Preoxygenation and Anesthesia: A Detailed Review

Area of Science:

• Anesthesiology
• Respiratory Physiology

Background:

• Preoxygenation is standard practice before anesthetic induction and tracheal intubation.
• It aims to increase the body's oxygen stores, delaying arterial hemoglobin desaturation during apnea.

Purpose of the Study:

• To review the advantages of preoxygenation techniques.
• To highlight risks and inadequacies, particularly in high-risk populations.

Main Methods:

• Review of existing literature on preoxygenation techniques.
• Analysis of efficacy indices like alveolar O2 fraction (FAO2) and oxyhemoglobin desaturation (SAO2).
• Discussion of three common methods: deep breathing, rapid breathing (FiO2 1 for 2-5 min), and vital capacities.

Main Results:

• Preoxygenation effectiveness is measured by increased FAO2, decreased alveolar nitrogen fraction (FAN2), and improved arterial O2 tension (PAO2).
• Key risks include delayed esophageal intubation diagnosis, absorption atelectasis, reactive oxygen species generation, and hemodynamic effects.
• Minimal preoxygenation time limits adverse effects.

Conclusions:

• Preoxygenation is crucial for all patients, with specific attention to high-risk groups.
• Alternative methods like trans-tracheal ventilation are vital for emergencies.
• Adequate training and equipment are essential for preparedness.