Difficult Direct Laryngoscopy Research Articles

Prospective validation of a new airway management algorithm and predictive features of intubation difficulty

BackgroundSome patients have features that indicate possible difficulty with direct laryngoscopy for tracheal intubation. Prediction of the likely outcome and selection of patients for an enhanced management algorithm would reduce the possible harm from failed intubation attempts. MethodsAdult elective patients were assessed for seven features associated with difficult direct laryngoscopy, ranked in difficulty from 0 to 3. For a patient with at least one Class 3 feature, or two or more features of class 1 or higher, the enhanced management used a channelled videolaryngoscope Airtraq™ instead of a Macintosh laryngoscope. A long flexible angulated stylet and a flexible fibrescope would be used as the second and third steps. For patients with lesser difficulty scores, a Macintosh laryngoscope was used. Outcomes of enhanced management were analysed. Logistic regression and Random Forest algorithm, using the ranks of the predictive features, were used to predict difficulty during enhanced management. ResultsWe prospectively studied 16 695 patients. We selected 1501 (9%) for enhanced management, and tracheal intubation was successful in all of them. Of these, 73% were intubated in less than 30 s, and only 4.5% required more than 4 min for intubation. Progression to the second and third steps of enhanced management was predicted by restriction of mouth opening and reduced cervical spine mobility. ConclusionsAn enhanced management algorithm allowed successful tracheal intubation of all patients with anticipated difficult laryngoscopy. The need to combine the use of a stylet and a fibrescope with the Airtraq™ could be predicted with a high degree of certainty.

A prospective study assessing the anatomical parameters of neck for predicting the difficult direct laryngoscopy in adult Indian population

IntroductionDifficult airway is a calamitous incident as it can lead to airway or oesophageal mucosal tear, leading to aspiration, severe hypoxaemia and finally death. The aim of the study is to measure thyromental distance, sternomental distance, ratio of height to thyromental distance and neck circumference to anticipate difficult intubation as defined by Cormack-Lehane grading and to evaluate anatomical predictors of neck for difficult direct laryngoscopy in adult Indian population. MethodsThe study is conducted in Teerthanker Mahaveer Medical College & Research Centre, Moradabad for the period of one year on 200 patients undergoing general anaesthesia. Following parameters like Thyromental distance, Sternomental distance, Neck circumference and Ratio of height to thyromental distance were measured and prediction of difficult laryngoscopy was done by Cormack-Lehane grade. ResultsThe cut-off points of neck parameters in both the genders in Indian population were TMD ≤ 9.7 / ≤ 7.6 cm, STMD ≤ 18.6 / ≤ 15.8 cm, NC ≥ 40.3 / ≥ 38.2 cm and RHTMD ≥ 18.2 cm /≥ 21.5 cm. There was significant difference (p value <0.001) in all the parameters between the two genders. The Kappa values for TMD, STMD, NC and RHTMD are 0.7, 0.5, 0.72 and 0.45 respectively. DiscussionTMD and NC has good agreement with kappa value of 0.7 and 0.72 respectively. STMD and RHTMD with kappa values of 0.57 and 0.45 (Moderate agreement) shows that they are not good predictors of difficult intubation.

Evaluación del videolaringoscopio Airtraq como dispositivo de rescate tras laringoscopia directa difícil

Background and objectivesUnexpected difficult tracheal intubation and failure to intubate are among the leading causes of anesthesia-related morbidity and mortality. This study was undertaken to evaluate the effectiveness of the Airtraq video laryngoscope for tracheal intubation after difficult direct laryngoscopy. Methods75 patients undergoing elective surgery under general anesthesia and whose direct laryngoscopy by a senior anesthesiologist exhibited Cormack-Lehane grade 2b, 3 or 4 were enrolled. ResultsThe Glottic view was improved in all patients when using the Airtraq video laryngoscope, compared with Macintosh laryngoscope. The view was improved by 2 degrees in 17.3% of the cases, by three in 60% and by four grades in 22.7% (P<0.0001). The success rate for intubation was 100% with the Airtraq. Fifty-six patients (74.7%) required a single attempt, sixteen (21.3%) two attempts and three (4%) a third attempt. Intubation difficulty scale indicated that tracheal intubation was performed easily in most cases There were no critical events. ConclusionsTracheal intubation using the Airtraq was effective, simple and safe in patients with difficult laryngoscopy. These results confirm that the Airtraq is a reliable video laryngoscope as a rescue device in cases of difficult laryngeal view with direct laryngoscopy.

