What is this page about?
Scott Weingart, MD and Richard Levitan, MD published an article in the Annals of Emergency Medicine entitled Preoxygenation and Prevention of Desaturation during Emergency Airway Management.
This page serves as a repository for supplementary material on the subjects raised in the article.
CPAP for Preoxygenation
In a patient with shunt, CPAP is needed for preoxygenation. In my ED, we make this happen with the ventilators installed next to every resuscitation bed.
However, not every ED has ventilators readily available and it might take >15 minutes to have respiratory bring a NIV machine or a vent. In that case, you want to use a BVM with a PEEP valve.
However, this device provides CPAP only when the patient is expiring. In a patient who is not breathing rapidly, most of the cycle will be spent at zero PEEP. Once the patient is apneic, the device won’t supply PEEP unless you manually give ventilations–even then the PEEP will only be there immediately following the ventilation. However, if you add a constant source of flow, like a nasal cannula set to 15 lpm then the BVM/PEEP Valve combo will give continuous PEEP regardless of the patients resp rate or even when they become apneic. In the following video, a PEEP valve set to 10 cm H20 provides between 6-8 cm H2) of PEEP throughout the cycle. This same nasal cannula should be on the patient anyway for apenic oxygenation and NO DESAT (Nasal Oxygen During Efforts Securing A Tube) during the intubation procedure.
Other Articles of Interest on Preoxygenation/Reoxygenation/Preventing Deoxygenation
Dr. Levitan’s site for airway videos and courses
The airwaycam site is an amazing source for educational materials and equipment to help you manage ED airways.
If you liked the article and/or this page, you’ll probably like the EMCrit Blog and Podcast…
why not check it out at emcrit.org?
Want Additional Information?
Email us on the contact page.
Additional Articles for Version 2.0
More evidence that if the patient starts low, their risk of desat is much greater (Acta Anaesthesiologica Scandinavica Volume 57, Issue 2, pages 199–205, February 2013)
Nicholas Chimes revalidates many of these concepts on his FiO2 Testing Page
Here is the evidentiary table published in the Original Article
ApOx for PanEndoscopy (10.1177/0194599813486248 Otolaryngol Head Neck Surg April 12, 2013 0194599813486248)
Apneic Oxygenation via Nasal Prongs at 10 L/min Prevents Hypoxemia During Elective Tracheal Intubation
Chest. 2013 Oct 1;144(4_MeetingAbstracts):890A. Christodoulou C, Mullen T, Tran T, Rohald P, Hiebert B, Sharma S.
PURPOSE: Hypoxemia during airway management remains an important cause of morbidity and mortality. Oxygenation during intubation via nasal prongs may prevent critical desaturations (Anesthesiology 1988, J Korean Med Sci 1998). We evaluated the effectiveness of oxygen administration via nasal prongs during apneic period following induction of general anesthesia.
METHODS: We conducted a randomized, controlled, double-blind study in patients without significant cardiac or respiratory disease undergoing elective surgery (age 18-65, ASA I-III). Patients randomly received oxygen via nasal prongs at 0, 5, or 10 L/min. Following preoxygenation, general anesthesia was induced. At 90 seconds after induction, nasal prongs were applied and oxygen was delivered according to the experimental group. At 4.5 minutes post-induction the patients were intubated.
RESULTS: The final study population consisted of 41 individuals, with 14 in the 0 L group, 13 in the 5 L group, and 14 in the 10 L group. The mean values are 134 ± 75, 168 ± 138 and 253 ± 146 mmHg respectively. A statistically significant difference was demonstrated between the three treatment protocols (p=0.030), across time (p=0.028), and in the treatment effect across time (p=0.017). Mean PaO2 was higher in the 10 L group (p=0.001) than the 5 L group and 0 L group at 4.5 minutes (p=0.004). CONCLUSIONS: Apneic oxygenation with 10 L/min compared to 5 Lmin via nasal prongs demonstrated delay of desaturation and maintenance of higher PaO2 levels during elective intubation.
CLINICAL IMPLICATIONS: Nasal prongs are available in all of the patient care areas; therefore this simple, benign, inexpensive technique may be useful as a routine addition to airway management.
ApOx and Shunt Physiology
This article lends credence to the point that patients with shunt physiology either preexisting for during apnea will not benefit to same extent (Anesthesiology 1973;39(6):588)
Nasal Cannula to Augment Face Masks (as Rich and I advocate)
Supplementation of standard pre-oxygenation with nasal prong oxygen or machine oxygen flush during a simulated leak scenario
The presence of a facemask leak significantly reduces the effectiveness of pre-oxygenation and increases the risk of post-induction hypoxia. We randomly assigned 24 healthy volunteers to a six-period crossover trial with and without a simulated facemask leak. Pre-oxygenation was performed using a standard anaesthesia machine circuit supplemented either by nasal prong oxygen or by anaesthesia machine flush oxygen. Each intervention was completed with both 3-min tidal breathing and 8 deep breath techniques: end-tidal oxygen fraction was used as the measure of pre-oxygenation effectiveness. The presence of a stimulated mask leak significantly reduced the effectiveness of pre-oxygenation regardless of the breathing method used. With a simulated facemask leak introduced, the mean (SD) end-tidal oxygen fraction with the 3-min tidal breath technique was 74.7 (9.3)% compared with 57.5 (6.2%) for the 8 deep breath technique with 3-min tidal breathing and a leak. End-tidal oxygen fractions increased by 11.0% (95% CI 7.8–14.3%) (p < 0.0001) with the addition of nasal prong oxygenation and 16.8% (13.6–20.0%) (p < 0.0001) with machine oxygen flush compared with standard pre-oxygenation. When a leak is present, 3-min tidal breathing with either nasal prong or anaesthesia machine flush oxygenation is an effective pre-oxygenation method, and preferable to the 8 deep breath method.
Best Review of High-Flow Nasal Cannulae(23271822)
High Flow Nasal Cannulae for both Preox and ApOx
Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways (doi:10.1111/anae.12923)