Basic Airway Management of the Pediatric Patient
Since the head of the pediatric patient is larger relative to the body, compared to adults, with a prominent occiput, there is a predisposition to airway obstruction in asleep children, because the neck is flexed when lying supine; it is good to put a folded towel under the shoulders to achieve a neutral position of the head and have a patent airway. A large occiput combined with a short neck makes laryngoscopy more difficult, the alignment of the oral, laryngeal and tracheal axes being more difficult to achieve.
The tongue is larger and the mandible shorter in small children; for this reason, babies are obligate nasal breather until 5 months. Preschool age children have often adenoids and tonsils. These common findings can make mask ventilation difficult and obstruction during spontaneous ventilation possible.
The larynx is relatively higher in the neck in children, with the cricoids ring located at C4 at birth, C5 at age 6 and C6 at adult age. The epiglottis is more “U” shaped compared to adults and is less in line with the trachea and may lie across the glottis opening; for this reason some anesthesiologists prefer to use a straight laryngoscope blade such as Miller, which is designed to lift the epiglottis out of view. The cartilaginous portions of the airway are compliant and can predispose to dynamic obstruction with negative pressure ventilation, especially when together with upper airway obstruction.
The cricoid ring has been stated to be the smallest part of the airway; this is not completely true since more recent studies have described that the glottis opening is smaller than the cricoid. However, since the glottis tissues are more distensible and cricoid ring is not, the effect is that an endotracheal tube passes easily through the vocal cords and may not pass the cricoid.
Oxygen consumption is greater in children than in adults – 6 vs 3 ml/kg/min; this, combined with a smaller functional residual capacity, predisposed to rapid desaturation during apnea despite preoxygenation. At the same time, CO2 production is higher – 150 vs 60 ml/kg/min – and this explains the need for higher Respiratory Rates in children.
The resistance to air flow depends on the Poiseuillle’s Law: R =8ƞL/πr4. The resistance is thus inversely proportional to the radius if the airway, meaning that a small amount of airway narrowing (inflammation, oedema) can have important consequences on flow.
The most important skill to achieve for dealing with pediatric airway is good mask ventilation. Upper airway obstruction can be relieved with head tilt – chin lift, jaw thrust, and application of continuous positive pressure. Lateral position can also improve airway patency. The use of an oral airway is helpful in maintaining airway patency, and so the use of a nasopharyngeal one.
Supraglottic airways are available for all kinds in pediatric sizes; differences between different kinds of LMA are those of that particular kind. The use of supraglottic airways has advantages – in the right kind of surgery – over tracheal intubation in children with recent upper respiratory tract infections because the less invasive manipulation of airway leads to less frequents airway complications in that group with particular reactivity.
It is important that cuff pressure is measured in LMA as well as in endotracheal cuffed tubes, because also with supraglottic devices there’s a risk of mucosal damage associated with overinflation.
The historical debate whether to use cuffed or uncuffed tubes in small children is now partially abandoned since it is now believed that cuffed tubes can provide better ventilating conditions while also minimizing trauma to the delicate airway of pediatric patients, and that because of the elliptical shape of the cricoid, it is still possible that an uncuffed tube with acceptable leak is causing harm to the mucosa.
In the event of anticipated difficult intubation, the use of inhalational induction tends to maintain spontaneous respirations but also depresses upper airway musculature and may worsen upper airway obstruction. Awake fiberoptic intubation requires significant cooperation by the patient which is obviously impossible in the pediatric population, and it requires a degree of sedation and analgesia maintaining spontaneous ventilation.
Another option is the placement of a supraglottic device through which the endotracheal tube is advanced with the aid of a fiberscope.
Relevant Article Depot:
The pediatric airway: Historical concepts, new findings, and what matters
Paediatric adenotonsillectomy (considerations for anaesthesia), part 1
part 2
AnesNews: 10 Common Pediatric Airway Problems—And Their Solutions
Difficult tracheal intubation in neonates and infants. (NECTARINE)
The Paediatric AirWay Suction (PAWS) appropriateness guide for endotracheal suction interventions
Assessment of Common Criteria for Awake Extubation in Infants and Young Children
Weaning from ventilation and extubation of children in critical care
Pediatric Airway Management: Unique Perspectives and New Thoughts
Physiological responses to facemask application in newborns immediately after birth