Tatsuo Kadoya

Approach combining the airway scope and the bougie for minimizing movement of the cervical spine during endotracheal intubation.

Background:The Airway Scope (AWS, AWS-S100; Hoya-Pentax, Tokyo, Japan), a recently introduced video laryngoscope, has been reported to reduce movement of the cervical spine during intubation attempts in comparison with conventional laryngoscopes. Use of the bougie as an aid for the AWS may cause further reduction. The authors compared cervical spine movement during intubation with the AWS with and without a bougie. Methods:Thirty patients without cervical spine abnormality were randomized into two groups: intubation with AWS only and intubation with the AWS and the bougie. The cervical spine motion between the occiput (C0) and the fourth cervical vertebra (C4) was observed fluoroscopically, and change in movement between adjacent vertebrae created by each intubation method was compared. Time to intubation was also measured. Results:Laryngoscopy with the AWS produced extension of the cervical spine segments assessed (C0-4). Median extension angle of the C0-4 during intubation using the AWS was reduced from 16.0 degrees without the bougie to 6.5 degrees with the bougie (P < 0.01). There was no significant difference in time to intubation between them. Conclusions:Use of the bougie resulted in significantly reduced extension of the cervical spine during intubation attempt with the AWS in patients with a normal cervical spine.

The sniffing position provides greater occipito-atlanto-axial angulation than simple head extension: a radiological study.

PurposeWhile the anatomic sniffing position has traditionally been considered the standard head and neck position for laryngoscopy, recent evidence suggests that the sniffing position provides no significant advantage over simple head extension. To establish if the sniffing position provides an anatomic advantage, we compared the occipito-atlanto-axial extension angle, a key determinant for obtaining a good laryngeal view during laryngoscopy, in simple head extension and sniffing positions.MethodsThirty volunteers with normal cervical spines were studied. Radiological examinations of the lateral cervical spine were taken and compared in each of the following three positions for each subject: neutral position (flat on the table with no pillow and without head extension or flexion); simple head extension (head maximally extended without a pillow); and the sniffing position (head extension with cervical flexion obtained by 7 cm occipital elevation).ResultsMean angles of the occipito-atlanto-axial extension in simple head extension and the sniffing position were 20.4°±5.1°and 24.2°± 5.6°, respectively (P < 0.01).ConclusionThe anatomic sniffing position provides greater occipito-atlanto-axial extension compared to simple head extension. These findings should be taken into consideration when optimizing patient positioning for laryngoscopy.RésuméObjectifLa position anatomique de reniflement est traditionnellement considérée comme la position standard de la tête et du cou pour la laryngoscopie; toutefois, des études récentes suggèrent que cette position ne présente aucun avantage significatif par rapport à la simple extension de la tête. Nous avons comparé l’angle d’extension occipito-atlaïdo-axial dans les positions de simple extension de la tête et de reniflement afin de déterminer si la position de reniflement présentait un avantage anatomique, l’angle étant un élément-clé dans l’obtention d’une bonne vision laryngée pendant la laryngoscopie.MéthodeL’étude portait sur trente volontaires avec colonnes cervicales normales. Chaque sujet a subi des examens radiologiques de la colonne cervicale latérale dans les trois positions suivantes: position neutre (à plat sur la table sans oreiller et sans extension ou flexion de la tête); extension simple de la tête (tête en extension maximale sans oreiller); et position de reniflement (extension de la tête avec flexion cervicale obtenue par une élévation occipitale de 7 cm). Les résultats ont ensuite été comparés.RésultatsLes angles moyens d’extension occipito-atlaïdo-axiale dans l’extension simple de la tête et la position de reniflement étaient de 20,4° ± 5,1° et 24,2° ± 5,6° respectivement (P < 0,01).ConclusionLa position anatomique de reniflement présente une plus grande extension occipito-atlaïdo-axiale que la simple extension de la tête. Ces résultats devraient être pris en compte pour obtenir un meilleur positionnement du patient lors de la laryngoscopie.

Potential damage to the larynx associated with light-guided intubation: a case and series of fiberoptic examinations.

