Video-intuboscopy: a new aid to routine and difficult tracheal intubation

A Manikin Study to Compare Video-Optical Intubation Stylet versus Macintosh Laryngoscope Used by Novice in Normal and Simulated Difficult Airway Intubation

Objective

To compare Macintosh laryngoscope with video-optical intubation stylet on rates and time durations of successful tracheal intubation in normal and simulated difficult airway.

Design

Crossover experimental study.

Setting

Intubation training laboratory.

Methods

A group of novices (58 medical students) attempted intubation on manikin under normal and simulated difficult airway (grade 3 larygnoscopic view) settings using both Macintosh laryngoscope and video-optical intubation stylet. The success rate, duration to intubate and occurrence of complications (oesophageal intubation and incisor breakage) when using the two different devices were measured and compared. The time results were analysed by paired t-test and categorical results by chi square test or Fisher's exact test.

Results

The success rate to intubate difficult airway using video-optical intubation stylet (0.92) was significantly higher than using Macintosh laryngoscope (0.59) (p=0.002). The mean time taken to intubate difficult airway using video-optical intubation stylet was significantly shorter than using Macintosh laryngoscope by 10.90 seconds (p=0.004). Oesophageal intubation rate was significantly higher when using Macintosh laryngoscope to intubate difficult airway compared to video-optical intubation stylet (p=0.002). There was no significant difference on the rate of incisor breakage between the two instruments.

Conclusions

Novice can learn to use both Macintosh laryngoscope and video-optical intubation stylet to intubate successfully after a short training. Video-optical intubation stylet is an effective “Plan B” instrument because it shortens the duration and increases the rate of successful intubation in difficult airway situations.

Video-Assisted Airway Management: Experience in a Hong Kong Emergency Department

Video-assisted airway management is a new concept for monitoring and managing both normal and difficult tracheal intubations, with the aid of video-transmission of the view from the tip of intubating devices such as stylets or intubating laryngoscopes. Its principle, practical application and local experience are illustrated by some sample cases and its future development is discussed.

Seldinger-assisted videotelescopic intubation (SAVI): A common sense approach to the difficult pediatric airway

OBJECTIVES: To describe the Seldinger-assisted videotelescopic intubation (SAVI) technique, a complementary method for aiding in difficult pedi-atric intubations that uses common equipment available to the practicing otolaryngologist.

STUDY DESIGN: Technique description.

METHODS: Detailed description of technique for use of a pediatric laryngoscope with video-assisted endotracheal tube (ETT) covered rigid tracheoscopy controlled intubation in difficult pediatric airways.

RESULTS: In our practice, SAVI is vital in establishing a secure airway in the difficult-to-intubate child. After insertion of a laryngoscope, an appropriate sized endotracheal tube is delivered through the glottis under direct video-visualization from a rigid telescope using a variation of the well-established Seldinger technique. The telescope serves as the stable ETT stylet that also provides panoramic visualization. The ETT slides over the telescope to provide a secure airway directly visible to all in the operating room. Benefits of the SAVI technique to previously described video-assisted intubations with flexible or specially designed endoscope devices include decreased cost, employment of previously existing endoscopy skills, the benefit of rigid delivery of the endotracheal tube as well as innate versatility to a multitude of clinical situations.

CONCLUSIONS: The SAVI technique offers an additional practical clinical solution to the difficult pediatric airway. Although ultimately establishing the airway depends on the skills of the operator, the SAVI technique has saved multiple lives by using common equipment through a common-sense approach. EBM rating: D. (Otolaryngol Head Neck Surg 2005;132:677-680.)

Pioneers of Laryngoscopy: Indirect, Direct and Video Laryngoscopy

Airway management is one of the core skills of the anaesthetist and various techniques of airway management have developed over many years. Initially, the only view of the glottis that could be obtained was an indirect view (indirect laryngoscopy). Late in the 19th century, a direct view of the glottis was obtained via various direct laryngoscopes. Currently, in the early 21st century, there has been a return to indirect laryngoscopy via videolaryngoscopy using a videolaryngoscope. The aim of this paper is to give a historical overview of the development of both direct and indirect laryngoscopy.

