NDC or because they recur after initial improvement. 26,27
tunities for improvement in TCCC reported that seven combat
casualties were found to have arrived at medical treatment fa-
cilities with no vital signs and without having had prehospi- Scenario
2
tal NDC performed. TCCC recommends that casualties with A Marine Corps Special Operations unit was conducting a con-
torso trauma or polytrauma who suffer a traumatic cardiac ar- voy operation in Western Afghanistan. The unit was ambushed
rest have bilateral NDC performed to treat a possible tension in a mountain draw, taking fire from high ground on both sides
3,4
pneumothorax. There have also been two recent fatalities of the draw. There were 14 casualties sustained in the engage-
identified on Joint Trauma System (JTS)/Armed Forces Med- ment, including the treating corpsman. One casualty sustained
ical Examiner System (AFMES) preventable death reviews in a gunshot wound (GSW) to the left side of the chest. Evac-
which the deceased casualty had a tension pneumothorax at uation of casualties was delayed several hours due to heavy,
autopsy with no other obviously fatal wounds and without accurate fire and rocky terrain—a scenario with an unusually
NDC having been attempted. Note that the diagnosis of ten- long Care Under Fire period. The casualty was subsequently
sion pneumothorax at autopsy is made more complex by the treated with 14 needle decompressions—all performed in the
absence of observable physiologic effects and by the potential second ICS at the midclavicular line—for suspected tension
for post-mortem artifact.
pneumothorax. The needles and the catheters were both re-
moved approximately 5 seconds after each insertion. The
The initial manifestation of a developing tension pneumo- corpsman providing care observed that the casualty had “relief
thorax in a spontaneously breathing and conscious casualty on his face” and improvement of his respiratory distress with
is respiratory distress, but an untreated tension pneumotho- each NDC procedure. The NDCs were performed in the su-
rax may progress beyond respiratory symptoms to circulatory pine position, because of the hostile fire as well as the treating
shock and traumatic cardiac arrest. NDC is a rapid and ef- corpsman’s concerns that sitting the casualty up might worsen
fective means of decompressing a tension pneumothorax, but his hemodynamic status, given his wounding pattern, which
it is not a completely benign intervention and the procedural placed him at high risk of internal hemorrhage, which was later
risks that it entails require that a reasonable expectation of confirmed at surgery. The casualty survived his wounds and
clinical benefit be present before undertaking the procedure. remained on active duty until his retirement some years later
As a minimum, in the absence of penetrating thoracic trauma, (personal communication – HMCM Jeremy Torrisi, 2008).
NDC may necessitate the placement of a chest tube in a casu-
alty who would not otherwise have required one. There is also BACKGROUND
the potential for life-threatening hemothorax as a complica-
tion of the procedure. As a result of these considerations, there Tension Pneumothorax Physiology
is some disagreement in the medical literature about when
in the sequence of evolving signs/symptoms that NDC for a There is no single, universally accepted definition of tension
suspected tension pneumothorax should be undertaken. This pneumothorax, 28–31 but all definitions include an injury to
report will discuss some of these varying perspectives and will the lung that results in air leaking into the pleural space and
reevaluate the CoTCCC recommendations on this topic. being trapped there with a secondary increase in intrapleural
pressure. Even when these events have occurred and a shift
There is also recent literature reporting that a 14-gauge nee- in position of the intrathoracic organs has resulted, however,
dle has a high failure rate in some animal models of tension the patient may remain stable for a time. One case report de-
pneumothorax, but that is countered by other studies in scribed a patient with a tension pneumothorax that was found
5–8
both animal models and the clinical literature that indicate on ultrasound to have caused displacement of the heart into
that the currently recommended device for NDC in TCCC (a the right hemithorax and yet still appeared clinically stable
14-gauge, 3.25-inch needle/catheter unit) is adequate. 9–12 This without significant dyspnea or hypotension. 32
proposed change will evaluate what, if any, action should be
taken about the specific device recommended to perform NDC For the purpose of this review, tension pneumothorax is de-
in light of the current evidence. The potential for increased fined as the accumulation of air under pressure in the pleural
risk of complications when using longer or larger gauge de- space. In the early stages of the process, the casualty can com-
vices must be considered in addition to the expected increased pensate physiologically. Once the individual is no longer able
efficacy of these larger gauge devices. to compensate, however, progressive respiratory failure and/or
shock will develop. Traumatic cardiac arrest may ensue if the
Recent literature suggests that the lateral site (fifth ICS at the tension pneumothorax is not treated.
AAL) may be the preferred location for NDC. 13–22 The lateral
site is currently recommended as the primary site for NDC in Combat casualties with tension pneumothorax are typically
Advanced Trauma Life Support (ATLS). Prior to this change, breathing spontaneously, at least for a variable time period,
23
33
TCCC recommended the anterior site as the primary option after their injury. Much of the tension pneumothorax litera-
for NDC and the lateral site as the alternate location. 3,24 ture is based on mechanically ventilated patients. 28,30,31,34 Ten-
sion pneumothorax in patients who are being mechanically
Finally, the TCCC Guidelines at present do not indicate what ventilated may have a more fulminant course than that seen
constitutes a successful needle decompression, nor do they in- in patients who are breathing spontaneously. To quote one re-
clude a sequence of steps to be undertaken if NDC fails to relieve port: “In ventilated patients, (tension pneumothorax) presents
the signs and/or symptoms of a suspected tension pneumotho- rapidly with consistent signs of respiratory and cardiac com-
25
rax. This has resulted in reported incidents in which repeated promise. In contrast, awake patients show a greater variability

20 | JSOM Volume 18, Edition 2/Summer 2018