Additional Techniques for Managing the Difficult Pediatric Airway

Abstract

Difficult pediatric airways often present unique challenges, and techniques used in adult patients may have to be modified. Patient size and the frequent need for sedation or general anesthesia demand different solutions than in adults with similar conditions. Although equipment has radically improved over the last several years, it is still at times necessary to improvise. Management strategies of two patients are presented: a difficult to sedate, ventilate, or intubate adolescent and a small neonate with a difficult airway and lung disease. Case One A 16-yr-old, 45.4-kg boy with Treacher Collins syndrome presented for repeat sphincter pharyngoplasty. Since age 10, mask ventilation and tracheal intubation had become increasingly difficult. Surgery had been canceled on two occasions for inability to intubate, and a tracheostomy had been kept in place for two years and was removed at age 13. The patient suffered from acute situational anxiety, cooperated poorly with attempts to anesthetize the airway locally, and was difficult to satisfactorily sedate short of general anesthesia. His last oral surgery had been accomplished after fiberoptic intubation under deep sedation with propofol and ketamine, complicated by frequent patient movement and recurrent airway obstruction. Postoperative recovery had been complicated by bleeding and airway obstruction approximately 1 h after extubation. Transcricoid jet ventilation via a 16-gauge catheter was necessary as rescue from profound hypoxemia, and an urgent tracheostomy was then performed, to be decannulated 2 mo later. Airway examination revealed limited mouth opening (Mallampati Class IV) (1), decreased mobility of the cervical spine, and micrognathia. IV glycopyrrolate 0.4 mg and midazolam to a total of 6 mg were given. The oropharynx was sprayed with a mixture of benzocaine and tetracaine; lidocaine and oxymetazoline (2) nose drops were placed. An additional 3.5 mg of IV midazolam allowed mask placement, but placement of the fiberoptic endoscope was not tolerated. Attempts to improve local anesthesia of the nasopharynx resulted in patient agitation. With naloxone and flumazenil at hand, remifentanil infusion was begun at 0.2 μg · kg-1 · min-1. Fiberoptic intubation could not be quickly performed: the abnormal postsurgical anatomy combined with airway obstruction made it impossible to identify a path to the lower airway. Attempted mask ventilation was insufficient because of oropharyngeal airway obstruction. SpO2 began to decrease. Because of previous experience with successful transcricoid jet ventilation in this patient, this had been planned as the first backup option. (Reversal of drugs was the second backup plan.) A 16-gauge IV catheter was placed through the cricothyroid membrane with caudad angulation, the metal needle was removed, and jet ventilation was begun with 100% oxygen by using an adjustable pressure, hand-triggered jet ventilation device (Anesthesia Associates Inc., San Marcos, CA). The proximal pressure-reducing valve was limited to 20 psi (∼140 kPa), while the distal valve was set to allow a maximum pressure of 12 psi (∼82 kPa) while delivering via a 16-gauge catheter. Jet ventilation was performed at a rate of 20–24 breaths/min, and SpO2 rapidly recovered to 97%. Gas could be heard to escape from the upper airway. A 20-gauge IV catheter was then placed through the cricothyroid membrane with cephalad angulation (Figure 1A), and a 0.021-inch diameter, 140-cm J-tip guidewire advanced via the IV catheter, spontaneously exiting the left nostril. While jet ventilation continued, the wire was threaded through the working channel of a flexible fiberoptic endoscope sheathed with a reinforced endotracheal tube (ETT). The scope-and-tube assembly was then advanced following the wire through the abnormal and collapsed tissues. At the laryngeal inlet, airway space was again apparent. The tip of the scope was advanced to just below the vocal cords. The wire was removed with caudad traction, the scope was threaded into the distal trachea, and the ETT was slid into place, completing the retrograde-assisted fiberoptic tracheal intubation (3). The 16-gauge translaryngeal catheter was left in place for the possibility of postextubation difficulties. The patient’s postoperative course was unremarkable, and there were no complications related to the punctures of the cricothyroid membrane.Figure 1: A, The double transcricothyroid catheter procedure as used in Case One. ET = endotracheal, JV = jet ventilator. B, The cut Fogarty embolectomy catheter is shown in use for oxygen insufflation or oscillatory ventilation, simultaneously serving as a reintubation guide, as described in Case Two. JV = jet ventilator, F = Fogarty catheter, E = endotracheal tube, A = IV catheter through bronchoscope adapter as guide and to prevent leak.Case Two A 1.6-kg neonate had been delivered at home after 32 wk gestation and brought to the pediatric emergency department. The infant was in respiratory distress, and emergency department personnel requested a pediatric anesthesiologist’s assistance with intubation of the trachea. This was performed with great difficulty and without view of laryngeal structures. On Day 5, unintentional extubation occurred, and after many attempts