Raising the awareness for insufficient oxygen delivery from self-inflating resuscitation bags lacking expiratory valve during preoxygenation

We recently read an interesting study which demonstrated that self-inflating resuscitation bag (SIRB) lacking expiratory valve has unreliable performance in oxygen delivery during spontaneous breathing mimicked by mechanical lung simulator. It was postulated that the absence of an expiratory valve and the resulting air entrainment via the exhaust port accounts for the poor oxygen delivery performance. The current disposable SIRB in-use in our institutions (Med-Rescuer Disposable BVM Resuscitator 4000, BLS Systems Limited, ON, Canada) has a duckbill valve but no expiratory valve. Safety concerns regarding its oxygen delivery performance during spontaneous breathing were raised, as this SIRB was commonly used to preoxygenate critically ill patient with potentially transmissible respiratory infection (e.g. COVID-19) before tracheal intubation. We therefore performed an experiment on this SIRB using one of us as a healthy volunteer. Our small experiment demonstrated that air entrainment could occur via the exhaust port and affect oxygen delivery performance. Our experiment also demonstrated that attaching a positive end-expiratory pressure (PEEP) valve to the exhaust port improves the oxygen delivery performance. The findings of this experiment were sent to the relevant department of our institutions for safety consideration.

Early intubation versus late intubation for COVID-19 patients: An in situ simulation identifying factors affecting performance and infection control in airway management.

COVID-19 poses an infectious risk to healthcare workers especially during airway management. We compared the impact of early versus late intubation on infection control and performance in a randomised in situ simulation, using fluorescent powder as a surrogate for contamination. Twenty anaesthetists and intensivists intubated a simulated patient with COVID-19. The primary outcome was the degree of contamination. The secondary outcomes included the use of bag-valve-mask ventilation, the incidence of manikin cough, intubation time, first attempt success and heart rate variability as a measure of stress. The contamination score was significantly increased in the late intubation group, mean (standard deviation, SD) 17.20 (6.17), 95% confidence intervals (CI) 12.80 to 21.62 versus the early intubation group, mean (SD) 9.90 (5.13), 95% CI 6.23 to 13.57, P = 0.005. The contamination score was increased after simulated cough occurrence (mean (SD) 18.0 (5.09) versus 5.50 (2.10) in those without cough; P<0.001), and when first attempt laryngoscopy failed (mean (SD) of 17.1 (6.41) versus 11.6 (6.20) P = 0.038). The incidence of bag-mask ventilation was higher in the late intubation group (80% versus 30%; P=0.035). There was no significant difference in intubation time, incidence of failed first attempt laryngoscopy or heart rate variability between the two groups. Late intubation in patients with COVID-19 may be associated with greater laryngoscopist contamination and potential aerosol-generating events compared with early intubation. There was no difference in performance measured by intubation time and incidence of first attempt success. Late intubation, especially when resources are limited, may be a valid approach. However, strict infection control and appropriate personal protective equipment usage is recommended in such cases.