A lighted stylet is a useful device for routine or difficult endotracheal intubation. 1-3 With light-guided intubation, the incidence of complications is reported to he low, but the larynx can be injured during the blind advancement of the endotracheal tube. 1 We report a case in which malpositioning of the epiglottis occurred after tracheal intubation with a lighted stylet, and difficulty was encountered in replacing the displaced epiglottis. This case prompted us to observe closely a series of intubations by use of a light wand.

The reliability of the Bellhouse test for evaluating extension capacity of the occipitoatlantoaxial complex.

We examined the reliability of an airway evaluation test to assess the occipitoatlantoaxial (OAA) extension capacity described by Bellhouse et al. (Bellhouse test) in 20 adult volunteers with normal cervical spines. Each subject sat upright with the head in the neutral position and was then asked to extend the head maximally while attempting to move the neck as little as possible. The angle from the neutral position to the extreme extension was measured using the goggle-goniometer. Lateral cervical radiographs were taken in these positions, and the OAA extension angle was radiographically measured. Median values for OAA extension measured radiographically and extension of the head measured with the Bellhouse test were 21.5° and 30°, respectively. Extension of 9.5° occurred at the subaxial regions, which could not be detected by inspecting surface contours of the neck. The extent of the subaxial extension was almost consistent with the degree of overestimation of the OAA extension capacity by the Bellhouse test. Because the subaxial extension occurred independent of the degree of the OAA extension, a strong relationship between the angle measured with the goggle-goniometer and the OAA extension angle measured radiographically was not established (P < 0.01, r2 = 0.44). These findings mean that the test is not always accurate to evaluate the OAA extension capacity and will fail to detect a reduction of the OAA extension capacity if the subaxial regions are normal. Therefore, these problems derived from the Bellhouse test offer a potential for missing a prediction of difficult tracheal intubations because reduced OAA extension is one of the important factors that make intubation difficult.

Fibreoptic assessment of laryngeal aperture in patients with difficult laryngoscopy

PurposeTo determine the relationship between the area of the laryngeal aperture (LA) seen fibreoptically during laryngoscopy and the difficulty of tracheal intubation in patients with difficult laryngoscopyMethodsIn 587 adult patients after induction of general anesthesia and muscle relaxation, the best laryngoscopic view of the larynx using a Macintosh 3 blade was classified according to Cormack. When the LA could not be seen, with laryngoscope blade in place, the LA view provided by a fibreoptic bronchoscope (FOB)-camera passed nasally was photographed. Then, the laryngoscopist attempted to intubate the trachea using the Macintosh blade. Tracheal intubation requiring more than three attempts was defined as difficult. After the third attempt, the trachea was intubated orally aided by FOB. The LA view after jaw thrust during FOB-aided intubation was photographed.ResultsLaryngoscopy was difficult in 17 of 587 patients. In four, intubation was difficult. In the remaining 13 patients the trachea was easy to intubate. The LA area obtained by the FOB in the difficult group (median, 0.19; intra-quartile range, 0.14 to 0.39 cm2) was smaller than that in the easy group (2.43; 1.84 to 2.93 cm2)(P =0.003). In contrast, the LA area provided by jaw thrust during the FOB-aided intubation in the difficult group (2.28; 1.99 to 2.73 cm2) was similar to that during laryngoscopy in the easy group.ConclusionInability of the laryngoscope to provide an adequate LA view is one cause of difficult intubation with the Macintosh laryngoscope in patients with difficult laryngoscopy.RésuméObjectifDéterminer la relation entre la zone d’ouverture laryngienne (OL) décelée pendant la laryngoscopie fibroscopique et la difficulté d’intubation endotrachéale chez des patients dont la laryngoscopie est difficile.MéthodeAprès l’induction de l’anesthésie générale et la curarisation chez 587 adultes, la meilleure vision laryngoscopique du larynx obtenue avec une lame de Macintosh 3 a été classée selon Cormack. Quand on ne pouvait visualiser l’OL à partir de la lame du laryngoscope en place, on a photographié l’OL obtenue avec une caméra de fibroscope bronchique (FOB) introduite par voie nasale. Ensuite, on a tenté l’intubation endotrachéale avec la lame Macintosh. L’intubation qui nécessitait plus de trois essais était jugée difficile. Après le troisième essai, l’intubation était réalisée par voie orale avec le FOB. On a photographié l’OL après la subluxation de la mâchoire pendant l’intubation facilitée par le FOB.RésultatsLa laryngoscopie a été difficile chez 17 patients et l’intubation a été difficile chez 4 d’entre eux. La zone d’OL obtenue à l’aide du FOB dans le groupe à intubation difficile (médiane, 0,19; intervalle intra-quartile, 0,14 à 0,39 cm2) était plus petite que celle du groupe à intubation facile (2,43; 1,84 à 2,93 cm2; P = 0,003). Par ailleurs, l’OL obtenue par la subluxation de la mâchoire, pendant l’intubation facilitée par le FOB dans le groupe difficile (2,28; 1,99 à 2,73 cm2), était similaire à celle qu’on a obtenue pendant la laryngoscopie dans le groupe facile.ConclusionLimpossibilité du laryngoscope de fournir une vision valable de l’OL est l’une des causes de l’intubation difficile avec le laryngoscope Macintosh chez des patients dont la laryngoscopie est difficile.

