Lightwand intubation of infants and children

ELSEVIER

Lightwand Intubation Infants and Children Quentin

A. Fisher,

Department

of

Otolaryngology,

MD,*

David

of

E. Tunkel,

MDT

Anesthesiology and Critical Care Medicine, and Department of Head and Neck Surgery, Johns Hopkins University, Baltimore, MD.

Study Objective: To examine factors contributing to successful lightwand (lighted stylet) intubation of infants and children. Design: Prospective observational study. Setting: University hospital. Patients: 125 children under age 10 years presenting for elective surgery. Interventions: Prototype lightwands specifically designed for pediatric patients were used. Intubations were done by anesthesia residents with little or no prior lightwand experience. All attempts were recorded on videotape. In a subgroup of 14 patients, an endoscopic view of the lightwand was also recorded with a flexible nasophayngoscope. Measurements and Main Results: 125 patients with a mean age of 3.0 years (22.4 years SD; range: 3 weeks to 9 years) were enrolled. 83.2% were intubated using the lightwand, including 75.5% (34 of 45) of anf an ts weighing less than 10 kg. Of the 21 failed intubations, 8 were due to an inafiropriately large endotracheal tube, as recognized du,ring direct layngoscopy; 4 were due to other reasons discussed; and 9 (persistent uallecular or esophageal enty) could not be explained from videotape analysis. Factors contributing to successful intubation included: (1) use of a shoulder roll and slight head extension; (2) conscientious alignment of airway axes; (3) anteriorjaw lift to elevate the epiglottis; and (4) gentle handling of the lightwand to avoid displacing soft tissue. Inability to advance the lightwand despite correct glow is caused by entrapment in the uallecula, hang up of the lightwand on the ayepiglottic folds, subglottic narrowing, or vocal cord closure. Conclusions: Lightwand intubation in children uses both tactile and visual cues regarding the location of the endotracheal tube tip. Attention to detail results in a high level of success among novice users of the pediatric lightwand. Endoscopic and external videotaping gave us a means of monitoring the progress of mechanical skills among novice users. 0 1997 by Elsevier Science Inc.

*Assistant Professor of Anesthesiology Critical Care Medicine tA.ssistant and Neck

Professor Surgery

of Otolaryngology,

and Head

Address correspondence to Dr. Fisher at the Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University Hospital, 600 No. Wolfe St., Halsted 842, Baltimore, MD 21287-5842, USA. Supported poration, prototype

in part Armonk, pediatric

by Laerdal NY, who lightwands.

Medical provided

Corthe

Received for publication November 1, 1996; revised manuscript accepted for publication February 3, 1997. Journal of Clinical Anesthesia 9:275-279, 0 1997 by Elsevier Science Inc. 655 Avenue of the Americas, New York,

Keywords: lighted.

Intubation,

intratracheal:

pediatric;

lightwand;

neonatology;

stylet,

Introduction Endotracheal intubation of a child whose larynx cannot be visualized by direct laryngoscopy presents unique problems. Awake intubation or tracheostomy, while useful in adults, may be complicated or impossible in children. Equipment for fiberoptic intubation may not be available in the small sizes necessary for use in young children. Thus, anesthesiologists faced with difficult pediatric intubations have had to rely on alternative approaches to direct laryngoscopy.‘-” The use of a lightwand (also known as a lighted stylet) for intubating the difficult pediatric airway has received increased interest in recent years. The lightwand is placed within an endotracheal tube, and this assembly is introduced and advanced in the midline until a characteristic glow in the neck occurs from transillumination through the cricothyroid membrane. Esophageal position is indicated by a less distinct glow pattern than when in the trachea. Early reports

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0952-8180/97/$17.00 PII SO9528180(97)00013-5

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Figure 1. The prototype pediatric lightwands (TrachlightR, Laerdal Medical Corp., Armonk, NY) used in this study. The TrachlightR consists of three parts: a battery-handle, a flexible wand incorporating the bulb and electrical contacts, and a retractable inner wire stylet. The wire provides rigidity and malleability during initial entry to the larynx. Two pediatric sizes are available: Infant for tracheal tubes 2.0 to 4.0 mm internal diameter (top), and Child, for tracheal tubes 4.5 to 6.0 mm internal diameter (bottom). in adults4-6 and more extensive recent experience have demonstrated that it is a rapid, safe method of securing to other indirect the airway,7*8 and it may be superior techniques.” Published experience with lightwand intubation in children is limited. One important issue has been the lack of an appropriate pediatric lightwand. This study reports our experience with the lightwand technique using a prototype device designed for infants and children.

