Lighted Stylet Tracheal Intubation: A Review

Historical Perspectives Tracheal intubation is older than the recognized history of general anesthesia itself. In the late 18th century, The Royal Humane Society of London used tracheal intubation for resuscitating the near-drowned. Approximately 100 years later, MacEwan (1) performed a digital tracheal intubation in an awake patient before a chloroform and air general endotracheal anesthetic for the resection of a tongue tumor, and in 1928, Magill (2) incorporated blind nasal tracheal intubation as a part of a general anesthetic. Although laryngoscopes were invented in the 19th century, tracheal intubation under direct visualization was greatly enhanced by the development of a special laryngoscope blade by Macintosh (3) in 1943. The first reported use of a lighted stylet used to facilitate intubation came in 1957 when (by now Sir Robert) Macintosh (4) described an 18-inch illuminated tracheal tube introducer, which was designed to stiffen the tube and better illuminate the cords by supplementing the light of the laryngoscope. Berman (5) described a similar device in 1959 and said it was useful “when the fickle light of the laryngoscope has gone out at the most inopportune time.” In the same year, Yamamura et al. (6) described a light bulb-tipped wire that was inserted into the tracheal tube before blind nasal intubation in awake patients. The tube position was then determined by the medial transillumination of the external throat and neck. In 1977, Foster (7) used a transilluminating fiberoptic bundle to facilitate tracheal intubation in a young child with trismus, and Ducrow (8), in the following year, used a flexible surgical light (Flexi-lum™, Concept Corporation, Clearwater, FL) to achieve the same end by first passing a guide (two plastic suction catheters connected end-to-end) into the trachea followed by passage of the tracheal tube over the guide. In a correspondence to the latter article, Rayburn (9) commented that the Flexi-lum™ could be positioned inside the tracheal tube, thereby shortening the intubation sequence and claimed that the technique, nicknamed “lightwand intubation,” had been used for some years at the Brooke Army Medical Center. Development of Commercial Devices The Flexi-lum™ was originally designed for intraarticular illuminations in orthopedic surgery. Its use as a tracheal intubation device ended after a serious complication in which the distal bulb became detached and had to be retrieved from the patient’s right lower lobe bronchus (10). In this case, the Flexi-lum™ had been reused after sterilizing and repeated handling and may have had a weakened bulb/stylet connection. The Tube-Stat™ (Xomed, Jacksonville, FL) evolved from the Flexi-lum™ in the mid1980s and included a sleeve surrounding the bulb designed to prevent bulb loss; however, the smallest tracheal tubes that could be fitted over the Tube-Stat™ were 5.5-mm internal diameter (ID), limiting their use in pediatric practice to children over six years. Current lightwands are largely fiberoptic in design and have either external or internal light sources (Figure 1). Most have addressed the demand for pediatric options. The Imagica™ (Fiberoptic Medical Products, Allentown, PA) lighted stylet can accommodate tubes as small as 2.5-mm ID and requires an external light source. The light source serves as the handle for the Anesthesia Medical Specialties (AMS; Santa Fe, CA) stylet which comes in adult and pediatric sizes and is stiff enough to maintain its shape. The pediatric stylet was developed after Krucylak and Schreiner (11) altered an adult stylet by grinding the distal brass bulb away to allow passage of a 3.5-mm ID tracheal tube. The Trachlight™ (Laerdal, Armonk, NY), also with an internal light source/handle, has a retractable stylet which allows for good stiffness but subsequent flexibility once the stylet is withdrawn. This improved on earlier models in which “because of the rigidity of the wand portion of the device, the tracheal tube was frequently dislodged from the glottic opening while withdrawing the light wand” (12). It also has a connector clamp which allows for securing of the tube during intubation. The Trachlight™ is now provided with three stylets which are reusable and will accommodate tracheal tubes from ID size 2.5–10 mm.Figure 1: Commercial lighted stylets. A, Internal light sources; top, the Laerdal Trachlight™ (Armonk, NY); middle and bottom, the Anesthesia Medical Specialties Fiberoptic Lighted Intubation Stylets (Santa Fe, CA), the adult stylet unloaded and the pediatric stylet and endotracheal tube loaded onto the handle/light source, respectively. Note the retractable stylet on the Trachligh™ and the rubber stopper mounted on the pediatric Anesthesia Medical Specialties to prevent the endotracheal riding up the wand. B, External light source. This example is the Imagica™ Fiberoptic Lighted Stylet manufactured by Fiberoptic Medical Products (Allentown, PA). It may be used with any standard light source.Newer devices have been developed that use transillumination or transmission of sound, in combination with other intubating guides. The AMS shuttle combines a lighted stylet with a fiberoptic scope (Fiberlightview™, Anesthesia Medical Specialties). This combination is intended to provide transillumination and internal visualization of the larynx either directly or on a screen. No published trials at Children’s Hospital of Philadelphia have demonstrated the utility of this approach, which, combined with direct laryngoscopy, has been termed “videointuboscopy” (13). Optical-audio feedback systems use the fine frequency discrimination of the human ear to direct the tube past the glottis (14). This technique relies on the principle that human hearing is more sensitive than visual detection and that therefore converting light intensity to an audio signal will enhance the changes in a visual signal. Aspects of several different commercial lightwands are