BVM Mastery

28th November 2019

It’s often considered a basic procedure, but there is nothing “basic” about BVM ventilation. Many people perform it poorly even though it’s an essential part of good airway management.  

Performed incorrectly, BVM ventilation can:

  • Accelerate hypoxia if not enough oxygen is provided

  • Accelerate hypercapnia if not enough CO2  is removed, increasing intercranial pressure and exacerbating traumatic brain injury.

  • Over-ventilation can cause, or exacerbate existing, lung injuries and risk gastric insufflation, increasing the likelihood of your casualty aspirating their own vomit.

  • Further obstruct the airway in an already unconscious casualty.

 

There are three main factors that contribute to poor BVM ventilation.

  1. Poor mask seal

  2. Improper airway management

  3. Excessive or inadequate volume, rate and pressure

 

 

Step 1.  Manage the airway

A properly sized nasopharyngeal airway (NPA) is our go-to adjunct for casualties with or without a gag reflex.   If the casualty can tolerate one NPA, consider a second NPA to increase airflow.   If the casualty has no gag reflex, consider an oropharnygeal (OPA) as well.

The aim here – known as the ‘Silo’ technique – is to provide the casualty with a larger artificial airway and as minimal ventilatory and respiratory resistance as possible.  (1-3)


Step 2.  Use a properly sized mask

When placed on the patient’s face, a properly sized mask will completely cover the nostrils and mouth without any gaps between the mask and face.  Adult BVMs or off-the-shelf Medic Bags will often come with only an ‘Adult Large’ mask.    For the professional or frequent responder, invest in a selection of different sized mask.  If you are likely to encounter a child or infant, include child and infant BVMs in your kit.   If you are unlikely to, but end up dealing with a child or adult, it is possible to use an Adult BVM with this technique.

Modern anatomical, pliable masks create a much better seal than the conventional inflatable cuff style masks. (4)

Modern anatomical mask (L) and traditional inflated-cuff mask (R)

 

 

Step 3.  Make a good seal

This is a technique in itself and the most common error.   The aim is to simultaneously apply a jaw thrust or head tilt / chin lift to maintain a patent airway. (5, 6)

The most commonly prescribed method is the CE technique (also known as the EC or ‘Anaesthetist Grip’)  When the responder is positioned at the head of the casualty the technique is to make a “C” shape with the thumb and index finger to grip the mask on one side and the little finger to hook under the jaw.  Attempting to provide an effective BVM seal using a single-hand EC clamp often tilts the mask to one side and allows air leakage from under the opposite side of the mask. (7)

When performed from the head of the casualty, the CE Grip can allow air escape from the opposite side of the mask.

When the rescuer is positioned to the side of the casualty, the mask is gripped around the lower half.  This often allows air to escape at the bridge of the nose.

When performed at the side of the casualty, the CE Grip can allow air escape at the bridge of the nose.

Shifting you grip between the two positions – known as the ‘Rotated Hold’ usually provides a better seal. (4, 8)

The ‘Rotated Hold’ technique.

 

Beards

Large beard present a particular problem thanks to the post 2012 Hipster and Tactical Operator renaissance.   There are a number of techniques, without any guarantee, which may help with these casualties.

  • The best solution is to use a supraglottic airway such as the Igel or King LT if your casualty is unresponsive and this is within your skillset.

  • The next best and tested technique is to use adhesive film such as Tegaderm which is used a as wound dressing or IV catheter covering can be applied as above and below the lips as long as the dressing makes a good seal with the lips.  Cling film does not work as air escapes underneath the film.  A great solution, as long as you have an adhesive film dressing.

  • Covering the nose with a paediatric mask and simultaneously clamping the mouth closed to provide nasal ventilation.   This will ONLY work if a) the paediatric mask can make a good seal around the casualty’s nose and b) without an OPA in place.

  • Fitting the catheter attachment of certain brands of suction unit between the NPA and the BVM an closing the mouth and other nostril.  (I have never done this but it looks pretty McGyver.   And McGyver is cool).

  • Smothering the beard with lubricating gel, which you will have with you NPAs….but less chance of making an actual seal, especially with large beards.  This probably has the lowest chance of success.

 

 

Step 4.  Use Two People

Side by side comparisons demonstrate that a BVM technique that utilizes two rescuers instead of one provides consistently more effective ventilation than a single person technique. (9-12)

In this two-person technique, one rescuer (the ‘Operator’) can concentrate on their BVM technique, with both hands available, while the second rescuer (the ‘Assistant’) can use both hands to provide an effective mask seal on the patient’s face.

Because maintaining a seal requires constant attention, there is a tendency for the Assistant to push the mask onto the face as their concentration wanes.  This action closes the mouth leaving the nostrils as the only route of ventilation and forces soft tissues of the pharynx to collapse blocking the airway.