Materials and Methods Prototype pediatric lightwands were used for all intubations (TrachlightR, Laerdal Medical Corporation, Armonk, NY). The design was based on the adult model of the Trachlight R.lo Two sizes were available: one for endotracheal tube (ETT) internal diameters 2.0 to 4.0 mm, and the other 4.5 to 6.0 mm (Figure I).* With Johns Hopkins University Institutional Review Board approval and written informed consent of parents, children age 10 years or less presenting for elective surgery with endotracheal intubation were enrolled. Patients with a history of gastroesophageal reflux or laryngeal abnormalities were excluded. Following induction of general anesthesia, which included a nondepolarizing muscle relaxant, endotracheal intubation was attempted using the appropriate-sized lightwand. All intubation attempts were recorded on videotape for analysis. Intubations were done by anesthesia residents with two or three years experience in anesthesiology but with limited or no experience with *Since the lighhvands

time of (Laerdal

commercially

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of this Infant

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the prototype have become

lightwand intubation techniques. If lightwand intubation was unsuccessful after three attempts, the patient was intubated with direct laryngoscopy. In a subgroup of 14 patients, an endoscopic view of intubation with the lightwand was recorded. After induction of general anesthesia, a fiberoptic endoscope was introduced through the nare and positioned in the pharynx to visualize the hypopharynx and larynx during intubation. While lightwand intubation was done, endoscopic and external views were videotaped simultaneously. The intubating anesthesiologist did not view the endoscopic images during intubation, but instead used transillumination of the neck to assess the appropriate tracheal position. Recorded views were then compared to analyze factors contributing to intubation success or failure and to assess transillumination patterns. The impact of changes in head position and jaw lift were evaluated.

Technique (Figure 2) The prototype lightwand consists of three parts: a reusable battery handle, a flexible wand that incorporates the electrical contact and distal bulb, and a stiff retractable inner stylet. After mounting the endotracheal tube, the wand is bent with a crisp 85” to 90” (in small infants, 90” to 100’) angle a few centimeters from the tip, as estimated from the length of the mandible. With the head in a neutral to slightly extended position, the lightwand is held in the dominant hand. The other hand is used to grasp the jaw in a pincer at the level of the molars and lift it forward, thereby bringing the tongue forward and elevating the epiglottis. The lightwand is then rolled around the base of the tongue, advancing with a gentle rocking motion until the larynx is sharply transilluminated. This action often occurs abruptly, with a distinct visual (and often tactile) “pop” as the lightwand enters the glottis. The rigid inner wire is withdrawn 3 to 4 cm, making the tip of the wand-ETT flexible. The whole instrument (wand and ETT) is then advanced down the trachea until the sternal notch is transilluminated, at which point the lightwand can be withdrawn. Several malpositions are possible. Lateral deviation into the pyriform sinus can be detected when bright lateral transillumination is seen. Esophageal placement causes a dimmer and more diffuse glow than the distinct and bright tracheal or pyriform sinus transillumination. Vallecular entrapment produces distinct transillumination slightly superior to the cricothyroid membrane; attempts to withdraw the inner wire or advance the ETT is met with tangible resistance and visible distension in the anterior neck.

Results We enrolled 125 patients with a mean age of 3.0 years (22.4 SD; range 3 weeks to 9 years) (Figure 3). We successfully intubated 104 patients (83.2%) using the lightwand, including 75.5% (34 of 45) of infants weighing less than 10 kg and 87.5% (70 of 80) of those weighing more than 10 kg. Of the 21 lightwand failures, eight were

Lightwand

intubation

of children:

Fishm and Gnkel

Figure 2. Technique for lightwand intubation. A. Airway axes are aligned. A small shoulder roll helps project the larynx anteriorly. The jaw is lifted with the non-dominant hand from the molar area. B. The lightwand is introduced in the midline and gently rolled behind the tongue. C. A crisply demarcated transillumination of the larynx signals intubation. The wire stylet is withdrawn several centimeters at this point, and the flexible sheath with endotracheal tube is advanced down the trachea. due to an inappropriately large ETT, a problem that was recognized during direct laryngoscopy. In these patients, a specific pattern of transillumination was common: while transillumination was initially favorable, attempts to withdraw the central wire repeatedly resulted in deviation of the ETT tip to one side. Two failures (using 4.0 and 4.5

40 35

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d 30 5 ‘$ 25 5 20 $ nE 15 3 10

mm ETT) occurred among the seven patients undergoing nasal lightwand intubation, a procedure that is more difficult than oral lightwand intubation in young children. Two patients were withdrawn (at the attending anesthesiologist’s discretion) before completing three attempts. The remaining nine failures were due to a variety of difficulties (persistent vallecular or esophageal entry) that could not be readily explained from analysis of the videotapes. There were no complications attributable to the use of the lightwand. One 6-year-old child had a loose primary tooth dislodged during direct laryngoscopy. There were no episodes of hoarseness or postextubation stridor in the immediate recovery period.