summarized in Table 1.Table 1: Commercial Lighted StyletsComparative Trials and Studies Learning the Technique Lighted stylet tracheal intubation requires practice, but is easily learned. Ellis et al. (15) found that intubator training in a cadaver laboratory and clinical experience influenced the speed of intubation, but not the success rate on the first attempt. In the first 25 attempts, the average time for a successful intubation was 42 seconds, and this time decreased to an average of 32 seconds for the second 25 attempts. Even early in the trial, all lighted stylet intubations were successful by the third attempt. Fisher and Tunkel (16) performed a videographic study of 125 children (mean age three years) who were tracheally intubated by anesthesia residents with little or no lighted stylet experience. They found an overall success rate of 83% and a 76% success rate in infants weighing <10 kg. Failures generally had one of two causes: either too large a tracheal tube was chosen or there was persistent vallecular or esophageal entry. Lighted Stylet Compared with Direct Laryngoscopy Many studies have been performed to compare lighted stylet technique with traditional methods of tracheal intubation (Table 2). Ellis et al. (15) were the first to show that lighted stylet intubation (Tube-Stat™) compared well with direct laryngoscopy by using a Macintosh blade. They found no time advantage in intubating the trachea in the traditional method nor was the use of a lighted stylet associated with a more frequent incidence of complications. In a trial comparing blind nasal with lighted stylet intubation, Fox et al. (17) found that both time to intubation (means 119.7 vs 37.9 seconds) and number of intubation attempts were significantly less in the latter group. These results are all the more impressive when one considers that three of the participants had not performed lighted stylet intubation before this study. Weis and Hatton (18) reported a case series of 253 patients in whom the lighted stylet had been used in a variety of clinical settings with much success. Two hundred fifty were successfully intubated by using the lighted stylet. The three failures occurred in grossly obese subjects. Twenty of these patients had been impossible to tracheally intubate by using direct laryngoscopy. The largest trial performed involved 950 patients comparing Trachlight™ with direct laryngoscopy, noting time to intubation in both groups, difficult intubation predictors such as the Mallampati score, success rate, and complication rate (19). The success rates were comparable for the two groups; however, the time to intubate was significantly shorter in the Trachlight™ group.Table 2: List of Clinical Trials of Lighted Stylet of of Intubation methods of of in tracheal intubation under direct laryngoscopy may not when a lighted stylet is and the use of the Tube-Stat™ on patients who also were for in laryngoscopy by using the and They found that of the patients were successfully intubated on the first by using a lighted were tracheally intubated three attempts, and that there was no in the number of attempts to the and In a series of 950 et al. found there was no the time to intubate and any of the in the Trachlight™ group. This with the direct laryngoscopy in which some of the such as the Mallampati and the of the with the time to intubate the Intubation Laryngoscopy and endotracheal intubation are both and are associated with of which may be in patients with such as and have the that lighted stylet intubation may in less than direct laryngoscopy and may some from study that compared two direct laryngoscope the Macintosh and the with lighted stylet intubation no in changes the three was a for the to have lower for lighted stylet for Macintosh and rates for lighted stylet for Macintosh at intubation. the not with patients in the study and were by the different of experience of the The speed of intubation in the lighted stylet compared with the direct laryngoscopy groups, that the that the lighted stylet tracheal intubation is no than traditional methods at et al. either laryngoscopy or intubation as part of a general anesthetic. rate and changes during intubation were the were by using a with et there was no the lighted stylet and the direct intubation patients of and were into this trial, and the were in a study with patients who had et al. no rate and changes during tracheal intubation. was no in the time to achieve tracheal intubation. with the two studies no was included in the the of these it that lighted stylet tracheal intubation, performed in the same time as direct laryngoscopy, not studies there was any advantage to the use of lighted stylet intubation in special patients with and and et al. compared the of tracheal intubation using direct laryngoscopy lighted stylet in an by of a by a were the and of and The had a significantly lower incidence of all three and less of and In et large trial, the of patient was for of and a the patients or was a significantly lower incidence of and in the lighted stylet group. that has been when using a lighted stylet is the of to the tracheal during intubation attempts. This is one of the the of the Trachlight™ have designed the bulb to on and after seconds of other is to the intubator that the patient has now been for seconds and may et al. the of by using the Trachlight™ in a with performed by a the tracheal in with a tracheal tube for one They the at the of the Trachlight™ and found that it at the time of the first and after seconds in were no of in any of the there was and in both the Trachlight™ and the there were no the two These that there is little of from the clinical use of the the that there may be and that the in the study and may not have been enough to This is of there is a bulb at the of the but in models the light is fiberoptic transmission of the light in the there will be no at the The distal end of the stylet be with or a surgical and the tracheal tube loaded onto which