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Lesson

Mainstem Intubation Recognition

10 min Airway & Breathing Skip to quiz

Objective: After every move, look for a right-mainstem tube. Check the depth at the teeth and chest rise on both sides. An end-tidal carbon dioxide (EtCO₂) number does not excuse a silent left lung.

Why this matters

You had a waveform and an oxygen saturation (sat) of 94%. After the move to the stretcher, the left chest is quiet. Crews add positive end-expiratory pressure (PEEP) and blame the patient.

A waveform tells you the tube is in the airway. It does not tell you the tube is ventilating both lungs.

Key points
  • Write the centimeter depth at the teeth or gums when you confirm the tube. Check that number again after every major move.
  • Look at both sides of the chest. Listen in both armpits. Still listen over the stomach.
  • End-tidal carbon dioxide (EtCO₂) plus a silent left chest means mainstem intubation or pneumothorax. The number does not make a silent lung good enough.
Front view of the trachea splitting into the bronchi. The patient's right bronchus is wider and steeper.
The patient is facing you, so the bronchus on your left is the patient’s right bronchus. It is shorter, wider, and steeper, so a tube that is too deep follows it. The left bronchus is longer and more horizontal. A waveform can still be present when only one lung is being ventilated. Pull the tube back. Do not push it deeper. Write the depth at the teeth and check it again after every move. A child’s trachea is short. Plate by Henry Vandyke Carter, Gray’s Anatomy (1918), public domain, via Wikimedia Commons. Contrast adjusted.

Clinical sequence

  1. When you confirm the tube, write the centimeter depth at the teeth or gums. Check that number again after every major move.
  2. Look at both sides of the chest. Listen in both armpits. Still listen over the stomach.
  3. If the waveform is present and the left chest is silent, treat it as a mainstem tube or a pneumothorax. Do not call it good enough.
  4. If you suspect mainstem placement, deflate the cuff if you need to. Pull the tube back 1 to 2 cm at a time toward the adult depth in your training. Inflate the cuff again. Confirm the waveform and chest rise on both sides.
  5. In children, mainstem placement happens quickly because the trachea is short. Check again after every bump.

Teaching points

  • The clues are one-sided chest rise, a bag that is hard to squeeze, a falling sat, and breath sounds on one side only.
  • The fix is a small pull-back, not a deeper push. Deflate the cuff if you need to, pull back 1 to 2 cm at a time, inflate again, and recheck both sides and the waveform.
  • In the DOPE check, displacement includes a mainstem tube. DOPE is displacement, obstruction, pneumothorax, and equipment. See DOPE-S.
  • Children have a short trachea. Recheck depth and both sides of the chest after every bump.

Common errors

  • Calling the tube good because EtCO₂ is 35 while the left chest is silent.
  • Never writing a depth, then guessing after you are in the ambulance.
  • Pushing the tube deeper to make sure it stays.

Practice

One-minute check

Partner: an adult endotracheal tube is at 26 cm. After a move, the left chest is silent and the waveform is still present. Name the first two actions. Say what you will check again after you pull the tube back.

Related: Post-intubation, Capnography.

Sources & Further Study

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

Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.

Check Your Understanding

Questions drawn only from this lesson. After you check, the key is highlighted. Education practice — not a certification exam.

1. Waveform EtCO₂ after intubation means:
2. Left chest silent, high bag pressure, sat falling, waveform present. What do you do?
3. The best time to note endotracheal-tube depth is:
4. Kids get mainstem intubation easily because:
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