Page 62 - JSOM Winter 2024

TABLE 4 Diagnosis of Tension Pneumothorax Positive Pressure commonly occurs in conjunction with obstructive shock in a
Ventilated Patients 5 trauma. Hemorrhage exacerbates obstructive shock (or ob-
Progression Rapid disease progression structive shock exacerbates hemorrhagic shock). These two
Reliable early signs • Decrease in SpO – Immediate forms of shock often occur simultaneously in the trauma pa-
2
• Decrease in Q tient and create rapid circulatory compromise and eventual
• Decrease in BP collapse. In the case of simple pneumothorax, which may be
• Tachycardia well tolerated in the uncompromised patient, a patient experi-
Disease lateralization encing hemorrhagic shock may be less tolerant. In the setting
Ipsilateral • Hyper-resonance of hemorrhagic shock, differentiating a simple from a tension
• Decreased breath sounds pneumothorax is more difficult.
• Chest hyper-expansion
• Chest hypo-mobility
• Added sounds Treatment
Contralateral • Increased ventilation pressure
• Surgical emphysema NDC of a tension pneumothorax is the accepted emergency
Other signs life-saving intervention. 15–18 In a positive pressure ventilated
Inconsistent Cyanosis patient, a finger thoracostomy may prove more effective allow-
Distended neck veins ing for more rapid egress of air. The definitive treatment for
Tracheal deviation a tension pneumothorax remains tube thoracostomy, with the
Monitor-dependent Increasing CVP chest tube connected to a negative pressure drain, an underwa-
Increasing pulmonary arterial pressure ter drain, or one-way valve. NDC is a common procedure in
ECG data prehospital practice and also common in the emergency depart-
Decreased mixed venous oxygen saturations
ment prior to tube thoracostomy. In the case of a chest wound
BP = blood pressure; CVP = central venous pressure; ECG = electro- covered with a chest seal, the seal should be “burped” as the
cardiogram; SpO = oxygen saturation.
2 first course of action if a tension pneumothorax is suspected.
in trauma (FAST) exam and is recommended for prehospital
use in lung ultrasound examination. Traditionally a 4-view NDC is the procedure of inserting a needle into the pleural
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exam created to find free fluid in the abdominal cavity or peri- space to allow the air to escape. Historically, intravenous (IV)
cardium, has been extended (E-FAST) to include thoracic as- catheters were recommended for accomplishing this task.
sessment for pneumothorax. The most common findings in the Postmortem autopsy data from the first decade of conflicts in
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patient with a pneumothorax are loss of lung sliding, absence Iraq and Afghanistan highlighted the need for longer needles
of comet tail artifacts, absent lung pulse artifact, and positive for NDC in combat casualties (predominantly young male
barcode sign (M mode). Less commonly, a pathognomonic patients with larger chest wall depth). These data resulted in
“lung point” can be identified. Ball et al. noted that up to 76% the recommendation of a longer (83mm) needle catheter unit
of all traumatic pneumothoraces were missed by the standard (NCU). The increased length of NCU is accompanied by ad-
supine anterior-posterior chest x-ray when interpreted by the ditional risk of damage to deeper structures. The traditional
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trauma team. This occurs due to intrapleural air rising to the site for NDC is the second intercostal space, mid clavicular
anterior surface of the chest. E-FAST has proven to be a use- line (2nd ICS-MCL), and more recently the lateral fifth inter-
ful adjunct in the identification of clinically significant pneu- costal space, anterior axillary line (5th ICS-AAL). The left 5th
mothorax, with sensitivity exceeding that of traditional chest ICS-AAL site carries increased risk of damage to the heart due
x-ray. Specificity is slightly less, such as in cases where pain due to its proximity to the chest wall at this location. If the nee-
to multiple rib fractures causes respiratory splinting and per- dle is placed inferiorly to the 5th ICS-AAL, it may damage
ceived absence of lung sliding. 8–11 Recent development of low the solid organs (liver and spleen). Studies have shown that
cost, portable, and rugged point-of-care ultrasound devices NDC is overutilized due to misdiagnosis (no simple or tension
has improved access and utilization. Increased availability pneumothorax) and has a high failure rate due to the catheter
and use in the prehospital setting are expected to improve the not being inserted into the pleural space. One retrospective
diagnostic accuracy and timing of appropriate interventions prehospital study showed a failure of catheter placement of
in patients with pneumothorax. While several studies have between 39% and 76%. 7
demonstrated the feasibility of lung ultrasound performed by
prehospital providers, high quality data directing implementa- Iatrogenic harm is a recognized and documented complication
tion into training and treatment protocols is needed. 12–14 of NDC. When performing an NDC, the provider should be
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cognizant of the anatomical areas of elevated risk and also
Tension Pneumothorax and Hemorrhagic Shock strategies to ensure the needle goes no farther than the pleu-
Shock is a term that encompasses a wide range of physiologic ral space. This can be achieved by attaching a half–fluid filled
disturbances that result in cellular hypoxia secondary to inad- syringe to the NCU. After insertion through the superficial tis-
equate oxygen delivery at the cellular level. The classic types sues the plunger of the syringe should be pulled back to create
of shock are hypovolemic, obstructive, distributive, and car- negative pressure while continuing the advance of the NCU.
diogenic. Hemorrhagic shock is a form of hypovolemic shock As soon as bubbles are noted in the syringe fluid, the needle
and remains the leading cause of preventable death in both and catheter have entered the air-filled pleural space. At this
2
military and civilian trauma. The loss of circulating blood point the catheter should be gently advanced over the needle.
volume reduces venous return, which, in turn, reduces cardiac An alternative technique, not requiring extra equipment, is to
output and thus the delivery of oxygen. Tension pneumotho- advance NCU no farther than half of its total length at which
rax is a form of obstructive shock and reduces venous return point only the outer sheath of the cannula is advanced while
caused by increased pressure in the right atrium and collapse the needle is held in place. Data on the effectiveness of these
of the thoracic vena cava. Hypovolemic (hemorrhagic) shock techniques on prevention of iatrogenic harm are lacking. Once

60 | JSOM Volume 24, Edition 4 / Winter 2024