Critical Care Medicine

Airway Management, pediatric

Pediatric airway management

Basic management of pediatric airway: 1) How it differs from adult airway 2) Pediatric intubation pearls 3) Pediatric difficult airway

1. Description of the problem

What every clinician needs to know

The basic principles of airway management in children and adults are the same. Remember what patient(s) require is oxygen and not the plastic (as in endotracheal tube). This is an especially important tenet to remember in the 'difficult' pediatric airway. If a patient can be adequately/effectively bag-mask ventilated, then there is time to call for help (such as an experienced intubator or anesthesiologist) to assist with airway management. Calling for help should not be considered a sign of weakness. Studies have shown that multiple attempts to intubate airway can result in hypoxia, bleeding and cardiac arrest.

Clinical features

Anatomical differences with clinical significances in parentheses: 1.The pediatric patient has a relatively large tongue for the size of the oral cavity (straight blade is better to visualize the larynx). 2. Glottis is at a higher level. C1 for infants, C3-C4 by age 7 yrs and C5-C6 in adults (this makes pediatric larynx anterior as opposed to adults during laryngoscopy). 3. Large tonsils and adenoids (blind nasotracheal intubation is difficult and not indicated). 4. Small cricothyroid membrane (surgical cricothyroidotomy is difficult if not impossible). 5. Large occiput in infancy causes flexion of the neck (airway obstruction is alleviated by the sniffing position using a shoulder roll in infants). To summarize: Pediatric patients younger than 2 years of age have high anterior airways. Children older than 8 years tend to have airways similar to the adult, whereas years 2 to 8 represent a transition period.

Physiologic differences in pediatric vs. adults: 1. High basal O2 consumption in children is twice that of the adults (6 ml/kg/min vs 3 cc/kg/min can result in immediate desaturation during intubation). 2. Children also have smaller FRC compared to adults (resulting in decreased reserve and faster desaturation).

Equipment selection

Equipment selection can be a particular problem in pediatric airway management. A length-based, color-coded equipment reference chart (Broselow-Luten system) can be used to prevent errors.

Basics about useful equipment/adjuncts for pediatric airway:

1) Oral airway: Used in children who are unconscious. Correct size is the oral airway that fits the distance from the angle of the mouth to the angle of the jaw. Oral airway prevents airway obstruction by fitting over the tongue to hold it and the soft hypopharyngeal structures away from the posterior wall of the pharynx.

2) Nasopharyngeal airway: Can be used in children with or without intact cough and gag reflex. It provides an airway and channel for suctioning between the nares and the pharynx. An age-appropriate ETT can be used as a nasopharyngeal airway after appropriate lubrication.

3) Endotracheal tubes: In general uncuffed ETTs are preferred in kids (size 5.5 and below). Correct tube selection permits an air leak around the tube when the inflation pressure exceeds 15 to 25 cm H2O. If it is difficult to provide adequate ventilation with an uncuffed ETT, then replacement with larger or cuffed tube may be necessary. For pediatric patients > 1 year of age the ETT size formula is: (age in years +4)/4

Correct insertion distance formula (taped at the lip):- Internal diameter of ETT X 3

4) Nasogastric (NG) tubes: Bag-mask ventilation (BMV) can lead to insufflation of the stomach and prevent effective ventilation secondary to hindering of diaphragm excursion. A NG tube can be used to deflate the stomach during BMV or immediately post intubation.

5) Airway alternatives: The laryngeal mask airway comes in various sizes (small enough for newborns and young infants) and can be used as a temporizing measure when faced with a failed airway. Needle cricothyroidotomy can be used as a last resort in pediatric patients in "can't oxygenate, can't ventilate" (CICV) scenario.

2. Emergency Management

Appropriate positioning of the pediatric patient prior to intubation is crucial. The patient should be positioned in such a way as to align all 3 axes (mouth, pharynx and trachea), which allows for direct visualization of the glottis. The axes are correctly aligned for orotracheal intubation if the external auditory canal is anterior to the front edge of the patient's shoulders. Children < 2 years of age have a relatively large occiput and may actually need a towel or a roll under the shoulders to balance the disproportionate occipital size (Figure 1).

Figure 1.

Aligning the three axes (oral, pharyngeal and tracheal) in a pediatric patient.

Once the patient is placed in the optimal sniffing position, BMV should be attempted after adequate pharmacological preparation of the patient. An appropriate-size ETT should be used to intubate the patient.

For children < 2 years of age and those with a "difficult airway," a straight blade (Miller) is preferred. In children > 2 years a curved (mac) blade is preferred. There is no definite rule on blade selection and individual preference/experience plays an important role in blade selection.

If the glottis is difficult to visualize then the external laryngeal manipulation (backward, upward, and rightward push [BURP]) can be used.

If at any time during intubation process the patient's heart rate, oxygenation or clinical appearance deteriorates, then BMV should be provided.

Placement of ETT is verified clinically as well as by use of end-tidal CO2 monitor and chest X-ray.

In our PICU we do not use succinylcholine (SCh) to paralyze patients prior to intubation; we use rocuronium or vecuronium.

Although the FDA (in the early 1990s) warned against the use of SCh due to case reports of hyperkalemic arrest in undiagnosed neuromuscular disease, it is frequently used in controlled settings such as the operating room.

