Bag-Mask Ventilation Versus Apneic Oxygenation During Tracheal Intubation in Critically Ill Adults: A Secondary Analysis of 2 Randomized Trials

Background: Hypoxemia is common during tracheal intubation in intensive care units. To prevent hypoxemia during intubation, 2 methods of delivering oxygen between induction and laryngoscopy have been proposed: bag-mask ventilation and supplemental oxygen delivered by nasal cannula without ventilation (apneic oxygenation). Whether one of these approaches is more effective for preventing hypoxemia during intubation of critically ill patients is unknown. Methods: We performed a secondary analysis of data from 138 patients enrolled in 2, consecutive randomized trials of airway management in an academic intensive care unit. A total of 61 patients were randomized to receive bag-mask ventilation in a trial comparing bag-mask ventilation to none, and 77 patients were randomized to receive 100% oxygen at 15 L/min by nasal cannula in a trial comparing apneic oxygenation to none. Using multivariable linear regression accounting for age, body mass index, severity of illness, and oxygen saturation at induction, we compared patients assigned to bag-mask ventilation with those assigned to apneic oxygenation regarding lowest oxygen saturations from induction to 2 min after intubation. Results: Patients assigned to bag-mask ventilation and apneic oxygenation were similar at baseline. The median lowest oxygen saturation was 96% (interquartile range [IQR] 89%-100%) in the bag-mask ventilation group and 92% (IQR 84%-99%) in the apneic oxygenation group. After adjustment for prespecified confounders, bag-mask ventilation was associated with a higher lowest oxygen saturation compared to apneic oxygenation (mean difference, 4.2%; 95% confidence interval, 0.7%-7.8%; P = .02). The incidence of severe hypoxemia (oxygen saturation<80%) was 6.6% in the bag-mask ventilation group and 15.6% in the apneic oxygenation group (adjusted odds ratio, 0.33; P = .09). Conclusions: This secondary analysis of patients assigned to bag-mask ventilation and apneic oxygenation during 2 clinical trials suggests that bag-mask ventilation is associated with higher oxygen saturation during intubation compared to apneic oxygenation.

Comparison of the Effectiveness of High-Flow Nasal Oxygen vs. Standard Facemask Oxygenation for pre- and apneic oxygenation during Anesthesia Induction: A Systematic Review and Meta-analysis

BackgroundIn 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 ofRCTs.MethodsEMBASE, PUBMED, and COCHRANE LIBRARY databases were searched from inception to July 2021 for relevantrandomized controlled trails(RCTs) on the effectiveness of HFNO versus standard facemask ventilation(FMV) inpre- and apenic oxygenation. Studies involving one of the following six indicators: (1)Arterial oxygen partialpressure(PaO2), (2)End expiratory oxygen concentration(EtO2), (3)Safe apnoea time, (4)Minimum pulse oxygensaturation(SpO2min), (5)Oxygenation(O2) desaturation, (6)End expiratory carbon dioxide(EtCO2) or Arterial carbondioxide partial pressure(PaCO2) were included. We select random effect model or fixed effect model for analysisaccording to the heterogeneity of the article, and express it as the mean difference(MD) or risk ratio(RR) with aconfidence interval of 95%(95%CI). We conducted a risk assessment of bias for eligible studies and assessed theoverall quality of evidence for each outcome.Results14 RCTs and 1012 participants were finally included. We found the PaO2 was higher in HFNO group than FMVgroup with a MD(95% CI) of 57.38 mmHg(25.65 to 89.10; p=0.0004) after preoxygenation and the safe apnoeatime was significantly longer with a MD(95% CI) of 86.93 seconds(44.35 to 129.51; p<0.0001) during anesthesiainduction. There were no significant statistical difference in the minimum O2 saturation, CO2 accumulation, endexpiratory oxygen concentration and O2 desaturation rate during anesthesia induction between the two groups.ConclusionsThis systematic review and meta-analysis suggests that HFNO should be considered as an airway managementtool 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 safeapnoea time in surgical patients.

Efficiency of different flows for apneic oxygenation when using high flow nasal oxygen application – a technical simulation

Background Preoxygenation and application of apneic oxygenation are standard to prevent patients from desaturation e.g. during emergency intubation. The time before desaturation occurs can be prolonged by applying high flow oxygen into the airway. Aim of this study was to scientifically assess the flow that is necessary to avoid nitrogen entering the airway of a manikin model during application of pure oxygen via high flow nasal oxygen. Methods We measured oxygen content over a 20-min observation period for each method in a preoxygenated test lung applied to a human manikin, allowing either room air entering the airway in control group, or applying pure oxygen via high flow nasal oxygen at flows of 10, 20, 40, 60 and 80 L/min via nasal cannula in the other groups. Our formal hypothesis was that there would be no difference in oxygen fraction decrease between the groups. Results Oxygen content in the test lung dropped from 97 ± 1% at baseline in all groups to 43 ± 1% in the control group (p < 0.001 compared to all other groups), to 92 ± 1% in the 10 L/min group, 92 ± 1% in the 20 L/min group, 90 ± 1% in the 40 L/min group, 89 ± 0% in the 60 L/min group and 87 ± 0% in the 80 L/min group. Apart from comparisons 10 l/ min vs. 20 L/min group (p = .715) and 10/L/min vs. 40 L/min group (p = .018), p was < 0.009 for all other comparisons. Conclusions Simulating apneic oxygenation in a preoxygenated manikin connected to a test lung over 20 min by applying high flow nasal oxygen resulted in the highest oxygen content at a flow of 10 L/min; higher flows resulted in slightly decreased oxygen percentages in the test lung.