This is a four month old male who presents to the ED with respiratory distress. His mother states that he has been ill for several days with a runny nose, fever and a cough. Last night she noted that he was breathing "funny". This morning he refused his bottle and has had increased difficulty breathing. He has had an episode of vomiting with cough, but no diarrhea.
His past medical history is significant for a home birth and no immunizations. He has been well since birth, with the exception of noisy breathing especially when he is in the supine position.
Exam: VS T 39.0, P 80, R 16, oxygen saturation 82% on RA, 90% on oxygen by mask, weight 6kg (50%ile), length 59cm (10%ile). He is in moderately severe respiratory distress with nasal flaring and marked chest retractions. He has unusual facies and a small jaw. His tongue is protruding from his mouth. He has a slightly sunken fontanel. His heart rate is rapid, but regular and no murmurs are noted. His breath sounds are equal but diminished. Crackles and diffuse wheezes are present bilaterally. His abdomen is full, but soft and his abdomen expands with each breath. His capillary refill time is 3 seconds. His pulses are 2+ to 4+ peripherally. His muscle tone is poor. Arterial blood gas (ABG) pH 7.12, pCO2 100, pO2 60, base excess -4. Chest x-ray shows diffuse bilateral patchy infiltrates, with hyperinflation and areas of atelectasis.
The child is correctly assessed to be in respiratory failure and he is sedated and pharmacologically paralyzed for intubation. Unfortunately, as the neuromuscular relaxant is given, the child becomes blue and bradycardic despite bag mask ventilation. The mask is repositioned and a good seal is obtained. However, there is poor chest wall movement with bagging. The child has upper airway obstruction and a nasal trumpet is placed. He is again bag mask ventilated and his saturations rise to 100%. Attempts to intubate the child are unsuccessful. His vocal cords cannot be visualized due to his relatively large tongue and small jaw. He is successfully bag mask ventilated until an anesthesiologist on call arrives and is able to intubate the child's trachea, using advanced techniques. He is placed on mechanical ventilation. His RSV assay is positive. He requires mechanical ventilation for approximately one week and is successfully extubated. During his hospital stay he is evaluated by a geneticist who confirms a diagnosis of Pierre Robin syndrome.
There are multiple indications for endotracheal intubation. These include respiratory failure secondary to lung disease, upper airway obstruction, CNS disease (such as increased ICP or apnea) or chest wall problems. Whatever the indication, endotracheal intubation should be carried out in a systematic, controlled fashion. This requires preparation before a patient in need arrives in your facility. Equipment must be available, appropriate to all sizes of children and adults, since many teenagers will require adult sized equipment. Equipment must be stored in an organized fashion and readily available. It should be checked frequently to assure that it is in good working order, especially the light source for the laryngoscope blade. Equipment should include: laryngoscope blades and handles, extra lights/batteries, endotracheal (ET) tubes (cuffed and uncuffed, all sizes), suction catheters, ventilation bag/masks in all sizes, oral and nasal airways, ET tube (ETT) stylets, Magill forceps, NG tubes, and tape. It should be noted that the term endotracheal tube (ETT), has recently been replaced by the term "tracheal tube" (TT). This chapter will use these two terms synonymously.
A croupy cough or stridor should alert the clinician of possible airway narrowing and a smaller than usual ETT should be available. The child's airway should be assessed, paying particular attention to any unusual anatomy that may prevent adequate visualization and successful endotracheal intubation. These include a small mandible, large tongue and a restricted mobility of the mandible. Obtaining a history of prior intubations is also important. A history of a difficult intubation should raise concerns regarding a potentially difficult airway and assistance should be sought from an anesthesiologist.
Once it has been determined that the patient requires endotracheal intubation, a decision must be made as to what, if any drugs will be used to facilitate the procedure. While newborns are commonly intubated without the use of any sedatives or neuromuscular relaxants, it is common practice in pediatrics to sedate and pharmacologically paralyze children for endotracheal intubation. Sedatives and/or analgesics and paralyzing agents make the procedure more comfortable for the patient and help blunt some of the hemodynamic responses to intubation. Neuromuscular relaxants make the procedure easier, as the tissues are relaxed, facilitating visualization and intubation. A description of all the agents used is beyond the scope of this chapter; however, midazolam, propofol, etomidate, ketamine, opiate narcotic analgesics, thiopental, rocuronium and succinylcholine are commonly used. The clinician must be aware of the potential side effects of each medication and their duration of action. As a general rule, long acting neuromuscular relaxants and arguably any neuromuscular relaxant should be avoided in a child with a potentially difficult airway. Pharmacologic paralysis could make a bad situation worse if endotracheal intubation is unsuccessful, as in the case presented. An anticholinergic, such as atropine may be given prophylactically to prevent bradycardia due to an exaggerated vagal response to intubation.
ETT size selection is critical to optimally ventilate a patient. One very easy guideline to remember is to use the size is the outer diameter of the 5th finger which should approximate the size of the outer diameter of the ETT. This rule sounds attractive, but it is difficult to use accurately in an emergency. Term newborns require a 3.0 or 3.5 ETT. 12 month olds generally fit a 4.0 ETT. For children over 2 years of age, the correct ETT size can be estimated by the formula: 4 + age/4
Uncuffed ETTs are used in children less than 8 years old. This is because the narrowest portion of a child's larynx is the cricoid, versus the glottis in adults. An ET tube a half size smaller and larger than the estimated needed size should be available. Straight blades (e.g., Miller) are most useful in infants and young children. The tip of the blade is used to lift (compress) the base of the tongue; however, often the blade is inserted farther and the tip of the epiglottis is lifted. For older children curved (e.g., Macintosh) blades are generally used to lift the tongue and expose the epiglottis and laryngeal opening. The size of the blade depends on the size of the child: Blade size 0 (newborns), size 1 (infant and small children), size 2 (older children), size 3 (adolescents and adults).
