Getting A Good Mask Seal When Ventilating a Patient

Use of a bag-valve-mask device is one of the most important skills you can master in patient care. Many of my students have a hard time ventilating with a bag-valve-mask device because they fail to get a good seal with the mask. So let’s discuss how to place the mask step-by-step.

Mask Size Is Important To Mask Seal

First, choose the correct size mask for the patient. When you squeeze the bag, the gas will take the path of least resistance. A good mask fit makes an airtight seal against the contours of the patient’s face and forces the gas into the patient’s lungs, expanding the chest. The proper size mask just covers the space between the bridge of the nose and the crease in the chin.

The wrong size mask prevents a good seal, allowing gas to escape around the edges, making it difficult to inflate the lungs. Most women take a small to medium adult mask. Most men will use a medium. Tall or obese men may need a large. Edentulous patients will often need a smaller size because the mandible and maxilla tend to collapse inward without the support of the teeth. Large children need a size 3, toddlers a 2, infants a 1.

Seat The Mask Over The Bridge Of The Nose First

To apply the mask, pull the head into extension and open the airway by pulling the chin upward with your left hand. Then seat the mask over the bridge of the nose. Making sure you have a good seal at the top of the mask first is key to what comes next.

All masks are roughly triangular in shape. Place the apex of the triangle on the bridge of the nose with your right hand and press firmly where the nose meets the forehead between the eyes. My students will sometimes place the top of the mask lower down on the nose in order to protect the eyes. Although you do have to protect the eyes, the problem with this placement strategy is that the sides of the mask can’t hug the top of the nose from this position and air will leak out at the top.

After the mask is seated at the bridge of the nose, lower the mask over the chin and allow it to grab the cheek tissue.

mask bridge of nose

Start by seating the mask over the bridge of the nose. A poor seal here will sabotage all efforts to ventilate.

Make Sure The Lower Lip Is Inside The Mask

The entire lower lips must be inside the mask. Not only will you not get a seal if the lip is outside, you risk injuring the mucosa.

Finger Positions Are Key: Thumb And Index Form A “C”, The Other Three Will Form An “E”

The third, fourth and fifth fingers of your left hand are already on the jawbone and pulling it upward. Now move your left thumb into position at the top of the mask to maintain your seal against the bridge of the nose. Your left index finger will now fall naturally into place below the connection to the ventilation bag. This finger placement allows the index finger to control the angle and the pressure of the mask against the face on a breath-to-breath basis. Because the head will tend to move during ventilation and other treatments, such as CPR, this ability to continuously optimize mask seal as the head moves is important.

Let’s look at that final finger position again. Thumb and forefinger press the mask against the face and form a “C” shape. The remaining fingers grip the boney mandible and pull upward, forming an “E”.


Note the proper position for positioning the fingers for obtaining a good mask seal and opening the airway.

Pull The Face Into The Mask

Don’t think of this as pushing the mask onto the face, a strategy that invariably causes the provider to force the head into flexion and obstruct the airway. Instead, try to pull the face into the mask, creating a sandwich with the face between your fingers pulling up on the jaw and your thumb pressing down on the bridge of the nose. This action pulls the head further into extension and opens the airway.


Pull upward on the jaw and apply pressure downward over the bridge of the nose, effectively pulling the face into the mask and sealing any gaps.

Ventilating and Dealing With Leaks

Maintain your seal and jaw lift with the left hand while you take your right hand off the mask. Your right hand will squeeze the bag and ventilate the patient. If you have a good seal at the top of the mask, you can deal with any leaks lower down by shifting the angle of the mask with your index finger to press the mask more firmly against the opposite side of the face, rotating your ventilation bag to allow its weight to help you create a seal, or by having an assistant help seal the mask by pushing cheek tissue against the mask to block any leaks.


Using an assistant to help seal any leaks around the mask.

We’ll talk about ventilation strategies in later posts but its really important that you keeping checking to see how well you are ventilating. Look for chest movement and fogging of the mask, listen for breath sounds, and of you have it monitor end-tidal-CO2.

Let’s summarize how to get a good mask seal:

  • mask size is important to mask seal
  • seat the mask over the bridge of the nose first
  • make sure the lower lip is inside the mask
  • finger positions are key: thumb and index form a “C”, the other three will form an “E”
  • grasp the jaw bone, not the soft tissue under the chin
  • pull the face into the mask
  • constantly reassess ventilation and adjust

Note: Illustrations from Anyone Can Intubate, 5th Edition

Links to other articles on ventilation:

May The Force Be With You!

Christine E. Whitten MD, author
Anyone Can Intubate: A Step By Step Guide
Pediatric Airway Management: A Step By Step Guide

Button link to see inside or buy the book Anyone Can Intubate, A Step By Step Guide to Intubation and Airway Management, 5th edition on amazon
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