Prediction of difficult direct laryngoscopy

The article considers the interrelation between the detection of underlying factors of difficult intubation and the direct intraoperational laryngoscopy data based on case studies. The authors demonstrate the importance of detailed preoperative examination of the patient for the choice of adequate methods of better visualization of the airway.

Difficult Direct Laryngoscopy Followed by Easy Video Laryngoscopic Intubation in a Patient with Bilateral Mandibular Tori: Should the Patient be Labeled as Having a "Difficult Airway?"

Mandibular tori are intraoral bony prominences which can make direct laryngoscopic intubation difficult. We present a case where we were unable to intubate a patient with bilateral mandibular tori using direct laryngoscopy, but then succeeded using video laryngoscopy. A post-procedure retrospective chart review found previous anesthetics where the patient had also been successfully intubated using video laryngoscopy but the patient was not informed verbally or with a letter that he was difficult to intubate.

Ultrasound measurements as predictors of difficult direct laryngoscopy

Ultrasound measurements as predictors of difficult direct laryngoscopy

In Response

Incomplete Airway Assessment We thank Dr. Nørskov et al1 for their thoughtful comments concerning our editorial.2 We also are grateful for their clarification of methods used for airway assessment in their Danish Anaesthesia Database study.1 Although it is clear that airway evaluation before intervention is a critical step to minimize adverse outcomes, we agree with Nørskov et al1 that there is ample room for improvement in the evaluation tools we have to date. In other words, because unanticipated difficulties in managing the airway will likely continue to occur in our clinical practice, airway practitioners must be equipped with a strategy to manage an unanticipated difficult or failed airway (ie, plan B, plan C).3–5 Recognizing that the survey mentioned in our editorial2 was an informal solicitation of information regarding the airway evaluation section of preanesthetic assessment forms (an image taken from a smartphone), there is potential for bias in our data collection. The countries involved in our survey included Australia, Canada, England, Germany, Italy, the Netherlands, New Zealand, Singapore, Rwanda, and the United States. As summarized in our editorial, the airway assessment section on these forms varied substantially, ranging from descriptive text only to a list of predictors of difficult direct laryngoscopy with Mallampati score, this latter, the most common predictor present on these preanesthetic assessment forms. On the basis of the information collected, we concluded that assessment for difficult direct laryngoscopy remains the main focus of airway assessment at many centers around the globe. The form from our center at Dalhousie University was the only one asking for predicted difficulty in bag-mask ventilation and surgical airway (cricothyrotomy). None of the forms surveyed queried assessment of predicted difficulty in using an extraglottic device, such as a laryngeal mask airway. We agree with Nørskov et al1 that we must find solutions to improve and correct problems related to incomplete airway assessment. In addition to assessing the patient for predicted difficulty with direct or video laryngoscopy, we must stress the importance of assessing difficulties in other methods in oxygenation and ventilation. These include difficulties in bag-mask ventilation, the use of an extraglottic device (eg, a laryngeal mask airway), and front-of-neck access (cricothyrotomy) so that appropriate airway management strategies can be planned before intervention. Adverse patient physiology (eg, full stomach, anticipated intolerance of apnea) with the potential to impact the choice of approach to the airway also must be considered. Orlando Hung, MD, FRCPCJ. Adam Law, MD, FRCPCIan Morris, MD, FRCPCDepartment of Anesthesia, Pain Management andPerioperativeMedicineDalhousie UniversityHalifax, Nova Scotia, Canada[email protected] Michael Murphy, MD, FRCPCDepartment of Anesthesiology and Pain MedicineUniversity of AlbertaEdmonton, Alberta, Canada

First-Attempt Intubation Success of Video Laryngoscopy in Patients With Anticipated Difficult Direct Laryngoscopy

(Abstracted from Anesth Analg, 122:740–750, 2016) Video laryngoscopy helps to facilitate endotracheal intubation and can improve first-attempt success rates. However, although studies have demonstrated better intubation conditions with video laryngoscopy compared with direct laryngoscopy, it is unclear whether such results are generalizable to any type of video laryngoscope (VL) and whether all types of larygnoscopes are interchangeable.