The McCoy Laryngoscope Expands the Laryngeal Aperture in Patients with Difficult Intubation

To the Editor:-The McCoy levering laryngoscope is a useful device,’.’ but does not uniformly improve the view in some cases of difficult laryngoscopy.’.’ We report a case in which the McCoy laryngoscope did not improve the direct view of the larynx, but instead lifted the epiglottis and expanded structures around the laryngeal aperture (LA), thereby facilitating “blind” tracheal intubation. A 72-yr-old woman (155 cm, 55 kg) with femoral neck fracture was scheduled to undergo surgical repair. At the preoperative visit, the patient’s airway could not be evaluated because she had senile dementia and could not respond to verbal commands. Anesthesia was induced with fentanyl 50 p g and thiopental 225 mg, and vecuronium 6 mg was administered. The patient’s lungs were easily ventilated through a face mask. At laryngoscopy with a Macintosh 3 blade (Welch Allyn, NY), only the epiglottis could be seen despite the application of optimal external laryngeal manipulation.* Three attempts at intubation with a stylet by blind probing failed. After several additional minutes of mask ventilation, an assistant nasally inserted a fiber-optic bronchoscope (FOB) (BF-P30; Olyrnpus, Tokyo) into the laryngopharynx to assess the area of the LA during laryngoscopy.5 With the FOR still in place, laryngoscopy using the Macintosh 3 blade was reattempted. Fiberscopy revealed that the epiglottis was close to the posterior pharyngeal wall, that the laryngoscope did not expand the structures around the LA, and that the LA area was very small. A McCoy levering kdryngoscope (Penlon, Abingdon, UK) was used to reattempt a fiber-optic assessment of the LA area. With the blade in the neutral position, the direct view and the fiber-optic view were similar to those obtained during Macintosh laryngoscopy (fig. IA). When the tip of the levered blade was elevated, only the slightly lifted epiglottis could be seen under direct vision; however, fiberscopy showed that the epiglottis was lifted, that the LA was markedly expanded, and that the glottis was clearly visible through the FOB (fig. lB). The FOB was removed and an endotracheal tube with the curved stylet was readiiy inserted into the trachea by blind probing with the levering laryngoscope blade in the elevated position. Successful placement of the endotracheal tube was confirmed by capnogaphy and aus cultation. Our case illustrates that even if the McCoy laryngoscope does not

Severe subluxation in the sniffing position in a rheumatoid patient with anterior atlantoaxial subluxation.