[Video laryngoscopy olé! Time to say good bye to direct and flexible intubation?]

A number of video laryngoscopy systems have been introduced into anesthetic practice in recent years. Due to the technical concepts of these systems exposure of the laryngeal structures is usually better than with direct laryngoscopy, both in normal airways as well as in those that are difficult to manage. With the increasing use of video laryngoscopy it seems as if direct laryngoscopy and flexible fibrescopic intubation are at risk of becoming redundant. This article describes current developments and discusses why expertise in direct laryngoscopy and flexible fibrescopic intubation should be maintained, particularly by experts in airway management.

Novel automatic endotracheal position confirmation system: mannequin model algorithm evaluation

OBJECTIVE

A novel endotracheal intubation accurate positioning confirmation system based on image classification algorithm is introduced and evaluated using a mannequin model.

METHODS

The system comprises a miniature complementary metal oxide silicon sensor (CMOS) attached to the tip of a semi rigid stylet and connected to a digital signal processor (DSP) with an integrated video acquisition component. Video signals acquired and processed by an algorithm implemented on the processor. During mannequin intubations, video signals were continuously recorded. A total of 10 videos were recorded. From each video, 7 images of esophageal intubation and 8 images of endotracheal intubation (in which the carina could be clearly seen) were extracted, yielding a total of 150 images taken from arbitrary positions and angles which were processed by the confirmation algorithm.

RESULTS

The performance of the confirmation algorithm was evaluated using a leave-one-out method: in each iteration, 149 images were used to train the system and estimate the models, and the remaining image was used to test the system. This process was repeated 150 times such that each image participated once in testing. The system correctly identified 80 out of 80 endotracheal intubations and 70 out of 70 esophageal intubations.

CONCLUSIONS

This fully automatic image recognition system was used successfully to discriminate airway carina and non-carina endotracheal tube positioning. The system had a 100% success rate using a mannequin model and therefore further investigation including live tissue model and human research should follow.

Endoscopic intubation of exotic companion mammals

Rabbits, guinea pigs, chinchillas and many other small exotic mammals are not intubated routinely, because intubation requires specialized equipment and is difficult to perfect. Using a face mask for these species solely on the basis that they are unable to regurgitate ignores the numerous other benefits of airway control. This article summarizes the many advantages of endotracheal intubation and the various methods of intubation that have been reported. It introduces endoscopic intubation as a method that overcomes many of the difficulties associated with other methods and describes the equipment needed, how to intubate with an endoscope, how to confirm proper endotracheal tube placement, and possible complications. Over-the-endoscope intubation is discussed in detail, as it appears to provide the most versatile and reliable method of intubating exotic companion mammals.

A comparison of Bonfils intubation fiberscopy and fiberoptic bronchoscopy in difficult airways assisted with direct laryngoscopy

Background

To evaluate the usefulness of Bonfils intubation fiberscope assisted by direct laryngoscopy (BIF-DL) and flexible fiberoptic bronchoscope assisted by direct laryngoscopy (FOB-DL) using video recording in cases of unanticipated difficult intubation with respect to the time required to visualize the vocal cords and place the endotracheal tube. We compared two fiberscopes in patients with authentic difficult airways.

Methods

In this randomized, controlled clinical trial, 40 patients (grade 3 according to grades of difficulty in laryngoscopy), scheduled for surgery under general anesthesia were randomly allocated to BIF-DL group or FOB-DL group. Number of attempts, time required for visualization of the vocal cord (T1) and placement of the endotracheal tube (T2) from insertion of instrument during the last successful attempt, and duration of scope manipulation during all attempts (T_total) were recorded. If intubation failed with one method, the other method was tried; these cases were then excluded. The incidence of sore throat and hoarseness was assessed.

