Preoxygenation and general anesthesia: a review.

Area of Science:

• Anesthesiology
• Critical Care Medicine
• Respiratory Physiology

Background:

• Intubation procedures carry a risk of arterial oxygen desaturation due to potentially lengthy durations.
• Oxygen reserves may be insufficient to cover the entire intubation period, necessitating robust preoxygenation strategies.

Purpose of the Study:

• To review the importance and methods of preoxygenation to optimize oxygen reserves before intubation.
• To highlight techniques for enhancing oxygenation during intubation, especially in challenging patient populations.

Main Methods:

• Review of standard preoxygenation techniques, including spontaneous breathing with fraction of inspired oxygen (FiO2) of 1 and vital capacity breaths.
• Discussion of factors affecting preoxygenation effectiveness, such as equipment fit and patient positioning.
• Exploration of adjuncts and alternative oxygenation strategies during intubation, including positive pressure and specialized devices.

Main Results:

• Three minutes of preoxygenation with FiO2=1 can achieve nearly 95% alveolar oxygen (FAO2) and extend tolerable apnea time to nearly 10 minutes.
• Eight deep breaths within 60 seconds provide comparable oxygen reserve increases.
• Inadequate preoxygenation is common and associated with difficult mask ventilation criteria; specific patient groups (e.g., morbidly obese) and respiratory failure require tailored approaches.

Conclusions:

• Preoxygenation should be a routine component of intubation, with careful attention to technique and equipment.
• Clinicians must be prepared with alternative oxygenation methods and training to manage emergencies during intubation.
• Optimizing preoxygenation is vital for patient safety, reducing the risk of hypoxemia during airway management.