SPECIAL attention should be paid to airway management in rheumatoid patients with atlantoaxial subluxation (AAS) because they may be at risk of life-threatening neurologic injury caused by worsening the subluxation in the head and neck position during airway maneuver. 1-5 Atlantoaxial subluxation is found in 11-46% of patients with rheumatoid arthritis and is classified into four groups according to the direction of the subluxation, including anterior AAS, posterior AAS, vertical AAS, and lateral AAS. 6,7 Anterior AAS is the most prevalent form, accounting for 80% of all types of subluxations. 6,7 In rheumatoid patients with anterior AAS, the degree of subluxation has been estimated in association with flexion and extension at the entire cervical spine (the head and neck) as a functional unit. 6,7 During flexion of the entire cervical spine, the atlas separates anteriorly from the axis, and the subluxation is worsened. On the contrary, during extension, the atlas slides backward until it rests against the dens of the axis, and the subluxation is reduced. Therefore, standard anesthesia textbooks advocate avoiding flexion of the head and neck in rheumatoid patients with anterior AAS. 3,4 The sniffing position is widely recommended as the standard head and neck position for conventional laryngoscopy. 8,9 This position consists of two components, which are severe extension of the head at the occipitoatlantoaxial (OAA) complex and slight flexion of the neck at the subaxial cervical segments. 8,9 In this position, the direction of movement of the OAA complex (head movement) and that of the subaxial segments (neck movement) are opposite. 8,9 Theoretically, extension of the OAA complex reduces the subluxation, and flexion of the subaxial segments makes it worse in rheumatoid patients with anterior AAS. In general, it is believed that accomplishment of the sniffing position is tolerated in these patients because the OAA complex where the subluxation occurs is extended, and the degree of the subaxial flexion is mild. 2,10 However, whether this position is safe is still unknown. We report a case of the rheumatoid patient with anterior AAS that was markedly worsened by the sniffing position.

Preoperative evaluation of extension capacity of the occipitoatlantoaxial complex in patients with rheumatoid arthritis: comparison between the Bellhouse test and a new method, hyomental distance ratio.

Background: The authors devised a new method, the hyomental distance ratio (HMDR), for preoperatively identifying patients with a reduced occipitoatlantoaxial extension capacity, which was defined as the ratio of the hyomental distance in head extension position to that in the neutral position. They compared the accuracy of the HMDR with that of the Bellhouse test in 40 patients with rheumatoid arthritis. Methods: Each patient wearing goggles on which a goniometer was mounted sat upright with the head in the neutral position and then extended the head maximally. The angle of the goggles and the hyomental distance were measured in the two head positions, and a lateral cervical radiograph was taken simultaneously. The Bellhouse angle was defined as a difference in the angles of the goggles between these positions. Results: Median values of the radiologic occipitoatlantoaxial extension angle and the Bellhouse angle were 11.2° and 24.9°, respectively. In 21 of 40 patients, the radiologic occipitoatlantoaxial extension angle was less than 12° (reduced occipitoatlantoaxial extension capacity). In these patients, extension of the median angle of 16.4° occurred at the subaxial regions and was greater than that of 8.5° in patients with a radiologic occipitoatlantoaxial extension angle of 12° or more (P < 0.01). As a result, a strong relation between the Bellhouse angle and radiologic occipitoatlantoaxial extension angle was not established (P < 0.01, r = 0.48). In contrast, the HMDR correlated well with the radiologic occipitoatlantoaxial extension angle (P < 0.0001, r = 0.88). The areas under the receiver operating characteristic curve of the Bellhouse test and the HMDR were 0.72 and 0.95, respectively. Conclusions: The HMDR was a good predictor of a reduced occipitoatlantoaxial extension capacity in patients with rheumatoid arthritis, but the Bellhouse test was not a clinically reliable method.

Use of the univent bronchial-blocker tube for unanticipated difficult endotracheal intubation.