For the Assistant, replacing the two-handed CE grip with the Thenar Eminence (TE) grip improves both mask seal and airway management.  The TE grip is achieved by using muscles at the base of the thumb to place downward pressure on the mask while using the other four fingers of each hand to pull the jaw upwards into the mask. (11-16)

Two Handed CE Grip (L) and the recommended Thenar Eminance Grip (R)

 

Step 5.  Concentrate on the Volume, Rate and Pressure.

Volume

Historically the ventilated volume for adults has been an arbitrary 800mls however more recently a more conservative estimate has been taken to reduce the risk of gastric insufflation, hypocapnia and barotrauma to the lungs.  Current evidence points towards steady, regular ventilations at a volume of approximately 6-8mls / kg for an adult (approximately 480-640mls for a 80kg casualty) and even less for some casualties with known respiratory illnesses. (17, 18). European and UK Resucitation Council Guidelines now state a more conservative 500-600mls. (19)

This is just as well given that in manikin studies lone Responders deliver mean tidal volumes significantly lower than 800mls.  (13)  In the Lee study (19), solo Responders achieved 800mls ventilation volumes in only 27 percent of the ventilation attempts.

In reality, the metrics are not essential as they will vary with each casualty’s size and lung capacity – we are looking for adequate chest rise and fall with each ventilation.


Rate

For a casualty in respiratory or cardiac arrest, current UK and European guidelines recommend an inflation duration of one second, every 5 seconds resulting in a rate of one complete ventilation cycle every 6 seconds, or 10 ventilations a minute. (20).

For breathing casualties who need ventilatory support; the normal resting minute volume in humans is around 70-100mls/kg/min, and so in order to produce this minute volume with tidal volumes of 6-8mls/kg, one would require a respiratory rate of between 12-16 breaths per minute. We can start with that for all patients who have nothing wrong with their lungs.

That’s your normal resp rate by the way…so follow your own lead.


Pressure

With both Mouth-to-Mouth and BVM ventilation it is possible to over-inflate the casualty by blowing/squeezing, too hard, too fast or too much.  In general, inspiratory pressures greater than 20 cm H2O in the adult patient increases the risk of forcing air through the esophagus and into the stomach, a condition known as gastric insufflation. (21)

An inspiratory pressure of 15 cm H2O provides the reasonable balance between effective ventilation and the risk of gastric insufflation. (22)

Two in-line BVM manometers

Although a number of factors contribute to high airway pressures, Responders who ventilate patients slowly, deliver smaller tidal volumes, and reduce the inspiratory period decrease the risk of gastric insufflation.  In addition, ventilation using a bag-valve device equipped with a pressure-responsive, flow-limiting valve reduces mean airway pressure and the likelihood of gastric insufflation compared to using a standard BVM. (23)

The use of an in-line manometer fitted between the bag and the mask during BVM ventilation can decrease peak inspiratory pressure (24) if you have one.

 

Step 6.   Practice on people, not mannequins.

  • People’s faces are different, being able to make a good seal every time on the same mannequin does not prepare anyone for the realities of different shaped faces, with soft skin and occasionally, beards.

  • The Operator will have a much better 'feel' for the pressure needed to ventilate a casualty and receive real-time tactile feedback.

  • The Assistant will appreciate the skill required to make the correct seal whilst receiving live tactile and audible feedback in airway positioning.

  • The Casualty will appreciate the importance of appropriate rate and volume of each ventilation.

 

To begin with practice assisted ventilation to get the casualty used to being on the receiving end of the BVM, the Assistant can perfect their grip and the Operator becomes familiar with the Inhale-Exhale-Pause cycle of normal breathing

Next, move on to ventilating the Casualty. The Casualty is instructed to breathe normally and when ready, to tap the floor after their final breath out. They do not hold their breath, they just....stop breathing. This signals to the Operator they are required to start ventilation. Using simple hand signals for "faster", "slower", "more volume" and "less volume" the Operator and the Casualty work together to improve their BVM rather than simply going through the machinations on a mannequin.

Train like it’s real, because one day it will be.

Acknowledgements

With thanks to Tim Berrow, ODP and Remote and Expedition Medic and Russell Wells, ODP and Resuscitation Officer, for their valued opinions and insights.

 

References

  1. Weingart SD, Levitan RM.  (2012)  Preoxygenation and prevention of desaturation during emergency airway management.”  Annals of Emergency Medicine.  59(3), 165–175.

  2. Ley E, Webb T, Chesters A, Clarke B. (2015) "Essex and Herts Air Ambulance: a focused case series for pre-hospital practice". Journal of Paramedic Practice. 7:9, 438-445

  3. Nutbeam T, Boylan M. (2013). The ABC of Pre-Hospital Emergency Medicine. Chichester, West Sussex, UK: John Wiley & Sons Ltd. p.23

  4. Matioc AA.  (2012)  “The "rotated mask hold" and "chin lift grip" may improve the one-hand face mask ventilation airway maneuver.”  Journal of Clinical Anesthesia.  24(2), 167-168.

