Bag–mask ventilation

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23.2 Bag–mask ventilation

Background

Bag–mask (BM) ventilation is the most important skill in paediatric airway management. This non-invasive manoeuvre for assisted, positive-pressure ventilation is effective treatment for most children with hypoventilation and hypoxia. A child with respiratory insufficiency may require only temporary assisted ventilation with BM. Some children in respiratory failure who require prolonged ventilation or airway protection may need tracheal intubation (Chapter 23.3).

In the BM setup, oxygen flows into a bag reservoir, through a pop-off valve, and into a mask, which forms a tight seal around the child’s nose and mouth. Squeezing the bag administers oxygen under positive pressure to the lungs. While this manoeuvre does not fully protect the airway, as tracheal intubation does, BM ventilation adequately provides emergent airway support during the acute decompensation period (Table 23.2.1). Additionally, Gausche et al demonstrated that BM ventilation is as effective as tracheal intubation in the pre-hospital setting for airway management, regardless of the underlying aetiology.¹ Thus, both pre-hospital and in-hospital practitioners must be comfortable and proficient in performing BM ventilation.

Sample patient case BM Intubation Hypoventilation during procedural sedation + Hypoventilation during post-ictal stage + Hypoxia during asthma exacerbation despite non-rebreather oxygen mask + Persistent hypoxia or hypoventilation despite BM + Partial airway obstruction (laryngeal burn, angio-oedema) + Cardiopulmonary arrest + +

Indications

• Hypoventilation or apnoea.

• Respiratory failure.

• Hypoxia despite high-flow oxygen administration via a non-rebreather mask.

Contraindications

Do not perform BM ventilation in the setting of a complete airway obstruction. If this exists, first perform airway clearance and basic life-support manoeuvres. Then attempt foreign-body removal of the obstruction, if necessary, under direct laryngoscopy with Magill forceps.

Relative contraindication

In the presence of a congenital diaphragmatic hernia or a tracheo-oesophageal fistula, BM can cause insufflation of the stomach and subsequent extrapulmonary compression of the lungs. This may compromise adequate oxygenation and ventilation.

Equipment

Appropriately-sized mask (Fig. 23.2.1).

Self-inflating bag reservoir (Fig. 23.2.2).

Oxygen saturation monitor.

Fig. 23.2.1 Choosing the appropriately sized bag–mask.

Variously-sized, clear masks are available for all ages, ranging from neonates to adults. These masks have an inflated circumferential rim, which provides a tight seal to the patient’s lower face. With an appropriately-sized mask, the superior aspect of the mask should rest over the patient’s nasal bridge and the inferior aspect should rest over the cleft of the chin. Too large a mask may compress the patient’s eyes, and too small a mask may occlude the nostrils and impede adequate oxygenation and ventilation.

Fig. 23.2.2 Paediatric oxygen bag.

Supplemental, high-flow oxygen flowing into a bag serves as the oxygen reservoir for BM ventilation. A paediatric bag, which has a volume of 450–750 mL, is adequate to oxygenate and ventilate a small child. Alternatively, if a paediatric bag is not readily available, an adult bag, which has a volume of about 1200 mL, can also provide adequate oxygenation and ventilation. Be careful not to administer excessive tidal volumes with this larger bag.

Preparation

Select an appropriately-sized mask and ventilation bag.

Connect the oxygen tubing to the ventilation bag, and attach to the face mask.

Begin 15 litres of oxygen per minute.

Positioning

Patient positioning is essential for successful BM ventilation. Maintain a supine, neutral neck position to keep the airway patent. Because of their large occiputs, infants and toddlers are prone to hyperflexion of the neck and consequently benefit from a small towel roll under their shoulders to achieve a neutral ‘sniffing’ position. Both hyperflexion and hyperextension of the neck may worsen airway obstruction, compromise ventilation, and increase risk of spinal injury.

Procedure

Perform the head-tilt and chin-lift manoeuvre to open the airway and lift the tongue away from the soft palate of the oropharynx. Proper positioning and suctioning of excess secretions will often relieve the respiratory compromise without BM ventilation.

In the setting of trauma where spinal injury is a consideration, do not perform the head-tilt/chin-lift manoeuvre. Instead, provide in-line spinal immobilisation and perform a jaw-thrust manoeuvre to create a patent airway.

If airway patency is still suboptimal, reposition and suction the patient. If still inadequate, insert an oropharyngeal or nasopharyngeal airway underneath the mask to lift the tongue from the posterior oropharynx (Chapter 23.3).

