Endobronchial Intubation

Endobronchial intubation is placement of the tracheal tube tip beyond the carina, usually in the right main bronchus, so that only one lung is ventilated.

Epidemiology. It occurs in about 1% to 5% of intubations, more often in children and after patient movement. Tube depth changes by about 2 cm with head flexion or extension, and Trendelenburg position and laparoscopy move the carina upward.

Risk factors. Tube advanced too far, short trachea, children, head flexion, Trendelenburg position, pneumoperitoneum, lateral position, surgical traction and a tube not fixed.

Complications. Hypoxaemia, atelectasis of the unventilated lung, barotrauma, pneumothorax, and right upper lobe obstruction.

Pathophysiology.

Ventilation of one lung creates shunt through the non-ventilated lung. Over distension of the ventilated lung raises peak pressure and risks barotrauma.

Unilateral breath sounds (usually absent on the left), asymmetric chest movement, high peak airway pressure, low tidal volume, falling saturation, rising carbon dioxide and tachycardia.

Red flags.

• Saturation under 90% after correction.
• Sudden high pressure with hypotension (tension pneumothorax).
• Persistent unilateral signs after tube withdrawal.

Auscultate both axillae and apices. Check tube depth at the teeth or lips (about 21 cm in women and 23 cm in men for oral tubes, or 3 times the tube size). The tube tip should lie 3 to 7 cm over the carina on a chest radiograph. Confirm by bronchoscopy or lung ultrasound (absent lung sliding on the unventilated side).

Differential diagnosis.

• Pneumothorax.
• Mucus plug or lobar collapse.
• Bronchospasm.
• Tube kink or cuff herniation.
• Pulmonary embolism.
• Oesophageal intubation.

Withdraw the tube by 1 to 2 cm while auscultating and ventilating. Recheck breath sounds on both sides and waveform capnography, refix the tube, and note the depth. Perform a recruitment manoeuvre for atelectasis, and obtain a chest radiograph. Treat pneumothorax with a chest drain.

Prevention. Insert to a measured depth, check depth after each position change (including head movement and Trendelenburg), and use a bronchoscope or ultrasound for confirmation when position is uncertain. In children use age/2 plus 12 cm at the lips.

Monitoring. Peak and plateau pressure, tidal volume, saturation, capnography and repeat chest examination after every position change.

Referral and escalation. Senior help if hypoxaemia persists. Thoracic review for pneumothorax or lobar collapse.

Special groups. Neonates and infants have a short trachea, so tube position changes with small movement. Use radiograph confirmation.