to the end of the tracheal tube, the the tube and its most the tube connector be before and then once tracheal intubation is This of the tracheal tube over the distal of the stylet. the Trachlight™ this is not a connector is designed to the tube in on the stylet and the retractable stylet is before the tracheal tube, any at the distal The connector be in a that one its when the tracheal tube is in and to be connected to the the of the stylet inside the tracheal tube. rubber stopper is useful to prevent the riding up the stylet and the stylet to or tracheal The stylet is then it from the distal end to a a tracheal tube this be to the The be at the of the tongue the patient such that the stylet is at the of the when the portion is in the This allows light intensity to be the a well light first at the of the and then the (Figure 2: The a well of light the and the in the an position for passing the of the endotracheal tube the this the tube be easily the stylet and into the trachea its position will be by a light the the of anesthesia with or the patient’s are with and the and are positioned to the success rate of lighted stylet intubation. used for direct laryngoscopy, is not most of the will the from the and of the neck. with the be in a In the obese or a under the may of the and success the at this the of Trachlight™ that of intubations can be with light with or of the (19). et al. that transillumination the in requires an light intensity of but that an intensity is traditional intubation with direct laryngoscopy, lighted stylet intubation is an technique in which the the and the the The is and the from the or the In it is to the of tube and lighted stylet a is both the handle and the tube. intubation, the is used to the with the the while the is the of the this be as as to allow of the lighted stylet. the and intubation lighted stylet with the (Figure tracheal intubation with a lighted stylet with the and lighted stylet is into the from the and into the following the the The of the be under the and with a well of light at the of the that the in the (Figure may the tracheal intubation (Figure a is the then the of the may in one of the and the be and the is passage into the then the may be by a series of or the to the by using the light as a guide (Figure tracheal tube may be of the of the small of the will to at the The light will with successful tracheal intubation. the light and then a in the esophageal intubation. This is in infants and small The of light to passage the and the of light results from the tube in the may of tracheal intubation by as a for the tube is from the esophageal with the light with the of the of the stylet following the of the the is and the tracheal tube is in the The demonstrated as the lighted stylet the The of light the may to a of light the of the lighted stylet. Note that the of the tongue and and stylet of the or to position the stylet and the tracheal tube. The and intubation by the tube in the The intubator the tube and stylet the into the as by the infants and small the of the as as the of the a is when the tracheal is past the will the passage of the tube the stylet. using a lighted it is generally to a tracheal tube than one with a intubation, the same with the following The nasal be with a such as or The of the stylet be the patient before as in the The stylet will a more shape. is to the passage of the tracheal the and to of the stylet from the tube. tracheal intubation have been developed by using the lighted in combination with other anesthesia Direct to the Macintosh lighted stylet technique and combined direct laryngoscopy with a lighted stylet in an difficult laryngoscopy, that the lighted stylet improved the and the transillumination in the tube into the any in their of the the of the endotracheal tube onto the which was then to be more and less to its into the has been a useful in the of the difficult of the methods used to intubate the is to a the of the and into the and then to the endotracheal tube over the This technique may be however, as the may and in esophageal intubation. In an to intubate the and the with a Trachlight™ lighted stylet. They claimed a first success rate in passing the Trachlight™ wand into the trachea and reported no but could not this success rate when to the tracheal tube itself. et al. claimed a much success rate of tracheal intubation an using a Trachlight™ and that the for success was intubation once the was detection of a of light at the with the Trachlight™ inserted the Fiberoptic the most of awake fiberoptic intubation. This technique can be when or and the and an fiberoptic intubation in a patient with two using a Flexi-lum™ that the fiberoptic scope in an tube. by the lighted stylet provided visual that the position the fiberoptic scope and intubate the trachea in less than one The can also be positioned by using an which was designed originally as an to blind intubation. This device of the tube and the of the tube to into the that this device lighted stylet intubation and is more by an awake Although the technique described patients who are and the lighted stylet can also be used in the awake patient with anesthesia may be in the traditional with and anesthetic or the and an under the of a Medical which then the to on patient after intubation may be over a flexible which has been inserted the and to the This technique can be to the use of a lighted stylet at the of the endotracheal tube, which will then guide tube over the and used intubation in patients who had or and reported a first and second time success rate of and respectively. Tracheal of the by using a lighted stylet may not facilitate tracheal intubation but may also tube intubated adult patients by a lighted stylet in the of the tracheal tube such that the to the The of transillumination was distal to the when the tracheal tube was the were and found of the as and as This study included of both and is little for in tracheal tubes in the and pediatric methods to this