Results

T1, T2, and T_total were significantly shorter in BIF-DL group (T1: 21.9 ± 8.2 sec vs. 80.4 ± 29.9 sec, P < 0.001, T_total: 77.9 ± 41.2 sec vs. 145.5 ± 83.9 sec, P = 0.003). In two cases, it was impossible to intubate with BIF-DL, but the procedure was subsequently successful using fibreoptic bronchoscope.

Conclusions

Intubation of difficult airways can be performed more rapidly with BIF-DL, but sometimes it may not be possible to intubate with the scope.

Evaluation of the Video Intubation Unit in morbid obese patients

BACKGROUND

Tracheal intubation may be more difficult in morbidly obese (MO) patients than in the non-obese. The aim of this study was to evaluate clinically if the use of the Video Intubation Unit (VIU), a video-optical intubation stylet, could improve the laryngoscopic view compared with the standard Macintosh laryngoscope in this specific population.

METHODS

We studied 40 MO patients (body mass index >35 kg/m(2)) scheduled for bariatric surgery. Each patient had a conventional laryngoscopy and a VIU inspection. The laryngoscopic grades (LG) using the Cormack and Lehane scoring system were noted and compared. Thereafter, the patients were randomised to be intubated with one of the two techniques. In one group, the patients were intubated with the help of the VIU and in the control group, tracheal intubation was performed conventionally. The duration of intubation, as well as the minimal SpO(2) achieved during the procedure, were measured.

RESULTS

Patient characteristics were similar in both groups. Seventeen patients had a direct LG of 2 or 3 (no patient had a grade of 4). Out of these 17 patients, the LG systematically improved with the VIU and always attained grade 1 (P<0.0001). The intubation time was shorter within the VIU group, but did not attain significance. There was no difference in the SpO(2) post-intubation.

CONCLUSION

In MO patients, the use of the VIU significantly improves the visualisation of the larynx, thereby improving the intubation conditions.

Pediatric laryngoscopes and intubation aids old and new

This review summarizes the evolution of the pediatric laryngoscope using some of the established landmarks in the history of anesthesia. Children were rarely intubated before 1940 though the subsequent 30 years saw a proliferation of pediatric laryngoscopes in part driven by the developments in pediatric anesthesia and surgery, manufacturing techniques and materials and a change in airway management philosophy exemplified by Jackson Rees's argument against the notion that intubation was to be avoided in children. A perspective on the present day describes the modifications to popular straight and curved blade laryngoscopes and the development of new devices that enhance direct visualization of the larynx. There are an ever-increasing number of laryngoscope devices that assist in indirect visualization of the larynx such as rigid optical stylets and flexible fiber-optic scopes. Images from many of these devices may be enhanced by digital camera or real-time video technology. The prospect of future laryngoscope development is glimpsed in the arrival of light emitting diode light source technology and questions remain regarding the consequences of equipment disposability and at the fidelity of disposable equipment manufacture.

Bonfils semirigid endoscope for guidance during percutaneous tracheostomy

We report on the use of the Bonfils semirigid scope for endoscopic guidance during percutaneous dilational tracheostomy. Forty patients requiring percutaneous dilational tracheostomy on the General or Neurosurgical Intensive Care Unit were enrolled in this study. We used the '45 degree curved distal tip' scope in the first 15 patients, evaluating its ease of use, optical quality of focus and image resolution as well as light intensity on a 10-point scale. We evaluated straight and curved versions of it in another 15 and 10 patients, respectively. We examined the impact on ventilation and cardiovascular parameters. In all patients (n = 40) visualisation of the procedure was satisfactory. There were no clinically significant changes in ventilatory or cardiovascular parameters. The image quality for most patients received a score of 7-10. The Bonfils scope provides a practical alternative to flexible bronchoscopes in this setting.

First clinical experience of tracheal intubation with the SensaScope, a novel steerable semirigid video stylet

BACKGROUND

Problems with tracheal intubation are a major cause of anaesthesia-related morbidity and mortality. Difficulty with tracheal intubation is primarily a consequence of failure to see the vocal cords with conventional direct laryngoscopy. We report our experience with use of the SensaScope for tracheal intubation in routine clinical practice.

