What is the primary purpose of preoxygenating prior to anesthesia induction?

The primary purpose of preoxygenating prior to anesthesia induction is to fill the functional residual capacity (FRC) with oxygen-rich air. During preoxygenation, patients typically breathe a high concentration of oxygen, which significantly increases the amount of oxygen available in the lungs. This process serves to enhance the overall oxygen reserve in the body, allowing for a longer period of safe anesthesia without the risk of hypoxia, especially when the airway may become compromised or during rapid sequence induction.

Filling the FRC with oxygen-rich air is crucial since the FRC represents the volume of air remaining in the lungs at the end of a normal expiration. By maximizing the oxygen content in the FRC, it helps to prolong the time before the patient desaturates during periods when they may not be able to breathe adequately, such as during intubation or when ventilation may be impaired. This strategic approach aims to ensure that sufficient oxygen is available to the tissues until normal ventilation is restored.

The focus on preoxygenation significantly impacts patient safety by preparing the respiratory system for the induction of anesthesia, where the potential for reduced airway patency and various other complications can arise.