What are physical findings characteristic of tension pneumothorax?

Updated: Apr 28, 2020
  • Author: Brian J Daley, MD, MBA, FACS, FCCP, CNSC; Chief Editor: Mary C Mancini, MD, PhD, MMM  more...
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Answer

Although tension pneumothorax may be a difficult diagnosis to make and may present with considerable variability in signs, respiratory distress and chest pain are generally accepted as being universally present, and tachycardia and ipsilateral air entry on auscultation are also common findings. Sometimes, reliance on history alone may be warranted.

Findings may be affected by the volume status of the patient. In hypovolemic trauma patients with ongoing hemorrhage, the physical findings may lag behind the presentation of shock and cardiopulmonary collapse. Increased pulmonary artery pressures and decreased cardiac output or cardiac index are evidence of tension pneumothorax in patients with Swan-Ganz catheters.

When examining a patient for suspected tension pneumothorax, any clue may be helpful, as subtle thoracic size and thoracic mobility differences may be elicited by performing careful visual inspection along the line of the thorax. In a supine patient, the examiner should lower themselves to be on a level with the patient.

Tracheal deviation is an inconsistent finding. Although historic emphasis has been placed on tracheal deviation in the setting of tension pneumothorax, tracheal deviation is a relatively late finding caused by midline shift.

Abdominal distention may occur from increased pressure in the thoracic cavity producing caudal deviation of the diaphragm and from secondary pneumoperitoneum produced as air dissects across the diaphragm through the pores of Kohn.

If patients who are mechanically ventilated are difficult to ventilate during resuscitation, high peak airway pressures are clues to pneumothorax. A tension pneumothorax causes progressive difficulty with ventilation as the normal lung is compressed. On volume-control ventilation, this is indicated by marked increase in both peak and plateau pressures, with relatively preserved peak and plateau pressure difference. On pressure control ventilation, tension pneumothorax causes sudden drop in tidal volume. However, these observations are neither sensitive nor specific for making the diagnosis of pneumothorax or ruling out the possibility of pneumothorax.

The development of tension pneumothorax in patients who are ventilated will generally be of faster onset with immediate, progressive arterial and mixed venous oxyhemoglobin saturation decline and immediate decline in cardiac output. Cardiac arrest associated with asystole or pulseless electrical activity (PEA) may ultimately result. Occasionally, the tension pneumothorax may be tolerated and its diagnosis delayed for hours to days after the initial insult. The diagnosis may become evident only if the patient is receiving positive-pressure ventilation. Tension pneumothorax has been reported during surgery with both single- and double-lumen tubes.


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