Failed airway, falling saturation, radiated neck
A 58-year-old man (BMI 41, weight 122 kg) presents for urgent laparoscopic cholecystectomy with 12 hours of fever and right upper quadrant pain. Four years ago he had laryngeal cancer treated with 60 Gy external-beam radiation to the neck. Airway examination: mouth opening 3 cm, Mallampati 3, thyromental distance 5.5 cm, limited neck extension, thick beard. He is preoxygenated for 3 minutes to SpO2 100% with EtO2 88%. Following propofol 200 mg and rocuronium 50 mg, videolaryngoscopy shows a Cormack-Lehane grade 3 view; a bougie fails to pass, and a second attempt with a different blade does not improve the view. Over the next 90 seconds SpO2 falls to 82% and then 71% despite two-handed mask ventilation with an oral airway and jaw thrust; no capnography waveform is obtained. An i-gel size 4 is placed; there is a large audible leak and still no EtCO2. Heart rate 128/min, blood pressure 88/52 mmHg. The surgeon and a second anesthesiologist are at the bedside; a front-of-neck access kit is open.
1. Saturation is 71% and falling. Working with the team at the bedside, state your actions for the next 60 seconds in priority order, and justify each.
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Declare the state out loud: cannot intubate, cannot oxygenate (CICO). Naming it converts parallel, uncoordinated efforts into one plan and stops a third well-meaning laryngoscopy. Nominate one person to lead and one to prepare the neck.
Stop intubation attempts. Two failed videolaryngoscopies plus a failed bougie in a radiated neck predict failure; every further attempt consumes oxygen and adds edema and bleeding.
One timed, optimised supraglottic attempt is acceptable, not mandatory. The i-gel leaked, which means it is not sealing over the larynx. Either re-seat it with two-person jaw thrust and a head-elevated position and accept it only if a capnography waveform appears within about 15 seconds, or abandon it immediately because the patient is below 70%.
Go to the front of the neck with scalpel-bougie-tube cricothyrotomy. 100% oxygen, neck extended, vertical midline skin incision, blunt dissection, horizontal stab through the cricothyroid membrane, bougie, then a size 6.0 cuffed tube and confirm with capnography. Radiation fibrosis distorts landmarks but the cricothyroid membrane is usually spared and is the target, not a tracheostomy.
Pharmacology runs in parallel, not instead. Do not use sugammadex 16 mg/kg as the primary rescue: returning muscle tone does not relieve mechanical obstruction, and the onset is too slow when the saturation is 71% and falling. Keep boluses of propofol or ketamine ready for the moment the airway is secured, since awareness during a surgical airway is a real risk.
2. Why does the absent EtCO2 waveform change your management more than the SpO2 value does? Explain the physiology.
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The two monitors answer different questions.
SpO2 is a lagging indicator. Three minutes of preoxygenation fills the functional residual capacity with a large oxygen reservoir, so saturation can read 95% while alveolar ventilation has already ceased. When the reservoir empties the patient slides down the steep part of the oxyhemoglobin dissociation curve: a fall from 82% to 71% in 90 seconds means very little reserve is left. In a BMI 41 patient the FRC is small and the desaturation is faster still.
Capnography is an immediate ventilation monitor. A waveform requires three things: gas reaching the alveoli, pulmonary blood flow, and a patent sampling line. A flat trace with a working line means no alveolar ventilation - esophageal placement, complete upper airway obstruction, or apnea. That is definitive within seconds and does not depend on oxygen reserve or on peripheral perfusion.
The practical consequence is the decision rule: no EtCO2 after placement of a tube or a supraglottic device means the device is not in the airway, full stop. Do not wait for the saturation to confirm it, and do not be reassured by chest movement or by an audible leak. Spend a few seconds checking that the sampling line is not kinked, disconnected or blocked with secretions, but no more than that while saturation is under 70%.
3. The airway is eventually secured by cricothyrotomy and the case is cancelled. What do you document and what plan do you set for the next anesthetic?
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Documentation should be factual, timed and sequential: the pre-operative airway assessment including the radiation history, the drugs and doses given, each attempt and device used, the number of attempts, the lowest saturation, the moment CICO was declared, the time to front-of-neck access, and confirmation of the airway with capnography. Record who was present and what was said to the patient and family. Avoid retrospective euphemism; the next anesthetist needs the sequence, not a summary judgement.
Plan for next time. This patient has a documented impossible mask ventilation, failed videolaryngoscopy and a surgical airway in a previously irradiated neck. Options, in order of preference:
- Awake flexible scope or awake videolaryngoscopy with topical anesthesia and sedation, with the surgeon scrubbed and a tracheostomy set open, in the operating theatre rather than an induction room.
- ENT assessment of the larynx and airway before any elective surgery, including the degree of radiation fibrosis and any fixed narrowing.
- Consider elective awake tracheostomy for any procedure that cannot be done under local or regional anesthesia.
The airway alert should go in the record and on the wristband, and the patient should be given a written letter describing the event. Rocuronium was used: if a neuromuscular blocker is ever needed again, plan for an awake technique first.