Oxygenation is particularly important in children undergoing endotracheal intubation. They have higher oxygen consumption than adults and become hypoxemic more quickly with rapid sequence intubation. Apneic oxygenation (AO) is the process of providing a high flow rate of oxygen through a standard nasal cannula prior to endotracheal intubation (ETI) without bag-valve mask ventilation. It is thought that the high flow rate results in nitrogen washout (replacing nitrogen with oxygen) which provides an oxygen reservoir as well as provides some degree of positive end expiratory pressure keeping airways open. Apneic oxygenation with a standard nasal cannula has the advantage of using readily available airway equipment, does not require removal prior to intubation and avoids the complications that can be associated with bag-valve-mask ventilation. Apneic oxygenation was been shown to be beneficial in adults but pediatric data is limited.
In pediatric patients undergoing endotracheal intubation in the emergency department, is apneic oxygenation (high flow oxygen through a standard nasal cannula without ventilation), when compared to intubation without apneic oxygenation, associated with a decrease in hypoxemia during the procedure?
- Inclusion: <22 years, presenting to the ED, requiring endotracheal intubation (ETI) with/without rapid sequence medications
- Exclusion: Active cardiopulmonary resuscitation
- Setting: Single Children’s Hospital (US)
- Apneic oxygenation (Prospective: 8/2014 – 3/2017)
- 2 years: 4 Liters/min, >2 to 12 years: 6 Liters/min, >12 years: 8 Liters/min
- Delivered by a standard nasal cannula with wall oxygen
- Started by respiratory therapist as standard care at time of the intubation decision
- No apneic oxygenation (Retrospective: 1/2011 – 6/2011)
At discretion of treating physicians:
- Preoxygenation method: Non-rebreather mask or bag-valve mask ventilation
- Endotracheal intubation method: Direct/Video laryngoscopy, blade size/type
- Hypoxemia: SpO2 <90% during endotracheal intubation (ETI)
- During ETI = Mouth opening until laryngoscope blade removed from mouth
Observational: Retrospective cohort (before), prospective cohort (after)
N = 149 patients (42% <1 year of age)
After AO: n = 90
Before AO: n = 59 (includes 14 who did not receive AO in the after AO time period)
- Hypoxemia during endotracheal intubation was less common in the After AO cohort in both the univariable (unadjusted) analysis and the regression (adjusted) analysis.
- Adjusted odds ratio (AO/no AO): 3, 95% CI (0.1, 0.8)
- The difference in the proportion with hypoxia was greater than the 13% difference indicated by the authors as clinically significant.
- Additional independent predictors of hypoxia during ETI included
- Age (Every 1-year ): aOR: 8, 95% CI (0.7, 1.0)
- SpO2 before endotracheal intubation (Every 1% ): aOR: 8, 95% CI (0.7, 1.0)
- Each additional attempts at endotracheal intubation: aOR: 0, 95% CI (2.2, 7.2)
- Not independent predictors: Proceduralist level of training, direct versus video laryngoscopy
|PRIMARY OUTCOME: HYPOXIA DURING ENDOTRACHEAL INTUBATION|
|Before Apneic Oxygenation||After Apneic Oxygenation|
|Lowest SpO2 (Median (IQR))||93% (69, 99%)||100% (95, 100%)|
|25th% of Lowest SpO2*||69%||95%|
|*The authors considered a difference a 13% to be clinically significant|
- Regression analysis to accounts for potential confounders and differences in the two study cohorts
- Outcomes of sensitivity analysis excluding patients in the after AO cohort who did not receive AO and included in the before AO were similar to outcomes with all patients included
- Relatively small sample size (n= 149)
- Single children’s hospital possibly limiting generalizability to other settings
- Observational Before/After design. Concern that something other than the intervention of interest changed between the study periods (3-year interval between)
- Pediatric resident intubation and video laryngoscopy more common in the After AO cohort though neither was an independent predictor of hypoxia in the regression analysis
- Data not presented to calculate risk differences, confidence intervals and number needed to treat for the unadjusted analyses.
- Preoxygenation method (NRB Face mask or BVM ventilation) at discretion of treating physicians and data not presented about the distribution of this variable in the two cohorts
“In summary, in this observational analysis, utilizing apneic oxygenation was associated with reduced odds of hypoxemia during endotracheal intubation. Further, although a subset of patients in the apneic oxygenation group did experience hypoxemia, a larger proportion of patients not receiving the intervention experienced marked hypoxemia, with one quarter of patients having SpO2 69% during endotracheal intubation. Providers should recognize the potential importance of this easily-applied intervention at reducing the incidence of hypoxemia during endotracheal intubation. Future studies should aim at optimizing endotracheal intubation attempts and reducing hypoxemia using randomized, controlled methodologies, as well as identifying other potentially modifiable interventions associated with this outcome.”
Apneic oxygenation is simple to perform and readily available in the Emergency Department. Its use in this study was associated with a statistical and clinical improvement in the proportion of patients with hypoxia during ETI.
This question would benefit from a larger, multicenter clinical trial in the pediatric population. The potential for the nasal cannula to prevent an adequate seal during bag-valve mask ventilation merits further study.
It is important to acknowledge that approximately one quarter of the patients in the after apneic oxygenation cohort experienced hypoxia. This indicates room for improvement and further evaluation of targeting the other variables in the regression analysis that were found to be independent predictors of hypoxia during ETI.
Potential Impact To Current Practice
Since there are few if any adverse effects associated with its use it would seem prudent to recommend routine use apneic oxygenation the pediatric population.
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