Discussion

5 0 O-5

'5-10

MO-15

Weight Figure 3. Distribution

>15-20

>20-25

>25-30

(kg)

of study patients by weight.

Management of the difficult airway in infants and children presents challenges unique to this age group. First, only brief periods of apnea can be tolerated because of high oxygen consumption relative to reserves. Second, awake intubation is not an option for children who cannot be expected to cooperate peaceably with the procedure. Third, awake tracheostomy with an unsecured airway may be difficult, if not impossible, in infants.” Fourth, standard equipment available for adults often is not easily J. Clin.

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accessible for infants and small children (eg, fiber-scopes) or is simply not manufactured in pediatric configurations (eg, Augustine intubators, Combitubes), Lightwand intubation may be one alternative for managing several types of pediatric airway difficulties. As with other techniques, it requires training and experience, and it is not applicable to all cases of difficult intubation. In adults, lightwand intubation has been most useful for difficulties in access to an otherwise normal larynx, such as impaired mouth opening, reduced neck mobility, and micrognathia. This technique can be used for awakeg~12~‘3 or anesthetized patients, and intubations may be done via the oral or nasal routes, In contrast to liberoptic devices, lightwands are inexpensive tools that can be used frequently and require minimal maintenance or equipment preparation. Blood and secretions do not interfere with this technique. All types of single-lumen endotracheal tubes, including preformed (RAE) tubes and armored tubes, may be introduced with the lightwand. Several important features of successful technique were elucidated from review of the videotapes: (1) A small shoulder roll should be used to keep the head in neutral to slightly extended position (F@re 2). This is particularly helpful in a small infant, whose neck naturally flexes when lying on a flat surface because of the prominent occiput. Slight extension of the neck, if not contraindicated, rotates the larynx anteriorly and tightens the skin on the anterior neck, allowing for clearer transillumination. (2) The lightwand must remain aligned with the airway axes. Angled approaches to the laryngeal inlet frequently resulted in failure. In practice, this means that as soon as the lightwand is introduced into the mouth, it should be assured to cross the lips in the middle before the tip is advanced into the larynx. If the light deviates to the side, it should not be twisted back toward the midline. Rather, it should be withdrawn to the back of the tongue and repositioned. Several video recordings showed distortions of the laryngeal cartilages with twisting maneuvers. As lightwand intubation is a blind technique, attention to alignment of airway axes is essential to success. (3) The jaw should be firmly grasped from the side by the non-dominant hand and lifted. Endoscopic views (Figure 4) clearly documented elevation of the epiglottis with jaw thrust. By keeping the grasping thumb away from the incisor area, the midline is left clear for positioning the lightwand. (4) A frequent error was advancing the lightwand too far before assessing the transillumination. In part, this is because during direct laryngoscopy, the laryngoscope tends to push the glottis further away from the operator’s eye. Thus, the operator’s mental image of the glottis may be distorted by that prior experience. A related problem was that when the initial attempt was unsuccessful, the operator often failed to withdraw the lightwand suffciently to fully clear the glottis before re-positioning it. (5) Blind nasal intubation requires adjustments in method. In contrast to the technique in adults in which the rigid stylet is usually removed, we found that in children it was often easier with the rigid stylet left in place. In this technique, the wand with the ETT is bent less 278

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Figure 4. Jaw lift elevates the epiglottis and opens the laryngeal inlet (endoscopic view). A. Just prior to jaw lift, the epiglottis contacts the posterior pharyngeal wall, B. With jaw lift, the laryngeal inlet is exposed by the elevated epiglottis.

sharply than for an oral intubation (90” to 110”)) with the distal segment slightly longer than for an oral intubation. The well-lubricated ETT-wand is introduced into the nare and advanced until the bend is at the level of the posterior palate. It is then rocked around the palate and the procedure performed as in the oral technique. However, the ability to manipulate the position of the ETT tip is limited by the palate. If persistent entry into the esophagus or vallecula occurs, then it may help to change the angle of bend of the ETT-wand. Causes of failed lightwand intubation that we were able to document include entrapment in the vallecula, hang up of the lightwand on the aryepiglottic folds, subglottic

Lightwand

Table

1.