Predictors of difficult videolaryngoscopy with GlideScope® or C-MAC® with D-blade: secondary analysis from a large comparative videolaryngoscopy trial

BackgroundTracheal intubation using acute-angle videolaryngoscopy achieves high success rates, but is not without difficulty. We aimed to determine predictors of ‘difficult videolaryngoscopy’. MethodsWe performed a secondary analysis of a data set (n=1100) gathered from a multicentre prospective randomized controlled trial of patients for whom difficult direct laryngoscopy was anticipated and who were intubated with one of two videolaryngoscopy devices (GlideScope® or C-MAC® with D-blade). ‘Difficult videolaryngoscopy’ was defined as ‘first intubation time >60 s’ or ‘first attempt intubation failure’. A multivariate logistic regression model along with stepwise model selection techniques was performed to determine independent predictors of difficult videolaryngoscopy. ResultsOf 1100 patients, 301 were identified as difficult videolaryngoscopies. By univariate analysis, head and neck position, provider, type of surgery, and mouth opening were associated with difficult videolaryngoscopy (P<0.05). According to the multivariate logistic regression model, characteristics associated with greater risk for difficult videolaryngoscopy were as follows: (i) head and neck position of ‘supine sniffing’ vs ‘supine neutral’ {odds ratio (OR) 1.63, 95% confidence interval (CI) [1.14, 2.31]}; (ii) undergoing otolaryngologic or cardiac surgery vs general surgery (OR 1.89, 95% CI [1.19, 3.01] and OR 6.13, 95% CI [1.85, 20.37], respectively); (iii) intubation performed by an attending anaesthestist vs a supervised resident (OR 1.83, 95% CI [1.14, 2.92]); and (iv) small mouth opening (OR 1.18, 95% CI [1.02, 1.36]). ConclusionThis secondary analysis of an existing data set indicates four covariates associated with difficult acute-angle videolaryngoscopy, of which patient position and provider level are modifiable.

A Comparison of the Mallampati evaluation in neutral or extended cervical spine positions: a retrospective observational study of >80 000 patients

BackgroundThe Mallampati examination is a standard component of an airway risk assessment. Existing evidence suggests that cervical spine extension improves the predictive power of the Mallampati examination for detecting difficult laryngoscopy and tracheal intubation, but a comparative effectiveness study has not been conducted. MethodsThe extended Mallampati examination (EMS) was introduced to the standard preoperative airway assessment, in addition to the standard Modified Mallampati examination (MMP). This study compared the accuracy of both Mallampati examinations on the prediction of difficult laryngoscopy, tracheal intubation, and bag mask ventilation. Univariate and adjusted analyses were performed. Results80 801 patients with recorded MMP and EMS, and subsequent glottic view obtained during direct laryngoscopy, were examined. There was increased specificity (88.7% cf. 81.9%) but reduced sensitivity (33.3% cf. 45.7%) in the detection of difficult direct laryngoscopy with use of the EMS. The area under the receiver operating characteristic curve of each test performed in combination with other airway predictors for the models predicting difficult laryngoscopy was 0.740 (95% CI 0.731–0.753) for MMP and 0.739 (95% CI 0.729–0.752) for EMS. The area under the receiver operating characteristic curve of each test, performed in combination with other airway predictors for the models predicting difficult intubation was 0.699 (95% CI 0.688–0.711) for MMP and 0.695 (95% CI 0.683–0.707) for EMS. ConclusionsThis retrospective observational study demonstrates that cervical extension improves the specificity but decreases sensitivity of Mallampati examination. The Mallampati evaluation should be performed with the cervical spine in the neutral position to maximize test sensitivity.

First-Attempt Intubation Success of Video Laryngoscopy in Patients with Anticipated Difficult Direct Laryngoscopy

