Comparison of Two Ventilation Methods During Endoscopy of the Pharynx, Larynx and Oesophagus

Endoscopy of the pharynx, larynx and oesophagus (endo-PLO) is a diagnostic procedure that enables the anatomical structures that enable speech, breathing and swallowing to be visualised. By keeping the patient on spontaneous ventilation (SV) during this procedure, the anatomical structures can be better observed. The examination lasts an average of 45 minutes, from the time the patient enters the operating theatre until he or she leaves.

Today, endo-PLO is performed using two laryngoscopies. Laryngoscopy involves inserting a curved piece of metal approximately 10 centimetres long into the patient's mouth, to expose the patient's vocal cords and insert a laryngeal device (oxygen probe, intubation probe) to enable the patient to be ventilated.

As part of an endo-PLO, an initial laryngoscopy is carried out by the State-qualified Anaesthetist Nurse or Anaesthetist Resuscitator . This first laryngoscopy is used to instil a 2% lidocaine solution (3 ml) between the vocal cords via a local anaesthetic spray device, which helps to provide intra- and post-operative analgesia. In a second stage, this first laryngoscopy will enable an oxygen cannula to be introduced via the patient's nasal cavities to the entrance to the vocal cords. Once this first laryngoscopy has been performed, the anaesthetic is gradually lifted so that the patient regains VS while remaining unconscious. A second laryngoscopy (suspension laryngoscopy) is then performed by the surgeon to proceed with the operation. Once the procedure is complete, the nasal cannula is removed and the patient awakened in the operating theatre.

In the case of ENT cancers, this tumour damage weakens the anatomical structures and encourages bleeding at the slightest contact.

As with any procedure, there is a significant risk of damage to these anatomical structures during laryngoscopy. As the tissues of the laryngeal walls are very fragile, there is a major risk of bleeding, which may cause difficulties in carrying out the surgical procedure.

High-flow oxygen therapy (HFOT) is a medical technology that has been in use for many years, particularly at Poitiers University Hospital. This device enables oxygen to be administered and delivered at flow rates ranging from 20 to 70 litres per minute (L/min), with the capacity to produce an inspired fraction of oxygen (FiO2) of between 21% and 100%. It consists of a gas mixer, connected to a heater and humidifier for comfortable, optimal delivery of the gas mixture. The heater keeps the inspired gases at an average temperature of 37°C, while the humidifier prevents the patient's airways from drying out. The gas mixture comes from two different connections, linked to an air and oxygen intake, to ensure that the FiO2 recorded is the same as that delivered to the patient.

Inclusion criteria

• Patient aged 18 or over.
• Scheduled for upper aerodigestive tract endoscopy (pharynx, larynx, oesophagus).
• ASA physical status I to IV.
• No requirment for preoperative supplemental oxygen.
• Informed consent signed.

Exclusion criteria

• Endoscopy combined with another procedure.
• Body mass index ≥ 35 kg/m².
• Severe chronic obstructive pulmonary disease (GOLD stage IV).
• Allergy to one of the anaesthetic agents (remifentanil, propofol, lidocaine).
• Baseline SpO2 ≤ 92% on arrival in the operating room