How pneumothorax is tested on Step 1

Expect sudden pleuritic chest pain and dyspnea in a tall young man, a ventilated or trauma patient who suddenly becomes hypotensive, or a question about which way the trachea deviates.

workspace_premium Tension is a clinical diagnosis

A hypotensive patient with unilateral absent breath sounds, distended neck veins, and tracheal deviation needs needle decompression now — not a chest x-ray first.

Types and causes

Classification depends on the cause and whether pressure builds up.

PneumothoraxPrimaryspontaneousApical blebs;tall thinsmokersSecondaryspontaneousCOPD, CF, PCP,MarfanTraumaticRib fracture,penetratinginjuryIatrogenicCentral line,biopsy,ventilationTensionOne-way valve;any cause
Types. Positive-pressure ventilation can rapidly convert a simple pneumothorax into a tension pneumothorax.

Physical exam and imaging

Air conducts sound poorly and resonates on percussion.

FindingPneumothoraxPleural effusionLobar consolidationAtelectasis (obstructive)
Breath sounds↓↓Bronchial↓
PercussionHyperresonantDullDullDull
Tactile fremitus↓↓↑↓
Tracheal deviationAway if tensionAway if largeNoneToward

Chest x-ray shows a visible pleural line with no lung markings beyond it; in supine patients, a deep sulcus sign.

Simple pneumothoraxAir enters and exits freelyStable vital signsTrachea midline (or toward)Diagnose with chest x-ray or ultrasoundObserve, aspirate, or chest tubeTension pneumothoraxAir trapped by one-way valveHypotension, tachycardia, JVDTrachea and mediastinum shift awayClinical diagnosis — do not wait forimagingNeedle decompression, then chest tubevs
Simple vs tension. Hypotension is the dividing line.

Pathophysiology of tension

Tension physiology is obstructive shock, not hypoxemia alone.

One-wayvalveAir in, notout↑ PleuralpressureWith eachbreathMediastinalshiftAway fromaffected side↓ VenousreturnVena cavaecompressedObstructiveshockHypotension,arrest
Tension physiology. Needle decompression in the 2nd intercostal space midclavicular line (or 4th–5th space, anterior to midaxillary line) releases the pressure.
SituationManagement
Small primary spontaneous, stableObservation ± supplemental oxygen; repeat imaging
Large or symptomatic primaryNeedle aspiration or small-bore chest tube
Secondary spontaneousChest tube usually; admit
TensionImmediate needle decompression → chest tube
RecurrentPleurodesis or video-assisted thoracoscopic surgery (VATS) bleb resection

Smoking cessation lowers recurrence; avoid air travel and scuba diving until resolved.

Clinical application

Ventilated patients can deteriorate quickly.

functions Worked example — the ventilated patient crashes

An intubated trauma patient with rib fractures suddenly develops rising peak airway pressures, blood pressure 70/40, distended neck veins, absent breath sounds on the right, and a trachea deviated to the left. What is the next step?

  1. Rib fractures plus positive-pressure ventilation create a tension pneumothorax risk.
  2. Absent breath sounds on the right with tracheal deviation to the left indicates air under pressure on the right.
  3. Hypotension and JVD show obstructed venous return — obstructive shock.

Answer. Immediate needle decompression of the right chest, followed by chest tube placement. Do not delay for a chest x-ray.