METHODS

The SensaScope is a hybrid steerable semirigid S-shaped video stylet. Its handling and performance were assessed by anaesthetists with a minimum of 1 yr of experience. They performed four intubations each with the device in anaesthetized elective surgical patients. The view of the glottis with the Macintosh laryngoscope was compared with the view shown on the monitor by the SensaScope. The time taken to complete intubation, the final tracheal tube (TT) position and the degree of difficulty of the procedure were recorded.

RESULTS

Thirty-two patients were studied. All Macintosh Cormack and Lehane grade 3 patients were converted to grade 1 or 2 with the SensaScope. Mean intubation time was 25 (12) s and correct mid-tracheal TT cuff position was achieved in all cases. The degree of difficulty was 3.0 (1.8) on a numerical scale ranging from 0 to 10. All operators rapidly became familiar with the device and mastered its technique of use.

CONCLUSION

The SensaScope is a reliable and effective device for tracheal intubation under vision of the normal airway. It has great potential to facilitate management of difficult airway situations in anaesthetized and paralysed patients.

The paediatric upper airway: anaesthetic aspects and conclusions

PURPOSE OF REVIEW

Paediatric airway problems are among the most challenging clinicians will face throughout their career. Clinicians unaccustomed to dealing with children tend to approach paediatric airway problems with a disproportionate amount of fear that is often engendered by inexperience, and this fear can interfere with performance. Understanding the differences between the infant upper airway and the airway in older children is important to properly manage the airway.

RECENT FINDINGS

Airway manoeuvres and the important tools used for airway management, such as the laryngeal mask airway, the fibreoptic bronchoscope and the new intubating fibreoptic stylets for managing the difficult paediatric airway, have been elucidated in the literature.

SUMMARY

Planning, preparation, and teamwork are essential, and must include an awareness of problems that might occur in the recovery period. Special clinical situations such as management of the child with impending airway obstruction are discussed.

The Shikani Seeing Stylet for difficult intubation in children: initial experience

The Shikani Seeing Stylet is a recently introduced reusable intubating stylet, produced in adult and paediatric versions. It combines features of a fibreoptic bronchoscope and a lightwand. Inside a malleable stainless steel sheath, the Shikani Seeing Stylet has a fibreoptic cable leading to a distal light source and high-resolution lens. In use, the stylet is placed in the lumen of the selected endotracheal tube and the light source enables the stylet to be used as a lightwand, while the fibreoptic capability enables visualization of the laryngeal inlet. It is portable, relatively inexpensive and easy to maintain. This report describes the use of the stylet on eight occasions in seven children, all of whom were assessed preoperatively as being potentially difficult to intubate. Three had been difficult to intubate previously. All were anaesthetized using inhalational anaesthesia. Once an adequate depth of anaesthesia had been achieved, conventional direct laryngoscopy was performed and identified as Grade 3 in six of the patients and Grade 1 in one. Tracheal intubation was then attempted using the Shikani Seeing Stylet. On six of the eight occasions the attempt was made by different anaesthetists, none of whom had any prior clinical experience with the stylet. There were seven successful intubations and one failure in a patient who could not be intubated by any method. The Shikani Seeing Stylet seems a useful device for use in children with difficult airway problems, suspected cervical spine instability or limited mouth-opening.

Difficult airway management in the emergency department

Most airway management in the emergency department is straightforward and readily accomplished by the emergency physician. The exact incidence of difficult intubations is difficult to discern from available evidence, but these are probably more frequent in the Emergency Department than in the operating room, given the urgent nature of the procedure and the lack of preparation of the patient population. A variety of adjuncts for airway management are available to assist in both intubation and ventilation. The utility of these adjuncts is detailed in this review, with emphasis on techniques most useful to the emergency physician.

Improving styletted oral tracheal intubation: rational use of the OTSU

PURPOSE

To introduce an improved method of styletted oral laryngoscopic tracheal intubation.

