Occult pneumothorax after a stab wound may be delayed for up to 6 hours
If patient decompensates, obtain repeat imaging
If patient decompensates, obtain repeat imaging
Defined as having all of the following:
Resp rate < 24
Heart rate 60-120 beats per minute
Normal BP
SaO2 >90% on room air and patient can speak in whole sentences
CXR
Displaced visceral pleural line without lung markings between pleural line and chest wall
Upright is best
Expiratory films DO NOT improve accuracy
Lateral decubitus films with suspected side up do increase sensitivity. Good approach in pediatrics to avoid CT
Supine CXR = deep sulcus sign
CT Chest
Very sensitive and specific
Displaced visceral pleural line without lung markings between pleural line and chest wall
Upright is best
Expiratory films DO NOT improve accuracy
Lateral decubitus films with suspected side up do increase sensitivity. Good approach in pediatrics to avoid CT
Supine CXR = deep sulcus sign
Expiratory films DO NOT improve accuracy
Lateral decubitus films with suspected side up do increase sensitivity. Good approach in pediatrics to avoid CT
Very sensitive and specific
No lung sliding seen (not specific for pneumothorax)
May also identify "lung point": distinct point where you no longer see lung sliding (pathognomonic)
Absence of lung sliding WITHOUT lung point could represent apnea or right mainstem intubation
Evaluate other intercostal spaces because pneumothorax may only be seen in least dependent area of thorax
NO comet tail artifact
Bar Code appearance/"Stratosphere" sign on M-mode (absence of "seashore" waves)
Ultrasound has greater sensitivity than chest x-ray for pneumothorax in trauma patients 
NO comet tail artifact
Bar Code appearance/"Stratosphere" sign on M-mode (absence of "seashore" waves)

On a conventional, upright posterior-anterior chest radiograph:
Very small: <1 cm interpleural distance (confined to upper 1/3 of chest) OR only seen on CT
Small: ≤3cm lung apex to cupola (chest wall apex) on CXR
Large: >3cm lung apex to cupola (chest wall apex) on CXR
Very small: <1 cm interpleural distance (confined to upper 1/3 of chest) OR only seen on CT
Small: ≤3cm lung apex to cupola (chest wall apex) on CXR
Large: >3cm lung apex to cupola (chest wall apex) on CXR
Traumatic pneumothorax
Tension pneumothorax
Spontaneous pneumothorax
Hemothorax
Catamenial pneumothorax
Pulmonary contusion
Iatrogenic pneumothorax
Chylothorax