Background
In recent years, high flow nasal oxygen(HFNO) has been widely used in clinic, especially in perioperative period.
Many studies have discussed the role of HFNO in pre- and apneic oxygenation, but their results are controversial.
Our study aimed to examine the effectiveness of HFNO in pre- and apneic oxygenation by a meta-analysis of
RCTs.
Methods
EMBASE, PUBMED, and COCHRANE LIBRARY databases were searched from inception to July 2021 for relevant
randomized controlled trails(RCTs) on the effectiveness of HFNO versus standard facemask ventilation(FMV) in
pre- and apenic oxygenation. Studies involving one of the following six indicators: (1)Arterial oxygen partial
pressure(PaO2), (2)End expiratory oxygen concentration(EtO2), (3)Safe apnoea time, (4)Minimum pulse oxygen
saturation(SpO2min), (5)Oxygenation(O2) desaturation, (6)End expiratory carbon dioxide(EtCO2) or Arterial carbon
dioxide partial pressure(PaCO2) were included. We select random effect model or fixed effect model for analysis
according to the heterogeneity of the article, and express it as the mean difference(MD) or risk ratio(RR) with a
confidence interval of 95%(95%CI). We conducted a risk assessment of bias for eligible studies and assessed the
overall quality of evidence for each outcome.
Results
14 RCTs and 1012 participants were finally included. We found the PaO2 was higher in HFNO group than FMV
group with a MD(95% CI) of 57.38 mmHg(25.65 to 89.10; p=0.0004) after preoxygenation and the safe apnoea
time was significantly longer with a MD(95% CI) of 86.93 seconds(44.35 to 129.51; p<0.0001) during anesthesia
induction. There were no significant statistical difference in the minimum O2 saturation, CO2 accumulation, end
expiratory oxygen concentration and O2 desaturation rate during anesthesia induction between the two groups.
Conclusions
This systematic review and meta-analysis suggests that HFNO should be considered as an airway management
tool for patients with high-risk hypoxemia or difficult airway during anesthesia induction. Compared with FMV,
continuous use of HFNO during anesthesia induction can significantly improve oxygenation and prolong safe
apnoea time in surgical patients.