Possible

Uses of Pediatric

Lightwand

Intubation

Applications of lightwand intubation: 1. Orofacial types of airway problems: micrognathia, jaw immobility or restricted opening, neck immobility or cervical spine trauma 2. Soft tissue types of airway difficulty if the glottis is known to be normal: glossomegaly, glossoptosis, orofacial trauma 3. Restricted access to the airway: halo traction; stereotactic instrumentation. Cautions/contraindications for lightwand intubation: 1. Inability to transilluminate: thick neck, extreme obesity, inflammation 2. Location of the glottis is uncertain or airway axes cannot be aligned rostral-caudal: extrinsic lesions (tumor, hematoma), torticollis 3. Laryngeal pathology: stridor of unknown etiology, papilloma, glottic or subglottic stenosis 4. Danger of blind trauma: retropharyngeal abscess, foreign body

narrowing, and vocal cord closure. However, nine of the 21 failed intubations had no discernible cause for repeated vallecular or esophageal entry. Our subsequent clinical experience suggests that these attempts might have been helped by adjusting the angle of bend of the wand. Trauma from blind lightwand intubation was discussed in a report of arytenoid dislocation.14 While we did document distortion of the arytenoid cartilages when the lightwand was twisted from the pyriform sinus toward the midline, there were no instances of injury. Atytenoid subluxation is a rarely documented complication of rigid laryngoscopy. l5 Severe distortion of the laryngeal cartilages also occurs quite readily when, for example, a Miller laryngoscope is inadvertently advanced into the esophagus and the operator lifts it, attempting to visualize the larynx, but instead compresses it with the laryngoscope blade. Based on both clinical reports” and our own observations, we believe that lightwand intubation presents no appreciable difference from direct laryngoscopy in the risk of serious trauma during intubation. Several precautions should be observed (Table I). First, because lightwand intubation is a blind technique, it is not appropriate when intrinsic laryngeal abnormalities may be present or when neck anatomy precludes transillumination. Second, lightwand intubation is generally not an appropriate choice to rescue a “cannot intubate-cannot ventilate” situation; in that case, a laryngeal mask (LMA) or surgical airway may be more appropriate.16 Finally, because lightwand intubation appears to be more difficult in children and infants than in adults, experience with older patients should precede practice in younger ones.

intubation

of children:

Fisher and Tunkel

We have demonstrated that lightwand intubation can be a useful technique in children. This study evaluated the technique in children with normal airways. We hope to extend this experience to additional patients with abnormal airways. The technique requires developing familiarity with both tactile and visual cues to assessing the location of the ETT tip. Attention to details of the technique results in a high level of success among novice users of the pediatric lightwand.

References 1. Scheller JG, Schulman SR: Fiber-optic bronchoscopic guidance for intubating a neonate with Pierre-Robin syndrome. J Clin Anesth 1991;3:45-7. 2. Populaire C, Lundi JN, Pinaud M, Souron R: Elective tracheal intubation in the prone position for a neonate with Pierre Robin syndrome [Letter]. Anesthesiology 1985;62:214-5. 3. Benumof JL: Intubation and extubation of the patient with Pierre-Robin syndrome [Letter]. Anesthesiology 1992;77:401. 4. Macintosh R, Richards H: Illuminated introducer for endotrdcheal tubes. Anaesthesia 1957;12:223-5. I5 . Yamamura H, Yamamoto T, Kamiyama M: Device for blind nasal intubation. Anesthesiology 1959;20:221-2. 6. Berman RA: Lighted stylet. Anesthesiology 1959;20:382-3. 7. Ellis DG, Stewart RD, Kaplan RM, Jakymec A, Freeman JA, Bleyaert A: Success rates of blind orotracheal intubation using a transillumination technique with a lighted stylet. Ann Emerg Med 1986;15:138-42. 8. Hung OR, Pytka S, Morris I, Murphy M, Stewart RD: Lightwand intubation: II-Clinical trial of a new lightwand for tracheal intubation in patients with difficult airways. Can JAnaesth 1995; 42826-30. 9. Fox DJ, Castro T Jr, Rastrelli AJ: Comparison of intubation techniques in the awake patient: the Flexi-lum surgical light (lightwand) versus blind nasal approach. Anesthesiology 1987;66: 69-71. 10. Hung OR, Stewart RD: Lightwand intubation: I-a new lightwand device. Can JAnaesth 1995;42:820-5. 11. Crysdale WS, Feldman RI, Naito K: Tracheostomies: a lo-year experience in 319 children. Ann OtoZRhinol Layngol1988;97(5 Pt 1):439-43. 12. Vollmer TP, Stewart RD, Paris PM, Ellis D, Berkebile PE: Use of a lighted stylet for guided orotracheal intubation in the prehospita1 setting. Ann Emerg Med 1985;14:324-8. 13. Verdile VP, Heller MB, Paris PM, Stewart RD: Nasotracheal intubation in traumatic craniofacial dislocation: use of the lighted stylet. AmjEmerg Med 1988;6:39-41. 14. Szigeti CL, Baeuerle JJ, Mongan PD: Arytenoid dislocation with lighted stylet intubation: case report and retrospective review. Anesth Analg 1994;78:185-6. 15. Dudley JP, Mancuso AA, Fonkalsrud EW: Arytenoid dislocation and computed tomography. Arch Otololalyngol 1984;110:483-4. 16. Benumof JL: Laryngeal mask airway and the ASA difficult airway algorithm. Anesthesiology 1996;84:686-99.

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