Non-invasive ventilation beneficial for preoxygenation before general anesthesia: Study

Preoxygenation is essential for providing sufficient oxygen reservoir to a patient before intubation and allows the period between breathing termination and critical desaturation (safe apnoea time). Generally, face mask ventilation is used for preoxygenation. Non-invasive ventilation is a recently introduced method for preoxygenation. NIV settings include bilevel positive airway pressure, CPAP, and pressure support ventilation with or without positive end-expiratory pressure (PEEP).

Against the above background, Tsai-Lien Chiang, Taipei Medical University-Shuang Ho Hospital, Taiwan, and colleagues compared the outcomes of non-invasive ventilation and face mask ventilation for preoxygenation through a systemic review and meta-analysis.

For this purpose, the researchers searched the online databases for eligible studies published from database inception to September 2021. Randomized controlled trials comparing the outcomes of non-invasive or face mask ventilation for preoxygenation patients scheduled for surgeries met the inclusion criteria.

Safe apnea time was the primary outcome, and secondary outcomes included postoperative complications, minimal SpO2 during tracheal intubation, the proportion of patients who achieved the expired O2 fraction (FeO2) following 3 min of preoxygenation, partial pressure of carbon dioxide (PaCO2) after preoxygenation, partial pressure of oxygen in the arterial blood (PaO2), and PaO2 and PaCO2 after tracheal intubation. 13 trials met the inclusion criteria for inclusion in the study.

The study led to the following findings:

• The researchers observed significant differences in safe apnoea time, the number of patients who achieved FeO2 90% after preoxygenation for 3 min, and PaO2 and PaCO2 after preoxygenation and tracheal intubation.
• The non-obese subgroup observed no significant difference in safe apnoea time (mean difference: 125.38).

"The findings suggest that NIV is possibly more beneficial than conventional methods for preoxygenation, particularly in obese patients receiving selective surgeries," the authors wrote. "For non-obese patients, however, we suggest the need for further studies to assess whether NIV is superior to a conventional method."

"In some NIV groups, more gastric leakage and intolerance were observed, so the NIV's safety is a concern and may need further investigation."

To conclude, the results showed the possibility of NIV as a standard method of preoxygenation. Still, more studies are required to determine whether NIV is the better preoxygenation method or not.

Reference:

Chiang, TL., Tam, KW., Chen, JT. et al. Non-invasive ventilation for preoxygenation before general anesthesia: a systematic review and meta-analysis of randomized controlled trials. BMC Anesthesiol 22, 306 (2022). https://doi.org/10.1186/s12871-022-01842-y