DESCRIPTION OF THE TECHNIQUE

The oral tracheal stylet unit (OTSU) is constructed using a commonly available intubating stylet combined with an ordinary endotracheal tube (ETT). The ETT/stylet is created by a series of specific steps to form an OTSU, each with a standard shape and design that allows the tracheal tube to separate freely from the stylet. After construction, every unit is tested to confirm that the frictional resistance created by the tracheal tube, as it slides along the stationary stylet, is at an absolute minimum. Successful tracheal intubation is based on the following concepts: (a) The j-shaped OTSU, when correctly directed through the airway, passes freely from the mouth to the larynx, the laryngoscopic channel; (b) The tip of the ETT must first be placed between the vocal cords with every intubation. The tracheal tube is then launched and advanced into the trachea by sliding along and off a stationary stylette; (c) Only minimal force is required to propel the ETT during intubation; (d) Resistance to placement, launch or advancement means the tip of the OTSU has come into physical contact with the patient's airway; (e) When the epiglottis obscures the larynx, the tip of the OTSU is used to explore the hypopharynx and identify the glottis. The ability to differentiate where the ETT tip is located depends primarily on interpreting the sensations of touch and pressure transmitted from the bevel of the OTSU to the hand. Successful tracheal intubation is accomplished when all criteria for placement, launch, and advancement are met.

CONCLUSION

Styletted oral tracheal intubation is well known. However, we describe an improvement of the technique, based on solid physical principles and years of experience, that should prove useful both for routine intubations and unexpected difficult airways.

Comparison of two video-assisted techniques for the difficult intubation

BACKGROUND

Two recently developed video-optical intubation devices, the video-optical intubation stylet (VOIS) and the angled video intubation laryngoscope (AVIL) were compared for intubation times and success rate in a simulated difficult tracheal intubation setting.

METHODS

Thirty anaesthetists were asked to perform 5 intubation attempts with both techniques. Intubation times were recorded and the subjective degree of difficulty and preference for each technique were requested.

RESULTS

Intubation time with the VOIS was shorter (17.4+/-6.8 s) than with the AVIL (22.8+/-13.4 s; P=0.0001). Four of the 150 intubation attempts with the AVIL were scored as unsuccessful, due to prolonged intubation time (>60 s). The estimated degree of difficulty was not significantly different.

CONCLUSION

In conclusion, both video-assisted intubation devices, the video-optical intubation stylet and the angled video intubation laryngoscope, can be considered to be simple and effective tools which facilitate tracheal intubation and which require only brief instruction and training.

Video-intuboscopic monitoring of tracheal intubation in pediatric patients

PURPOSE

To evaluate the efficacy of video-intuboscopic monitoring during orotracheal intubation in a pediatric anesthesia teaching unit.

METHODS

In 100 pediatric patients direct laryngoscopy performed by residents or nurse anesthetists was monitored on a video display using a flexible, ultralight video-endoscopic system (O.D. 2.8 mm/length 1.8 m) within the endotracheal tube (ETT). Best direct laryngoscopic view was assessed by the intubator. The instructor observed the intubation procedure on the video display and noted number of intubation attempts, best laryngoscopic monitor view, tube passage through the larynx and final tube position. If required he gave instructions or corrections. After removal of the laryngoscope, tracheal tube position was adjusted using the monitor view. Difficulties attributed to the fibreoptic endoscope during intubation and removal from the ETT were recorded.

RESULTS

The trachea was successfully intubated at the first attempt in all patients. The supervisor detected one esophageal and 12 endobronchial intubations that were immediately corrected before starting ventilation. Final visualized endotracheal tube adjustment above the carina was possible in all patients except in one with copious tracheal secretions. Compared with direct laryngoscopy the video display provided an improved view of the vocal cords during intubation. In six patients direct laryngoscopy was difficult but the tracheas were intubated using the monitor view. No difficulties with the equipment were encountered except that the black coated endoscope compromised recognition of the black ETT depth-markings in small tubes.

CONCLUSIONS

Video-intuboscopic monitoring is a useful monitor of tracheal intubation. "The improved view of the cords may provide assistance during difficult laryngoscopy.