To the Editor:—In the face of difficult intubation, it is sometimes useful to insert a small-diameter introducer through the laryngeal aperture in the trachea and then pass the endotracheal tube over it. We report a modification of this technique using the Univent bronchial-blocker tube (Fuji System, Tokyo, Japan) in a patient with unanticipated difficult intubation. A 60-yr-old, 67-kg man with lung cancer was scheduled for right upper lobotomy. The patient had been in good health. After achieving the optimal head and neck position, anesthesia induction, and muscle relaxation, laryngoscopy was performed using a Macintosh No. 3 blade by an experienced anesthetist. Only the epiglottis was seen, despite application of external laryngeal pressure, and it was impossible to insert a 7.5-mm ID Univent tube into the trachea. The curvature of the distal end of the tube was changed using a stylet, but the second attempt at intubation also failed. After easy mask ventilation for a few minutes, the bronchial-blocker catheter was protruded maximally from the distal end of the main lumen of the Univent tube. At the third laryngoscopy, the bronchial-blocker catheter was gently advanced along the laryngeal surface of the epiglottis by blind probing. When a clicking sensation was felt with the curved tip, a 50-ml syringe was attached to the proximal end of a hollow lumen of the bronchial blocker. Withdrawal of the syringe plunger aspirated gas without resistance. This indicated that the bronchial blocker was in the trachea, and, therefore, the main body of the Univent tube was passed over it. The main lumen met with resistance under the epiglottis, but rotating its bevel 90° counterclockwise enabled easy advancement into the trachea. Successful intubation was confirmed by capnography during manual ventilation. The operation and the postoperative course were uneventful, except for a moderately severe sore throat, which improved gradually. There are some useful features of the Univent tube as an aid to difficult intubation compared with common bougies. First, special equipment is not needed because the Univent tube is a combination of an endotracheal tube with a bronchial-blocker catheter that can act as an intubating introducer. Second, it is relatively easy to control the direction of the tip of the bronchial blocker by rotating the main lumen. Its direction is also changed by twirling the proximal end of the bronchial blocker in the fingers. Finally, the hollow bronchial blocker (2-mm ID) enables use of the esophageal detector device or of the self-inflating bulb for confirmation of the placement of the catheter tip in the trachea. Successful tracheal placement is also confirmed by feeling a clicking sensation as the catheter tip slides over the tracheal cartilages. In addition, the hollow catheter can be used as a channel for oxygen delivery or as a suction catheter. We have experienced five cases of successful intubation using the Univent tube in which the laryngeal aperture was invisible during laryngoscopy. A possible problem with our technique is traumatic airway complication. Although the bronchial blocker is designed to pass safely into the trachea and bronchus, the bronchial-blocker catheter should be gently advanced. The fiberoptic bronchoscope– aided endotracheal intubation is the most reliable method in patients at risk for difficult intubation. However, the fiberoptic bronchoscope is not always readily available, and an intubation attempt may fail because of an inability to advance the endotracheal tube over the fiberoptic bronchoscope into the trachea. We believe that the Univent bronchial-blocker tube is a useful and simple aid to unanticipated difficult intubation.

Efficacy of the Airway Scope on tracheal intubation in the lateral position: comparison with the Macintosh laryngoscope.

Background The Airway Scope (AWS) may become a rescue airway device to secure the airway in the lateral position. We evaluated the efficacy of the AWS on tracheal intubation in patients in this position in comparison with the Macintosh laryngoscope. Methods Seventy patients scheduled for surgery in the lateral position under general anaesthesia with tracheal intubation were randomised into two groups: intubation with the Macintosh laryngoscope and that with the AWS. After general anaesthesia and muscle relaxation, experienced anaesthetists performed laryngoscopy and intubation using either laryngoscope in the right or left lateral position. Laryngoscopic view, intubation time, intubation difficulty scale score and success rate of tracheal intubation (within 60 s) were recorded and compared between intubation with the Macintosh laryngoscope and that with the AWS. Results In the lateral position, the laryngoscopic view with the AWS was significantly better than that with the Macintosh laryngoscope (P < 0.01). Tracheal intubation was successful at the first attempt with the AWS in all patients and with the Macintosh laryngoscope in 85.3% of patients (P < 0.05). The median times to intubation with the AWS and with the Macintosh laryngoscope were 14 (interquartile range, 9–19) s and 29 (20–31) s, respectively (P < 0.01). Also, the AWS significantly reduced the intubation difficulty scale score compared with the Macintosh laryngoscope (P < 0.01). Conclusion In the situation in which securing the airway in the lateral position is required, the AWS is more effective than the Macintosh laryngoscope.