Airway & Respiratory, Columns, Commentary, Patient Care

In the Bag or Out of Control? BVM Revisited

Issue 4 and Volume 43.

In the bag or out of control?

A recent article highlighting new changes to the comprehensive 2015 European Research Council (ERC) Guidelines for Resuscitation states that there’s “little new in how we should manage the airway in 2017.”1,2

The article references two studies that demonstrate increased use of, and better success rates with, videolaryngoscopy for endotracheal intubation (ETI), as well as another study showing that inexperienced providers can successfully perform cricothyroidotomies on fresh cadavers using pocket knives and ballpoint pens.

Although the increasing use of video technology may lead to decreasing rates of unrecognized misplaced ETI, most systems probably won’t be incorporating pocket knives and ballpoint pens anytime soon.

ETI or BVM?

The guidelines state that though ETI provides the most reliable form of airway management, there are no randomized, controlled trials showing that its use leads to improved survival following cardiac arrest. They also suggest that, to limit interruptions in chest compressions during CPR, ETI can be delayed until return of spontaneous circulation (ROSC).

Several limited observational studies are referenced, as is one meta-analysis, that demonstrate improved outcomes with use of bag-valve mask (BVM) ventilation when compared to advanced airway management with ETI or blind insertion supraglottic airway (SGA).

Continuous end-tidal carbon dioxide waveform capnography (EtCO2) is recommended to confirm and monitor ETI, and is considered preferable to non-waveform colorimetric CO2, other airway confirmation devices, or unreliable clinical assessments like chest rise, tube condensation, or auscultation.

Finally, the guidelines state that anyone attempting ETI must be well-trained and equipped with EtCO2. In the absence of these, responders should consider use of BVM (and/or SGA) until other appropriately experienced and equipped personnel arrive on scene.

The guidelines also recognize that use of BVM, especially by a single responder, requires considerable skill. In contrast to the case for ETI, the section on basic-level airway management speaks in detail to positioning the airway, utilizing adjuncts, administering appropriate oxygen concentration, suctioning, and controlling the rate and volume of ventilation with BVM. However, there’s no mention of monitoring modalities like EtCO2.

This European approach to airway management is echoed in the American Heart Association (AHA) 2015 guidelines, which state that providers should observe a persistent capnographic waveform “in the field, in the transport vehicle, on arrival at the hospital, and after any patient transfer to reduce the risk of unrecognized tube misplacement or displacement.”3

Notably, the AHA also gives a nod to the use of EtCO2 both to confirm and to monitor correct SGA placement—even though its utility for that purpose hasn’t been well established.

Just a Basic-level Intervention?

So, let’s get this straight. BVM is at least as good as ETI, and is going to be used by first responders prior to the arrival of advanced-level providers on scene. Not unlike ETI, BVM is an extraordinarily complex skill to master, not only to ensure adequate ventilation but also to avoid a host of potentially deadly complications.

Specifically, it’s hard to achieve or maintain a face seal. BVM use can collapse and obstruct the airway, especially in the supine patient, and therefore requires continuous downward pressure on the mask and continuous upward lifting of the mandible to overcome.4

Ineffective BVM use can lead to hypo- or hyperventilation and, subsequently, to inadequate oxygenation, decreased cardiac output, and worsening brain injury. Gastric distention may also precipitate vomiting, aspiration, and pneumonia, as well as cause diaphragmatic elevation, restricted lung movement, and decreased pulmonary compliance.

It’s no wonder, then, that the use of BVM by anesthesiologists in the OR has been largely supplanted by the laryngeal mask airway (LMA).

But, hey, BVM is just a basic-level intervention, right?

A new approach to an old skill

It’s clear that we shouldn’t be performing ETI or SGA in the field in the absence of EtCO2 confirmation, monitoring, and post-event quality assurance. It’s also probably high time that we take our collective heads out of the sand and realize that we probably shouldn’t be performing BVM in the absence of EtCO2, either. We owe it to ourselves—and to our patients—to focus on first principles first.

Although BVM is considered basic, that may just be an unfortunate historical misnomer. BVM is no more basic than ETI, and it should probably be treated with the same advanced degree of respect and care.

References

1. Perkins GD, Olasveengen TM, Maconochie I, et al. European Resuscitation Council Guidelines for Resuscitation: 2017 update. Resuscitation. 2018;123:43–50.

2. Wyllie J, Bruinenberg J, Roehr CC, et al. European Resuscitation Council Guidelines for Resuscitation 2015: Section 7. Resuscitation and support of transition of babies at birth. Resuscitation. 2015;95:249–263.

3. American Heart Association. 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2015;132(18, Suppl 2).

4. Levitan RM. (Jan. 11, 2017.) Should emergency physicians abandon face-mask ventilation? ACEP Now. Retrieved March 1, 2018, from www.acepnow.com/article/emergency-physicians-abandon-face-mask-ventilation.