Endotracheal (ET) intubation is a life-saving procedure requiring background knowledge, psychomotor skills, effective communication, and coordinated teamwork to successfully and safely complete the procedure in a timely fashion. This chapter outlines the key steps and considerations for ET intubation of the neonate, laryngeal mask placement as well as other procedures related to the maintenance of endotracheal tube (ETT) patency.
A. Indications
1. For respiratory failure unresponsive to noninvasive ventilation
a. Neonatal lung disease
b. Cardiac disease with significant hypoxemia
c. Upper airway obstruction
d. Frequent apnea and bradycardia events
e. Neuromuscular weakness
2. Surfactant administration
3. For maintenance of airway patency during procedures with moderate/deep sedation
4. When suctioning is required to clear an intratracheal obstruction or where airway clearance of secretions is impaired
5. When diaphragmatic hernia is prenatally diagnosed or suspected
B. Contraindications
There is no absolute contraindication to intubating a neonate who has one of the above-mentioned indications except in the patient with an advanced directive that specifies “Do Not Intubate.” A relative contraindication is the patient who may be difficult to intubate based on history or physical examination findings. In these cases, if the patient is able to be transiently supported with noninvasive ventilation, consultation with anesthesia and otolaryngology should be considered. In older patients, the presence of cervical injuries is a contraindication to intubation with a laryngoscope; however, because the occurrence of cervical injuries/anomalies is infrequent in neonates, we consider that ET intubation is associated with less risk than performance of an emergency tracheotomy.
C. Considerations
1. Choice of blade size
a. Miller (straight) blades are typically preferred for neonatal intubation, rather than Macintosh (curved) blades. Miller no. 1 blades are recommended for term infants, no. 0 blades are recommended for preterm infants, and no. 00 may be considered for extremely preterm infants (1).
b. Adaptations to these guidelines may be needed in infants who are small or large for gestational age, who have limitations in opening their mouths, or have airway abnormalities.
c. Alternate blade shapes and designs have been developed but their use is beyond the scope of this chapter.
2. Choice of ETT
a. ETTs used for neonatal intubation should be of uniform internal and external diameter. Tubes that are tapered or cuffed are not typically recommended due to potential for increased risk of injury (2). The use of cuffed tubes is considered at some institutions for specific populations with small studies demonstrating no increase in adverse events (3). However, further research is needed before this can be recommended for broader use.
b. ETT size is depicted by the internal diameter of the tube in millimeters. Optimal tube size selection is important to avoid potential airway injury from a large tube or large air leak or obstruction by secretions with a small tube. Size may be selected using an infant’s gestational age and/or weight (Table 38.1).
TABLE 38.1 Recommended Size of ETT Based on Patient Weight and Gestational Age
WEIGHT (g)
GESTATIONAL AGE (wk)
ENDOTRACHEAL TUBE SIZE (mm ID)
Below 1,000
Below 28
2.5
1,000-2,000
28-34
3.0
Greater than 2,000
Greater than 34
3.5
Data from Weiner GM, ed. Textbook of Neonatal Resuscitation. 7th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2016.
3. Depth of insertion
a. Ideal ETT position is in the midtrachea, approximately 1 to 2 cm below the vocal cords and above the carina and bronchi in most patients. Radiographic positioning of the end of the tube should lie between the first and second thoracic vertebral bodies (Fig. 38.1) (4).
FIGURE 38.1 Chest radiography showing appropriate positioning of the ETT between thoracic vertebral bodies T1-T2.
b. Methods of estimation of tube depth at infant’s lip for orotracheal intubation
(1) Gestational age and/or weight can be used to estimate appropriate depth of insertion. Cognitive aids are published and are available to providers. In general (5):
(a) 25 to 26 weeks gestation infants: ET insertion depth 6 cm
(b) 30 to 32 weeks gestation infants: ET insertion depth 7 cm
(c) 35 to 37 weeks gestation infants: ET insertion depth 8 cm
(d) >37 weeks gestation infants: ET insertion depth 9 cm
Depth should be adjusted appropriately for patients who are extremely preterm, or small/large for gestational age.
