Page 64 - JSOM Winter 2024

exceeds atmospheric pressure. To minimize ingress of outside Technique
air and debris into the pleural space and to allow air egress When performing a NDC, the provider should be cognizant
from the pleural space, initial treatment of an open pneumo- of the areas of high risk and strategies to ensure the needle
thorax includes prompt coverage of the communicating chest goes no farther than the pleural space and only the catheter
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wall opening with a vented chest seal. A first aid measure is advanced.
is an improvised occlusive dressing taped securely to skin on
three sides to ensure a venting flutter-valve effect through the Risk Benefit
15
free side. A finger thoracostomy is mostly performed on a Due to the risk of harm, suspected low incidence, high rate of
positively pressure ventilated patient, so no chest seal is re- misdiagnosis, and low rate of procedural success, a conservative
quired. If the casualty is spontaneously breathing then a vented approach is advised for NDC in suspected spontaneously breath-
chest seal can be applied, in practice the incision edges act as ing-tension pneumothorax, as outlined in Table 1. In sponta-
a one-way valve in the same manner as the vented chest seal. neously breathing patients presenting with thoracic injury and
shock, NDC should be delayed until adequate resuscitation of
The true indication for a chest seal is a sucking chest wound, shock “a needle in the arm before a needle in the chest” ~75th
which is rare and, when observed, typically manifests as a Ranger Regiment or identification of significant progressive re-
wound that is at least 66% of the diameter of the trachea. No- spiratory compromise. This recommendation is supported by the
tably, the normal transverse internal diameter of the trachea significantly higher incidence of hemorrhage, a source of death
ranges from 15 to 25mm in males and 10 to 21mm in females, from shock, compared with pneumothorax in spontaneously
with a cross-sectional area of 250–350mm and a volume of 30– breathing patients. Formal chest drain remains the definitive
2
1,3
40cm at total lung capacity. Definitive management of this procedure in the setting of tension pneumothorax in general.
3
wound includes placement of a chest tube and closure of the
chest wall defect. In positive pressure ventilated patients, the likelihood of a
tension pneumothorax developing may be greater, the time to
Chest Seal Burp severe physiological impact shorter, thus the threshold for per-
A wound that communicates with the pleural space should forming NDC should be lower.
release any air build-up from the pleural space that exceeds
atmospheric pressure. However, depending on the size of the For prehospital patients, NDC will remain a temporizing mea-
wound, atmospheric air can enter the chest on inspiration in sure, and misplaced NDCs with consequent iatrogenic injuries
spontaneously ventilating patients. Vented chest seals should may be treated within a reasonable time frame. On the other
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be used in communicating chest wounds to both prevent air hand, in remote locations or delayed evacuation, NDC can ex-
ingress into the thoracic cavity and pleural space and to allow pose patients to iatrogenic injuries without the possibility of
air egress from the pleural space if it begins to accumulate prompt recognition and correction.
again. Every effort should be made to prevent chest seal vent
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failure which can be caused by lying the patient on the chest Post-procedure Identification
seal. It should be recognized that placement of a chest seal may If a catheter is removed from the thorax, the site of NDC
create a pneumothorax by trapping air in the thoracic cavity should be clearly marked with the letters NDC, as well as to be
in the event of valve failure, thus the seal should be burped as documented on a casualty card along with procedural success.
the first course of action if tension pneumothorax is suspected.
Need for Further Research
Discussion
Every effort should be made to standardize the naming con-
Education and Training ventions and definitions, in particular whether the suspected
Educational programs that encompass NDC are faced with tension pneumothorax is in a positive pressure ventilated or
a didactic challenge, addressing the oftentimes difficult diag- a spontaneously breathing patient. Capturing the data may
nosis and proper technical execution of the procedure while improve our understanding of the pathology and guide fu-
balancing the overall low incidence of tension pneumothorax. ture recommendations. Whenever possible, appropriate ra-
Often training participants are left with a misunderstanding diographic imaging (chest x-ray and/or CT scan) should be
of how rarely NDC is required. Emphasis should be placed on accomplished with the NDC left in situ to document its correct
the diagnosis of tension pneumothorax and technical skill of placement and potential efficacy.
NDC, rather than on incorporating the pathology into multi-
ple simulations. Attention should be drawn to the prevalence Author Position Statement
of hemorrhagic shock. Numerous uncertified online learning
sources represent a risk for miseducation. In trauma patients with a pneumothorax the author group
takes the following 16 positions:
The iatrogenic risk of NDC should be offset by including
training in the identification of anatomical landmarks but also 1. A simple pneumothorax is defined as gas in the pleural
an emphasis on areas of high risk, including too medial thus, space with limited impact on respiratory and circulatory
placing the NCU in the cardiac box; too high, with risk to physiology.
the subclavian vessels; too low and laterally, with risk to the 2. A tension pneumothorax is defined as an increasing volume
spleen and liver; and left laterally, with the risk of proximity of gas under pressure in the pleural space, causing wors-
to heart. In assessment of competence, the student should be ening respiratory or circulatory physiology which may be
able to correctly identify the anatomical landmarks for NDC fatal if left untreated.
and the areas of high risk. Recognition of procedure success 3. Both conditions may occur in spontaneously breathing or
and actions on failure must also be incorporated in training. positive pressure ventilated patients.

62 | JSOM Volume 24, Edition 4 / Winter 2024