and on patient are in most to tube and a tracheal tube with a fiberoptic incorporated into the and that transillumination well with to tube the of the tracheal tube in an position at the of the first then the intensity of the light was at the tube in infants from to found that the tube was positioned and while this technique not for other in the it the for to tracheal tube In a of the transillumination described a to an endotracheal tube for use in when was The which has a small light source mounted at its distal into the of the tube the patient was and the bronchus to be by the The was into the bronchus by using transillumination for the for The The difficult is the most for the use of the lighted stylet. who for a variety of are by direct or fiberoptic laryngoscopy, can be intubated by using this The for this to be the of a lighted stylet to in in which is or advantage is that are not an as can be in direct or fiberoptic laryngoscopy. In its practice for of the difficult the of the Society of the of lighted stylet the for the with any technique, experience be from intubating before it can be on for the difficult et in included adult patients in whom a difficult intubation was but were easily intubated by using a The included for and In a series of 253 patients reported by Weis and Hatton patients were intubated by using a Tube-Stat™ successfully on the first after found impossible to intubate by using direct laryngoscopy. These patients included patients with who were intubated The lighted stylet can be inserted into the of a tracheal tube for in a patient with an difficult intubation It may be to the from the tube for the lighted to at the distal end In the largest series reported to et al. patients into with and with difficult in whom the Trachlight™ was to be In all but two tracheal intubation was successful with the the on the first attempt. The failures were patients who were grossly et al. patients who had a variety of difficult and either or difficult endotracheal of these patients were years. In all but one case, the trachea was intubated by using a lighted stylet in an average of seconds, on the of the Two patients repeated by more than two and was in three patients. wand intubation was to tracheal tubes 5.5-mm ID or more Krucylak and Schreiner (11) reported the use of a fiberoptic to intubate an with The size of the fiberoptic stylet passage of a 3.5-mm tube. Schreiner and and Schreiner and the successful use of the in difficult pediatric in which fiberoptic and direct laryngoscopy had Two of the patients had one had of the and the had In the case, a lighted stylet was described passing of a tracheal tube direct laryngoscopy and a Trachlight™ had The of a bundle and a stylet with the stylet to the tracheal and esophageal The same bundle has been used to the light of commercial lightwands for obese and for patients. The Although such as tracheal intubation and of are when could patients to more and better and are on to a in the direct laryngoscopy is lighted stylet intubation is an easily and technique for and residents in an et al. tracheal intubation using a lighted stylet technique in patients with in whom nasal intubation was The lighted stylet was inserted the the third either or as the was The of the tracheal tube was then the larynx in a and was by the a for for the is to be with and and the be nor the to laryngoscopy. Lighted stylets may be useful under these but not be used there is of a of the Weis claimed a success rate in securing the by using lighted stylet intubation in and that the use of lighted stylet intubation was not influenced by in the of and most the in the with lighted this of intubation with direct laryngoscopy in children with The with an difficult tracheal intubation, fiberoptic visualization of a of or this may not be a in Fox and were to two children who had of the and to In one the was to the by The second patient had a small and to Direct laryngoscopy for both tracheal intubations was to be In both by using of the technique, the were intubated with a lighted stylet in These may have been successfully with fiberoptic but this have the of and to the Lighted stylets are and in such which with are to the use of the The most is the of an tumor, or other the intubation who may have have direct visualization than blind intubation. a difficult and a fiberoptic to be a a blind intubation which could subsequent fiberoptic visualization of the larynx In however, of the lighted stylet to the of and one or two attempts with this not with subsequent fiberoptic attempts. Although lighted stylet intubation has been for there have been reported complications. are two reported of In the the bulb from a Flexi-lum™ and in the patient’s right lower lobe after intubation of an which had been with for two of the larynx (10). The bulb was by using a fiberoptic but the patient developed a of intubation and In the second case, the at the of the handle and the which was to stylet which on No patient was have their that lightwands are and have or fiberoptic to the after lighted stylet intubation is generally of a and and In et large these were less with a lighted stylet as compared with a direct tracheal intubation. The most reported after lighted stylet intubation are two reported of In case was more than reported in the intubation and in both the was after any tracheal intubation may be a of and be to an for and under direct may with direct laryngoscopy and is it is impossible with the to use of a lighted stylet an in Lighted stylet intubation is a technique that is easily and could be tracheal intubation by using direct laryngoscopy is fiberoptic intubation, is when intubation with Lighted stylets can be and and are easily to The technique can be combined with other and is useful in a variety of the technique is as good as traditional at and in it is more and better by the the right of it can be used for all sizes of patients and will not significantly It be in all anesthetic and to all