A Levitan Optical Stylet with a modified curve was used in the operating theatre for 301 timed tracheal intubations. Jaw lift was provided manually instead of with a direct laryngoscope. All tracheas except one were intubated successfully (99.7%). Mean (SD) intubation times were 23 (24) s. Three patients (1%) suffered minor trauma. The modified Levitan Optical Stylet can be used without direct laryngoscopy as an effective, rapid and relatively atraumatic tool for intubation, even in difficult airways. It may be appropriate as an alternative or primary intubation technique instead of direct laryngoscopy.
The Levitan Optical Stylet is a semi-rigid intubating fibrescope derived from the Shikani Optical Stylet (Clarus Medical Products, Eden Prairie, MN, USA, Fig. 1) and designed for use in the emergency department aided by direct laryngoscopy . Its use as a solo intubation device without a direct laryngoscope has not been described. Optical stylets offer a useful alternative to direct laryngoscopy as a primary intubation technique or when direct laryngoscopy fails [2–7].
This study reviewed the use of the Levitan stylet in the operating theatre as a solo device in a large clinical series. The use of other optical stylets without the aid of a direct laryngoscope has been described, but not formally evaluated . Therefore, the Levitan stylet was modified into the S shape of the Shikani stylet (Fig. 2). Use of the Levitan stylet for operative airway management has not been previously described.
This primary aim of this study was to identify the success rate for tracheal intubation in a large clinical series with a broad patient population. Secondary outcomes included intubation time and complications associated with Levitan stylet intubation.
This study was approved by the Institutional Review Board (Legacy Health System, Portland, OR, USA). As the format was a retrospective chart review of anaesthesia and personal records, the Institutional Review Board waived requirement for written informed consent.
We reviewed records of 315 consecutive adult patients requiring an tracheal tube for elective or emergency surgical procedures. One clinician (SM), experienced with optical stylets, performed or supervised all intubations and, as is his convention, recorded intubation time. We included all clinical records of tracheal intubations with the Levitan optical stylet in this chart review, and excluded tracheal intubations that were performed by a trainee. Patients were not further studied for this technique if they required a nasal intubation or a tracheal tube length greater than 27 cm.
In all patients, tracheal tubes were cut at 27 cm and threaded over the stylus portion of a modified Levitan Optical Stylet such that the stylus tip was within the end of the tracheal tube (Fig. 2). Anti-fog was applied to the stylet.
Anaesthesia and neuromuscular blockade were achieved with propofol and suxamethonium in all patients. Suxamethonium was used to achieve rapid intubation conditions and to avoid the potential difficulty of prolonged neuromuscular blockade, with a non-depolarising agent, as is the practice standard of the laryngoscopist (SM). Cricoid pressure was applied for rapid sequence inductions. If necessary, the pharynx was suctioned before insertion.
The jaw was lifted with the left thumb. The device was then used as described for the Shikani stylet . During observation through the eyepiece, the stylet was inserted in the midline into the mouth then manipulated under the epiglottis and through the vocal cords. The tracheal tube was threaded off the stylet. No external laryngeal manipulation was used beyond cricoid pressure for rapid sequence inductions. All patients were positioned supine without ramps or in the sniffing position. A stop watch, mounted on the console of the anaesthesia machine, was started when the stylet was picked up and stopped when the stylet was replaced. Between patients, the stylet was sterilised in a virucidal solution of benzyl ammonium chloride.
Pre-operative history and physical examination reports were reviewed for possible predictors of potential difficult direct laryngoscopy. The following objective predictors were considered positive predictors of difficult direct laryngoscopy: history of previous difficult direct laryngoscopy; limited mouth opening or neck extension; Mallampati classifications of 3-4; or the presence of a large submental fat pad [9, 10].
Out of the 315 consecutive intubations reviewed, 13 tracheas were intubated successfully by trainees with the Levitan stylet, but these intubations not timed and were excluded from further analysis. One patient with the potential for difficult mask ventilation was excluded and intubation achieved with an awake flexible fibreoptic technique. A further 301 intubations were included for further analysis. Forty-one tracheas were intubated with a rapid sequence induction and cricoid pressure.
The success rate of intubation was 300/301 (99.7%). The only one failed intubation was in a patient with a known history of failed direct laryngoscopy. Mask ventilation was easy. A rescue attempt with direct laryngoscopy failed. Fibreoptic nasal intubation, after resumption of spontaneous ventilation, was successful. Five tracheas were technically difficult to intubate, but were subsequently successfully intubated with the Levitan stylet after release of cricoid pressure, removal of the pillow, or application of two-handed jaw lift by an assistant.
Forty-nine patients (16%) had predictors of difficult direct laryngoscopy. As noted above, the one patient whose tracheas could not be intubated with the modified Levitan scope had a previously documented failed direct laryngoscopy. One patient was immobilised with a cervical spine collar, four had a severely limited range of neck motion, and the remaining 44 patients had a Mallampati class 3 or 4 airway or had large submental fat pads.
The mean (SD) time to intubation was 23 (24) s. The median intubation time was 19 s.
There were three documented traumatic laryngoscopies (1%). These included two cut lips and one occurrence of bloody secretions suctioned after a lengthy intubation attempt. None of these complications required treatment. No patient suffered dental damage and there were no oesophageal intubations.
This study reviewed the experience of the modified Levitan Optical Stylet for primary tracheal intubation and found it highly successful, rapid and minimally traumatic. Another much smaller clinical series, with other optical stylets, demonstrated high success rates, but this much larger series uniquely confirms the utility of the Levitan Optical Stylet for routine primary airway management [5, 11].
Difficult intubation may precipitate an airway crisis which, in turn, can contribute to anaesthesia-related morbidity and mortality . Alternative intubation devices other than conventional direct laryngoscopy may reduce the incidence of difficult intubation as well as morbidity and mortality related to repeated laryngoscopy attempts, thereby improving patient safety .
The laryngoscopy time reported in this series is similar to that reported for other optical stylets. Although definitions of time points vary [5, 8, 11], this device demonstrated rapid tracheal intubation.
This study has several limitations. First, the experience of a single clinician comfortable with other optical stylets may not reflect that of clinicians still learning the technique. Secondly, this retrospective chart review offers no comparative analysis of direct laryngoscopy or alternate video techniques. In addition, these intubations were performed in the operating theatre. These results may not translate to other clinical settings such as the emergency department, pre-hospital environment or intensive care unit. Finally, patients requiring tracheal tubes with lengths greater than 27 cm or nasal intubations were not studied, so the use of shorter tubes or the need for nasal intubation cannot be evaluated. Prospective comparative studies are warranted to determine the comparative advantage of this technique over others.
In conclusion, this study demonstrated that a modified Levitan Optical Stylet may be used without direct laryngoscopy as an effective, rapid, and safe tool for intubation in the operating theatre, even in patients considered having difficult airways. It may be appropriate as an alternative when direct laryngoscopy fails or as a primary device instead of direct laryngoscopy.
No external funding. Michael Aziz has received research funding from a competing vendor: Karl Storz Endoscopy America, El Segundo, California, USA.