[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anaesthesia and ICU](https://durgical.com/en/anaesthesia/) › [The airway](https://durgical.com/en/anaesthesia/areas/airway/) › Tracheal intubation

# Tracheal intubation

- Technique

Passing a tube through the vocal cords into the windpipe, so the lungs can be ventilated safely and protected from stomach contents.

Updated Nov 13, 2026

## Key points

- Indications: failure to protect the airway, to keep it open, to oxygenate or to ventilate, or the expected course of the illness.
- Sustained waveform capnography is the standard to confirm tracheal placement: «no trace, wrong place».
- Sniffing position: neck flexed on the chest and head extended, so the ear is level with the sternal notch.
- Cormack–Lehane grades: 1 whole glottis, 2 part of it, 3 epiglottis only, 4 no epiglottis.
- Watch for post-intubation hypotension: induction drugs and positive pressure reduce venous return.

On this page

- The basics Key points
- What it is
- Indications
- Equipment and preparation
- Step by step (and why)
- Cormack–Lehane grades of the laryngoscopic view
- Next step
- Memory aid
- Elsewhere in DurgiPedia

- Clinical Complications

- Safety Contraindications and precautions

- Study Test yourself

- Connections Connections

## What it is

Tracheal intubation places a cuffed tube through the mouth (or nose) and the vocal cords into the trachea. It gives a secure airway: the cuff seals the trachea so the lungs can be ventilated with positive pressure and stomach contents or blood cannot run into them. It is used for many general anaesthetics and in patients who cannot protect, keep open, oxygenate or ventilate their own airway. Most intubations are done under general anaesthesia with an induction agent and a neuromuscular blocker; the operator uses a laryngoscope to lift the tongue and epiglottis, sees the glottis and passes the tube under direct vision. The view is graded with the Cormack–Lehane scale. Placement is proven by a sustained waveform on capnography, which is the single most reliable sign; chest movement and listening support it but can mislead. The commonest life-threatening error is an unrecognised oesophageal intubation, and the commonest early harms are hypoxaemia and a fall in blood pressure after induction, so the whole process is planned with a backup in mind.

## Indications

- Failure to protect the airway: low level of consciousness, absent airway reflexes, risk of aspiration.
- Failure to keep the airway open: burns, angioedema, trauma, infection or swelling of the upper airway.
- Failure of oxygenation or ventilation despite noninvasive support.
- Expected deterioration or transfer: severe trauma, combative patient needing a scan, long transfer.
- Anaesthetic needs: muscle relaxation, prone or long surgery, airway or thoracic surgery, high aspiration risk.

## Contraindications and precautions

- Predicted difficult airway: consider awake intubation (for example with a flexible bronchoscope) instead of induction first.
- Suspected cervical spine injury: manual in-line stabilisation and minimal neck movement; a videolaryngoscope helps.
- Full stomach: use rapid-sequence induction.
- Shock: resuscitate first and have a vasopressor ready, because induction can cause collapse.
- Severe laryngeal trauma or complete obstruction: a surgical front-of-neck airway may be the first choice.

## Equipment and preparation

- Suction switched on and within reach, and oxygen with mask and bag.
- Laryngoscope (direct and video) with two blades, tubes in the chosen size and one smaller, stylet and bougie.
- Syringe for the cuff, tape or tie, and a cuff pressure gauge.
- Drugs drawn up and labelled: induction agent, neuromuscular blocker, vasopressor; intravenous access running.
- Monitoring: pulse oximetry, blood pressure, ECG and waveform capnography; a supraglottic airway ready for rescue.

## Step by step (and why)

- Check the kit, the team roles and the backup plan aloud — a shared plan avoids freezing when the first attempt fails.
- Position in the sniffing position, ramped if obese — this aligns the mouth, pharynx and larynx for a direct view.
- Preoxygenate to an end-tidal oxygen of about 90% — this builds the oxygen store for the apnoea.
- Give the induction agent and neuromuscular blocker, then wait for full relaxation — relaxed cords and no cough make passage easy.
- Open the mouth and insert the blade on the right, sweeping the tongue to the left — this clears space to see and pass the tube.
- Advance the curved blade tip into the vallecula and lift along the handle, never levering — levering breaks teeth and worsens the view.
- Identify the cords and grade the view; use external laryngeal pressure or a bougie if needed — a better view raises first-pass success.
- Pass the tube under vision until the cuff is just below the cords, then inflate it — too deep enters the right main bronchus.
- Confirm with sustained waveform capnography, then chest rise and breath sounds on both sides — capnography rules out the oesophagus.
- Secure the tube, record its depth at the teeth and check the cuff pressure — the tube must not move or damage the trachea.

