For children, the difficult airway occurs frequently at a young age (0.24% of intubations in children <1 year).1 In addition, the reasons for the difficult airway in children differ from those in adults.2 In some instances, as with very small children, the suggested rescue algorithms may not be applicable to children because of anatomical or equipment limitations. The clinical presentation of the difficult airway in children is also critical because the management of unanticipated and anticipated difficult airways has different practical considerations for the anesthesiologist.3,4
We describe the care of a child with previously undiagnosed congenital tracheal stenosis who came to the operating room (OR) first as an unanticipated and later as an anticipated case of difficult airway management.
Written consent was obtained from the patient’s guardian for publication of this case report.
On day 1 of life, a newborn female (gestational age, 32 weeks; weight, 1440 g) presented to the OR for an emergency laparotomy for small bowel obstruction. Before surgery, a gastrointestinal contrast study confirmed a distal duodenal obstruction; the chest radiograph (Fig. 1) showed complete opacification of the left hemithorax and absence of the left lung; an echocardiogram confirmed the absence of the left pulmonary vasculature but an otherwise structurally normal heart with qualitatively good function. Laboratory investigations, including an arterial blood gas, were within normal limits. On examination before surgery, there was no evidence of hemodynamic or respiratory compromise, and the child had no dysmorphic features. Due to the urgency of the surgery, and because the child did not have any respiratory compromise, we decided to proceed without further investigation of the pulmonary anatomy.
After oxygen administration, a modified rapid-sequence induction was performed using propofol (3 mg/kg), fentanyl (2 mcg/kg), and rocuronium (1 mg/kg). Bag-mask ventilation was easily established. The vocal cords were visualized (grade 1, Cormack & Lehane) by direct laryngoscopy, but we were unable to advance the tip of an uncuffed 3.0-mm endotracheal tube (ETT) into the distal trachea. Tracheal intubation was reattempted using a 2.5-mm ETT but again was not successful. No cause of airway obstruction was seen during the laryngoscopy, and 3 attempts in total were made to intubate the trachea before assistance was requested. During this time, the patient remained hemodynamically stable and ventilation was maintained via facemask.
The ear–nose–throat team performed a rigid endoscopy and confirmed that the trachea was stenosed, beginning <10 mm from the vocal cords. The length and diameter of the stenosis could not be confirmed because the airway diameter was less than that of the smallest rigid bronchoscope available (1.8 mm). After a multidisciplinary discussion, a decision was made to not continue with the surgery without further investigation of the airway pathology and the availability of airway rescue and reconstruction options. Spontaneous ventilation could not be reestablished in the OR, despite antagonizing the effects of both the opioid and muscle relaxant. Consequently, the airway was maintained using a 1 (<5 kg) laryngeal mask airway (LMA), and pressure support ventilation was started. The child was transferred to the neonatal intensive care unit and was transitioned to nasal continuous positive airway pressure (CPAP) within 12 hours.
In the neonatal intensive care unit, the gastrointestinal tract was decompressed with a gastric tube, parenteral nutrition was established, and the child needed CPAP (6 cm H2O) to maintain adequate oxyhemoglobin saturations. Computed tomography confirmed a long-segment (more than one-third of the length of the trachea) tracheal stenosis, secondary to complete tracheal rings, with a 1.4-mm minimum diameter (Fig. 2). Two months after birth, due to the onset of parenteral nutrition–induced liver dysfunction and cholestasis, the child (gestational age, 40 weeks; weight, 3000 g) returned to the OR for repair of the duodenal atresia. After a multidisciplinary discussion, the surgery was planned with both cardiovascular and ear–nose–throat rescue options. Due to the small size of the child and the type of tracheal stenosis, in the event of an airway emergency, the proximal trachea was to be intubated temporarily with a 2.5-mm ETT to maintain oxygenation before initiating cardiopulmonary bypass (CPB). If CPB was needed, a primary repair of the trachea (a slide tracheoplasty) would be performed because the type of stenosis and airway dimensions met the indications for a surgical repair.
After inhaled induction of anesthesia using sevoflurane, additional IV and arterial access were obtained. A #1 (<5Kg) LMA was then inserted before the start of surgery, and pressure support ventilation (9–12 cm H2O) was used to maintain normocapnia. Anesthesia was maintained with sevoflurane (1.0 minimum alveolar concentration) in oxygen and air. Ketamine (1 mg/kg), fentanyl (2 mcg/kg), and local anesthetic (7.5-mg bupivacaine) infiltration were administered for analgesia. The intraoperative course (120 minutes) was uneventful, and the LMA was successfully removed with the child transitioning to nasal CPAP in the OR. The postoperative course was unremarkable.
