Tension Pneumothorax Recognition

Why this matters

A tension pneumothorax is air under pressure in the chest. It is obstructive shock. Rising pressure collapses the lung, shifts the mediastinum, kinks venous return, and drops cardiac output. The mediastinum is the heart and great vessels in the center of the chest. Venous return is blood coming back to the heart. Patients die from that shock, not from an x-ray you will not see in the ambulance.

First, treat the shock picture. Check one-sided breath sounds, how hard the bag-valve mask is to squeeze, the neck veins, and the blood pressure. Do not wait for the trachea to move. That sign is late. Do not needle a simple pneumothorax. A simple pneumothorax is air in the chest without shock.

Positive-pressure ventilation, from a bag-valve mask or a tube, can turn a simple pneumothorax into tension. Watch for that after you intubate a trauma patient. Watch for it in severe asthma or chronic obstructive pulmonary disease as well.

Clinical sequence

1. Treat tension as obstructive shock. Do not wait for the trachea to deviate. That sign is late.
2. Needle only for tension physiology, and only if you are authorized. Do not needle low oxygen by itself. Do not needle a simple pneumothorax.
3. Adult teaching prefers a lateral site: the 4th or 5th intercostal space, at the anterior axillary line or the mid-axillary line. The 2nd intercostal space at the midclavicular line is an alternate. Your protocol owns the exact site. The hands-on steps are in the needle lesson.
4. After you decompress, reassess how hard the bag-valve mask is to squeeze, the blood pressure, breath sounds, oxygen saturation, and end-tidal carbon dioxide.

Pattern Recognition (Field)

• Mechanism: chest trauma, blunt or penetrating, blast, rib fractures, a spontaneous pneumothorax in a tall thin patient or a patient with known blebs, or positive-pressure ventilation. A bleb is a weak air pocket on the lung.
• The patient has worsening shortness of breath, low oxygen, agitation, and air hunger.
• Breath sounds are decreased on one side. A drum-like sound is possible, and it is hard to hear in a noisy environment.
• The bag-valve mask gets harder to squeeze, or resistance rises on one side after intubation.
• The neck veins distend, the blood pressure falls, and obstructive shock appears as the pressure rises.
• Air under the skin can occur with airway or chest injury. It is a supporting clue, not proof by itself.
• Tracheal deviation is late. Do not require it before you act on a clear picture, within your training and protocol.

Do not anchor on one finding

• Simple pneumothorax without tension may not need a field needle. Support the patient and transport per protocol.
• Hemothorax may sound dull. The neck veins can be flat because of blood loss. A needle does not remove a large volume of blood from the chest.
• Right mainstem intubation means the tube is too deep. Check the depth. Listen again after you pull the tube back. End-tidal carbon dioxide is still present.
• Pericardial tamponade is a different problem. Breath sounds are equal. A needle in the chest will not fix it.
• Massive pulmonary embolism or cardiogenic shock can obstruct flow or fail the pump without one-sided chest findings.
• Severe asthma can trap air on both sides and make the bag-valve mask hard to squeeze. That is not always tension on one side.

What You Do in the Field

1. Support the airway, breathing, and circulation. Give high-flow oxygen as indicated. Until you decompress a clear tension picture, avoid extra positive pressure if you can.
2. If you identify tension and you are authorized, perform needle decompression only as you were trained and as your protocol allows. Adult teaching prefers a lateral site, the 4th or 5th intercostal space at the anterior axillary line or the mid-axillary line, because the chest wall is often thinner there than at the 2nd intercostal space in the midclavicular line. The 2nd intercostal space at the midclavicular line remains an alternate in many protocols. Catheter length, passing the needle over the rib, and immediate reassessment all matter. Those steps are the needle lesson.
3. Reassess breath sounds, how hard the bag-valve mask is to squeeze, blood pressure, mental status, oxygen saturation, and end-tidal carbon dioxide.
4. Transport quickly. Watch for the tension to return. Catheters kink and clog. Some systems allow finger thoracostomy or a repeat decompression, but only with protocol and training.
5. Treat bleeding and shock at the same time. Tension can exist with hemorrhage.

This lesson does not teach the hands-on skill. It builds recognition and the field decision. Needle decompression belongs in authorized training with your medical director's protocol.

Team Communication

• Say, "Right chest trauma, decreased sounds on the right, the bag-valve mask is hard to squeeze, and the patient is hypotensive. I am treating this as tension and preparing decompression per protocol."
• After the procedure, say whether the bag-valve mask and blood pressure improved, or say that nothing changed and you are reconsidering the cause and a second site per protocol.

Common errors

• Waiting for the trachea to deviate.
• Decompressing for low oxygen alone, without a tension picture.
• Choosing the wrong side, or using a catheter that is too short for a thick chest. Know your equipment.
• Skipping the reassessment after the procedure.
• Missing a mainstem intubation as the cause of one-sided breath sounds.

Practice

Related: Shock categories, Failed oxygenation.

Sources & Further Study

Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.

• NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; your protocol decides
• ATLS (ACS) — adult needle decompression teaching shifted toward 4th/5th ICS anterior/mid-axillary because chest wall thickness makes 2nd ICS midclavicular fail more often
• NAEMSP 2024 Prehospital Trauma Compendium: Traumatic Pneumothorax Care — decompress tension, not simple pneumothorax; needle thoracostomy is the usual EMS primary strategy; site and catheter are individualized
• Current trauma teaching prefers a lateral site, the 4th or 5th intercostal space at the anterior or mid-axillary line, in adults because chest-wall thickness makes 2nd intercostal midclavicular decompression fail more often. The 2nd intercostal space at the midclavicular line remains an alternate in many protocols. Use the site and catheter your training authorizes.
• Your needle decompression protocol and hands-on training.