Once all the equipment has been assembled and checked, and medications are drawn up and available, the child is positioned supine in the "sniffing" position (the head is slightly extended with the jaw thrusting upward). Depending on the age of the child, a folded towel under the head may facilitate endotracheal intubation. This is generally not needed in infants due to the prominence of their occipital region. Placement of the head in this position allows for easier visualization of the epiglottis and vocal cords. If, however, the child is suspected of having a cervical spine injury, the neck should be stabilized in neutral position during endotracheal intubation. Ideally the child will have been NPO for several hours prior to intubation to avoid emesis and aspiration. If not, place a NG tube and aspirate the stomach contents. An NG tube is also useful to prevent insufflation of the stomach with air during preoxygenation and bag mask ventilation. If the child has not been NPO, "rapid sequence intubation" should be performed which minimizes bag mask ventilation and reduces the risk of aspiration (1). With the left hand, the blade of the laryngoscope is placed in the right corner of the mouth and the tongue is swept superiorly and to the midline. Avoid using the blade as a lever, instead lift up and away from you. Slowly pull back on the laryngoscope blade until the vocal cords are visualized. Use your right hand to suction the oropharynx if needed, then use your right hand to pass the ETT between the cords. Do not force the tube if it does not pass easily. Stop the attempt if the child becomes bradycardic or if the saturations begin to fall, and resume bag mask ventilation. Once the ETT has passed between the cords, advance it until the "oral" mark on the ETT is at the level of the lip. As a rough guide, the lip to tip distance is 3 times the ETT size. A stylet may be used to facilitate intubation if there is difficulty placing the ETT anteriorly. Auscultate for breath sounds bilaterally and look for condensation in the ETT. If breath sounds are present on the right, but not the left, suspect a right mainstem intubation and slowly pull back on the ETT until breath sounds are heard bilaterally. Auscultate over the stomach as well, to rule out an esophageal intubation. End tidal CO2 monitors and detectors are the best means of confirming tracheal intubation in most instances. Then secure the ETT to both the upper and lower lip using an adhesive (such as benzoin) and tape. Appropriate respiratory support should be initiated immediately. A CXR should be obtained immediately to confirm proper positioning of the ETT. Remember that an intubated child is at risk for the displacement of the ETT, ETT plugging, pneumothorax or an equipment failure (ventilator malfunction). Assume that any deterioration in the child's status is an airway problem until that is ruled out as a cause. "DOPE" is a useful mnemonic to remember potential causes of airway/ventilation problems in intubated patients.
D: Displaced ETT
O: Obstructed ETT
E: Equipment failure (such as ventilator malfunction or disconnect)
1. True/False: Neuromuscular relaxants should always be used for endotracheal intubation.
2. The appropriate ETT size for a 4 y.o. is:
a) 5.0 b) 4.0 c) 6.5
3. True/False: A cuffed ETT is appropriate for a 5 year old in respiratory failure.
4. True/False: Bag mask ventilation should be used to ventilate a child with dysmorphic features until an anesthesiologist is available for endotracheal intubation.
5. True/False: For infants, a Macintosh blade is the most useful for endotracheal intubation.
6. In an intubated patient the most likely cause of acute deterioration is:
. . . . . a. shock
. . . . . b. airway problems
. . . . . c. need for chest physiotherapy
1. Gerardi MJ, Sacchetti, AD, Cantor RM, Santamaria JP, et al. Rapid Sequence Intubation of the Pediatric Patient. Ann Emerg Med 1996;28:55-74.
2. Morris FC, Stone J, Butler LM. Chapter 127-Intubation. In: Levin DL, Morris FC (eds). Essentials of Pediatric Intensive Care. 1990, St. Louis: Quality Medical Publishing, Inc., pp. 888-896.
3. Thompson AE. Chapter 14 Pediatric Airway Management. In: Fuhrman B, Zimmerman JJ (eds). Pediatric Critical Care. 1992, St. Louis: Mosby Year Book, Inc., pp. 111-128.
4. Wheeler M, Cote CJ, Todres ID. Chapter 7-Pediatric Airway. In: Cote CJ, Todres ID, et al (eds). A Practice of Anesthesia for Infants and Children, 3rd edition. 2001, Philadelphia: W.B. Saunders Company, pp. 79-120.
Answers to questions
1. false, 2.a, 3.false, 4.true, 5.false, 6.b
1. Anas N. Part II Chapter 9 - Respiratory Failure. In: Levin D, Morris FC (eds). Essentials of Pediatric Intensive Care, second Edition. 1997, St. Louis: Quality Medical Publishing, Inc., pp. 69-82.
2. Aoki B, McClosky K. Chapter 2-Respiratory System. In: Aoki B, McClosky K (eds). Evaluation, Stabilization & Transport of the Critically Ill Child. 1992, St. Louis: Mosby Yearbook, pp. 17-56.
3. Chapter 2-Recognition of Respiratory Failure & Shock. In: Chameides L, Hazinski MF (eds). Pediatric Advanced Life Support. 1997, American Heart Association, pp. 2.1-2.10.