Congenital tracheal stenosis is rare, is often associated with other anatomical anomalies, and when it presents in the newborn has a mortality rate exceeding 73%.5 This case of a child with congenital long-segment tracheal stenosis, complicated by lung agenesis, highlights some of the anesthetic and airway considerations for managing the difficult airway in very small children.
Causes of congenital tracheal stenosis may be extrinsic or intrinsic to the trachea and are classified anatomically (Cantrell and Guild) into 3 types: generalized hypoplasia, a funnel-type stenosis with one normal end and the other one stenotic, and segmental stenosis with 2 or 3 cartilage rings involved.6 The standard intervention for diagnosis remains rigid bronchoscopy, but because of the potential for significant perioperative airway obstruction, other diagnostic investigations such as helical computed tomography or magnetic resonance imaging may be preferable.7 Tracheal stenosis typically presents in the first year of life, precipitated by an acute respiratory event.7 Most children with congenital tracheal stenosis will require surgery, but some can be conservatively managed and will outgrow the stenosis without surgical intervention.8 These children tend to be symptom-free, without generalized hypoplasia, and the smallest tracheal diameter is >60% of the expected diameter.8 In the case of our patient, it is hoped that conservative management will suffice or that tracheal reconstruction can be delayed until she grows.
Difficult airway management is defined as the clinical situation in which a trained anesthesiologist experiences difficulty with facemask ventilation of the upper airway, difficulty with tracheal intubation, or both.9 Although the principles underlying difficult airway management remain unchanged for all ages, some items in pediatric difficult airway algorithms are not suitable for very small children due to anatomical or equipment limitations. In a “cannot intubate” scenario in newborns, for example, there is very limited evidence to support LMA use.10 Current international consensus recommendations are that an LMA should only be used as an alternative to tracheal intubation in children ≥2 kg or 34 weeks’ gestational age.11 In this case, in the first instance, an LMA was successfully used for approximately 12 hours in a child <2 kg. Using an LMA in this child is controversial considering the small size of the child, the duration of LMA placement in the first instance, and finally the type of surgery. After establishing that effective ventilation could be maintained with an LMA, we preferred to use this approach rather than an ETT positioned superior to the stenosis because of the risk of displacement and airway edema that could occur with the ETT. For the second presentation to the OR, because we anticipated that spontaneous ventilation via facemask would be insufficient to maintain normocapnia and that ventilatory support would be required, we instrumented the airway and again chose to use an LMA.
Similarly, in a “cannot intubate, cannot ventilate” scenario, a cricothyroidotomy can be successfully performed in infants and children.12 However, in neonates a cricothyroidotomy is not considered feasible because the membrane is as small as 2.6 mm × 3.0 mm.13 A surgical tracheostomy, which is often the invasive procedure of choice in very small children, may not be possible due to the dimensions and location of the tracheal stenosis. Due to these considerations, in this case a decision was made to use CPB, via a midline sternotomy, as the preferred rescue option in the event of an airway emergency. Extracorporeal membrane oxygenation was considered as an alternative to CPB, but we did not anticipate it to be safe to cannulate the neck vessels during an airway emergency without a secure airway in this child.
Providing safe anesthesia and optimal analgesia for this case was challenging. Because difficult airway management was not anticipated on the first presentation, we did not maintain spontaneous ventilation during the induction of anesthesia, with significant consequences to airway management. The endoscopy indicated complete tracheal rings, but lung agenesis is also associated with extrinsic tracheal stenosis because of the malformation of the surrounding vessels, such as anomalous aortic arch compressing the trachea.14 Without adequate knowledge of the airway pathology and appropriate rescue options, we did not proceed with the surgery at the first presentation. During the subsequent abdominal surgery, we maintained spontaneous ventilation, but the increased abdominal tone without muscle relaxation did contribute to the difficulty of the surgery. Neuraxial anesthesia might have had several advantages compared with IV opioids but was rejected due to the possibility of heparin anticoagulation for CPB within 1 hour of an epidural placement.
In summary, we present the case of a very small child with congenital tracheal stenosis presenting as both an unanticipated and anticipated difficult airway management. For this very small child, we successfully used an LMA on 2 separate occasions to manage ventilation without any adverse sequelae.
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