Cannot Intubate Cannot Oxygenate

Cannot intubate cannot oxygenate (CICO) is failure of tracheal intubation together with failure of face mask or supraglottic airway ventilation, with falling oxygen saturation. It is an immediate threat to life and brain.

Epidemiology. It occurs in about 1 in 50,000 general anaesthetics and is the commonest cause of death from airway complications. Brain injury follows within 4 to 6 minutes of anoxia.

Causes. Unanticipated difficult airway, obesity, airway tumour, infection or oedema, trauma, bleeding, burns, bad positioning, inadequate muscle relaxation, laryngospasm and unrecognised oesophageal placement.

Pathophysiology.

No gas exchange occurs. Oxygen stores fall rapidly in the apnoeic patient (faster in obesity, pregnancy and children), and hypoxaemia leads to bradycardia, then arrest.

Failed laryngoscopy and failed attempts with face mask and supraglottic airway, absent end tidal carbon dioxide trace, falling saturation (under 90%), bradycardia, cyanosis and loss of consciousness.

Red flags.

• Saturation under 90% despite oxygen.
• Heart rate falling.
• Flat capnography after a second generation supraglottic airway.
• Loss of anatomical landmarks (trauma, swelling).

A clinical emergency. Declare it aloud, and confirm that equipment is not faulty. Confirm neuromuscular relaxation (train-of-four count 0) and that the capnography trace is absent.

Differential diagnosis.

• Laryngospasm.
• Opioid induced chest wall rigidity.
• Bronchospasm.
• Equipment failure.
• Foreign body.
• Anaphylaxis.
• Tension pneumothorax.

Declare the emergency, call for help and ask for the front-of-neck access kit. Give 100% oxygen throughout.

Steps before surgery on the neck (take under a minute each).

• Optimise mask ventilation with a two person technique and an oral airway.
• Insert a second generation supraglottic airway.
• Ensure full paralysis, so that muscle tone is not the cause.
• Rocuronium: 1.2 mg/kg IV as a single dose; maximum 1.2 mg/kg; monitor train-of-four; dose on ideal body weight in obesity; prolonged action in hepatic impairment.
• Sugammadex (if rocuronium was used and recovery is wanted): 16 mg/kg IV as a single dose; maximum 16 mg/kg; confirm ratio 0.9 or more; avoid if creatinine clearance is under 30 mL/min; bradycardia and anaphylaxis can occur.

Front-of-neck access (when oxygenation fails). Extend the neck. Palpate the cricothyroid membrane. Make a horizontal stab through the membrane with a size 10 scalpel, rotate the blade 90 degrees with the sharp edge toward the feet, slide a bougie along the blade into the trachea, and railroad a lubricated cuffed tube (size 6.0). Inflate the cuff, ventilate and confirm with capnography.

If the landmarks cannot be felt, make a vertical midline incision of 8 to 10 cm, use blunt dissection to find the membrane, then continue with the same steps used for the horizontal technique. Large bore cannula techniques with a high pressure oxygen source are a second option for trained operators.

Cardiac arrest. Start cardiopulmonary resuscitation. Adrenaline 1 mg IV every 3 to 5 minutes (maximum directed by arrest duration); monitor rhythm and capnography; central access preferred.

After the event. Obtain a post-event neurological and respiratory review. Tell the patient, document the airway findings, issue an alert and write to the general practitioner. Check for complications such as bleeding, pneumothorax, surgical emphysema and hypoxic brain injury.

Monitoring. Continuous capnography, saturation and ECG. Arterial gas after stabilisation.

Referral and escalation. Critical care, ENT for conversion of an emergency cricothyroidotomy to a formal airway, and neurology for hypoxic injury.

Special groups. In children under about 8 years a needle cricothyroidotomy is used because the membrane is small. In obstetric patients and obesity, desaturation is rapid so act early.