What You Need to Know About Bag-Valve Mask Devices (BVMs)
Bag-valve-mask devices are the preferred method of ventilation delivery in a code situation for the victim in respiratory and/or cardiac arrest, at least until a definitive airway has been inserted (and sometimes instead of a definitive airway). When used correctly, a bag-valve-mask device can deliver highly effective ventilations while providing 90 to 100% oxygen; used incorrectly, they may lead to ineffective ventilations, a deteriorating victim and a waste of valuable time. Learning to use a bag-valve-mask device takes practice- ideally, you should be proficient in using one before you are called upon to use one on an actual victim, rather than a mannequin. The following article will outline the basics of this commonly used device.
When are they used?
BVMs are used in the following situations:
- Prehospital airway support for victims in respiratory/cardiac arrest
- Children in respiratory arrest
- When endotracheal intubation in not possible or is contraindicated
- Minor procedures/surgeries when endotracheal intubation is not required (Note: laryngeal mask airways are being increasingly used in this situation)
Who might you have difficulty using a BVM on?
- Edentulous patients (it is difficult to obtain a good seal on patients lacking teeth to give their mouth shape)
- Patients with excess facial hair (beards and/or substantial moustaches make it difficult to obtain an effective seal)
- Obese or very thin patients (due to difficulty obtaining a good mask fit)
- Patients with a snoring history (these patients may have abnormalities of the airway that make using a BVM more difficult)
What equipment is needed when using a BVM?
In an ideal world, you should have the following available when using a BVM:
- Connector tubing(connects the BVM to an oxygen source)
- Oxygen source (capable of delivering high flow oxygen)
- Suction (in case of aspiration of stomach contents)
- Oral or nasal airway of varying sizes (assist in maintaining an open airway while delivering ventilations with a BVM)
How should the victim be positioned when using a BVM?
The victim’s head should be extended slightly. It may be helpful to use a towel under the victim’s head to ensure an open airway. Try to position the victim’s head so that the victim’s ear is level with the sternal notch. If you suspect a neck or spinal cord injury, you should use the jaw thrust maneuver to open the patient’s airway; otherwise, use the head tilt-chin lift maneuver to open the airway. If the patient is unresponsive and does not have a gag reflex, use an OPA (oropharyngeal airway) to maintain an open airway. If the patient does not tolerate an OPA (the victim is semi-conscious or has an intact gag reflex) use a nasal airway adjunct. [Note: a nasal airway should not be used if there is trauma to the mid-face region or significant head trauma, as the airway could enter the intracranial space].
How should the mask be positioned?
Positioning the mask properly to deliver effective ventilations is the most difficult part of mastering a BVM. It is important to remember the following:
Choosing a mask: the mask should cover both the mouth and nose. It should not extend beyond the chin and should cover the cheek area without encroaching into the soft tissue under the eyes. You may need to change the mask in order to obtain a good seal- don’t be afraid to try another mask if you cannot get a good seal.
Positioning the mask: Using the bridge of the nose as a guide, place the mask on the victim’s face. Position the mask first before attaching the bag. (Note: some BVMs are disposable and come as one unit). Using your nondominant hand, place the index finger and thumb around the top of the mask in a C-shape; your other three fingers should hook the mandible, drawing it up into the mask without compressing the soft tissue under the jaw. This is known as the E-C clamp technique.
If a second rescuer is available, one person should maintain a tight seal with the mask while the other person delivers the ventilations by squeezing the bag. With two hands, it is far easier to obtain a good seal and maintain it. The mask can be applied to the face with the thumb and forefinger of each hand pressing down on the mask in a C formation (or a semicircle if you prefer). Alternately, the thumbs of each hand can be used to press the mask firmly to the face while the rest of the fingers hook the mandible to bring the victim’s jaw up to the mask (without compressing the soft tissues under the victim’s jaw).
How should breaths be delivered?
- The bag should be squeezed evenly and breaths should be delivered over one second (for an average adult you will be delivering approximately 500 ml with each ventilation)
- Avoid excessive pressure or delivering breaths too quickly, which can result in gastric inflation and subsequent aspiration
- Deliver breaths at a rate of 10 to 12 breaths per minute for patients in respiratory arrest or patients with a perfusing rhythm (if the patient is attempting to breathe, assist respirations)
- Deliver breaths at a rate of 8 to 10 breaths per minute for the victim in cardiac arrest
How will I know if my ventilations are effective?
The best way to ensure that your ventilations are effective is to observe adequate rise and fall of the victim’s chest. You may also notice that the victim’s color and oxygen saturation improve. Listen and feel for air leaking around the mask and reposition the mask if necessary. Observe for gastric distention, which can be mitigated by placement of an airway (oral or nasal) and by delivering ventilations at the recommended rate and pressure.
Bag-valve-mask devices are an integral part of successful resuscitation. It is important to learn how to use a BVM effectively before you are required to use one on an actual victim. Remember, practice makes perfect!
Bosson, N. Bag-valve-mask ventilation. Medscape. Updated December 2013. http://emedicine.medscape.com/article/80184-overview#showall