Preoxygenation for Tracheal Aspirations in Intensive Care

Rate of suctioning leading to deep desaturation

Clearing the airways is a complex phenomenon involving the production of secretions, the
 nature of mucus (viscosity, elasticity, stringiness, and adhesiveness), ciliary movement, and
 coughing. In intubated and ventilated patients, endotracheal suctioning occur when the
 patient is unable to clear the airways of obstructions hindering the free passage of air.
 These suctioning can lead to transient desaturation exacerbated by a decrease in cardiac
 output due to increased mean arterial pressure, promoting cardiac arrhythmias. To minimize
 these effects, it is recommended to perform additional preoxygenation, by increasing the
 fraction of O2 in the air delivered to the patient by the ventilator 2-3 minutes before the
 procedure. These longstanding recommendations were reiterated in 2022, based on outdated
 studies involving systematic suctioning that required disconnecting the patient from the
 ventilator.
 
 Currently, suctioning are performed on-demand, based on the patient's congestion status,
 either through the endotracheal tube cap or a closed system. Desaturations have become
 infrequent without establishing that additional preoxygenation can prevent them. Moreover,
 additional preoxygenation is not without risks. By inducing de-nitrogenation atelectasis with
 a loss of lung volume, it can exacerbate pre-existing lung injuries in the most severe
 patients. In less severe cases, preoxygenation leads to transient hyperoxia, with various
 deleterious effects impacting patient prognosis. Thus, a short-term risk, such as deep
 desaturations, must be balanced against a medium-term risk of hyperoxia and de-nitrogenation.