Prior to intubation the SOAPME is an useful mnemonic to have all equipment ready:

S = Suction

O = Oxygen

A = airway (includes oral airways, ETT and nasopharyngeal airway, bag-mask and all equipment required for intubation, including laryngoscopes, etc.)

P = Pharmacy (all medications used for intubation)

M = monitors (cardiorespiratory monitors, pulse oximeter and BP measuring device)

E = equipment such as ventilators

Typical pediatric drugs prior to intubation:

Midazolam or lorazepam (IV 0.1 mg/kg repeat as needed) + fentanyl 1-2 mcg/kg IV (repeat as needed) and rocuronium 1 mg/kg IV (repeat as needed). IV atropine (0.02 mg/kg minimum of 0.1 mg and maximum of 1 mg) can be used to inhibit bradycardic response to laryngoscopy.

3. Diagnosis

The pediatric difficult airway is present if the intubator experiences difficulty in providing effective BMV or difficulty with tracheal intubation. This is best managed by anticipation and careful planning.

It is useful to obtain history of previous intubations and symptoms suggestive of upper airway obstruction (acute or chronic), obstructive sleep apnea. Limited range of motion at the neck, cervical spine injuries, dysmorphic facies (seen in various genetic syndromes), facial trauma, obesity may suggest a difficult airway.

Other difficult airway scenarios include: patient with mediastinal mass, increased intracranial pressure, mucopolysaccharidoses and other genetic syndromes, macroglossia, facial or laryngotracheal injury, cardiac failure and shock.

In case of epiglottitis or foreign body aspiration, patient should be immediately taken to the operating room, where the airway can be attended to by the anesthesiologist and ENT surgeon. In these two conditions we should intervene only if there is acute deterioration. The early intervention group includes patients who have burns compromising airway, patients with anaphylaxis, patients who have ingested caustic substances or patients who have facial trauma with potential for airway compromise.

Options for the difficult pediatric airway

1) If it is a stable situation: Always call for help (more experienced intubator, pediatric anesthesiologist)

2) Crash situation: Consider BMV, laryngeal mask airway and ET intubation. Needle cricothyrotomy can be used in COCV scenario.

All stable expected or known difficult airways should be managed by careful planning using the most experienced intubator. Video laryngoscopy or bronchoscopy may be useful in such scenarios.

Tools for difficult airway

1) Bronchoscopy: More useful in elective cases (OR or known difficult airway). Difficult to use in trauma situations where the scope can be obscured by secretions, vomitus or blood. Also useful for nasotracheal intubations. Blind nasotracheal intubations are technically difficult in younger kids.

2) Video laryngoscopy (various proprietary devices available): Glidescope is most frequently used. Equipment is expensive, but disposable blades are now available even in pediatric sizes.

3) Laryngeal mask airway (LMA): Most useful to oxygenate/ventilate prior to calling help. LMAs cannot be placed when there is obstruction, restricted mouth opening, distortion of airway and stiff lungs (most LMAs cannot take > 25 cm H2O pressure).

4) Gum elastic bougie and airway tube exchangers: can be used in patients with an existing ETT to change ETT or for new intubation. The feel of tracheal rings confirms correct placement of the bougie, following which the ETT can be slid over the same for placement in the airway. Some bougies have a channel for oxygenation.

5) Lighted intubation stylet (light wand): It is a rigid stylet with a fiberoptic light at the tip. Useful in thin kids/adults. Difficult to see light in darker-skinned individuals. Not very useful in emergency situations as procedure takes time. Contraindicated in neck masses, obesity and foreign body.

6) Percutaneous needle cricothyrotomy: Useful in COCV scenario. Proprietary kits are available.

Pathophysiology

N/A

Epidemiology

N/A

Special considerations for nursing and allied health professionals.

A time out should be called prior to intubation and an airway intubation bundle checklist discussed with the team. This checklist clearly identifies roles during the intubation process: 1) Who is intubating? 2) Who is assisting/supervising? 3) Who is helping with bagging/respiratory equipment? 4) Who is pushing drugs? 5) Who is charting? 6) What is our backup plan in case of a difficult airway?

Failure to evaluate airway and predict difficulty is the single most important factor leading to a failed airway. Basic premise of airway management is gas exchange. So rather than being device focused, if patient's oxygenation can be maintained by BMV, then call for expert (experienced intubator or anesthesiologist).

What's the evidence?

Berry, F, Berry, F. "Anesthesia for the child with a difficult airway". Anesthetic Management of Difficult and Routine Pediatric Patients. Churchill Livingstone. 1990. pp. 167-98.

Brambrink, AM, Braun, U. "Airway management in infants and children". Best Pract Res Clin Anaesthesiol. vol. 19. 2005. pp. 675-97.

George, E, Haspel, KL. "The difficult airway". Int Anesthesiol Clin. vol. 38. 2000. pp. 47-63.

Rafei, K, Lichenstein, R. "Airway infectious disease emergencies". Pediatric Clin North Am. vol. 53. 2006. pp. 215-42.

Zaritsky, A, Nadkarni, V, Hickey, R. PALS Provider Manual. American Heart Association. 2002.

Walls, RM, Murphy, MF. Manual of Emergency Airway Management. Lippincott Williams and Wilkins. 2008.

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