  5. Bauman EB, Joffe AM, Lenz L, DeVries SA, Hetzel S, Seider SP.  (2010).  “An evaluation of bag-valve-mask ventilation using an ergonomically designed facemask among novice users: a simulation-based pilot study.”  Resuscitation.  81(9), 1161–1165.

  6. Noordergraaf GJ, van Dun PJ, Kramer BP, Schors MP, Hornman, HP, de Jong W, Noordergraaf A.  (2004)  “Airway management by first responders when using a bag-valve device and two oxygen-driven resuscitators in 104 patients.”  European Journal of Anaesthesiology.  21(5), 361–366.

  7. Matioc AA. (2009)  “The adult ergonomic face mask concept: Historical and theoretical perspectives.”  Journal of Clinical Anesthesia.  21(4), 300–304.

  8. Perel A, Berkenstadt H, Yusim Y, Ezri T.  (2009)  “The rotated mask hold.”  Journal of Clinical Anesthesia.  21(8), 617-618.

  9. Davidovic L, La Covey D, Pitetti RD. (2005)  “Comparison of 1- versus 2-person bag-valve-mask techniques for manikin ventilation of infants and children.”  Annals of Emergency Medicine. 46(1), 37–42.

  10. Jesudian MC, Harrison RR, Keenan RL, Maull KI. (1985)  “Bag-valve-mask ventilation; Two rescuers are better than one: Preliminary report.”  Critical Care Medicine.  13(2), 122–123.

  11. Otten D, Liao MM, Wolken R, Douglas IS, Mishra R, Kao A, Barrett W, Drasler E, Byyny RL, Haukoos JS  (2013)  “Comparison of bag-valve-mask hand-sealing techniques in a simulated model.”  Annals of Emergency Medicine.  63(1), 6-12.

  12. Wheatley S, Thomas AN, Taylor RJ, Brown T.  (1997)  “A comparison of three methods of bag valve mask ventilation.”  Resuscitation.  33(3), 207–210.

  13. Brown EL,  Walls RM reviewing Joffe AM et al. (2010)  “Bag-Mask Ventilation: One or Two Hands?”  Anesthesiology.  Oct

  14. Gerstein NS, Carey MC, Braude DA, Tawil I, Petersen TR, Deriy L, Anderson MS.  (2013)  “Efficacy of facemask ventilation techniques in novice providers.”  Journal of Clinical Anesthesia.  25(3), 193-197.

  15. Hart D, Reardon R, Ward C, Miner J.  (2013)  “Face mask ventilation: a comparison of three techniques.”  The Journal of Emergency Medicine.  44(5), 1028–33.

  16. Horton CL, Walls RM, reviewing Gerstein NS et al.  (2013)  “Thenar-Eminence Grip Is Better Than the E-C Clamp Grip for Mask Ventilation.”  Journal of Clinical Anesthesia.  Apr 22

  17. Davies JD, Senussi MH, Mireles-Cabodevila E.  (2016)  “Should A Tidal Volume of 6 mL/kg Be Used in All Patients?”  Respiratory Care.  61 (6).

  18. Bowden DL, Scott LK.  (2016)  “Ventilatory Management of the Noninjured Lung.”  Clinics in Chest Medicine.  37(4). 701 - 710

  19. Lee HY, Jeung KW, Lee BK, Lee SJ, Jung YH, Lee GS, Min YI, Heo T.  (2013)  “The performances of standard and ResMed masks during bag-valve-mask ventilation.”  Prehospital Emergency Care.  17(2).

  20. 18. Perkins GD et al.  (2015)  “European Resuscitation Council Guidelines for Resuscitation 2015: Section 2. Adult basic life support and automated external defibrillation.”  Resuscitation. Oct;95: p89

  21. Weiler N, Heinrichs W, Dick W.  (1995)  “Assessment of pulmonary mechanics and gastric inflation pressure during mask ventilation.”  Prehospital Disaster Medicine.  10(2), 101–105.

  22. Bouvet L, Albert ML, Augris C, Boselli E, Ecochard R, Rabilloud M, Chassard D. Allaouchiche B.  (2014)  “Real-time detection of gastric insufflation related to facemask pressure-controlled ventilation using ultrasonography of the antrum and epigastric auscultation in nonparalyzed patients: A prospective, randomized, double-blind study.”  Anesthesiology. 120(2), 326-334.

  23. von Goedecke A, Wagner-Berger HG, Stadlbauer KH, Krismer AC, Jakubaszko J, Bratschke C, Wenzel L, Keller C.  (2004)  “Effects of decreasing peak flow rate on stomach inflation during bag-valve-mask ventilation”.  Resuscitation.  63(2).

  24. Karsdon J, Stijnen T, Berger HM.  (1989)  “The effect of a manometer on the mean airway pressure during hand ventilation, an in vitro study”.  European Journal of Pediatrics.  148(6), 574-576.