(2) Nasotragal length (NTL) is a measurement of the distance from the infant’s nasal septum to their tragus in centimeters. This length +1 cm can be utilized to estimate depth of insertion (1).
(3) Vocal cord guides on ETTs vary significantly between manufacturers, and may not provide an accurate estimate for depth of insertion, especially among extremely premature infants (6).
(4) Other considerations that may affect depth of insertion:
(a) Infants with congenital diaphragmatic hernia have been noted to have cephalad displacement of the carina upon antenatal MRI and confirmed on postnatal radiographs, which may increase risk for right-mainstem intubation. Recent authors have suggested modifying depth of insertion to 5.5 cm + infant weight in kg in this population (7).
(b) In some cases, an anatomic defect (such as a tracheal fistula or subglottic/tracheal stenosis) may require a deeper position of the tube to allow for “bypassing” the level of the defect.
c. Estimation of tube depth for nasotracheal intubation
(1) For nasotracheal intubation, the tube depth should be approximately 2 cm more than the estimated depth for orotracheal intubation. A recent study of additional available formulas to calculate appropriate tube depth in pediatric patients found that there were high rates of inaccurate estimation, so clinical and radiographic assessment remain important (8).
d. Confirmation of appropriate depth of insertion
(1) As the above methods provide only an estimation of depth of insertion, providers should confirm appropriateness of depth using a number of methods:
(a) Primary methods:
i. Detection of exhaled CO2
a. Colorimetric CO2 detection: if CO2 present, the indicator will change from purple to yellow (Fig. 38.2)
b. Capnographic CO2 detectors: detect the concentration of CO2 present, less commonly used in the delivery room setting
ii. Improvement in heart rate
(b) Secondary methods:
i. Auscultation with bilateral equal breath sounds in axillae and absent over stomach
ii. Symmetric chest rise with positivepressure ventilation
FIGURE 38.2 CO2 detector. Note the indicator’s change from purple to yellow upon CO2 detection.
(c) Chest radiography can be used to confirm proper placement of the tube in the trachea. The chest x-ray (CXR) should be taken with the head in a midline position, the neck in a neutral position, and with the neonate supine. If the neck is in an extended position or if the infant is prone, the ETT will appear more cephalad (9, 10). If the neck is flexed then the ETT will appear more caudad. In addition, with the head turned to the side, the ETT has been shown to appear more cephalad in children (11).
4. Premedication
a. Use of premedication, including paralytics, for nonemergent intubation attempts in neonates has been shown to improve success rates; decrease risk of airway injury, pain and discomfort, and risk of intraventricular hemorrhage; and potentially positively impact neurodevelopmental outcomes (12, 13, 14, 15, 16, 17, 18). The American Academy of Pediatrics has issued a statement that endorses the use of premedication for neonatal intubation (19). A standardized premedication regimen has not been endorsed, but many providers choose to administer atropine (to decrease vagally mediated bradycardia and decrease oral secretions), a narcotic to decrease pain/discomfort, and a paralytic medication. Institutional guidelines should be developed. See Table 38.2 for considerations for choice of premedications (19, 20, 21).
5. Length of attempt
a. Intubation attempts should be limited to approximately 30 seconds, and should be discontinued earlier if significant hypoxia or bradycardia are present (1). The patient should receive positive-pressure ventilation via face mask or supraglottic device to stabilize their condition in between attempts.
6. Empty stomach
a. Prior to intubation attempts, the infant’s stomach should be emptied of any residual milk/formula. This recommendation is due to possible risk of emesis occurring with the administration of positive-pressure ventilation or the induction of the gag reflex with insertion of the laryngoscope blade, which can increase the risk of aspiration.