the neonatologists, using a combination of laryngoscopy and digital intubation (4), placed a 2.5-mm internal diameter ETT. Because of persistent bleeding in the proximal airway and small amounts of blood from the ETT, the neonatologists had requested rigid bronchoscopy. Preanesthetic evaluation revealed a small neonate with severe micrognathia, cleft palate, and blood in the airway as noted. The cervical spine was held in moderate extension and motion seemed restricted. A 2.5-mm internal diamter ETT was in place orally. The infant’s history was notable for prematurity with respiratory disease, possible syndrome, and complex congenital heart disease (single atrium, ventricular septal defect, patent ductus arteriosus). Faced with a neonate whose larynx had been impossible to visualize and who had recent airway trauma, and because of a concern for cervical spine limitations versus instability, the anesthesiologist and surgeon agreed that extubation and rigid bronchoscopy should not be attempted. They decided to perform a tracheostomy, with proximal airway examination by flexible endoscopy to follow. Before tracheostomy began, it was deemed prudent to place a reintubation guide via the ETT, in case difficulties arose. The guide needed to be small enough to occupy the trachea without interfering with placement of the tracheostomy tube. The distal 30 cm portion of an 80-cm, 3F Fogarty embolectomy catheter was cut off, and the new distal tip smoothed by abrading it with an electrocautery tip cleaner. A 16-gauge IV catheter was placed through the elastic membrane of a bronchoscope swivel adapter, and its introducer needle was removed. The distal end of the Fogarty was then threaded to just beyond the tip of the ETT (Figure 1B). The proximal end of the Fogarty catheter was connected to an adjustable pressure, hand-triggered jet ventilation device. The proximal pressure-reducing valve was limited to 16 psi (∼110 kPa), while the distal valve had been set to allow a maximum pressure of 8 psi (∼55 kPa) while delivering through the Fogarty catheter. At the appropriate juncture, conventional ventilation was discontinued, and ventilation via the modified Fogarty catheter was begun at a rate of 30–32 breaths/min, with approximately equal inspiratory and expiratory times. The chest rose and fell during these maneuvers at roughly half the excursion seen with conventional ventilation. The 2.5-ETT was then withdrawn above the surgical incision. The surgeon had a clear view of the catheter in the trachea, and the tracheostomy was completed with minimal decrease in oxygenation (SpO2 98%–92%). Discussion Case One presents the combination of a difficult airway with postsurgical changes, acute situational anxiety in a recurrently hospitalized adolescent, resistance to sedation, and difficult mask ventilation. A variety of regimens have been used for maintaining spontaneous ventilation in the child undergoing fiberoptic intubation. Ketamine is the most commonly recommended anesthetic (5), often supplemented with other sedatives and local anesthetics. Volatile anesthetics have also been used. Although such techniques generally maintain respiratory drive, sedative effects can still cause airway obstruction, particularly in the difficult airway population. This had been the previous experience with this patient, not only with ketamine and propofol, but also with volatile anesthetics. In contrast, although apnea was expected from the combination of midazolam and remifentanil, both of these drugs could be reversed. A large dose of benzodiazepine with a relatively smaller dose of narcotic was chosen to avoid the additional problem of chest wall rigidity or vocal cord closure (6). Had jet ventilation been inadequate, or had tracheal intubation failed, the medications could have been reversed or tracheostomy performed. Either reversal of medications or surgical intervention would require at least a few minutes to achieve (7), and jet ventilation as a temporary measure was necessary. The combination of jet ventilation via one cricothyroid catheter coincident with retrograde-assisted tracheal intubation via another proved invaluable and was quickly performed. This case also demonstrates the utility of the retrograde-assisted fiberoptic technique when airway spaces are collapsed and anatomic landmarks are obscured or absent. Case Two presented a difficult airway complicated by previous traumatic intubation, lung and heart disease, and extremely small patient size. [The infant was later diagnosed as having Toriello-Carey syndrome (agenesis of the corpus callosum, facial anomalies, Robin sequence, cardiac anomalies, and hypotonia) (8) and hypoplasia of C4 and C5.] There are no commercially available tube change obturators for 2.5-mm internal diameter ETTs. Although a wire (9) could have been placed as a guide, we preferred the Fogarty catheter because of its increased stiffness and because oxygen could be insufflated or jetted through its lumen. Even low flow tracheal oxygen can help maintain oxygenation (10,11). This technique could also be used to exchange an obstructed or too small ETT for another. The proximal Luer fitting of the Fogarty catheter would also have to be cut off to accomplish this. If jet ventilation or insufflation was then needed, a blunt needle could be inserted into the cut proximal end.