The main objective of this pilot study is to determine if our protocole using EtO2 monitoring during preoxygenation before intubation is feasible in a population of critically ill patients in acute hypoxemic respirator failure (AHRF) in Intensive Care Unit (ICU).

We hypothesize that using EtO2 monitoring during preoxygenation before intubation is feasible and safe in a population of critically ill patients in AHRF in ICU setting.

Background : acute hypoxemic respiratory failure (AHRF) is one of the most common causes of intensive care unit (ICU) admission requiring subsequent tracheal intubation for invasive mechanical ventilation. Complications related to tracheal intubation are more frequent in ICU than in operating room with an incidence reaching 20 to 50% in previous studies. Among them, severe hypoxemia and hemodynamic failure can lead to cardiac arrest. End-expiratory tidal oxygen (EtO2) monitoring during preoxygenation is routinely used during anesthesia for elective surgery but has never been evaluated in ICU setting.

Objective : to evaluate the feasibility of a protocol using EtO2 monitoring during preoxygenation before intubation of patients in AHRF in ICU.

Methods : this is an interventional, prospective, bicenter (two French tertiary teaching Hospitals ICUs), feasibility study of a protocol using EtO2 monitoring during preoxygenation before rapid sequence induction (RSI) and intubation of patients in AHRF in ICU. Eligible patients will be older than 18 years, admitted to the ICU, requiring intubation, in AHRF according to the following criteria : a respiratory rate greater than 25 breaths per minute or signs of respiratory distress, and a partial pressure of arterial oxygen (PaO2) to FiO2 ratio equal to or below 200 mmHg (calculation of estimated FiO2 under standard oxygen as follows: FiO2 = 0.21 + oxygen flow rate × 0.03). Main exclusion criteria will be contraindications to Non Invasive Ventilation (NIV) (recent laryngeal, oesophageal, or gastric surgery, and substantial facial fractures), severe haemodynamic failure (Norepinephrine ≥ 0.3 μg/kg/min), cardiac arrest, do not intubate order, pregnancy or breastfeeding and refusal to participate. In 72 consecutive eligible patients tracheal intubation procedure will be performed in accordance with current guidelines except for the duration of the preoxygenation to be individualized by EtO2 monitoring. A targeted EtO2 ≥ 90% will trigger RSI and intubation. During the procedure, preoxygenation modalities and duration, achieved EtO2 level, conduction of the induction and intubation, minimum SpO2 and occurrence of complications will be recorded. A 100- point ponderated score elaborated by an independent expert committee based on literature and updated national guidelines (4,5) will evaluate recommendations adherence. A score ≥ 85 / 100 adjudicates a procedure matching with good practices guidelines. The primary outcome is the percentage tracheal intubation procedures performed in accordance with current good practices guidelines.

Inclusion Criteria:

• Admitted in ICU
• In AHRF, defined as : respiratory rate greater than 25 breaths per minute or signs of respiratory distress, and a partial pressure of oxygen (PaO2) to FiO2 ratio equal to or below 200 mmHg (calculation of estimated FiO2 under standard oxygen as follows: FiO2 = 0.21 + oxygen flow rate × 0.03).
• Indication to intubate based on physician judgment
• Written consent obtained from the patient, relative, or emergency consent.

Exclusion Criteria:

• Contraindications to NIV (recent laryngeal, oesophageal, or gastric surgery, and substantial facial fractures)
• Severe haemodynamic failure (Norepinephrine ≥ 0.3 μg/kg/min to maintain MAP ≥ 65 mmHg) or cardiac arrest
• Do not intubate order
• Pregnancy
• breastfeeding
• Refusal to participate