## Cormack–Lehane grades of the laryngoscopic view

| Grade | What is seen | What it means |
| --- | --- | --- |
| 1 | Most or all of the glottis | Easy intubation |
| 2 | Only the back part of the glottis or the arytenoids | Usually possible; a bougie helps |
| 3 | Only the epiglottis | Difficult: bougie, external pressure or videolaryngoscope |
| 4 | Neither glottis nor epiglottis | Very difficult: change technique and follow the difficult-airway plan |

## Complications

- Unrecognised oesophageal intubation: lethal hypoxaemia; if in doubt, take it out.
- Endobronchial intubation (usually right main bronchus): one-sided breath sounds, high airway pressure, falling saturation.
- Hypoxaemia from prolonged attempts, and hypotension or arrest after induction in shocked patients.
- Trauma: broken teeth, lip or pharyngeal tears, sore throat, hoarseness, vocal cord injury.
- Aspiration, laryngospasm, bronchospasm, arrhythmias, raised intracranial or eye pressure from the stress response.
- Late: tracheal stenosis or injury from a high cuff pressure, ventilator-associated pneumonia.

## Next step

- After securing the tube, start sedation and analgesia before the neuromuscular blocker wears off, to prevent awareness.
- In intensive care, get a chest X-ray to check the tip sits a few centimetres above the carina.
- Call for senior help after a failed attempt; limit the number of attempts and move to the difficult-airway plan.
- Record the view grade, device, number of attempts and any difficulty, and tell the patient if the airway was difficult.
- Monitor cuff pressure and tube position regularly, especially after moving the patient.

## Memory aid

No trace, wrong place: without a sustained capnography waveform the tube is assumed to be in the oesophagus.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the most reliable way to confirm that a tracheal tube is in the trachea?

A sustained waveform on capnography over several breaths. Chest movement, breath sounds and tube misting can all occur with an oesophageal tube.

## What is the sniffing position and why is it used?

The neck is flexed on the chest and the head extended at the atlanto-occipital joint, with the ear level with the sternal notch; it lines up the axes for a direct view.

## What does a Cormack–Lehane grade 3 view mean?

Only the epiglottis is seen, no part of the glottis; intubation is difficult and usually needs a bougie, external pressure or a videolaryngoscope.

## After intubation, breath sounds are heard only on the right side. What is the likely cause?

The tube is too deep, in the right main bronchus, which is wider and more vertical; deflate the cuff, withdraw the tube a little and recheck both sides.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anaesthesia/tracheal-intubation/)

## Elsewhere in DurgiPedia

- [Bag-mask ventilation](https://durgical.com/en/clinical-skills/bag-mask-ventilation/)
- [Supraglottic airway devices](https://durgical.com/en/clinical-skills/supraglottic-airway-devices/)
- [Opening the airway: head tilt, jaw thrust and simple adjuncts](https://durgical.com/en/clinical-skills/opening-the-airway-head-tilt-jaw-thrust-and-simple-adjuncts/)

## Connections

## Related 6

- [Preoxygenation and apnoeic oxygenation](https://durgical.com/en/anaesthesia/preoxygenation-and-apnoeic-oxygenation/)
- [Rapid-sequence induction and intubation](https://durgical.com/en/anaesthesia/rapid-sequence-induction-and-intubation/)
- [Videolaryngoscopy, bougies and other adjuncts](https://durgical.com/en/anaesthesia/videolaryngoscopy-bougies-and-other-adjuncts/)
- [The unanticipated difficult airway: plans A to D](https://durgical.com/en/anaesthesia/the-unanticipated-difficult-airway-plans-a-to-d/)
- [Extubation: when and how](https://durgical.com/en/anaesthesia/extubation-when-and-how/)
- [Capnography: the waveform and what it tells you](https://durgical.com/en/anaesthesia/capnography-the-waveform-and-what-it-tells-you/)

## Related conditions 4

- [Acute respiratory failure (hypoxaemic and hypercapnic)](https://durgical.com/en/conditions/acute-respiratory-failure/)
- [Aspiration pneumonia and pneumonitis](https://durgical.com/en/conditions/aspiration-pneumonia-and-pneumonitis/)
- [Traumatic brain injury](https://durgical.com/en/conditions/traumatic-brain-injury/)
- [Cardiac arrest (VF, pulseless VT, asystole, PEA)](https://durgical.com/en/conditions/cardiac-arrest/)

## In Pharmacology 7

- [Propofol](https://durgical.com/en/pharmacology/propofol/)
- [Etomidate](https://durgical.com/en/pharmacology/etomidate/)
- [Ketamine](https://durgical.com/en/pharmacology/ketamine/)
- [Neuromuscular blockers](https://durgical.com/en/pharmacology/classes/neuromuscular-blockers/)
- [Rocuronium](https://durgical.com/en/pharmacology/rocuronium/)
- [Suxamethonium](https://durgical.com/en/pharmacology/suxamethonium/)
- [Fentanyl](https://durgical.com/en/pharmacology/fentanyl/)

[← All of anaesthesia](https://durgical.com/en/anaesthesia/)

Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: [Endotracheal Intubation Techniques](https://www.ncbi.nlm.nih.gov/books/NBK560730/) (StatPearls (NCBI Bookshelf), 2023); [Tracheal Intubation Medications](https://www.ncbi.nlm.nih.gov/books/NBK507812/) (StatPearls (NCBI Bookshelf), 2023).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anaesthesia/tracheal-intubation/