Vendor Viewpoint: Getting the BVM Right

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Working a sudden cardiac arrest (SCA) in the beginning of my career was a wild experience that usually ended up with two outcomes: 1) the patient being transported regardless of return of spontaneous circulation, and 2) the scene usually looking like a yard sale gone wrong, with equipment and packaging everywhere. I used to feel sorry for the ones who had to stay behind and clean up the devastated living room as the rest of us piled into the back of the ambulance to transport the patient.

Fast-forward two decades later to the advent of high-performance CPR and the widespread practice of working the patient on scene. Who knew prehospital care was where the magic really happened?

Implementing high-performance pit crew CPR with position benchmarks made working an arrest easier, so we practiced. Then one day at training it happened: While practicing CPR on a manikin, the person with the BVM was coached to slow down their ventilations. One squeeze every 2–3 seconds turned into one massive squeeze every six seconds, two massive hands, the whole bag.

The EMT with the BVM went from hyperventilating the patient with rate to hyperventilating with volume, even though the rate was now correct! 

It had been 10 years since the landmark paper “Death by Hyperventilation,”¹ and we were keying in on the rate, never thinking too much about volume. Actually we were reinforcing incorrect behavior.

An awakening happened, and we realized ventilation and oxygenation was a multidimensional issue that could not be solved by simply focusing on rate. We realized ventilation management consisted of tidal volume and rate in conjunction with feedback by way of end-tidal capnography and pulse oximetry.

The reality is that prehospital ventilation parameters are difficult to measure in a prehospital environment. Rate is the most measured ventilation metric.² The best-case scenario for ventilation rate accuracy was to have an observer on scene who only coached, observe EtCO₂ readings, or wait until after the event to look at other surrogates.

Many studies have looked at CPR feedback and the associated improvement in CPR quality. However, the ventilation aspect was not included in the initial EtCO₂ of care. The primary method to supply ventilation feedback to the first responders was to look at EtCO₂ in real time and thoracic impedance in the post-case review, neither of which is reliable guidance for ventilation in CPR.² In fact, chest compression artifact degraded algorithm performance in terms of ventilation detection, estimation of ventilation rate, and the ability to detect hyperventilation.³ Utilizing a thoracic impedance signal is another surrogate for ventilation measurement; however, it is affected by chest compressions, unable to calculate tidal volume during CPR, and mostly used post-event.⁴ 

Controlling or securing a patient’s airway is different from controlling the patient’s ventilation. While the endotracheal tube (ETT) has long been hailed as the gold standard of airway management, supraglottic airways (SGAs) have their role in providing high-quality patient care without degradation of patient outcomes.⁵ Aside from properly placing the airway of choice or protocol, the most crucial factor becomes ventilatory management. It has been shown that ventilation management without an adjunct will lead to hyperventilating the patient.⁶ 

Once again, surrogates have been identified to try to control the BVM volume delivered to patients. Simply using a smaller BVM has been hypothesized, but when studied 93% of participants exceeded the volume threshold with an adult BVM, and 82% exceeded it with a pediatric BVM.⁷ Another thought was how the BVM was held: thumb and three fingers, thumb and two fingers, or thumb and one finger. The median volumes delivered in the study were 836 mL, 834 mL, and 794 mL respectively, all too much.⁸

ZOLL Medical has developed Real BVM Help dashboard to provide real-time visual feedback and coaching to the person squeezing the BVM. Real BVM Help utilizes an AccuVent sensor that attaches directly to an ETT, HEPA filter, EtCO₂ adjunct, and BVM. The AccuVent sensor can detect when a breath has been delivered and the volume; then that information is displayed on the dashboard so the provider can instantly change the volume or rate. 

Researchers used the AccuVent sensor and Real BVM Help dashboard in conjunction with a simulated arrest and observed a dramatic increase in combined proper rate and volume, from an initial rate of 10% without feedback to 63% with.⁹ 

This is the first technology integrated into a cardiac monitor that can reduce hyperventilation in critically ill patients by providing real-time feedback.   

References

1. Aufderheide TP, Lurie KG. Death by hyperventilation: a common and life-threatening problem during cardiopulmonary resuscitation. Crit Care Med, 2004 Sep; 32(9 Suppl): S345–51.

2. Neth MR, Idris A, McMullan J, Benoit JL, Daya MR. A review of ventilation in adult out-of-hospital cardiac arrest. JACEP Open, 2020 Apr 28; 1(3): 190–201.

3. Leturiondo M, Ruiz de Gauna S, Ruiz JM, et al. Influence of chest compression artefact on capnogram-based ventilation detection during out-of-hospital cardiopulmonary resuscitation. Resuscitation, 2018; 124: 63–8.

4. Losert H, Risdal M, Sterz F, et al. Thoracic impedance changes measured via defibrillator pads can monitor ventilation in critically ill patients and during cardiopulmonary resuscitation. Crit Care Med, 2006; 34(9): 2,399–405. 

5. Wang HE, Schmicker RH, Daya MR, et al. Effect of a strategy of initial laryngeal tube insertion vs endotracheal intubation on 72-hour survival in adults with out-of-hospital cardiac arrest: a randomized clinical trial. JAMA, 2018; 320(8): 769–78.

6. Spaite DW, Bobrow BJ, Keim SM, et al. Association of Statewide Implementation of the Prehospital Traumatic Brain Injury Treatment Guidelines With Patient Survival Following Traumatic Brain Injury: The Excellence in Prehospital Injury Care (EPIC) Study. JAMA Surg, 2019 Jul 1; 154(7): e191152 [epub 2019 Jul 17].

7. Dafilou B, Schwester D, Ruhl N, Marques-Baptista A. It’s In The Bag: Tidal Volumes in Adult and Pediatric Bag Valve Masks. West J Emerg Med, 2020; 21(3): 722–6.

8. Kroll M, Das J, Siegler J. Can Altering Grip Technique and Bag Size Optimize Volume Delivered with Bag-Valve-Mask by Emergency Medical Service Providers? Prehosp Emerg Care, 2019; 23(2): 210–4.

9. Gould JR, Campana L, Rabickow D. et al. Manual ventilation quality is improved with a real-time visual feedback system during simulated resuscitation. Int J Emerg Med, 2020; 13: 18.

Sean Culliney began his EMS career in 1997 as an EMT, became a paramedic in 2001, and currently works for ZOLL Medical Corp.