7. Vallecular versus epiglottic holding
a. It is generally recommended that, during neonatal intubation, the tip of the laryngoscope blade is advanced beyond the base of the tongue until it reaches the vallecula (Figs. 38.3 (22) and 38.4). When the blade is positioned in this manner, gently lifting the handle of the blade in the direction the handle is pointing (45-degree angle with the warmer) will facilitate exposure of the glottis. In some situations, it may be preferable to utilize the tip of the laryngoscope blade to gently lift the tip of the epiglottis, compressing it against the base of the tongue (Fig. 38.5). Examples of these situations include extremely preterm infants, where the vallecula may be too small to accommodate the tip of the blade, or infants who have a large or floppy epiglottis.
FIGURE 38.3 Normal anatomic landmarks of the neonatal upper airway. The glottis sits very close to the base of the tongue, so visualization is easiest without hyperextending the neck. (From Normal Epiglottis by Med Chaos. http://bit.ly/2ar7yp4. CC-BY-SA-3.0.)
FIGURE 38.4 Positioning of blade in the vallecula. (Courtesy OPENPediatrics. Used with permission.)
TABLE 38.2 Premedication Considerations and Dosage Recommendations (19, 20, 21)
MEDICATION CATEGORY
PURPOSE
MECHANISM OF ACTION
TYPICAL MEDICATION,a RECOMMENDED DOSE, ONSET AND DURATION OF ACTION
NOTES
Vagolytic
Prevention of vagally mediated bradycardia; decrease in bronchial and salivary secretions
Antimuscarinic medication that competitively inhibits the postganglionic acetylcholine receptors and direct vagolytic action
Side effects include tachycardia and dry, hot skin
Analgesic +/-sedative
Pain control; decrease level of consciousness; minimize adverse hemodynamic response to laryngoscopy
Analgesic:
Acts at receptor sites in the central and peripheral nervous system to diminish perception of pain through modification of transmission of painful signals
Sedative:
Binds to receptor at GABA receptor-chloride ionophore complex in CNS, leading to membrane hyperpolarization and increase inhibitory effect of GABA in CNS, as well as interference with GABA reuptake
1-4 µg/kg IV or IM (only if IV access not available)
Onset:
Fentanyl preferable to morphine given more rapid onset of action; side effects include: apnea, hypotension, CNS depression, as well as chest wall rigidity; risk of the latter can be reduced using slow infusion, and can be treated with administration of naloxone (a competitive agonist at opioid receptors) or paralytic medication
Midazolam is not recommended for preterm infants given concern for prolonged half-life and exposure to the preservative benzyl alcohol; use of sedative medication without analgesic agent should be avoided
IV: almost immediate
IM: 7-15 min
Duration:
IV: 30-60 min
IM: 1-2 hrs
Midazolam
0.05-0.1 mg/kg IV or IM
Onset:
IV: 1-5 min
IM: 5-15 min
Duration:
IV: 20-30 min
IM: 1-6 hrs
Neuromuscular block
Improve conditions for intubation, and minimize chance of adverse events or need for multiple intubation attempts; decrease risk of increase in intracranial pressure during intubation
Depolarizing:
Blocks neuromuscular transmission by binding acetylcholine receptors of muscle membrane and depolarizing it.
Competes with acetylcholine for receptors on the motor endplate, but do not lead to membrane depolarization
Succinylcholine 1-2 mg/kg IV; 2 mg/kg IM
Onset:
Rare serious adverse events reported with use of succinylcholine in children include hyperkalemia, myoglobinemia, cardiac arrhythmia, and malignant hyperthermia; contraindicated in the setting of hyperkalemia or with a family history of malignant hyperthermia
Nondepolarizing agents are typically preferred for neonates and infants. Both vecuronium and rocuronium may cause mild histamine release, hypertension/hypotension, arrhythmia, bronchospasm. Their effects can be reversed by administration of atropine and neostigmine
aDespite the fact that there are many options for premedication for intubation, a standardized regimen does not exist. A typical practice is to administer atropine (vagolytic), fentanyl (analgesic), and a nondepolarizing paralytic (such as vecuronium) prior to commencing with intubation procedure.
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