In the one-person BM technique place the mask on the patient’s face and achieve an airtight seal over the mouth and nose. Using the non-dominant hand, place the thumb and index finger on the superior and inferior parts of the face mask, respectively. Cradle the tips of the other three fingers along the mandible and lift the jaw up toward the mask to create the seal. This is the ‘E–C clamp’ manoeuvre, based on the E-shape of the three fingers along the jaw and the C-shape of the thumb and index finger along the face mask (Fig. 23.2.3). In creating the seal, pull the jaw anteriorly rather than push the mask posteriorly into the patient’s face. To ventilate, squeeze the oxygen reservoir bag using the dominant hand. For prolonged BM ventilation, use the little finger of your non-dominant hand (used for the E–C clamp) and apply cricoid pressure to reduce gastric air insufflation.

In the two-person technique place the mask on the patient’s face and achieve an airtight seal over the mouth and nose. For operator #1, place the thumb and index finger of both hands on the superior and inferior parts of the face mask, respectively. Cradle the tips of the other three fingers of both hands along either side of the mandible and symmetrically lift the jaw up toward the mask to create a seal. This is a double ‘E–C clamp’ manoeuvre (Fig. 23.2.4). Again, pull the jaw anteriorly rather than push the mask posteriorly into the patient’s face. Operator #2 ventilates the patient by squeezing the oxygen reservoir bag, and applies cricoid pressure for prolonged BM ventilation to reduce gastric air insufflation.

Provide BM ventilation at a rate of 20, 30, and 40 inspirations per minute for the child, infant, and neonate, respectively. Squeeze and release the bag at an inspiratory-to-expiratory ratio of 1:2. A common error is to over-ventilate the patient with too rapid a rate.

Provide a BM tidal volume of 8 mL kg^–1 to oxygenate and ventilate the patient. As an equally effective alternative measure of appropriate ventilation volume, watch for bilateral chest rise and fall.

In addition to visualisation, auscultation of bilateral breath sounds in the mid-axilla and improvement of the oxygen saturation both corroborate with adequate ventilation.

With prolonged BM ventilation, decompress the likely over-distended stomach with an orogastric (OG) or nasogastric (NG) tube. This reduces the risk of emesis and consequent aspiration.

Fig. 23.2.3 E–C clamp BM technique.

Fig. 23.2.4 Double E–C clamp BM technique.

Complications

• Incorrect mask sizing causing inadequate ventilation or trauma to the eyes.

• Gastric insufflation and distension.

• Aspiration from emesis.

• Pneumothorax from poor lung compliance or excessive tidal volumes.

Tips

• In paediatric trauma cases requiring in-line spinal immobilisation, perform BM ventilation with the two-person technique. One operator focuses on providing an adequate mask seal, while the other operator focuses on squeezing the bag and maintaining spinal alignment. In comparison, a one-person BM technique often inadvertently extends the patient’s neck while trying to achieve an adequate mask seal.

• When elevating the jaw anteriorly to form a mask seal with the third, fourth and fifth fingers, be sure to lift up along the bony mandible rather than the submandibular soft tissue. In addition to trauma, compressing the submandibular soft tissue may inadvertently occlude the airway.

• Some BM reservoir bags have a pop-off valve to prevent excessive positive pressure ventilation. This may inadequately ventilate a patient with low lung compliance. Occlude this valve to allow higher positive pressures during inspiration, while watching for chest rise.

• For the neonate and infant, assessing chest rise and fall for adequate BM tidal volume is subtle. The optimal viewing angle is from the patient’s side at the level of his or her bed.

• In order to prevent the common complication of over-ventilating a patient, say aloud ‘squeeze – release – release’ repeatedly while correspondingly squeezing and releasing the bag. This approximates the correct ventilatory rate and inspiratory-to-expiratory ratio for the patient.

1 Gausche M., Lewis R.J., Stratton S.J., et al. Effect of out-of-hospital paediatric endotracheal intubation on survival and neurological outcome: A controlled clinical trial. JAMA. 2000;283(6):783-790.

Further reading

Brown R.E. Bag and mask ventilation. In: Dieckmann R.A., et al, editors. Paediatric emergency and critical care procedures. St Louis, MO: Mosby, 1997.

Chameides L., Hazinski M.F., editors. Paediatric advanced life support. Dallas, Texas: American Heart Association, 1997.

Dieckmann R.A., Brownstein DR, Gausche-Hill M, editors. Paediatric Education for Prehospital Professionals. Sudbury, MA: Jones & Bartlett Publishers, 2000.

Lee B.S., Gausche-Hill M. Paediatric airway management. Clin Paediatr Emerg Med. 2001;2(2):91-106.

Zideman D., et al. Airways in paediatric and newborn resuscitation. Ann Emerg Med. 2001;37(4 Suppl):S126-S136.

Textbook of Paediatric Emergency Medicine