Use of a fibreoptic stylet to visually evaluate tracheal intubation technique

To compare the tracheal intubation by novices with that of instructors, we videotaped the view obtained through a fibreoptic stylet during standard tracheal intubations with a Macintosh direct laryngoscope. The duration of visualization of the vocal cords was longer during intubation by instructors than during trainee attempts. The tracheal tube contact (with pharyngeal wall) time duration was higher during intubation attempts by trainees than instructors. The quality of the image of the vocal cords through the stylet was related to these video-view parameters. Our results demonstrated that visualization of the vocal cords by direct laryngoscope and manipulation of the tracheal tube in the oral cavity were different between anaesthesia trainees and instructors, and suggested that visually monitoring the tracheal intubation procedure through a fibreoptic stylet might be useful for the education of anaesthesia trainees.

Comparison of a new video-optical intubation stylet versus the conventional malleable stylet in simulated difficult tracheal intubation

Handling and efficacy of a new video-optical intubation stylet were assessed in a simulated difficult tracheal intubation setting and compared with a conventional malleable stylet. Forty-five anaesthetists performed 10 tracheal intubations using both techniques. Laryngoscopy was performed by the observer, who created a grade 3 view according the classification by Cormack and Lehane. The time taken to place the tracheal tube and the final tracheal tube positions were documented. Mean (SD) intubation time for the video-optical stylet was 20.4 (7.7) s and for the malleable stylet 10.2 (3.3) s (p<0.01). With the video-optical stylet the trachea was correctly intubated in all 225 attempts; with the malleable stylet 44 (19.6%) oesophageal and 44 (19.6%) endobronchial intubations occurred (p<0.01). The video-optical intubation stylet enabled us to recognise inappropriate tracheal tube positions and to correct them immediately. This equipment can be considered a reliable and effective tool for management of the difficult airway.

Difficult airway management: comparison of the Bullard laryngoscope with the video-optical intubation stylet

PURPOSE

To evaluate, whether the video-optical intubation stylet (VOIS) was more successful for difficult tracheal intubation than the Bullard laryngoscope (BL).

METHODS

An intubation mannequin head was modified so that, using a Macintosh blade size 3, only the epiglottis was visible at direct laryngoscopy, representing a grade III laryngoscopic view. Forty anesthesiologists attempted tracheal intubation using each technique. Tracheal intubation with the Bullard laryngoscope was performed using the attached non-malleable intubating stylet preloaded with an endotracheal tube. The video-optical intubation stylet inserted into an endotracheal tube was used with direct laryngoscopy. During conventional laryngoscopy, the video-view from the stylet tip allowed the tracheal tube to be guided behind the epiglottis into the trachea. Ten attempts with each technique were performed by each anesthesiologist in randomized order. Intubation time, and failed intubation (> 60 sec/esophageal intubation) were recorded. The operators assessed the degree of difficulty of each method using a Likert-scale.

RESULTS

Mean intubation time (19.2+/-4.5 sec for the BL and 18.8+/-4.6 sec for the VOIS) was almost the identical. The video-optical intubation stylet was associated with fewer failed intubations (8 vs. 41; P<0.005) and had a lower degree of difficulty (1.7+/-0.65 for the VOIS and 2.6+/-0.74 for the BL; P<0.0001). No correlation was found between the anesthesiologist's experience and mean intubation time, estimated degree of difficulty or number of unsuccessful intubation.

CONCLUSION

The video-optical intubation stylet was a more effective and simpler intubation device to facilitate difficult tracheal intubation than the Bullard laryngoscope.

Supervised teaching practice: a system for teacher support and quality assurance

Supervised teaching practice is practical supervision of teaching under the tutelage of an established teacher. It is proposed as a cost-effective integrated approach to linking the support and development of teachers with quality assurance. In modern undergraduate medical curricula increasing value is placed on teaching and teacher-training. The response to the General Medical Council's demand for a new style of undergraduate medical education requires a system of practical and continuous training which will ensure the highest standard among teachers. Supervised teaching practice offers such a system.