Intubation success in patients with predicted difficult airways is improved by video laryngoscopy. In particular, acute-angle video laryngoscopes are now frequently chosen for endotracheal intubation in these patients. However, there is no evidence concerning whether different acute-angle video laryngoscopes can be used interchangeably in this scenario and would allow endotracheal intubation with the same success rate. We therefore tested whether first-attempt intubation success is similar when using a newly introduced acute-angle blade, that is an element of an extended airway management system (C-MAC D-Blade) compared with a well-established acute-angle video laryngoscope (GlideScope). In this large multicentered prospective randomized controlled noninferiority trial, patients requiring general anesthesia for elective surgery and presenting with clinical predictors of difficult laryngoscopy were randomly assigned to intubation using either the C-MAC D-Blade or the GlideScope video laryngoscope. The hypothesis was that first-attempt intubation success using the new device (D-Blade) is no >4% less than the established device (GlideScope), which would determine noninferiority of the new instrument versus the established instrument. The secondary outcomes we observed included intubation success with multiple attempts and airway-related complications within 7 days of enrollment. Eleven hundred patients were randomly assigned to either video laryngoscope. Intubation success rate on first attempt was 96.2% in the GlideScope group and 93.4% in the C-MAC D-Blade group. Although the absolute difference between the 2 groups was only 2.8%, the 90.35% upper confidence limit of the difference exceeded the predefined margin (4.98%), indicating a rejection of the noninferiority hypothesis for first-attempt intubation success. For attending anesthesiologists, and upon multiple attempts, intubation success did not differ between systems. Pharyngeal injury was noted in 1% of the patients, and the incidence did not differ between interventional groups. Head-to-head comparison in this large multicenter trial revealed that the newly introduced C-MAC D-Blade does not yield the same first-attempt intubation success as the GlideScope in patients with predicted difficult laryngoscopy except in the hands of attending anesthesiologists. Additional research would be necessary to identify potential causes for this difference. Intubation success rates were very high with both systems, indicating that acute-angle video laryngoscopy is an exceptionally successful strategy for the initial approach to endotracheal intubation in patients with predicted difficult laryngoscopy.

Difficult tracheal tube insertion

Difficult direct laryngoscopy refers to inability on the part of the laryngoscopist to visualise the larynx because of anatomical abnormality or distortion of the larynx or trachea. There is, however, no mention in the literature of airways that appear to be simple during laryngoscopy and Cormach-Lehane grading , but turn out to be exceedingly difficult when actual insertion is being attempted. We consider that for such cases a new phrase, difficult tracheal tube insertion (DTTI), should be employed. Fortunately cases of DTTI can be managed successfully if smaller-size tubes are used or a malleable guide is introduced into the endotracheal tube prior to its insertion through the glottic opening.

A good laryngeal view does not guarantee perfectly successful tracheal intubation.

Difficult tracheal intubation is the most common factor related to serious airway complications during anesthesia [1]. Difficult tracheal intubation is defined as insertion of the endotracheal tube using direct laryngoscopy that requires more than two attempts lasting more than 10 min each or that requires an alternative technique [2]. The difficult airway involves interactions among patient factors, the clinical setting, and the practitioner's skills [3]. Many alternative tools and techniques have been developed to facilitate intubation in cases of difficult direct laryngoscopy. Among these, videolaryngoscopy (VL) improves glottis visualization using either an optical or video system, which allows communication between the operator and assistants and facilitates teaching; this method is gaining popularity [4]. Recently, VL has begun to be considered as a first-line tool for airway management, rather than as a rescue tool for difficult intubation [3,5,6]. However, VL does not achieve a 100% intubation success rate, and complications have been associated with the procedure [5,7,8]. With VL, the success of intubation lies not in the view obtained, but in the ease of inserting the endotracheal tube. Instead of the Cormack-Lehane scoring system, Swann et al. [9] proposed the Fremantle score, calculated using a three-part scoring system based on the laryngeal view (full, partial, or no view), ease of endotracheal intubation (easy, modified, or unachievable), and device used. The Korean Society of Anesthesiologists should consider the use of this new scoring system and various tools for cases of difficult intubation. In this issue of the Korean Journal of Anesthesiology, Shim et al. [10] compared GlideScope® and McGrath® laryngoscopes in simulated cases of difficult intubation. They used a four-grade videoscopic view. However, they did not precisely describe the grade. In addition, a tube exchanger and vascular forceps were used instead of a rigid stylet, which can be associated with complications [8]. Although a difficult airway was simulated with an extrication collar, actual patients with difficult airways were excluded. In the simulation, the first-attempt success rates were 82.8% (GlideScope® group) and 83.8% (McGrath® group). Failed intubation with the GlideScope® was also reported in this issue of the Korean Journal of Anesthesiology [11]. There was resistance to passage of the endotracheal tube into the larynx with a conventional laryngoscope. The GlideScope® then revealed that a septum divided the subglottic area into two sections. A laryngeal mask did not provide adequate ventilation due to laryngeal edema caused by multiple intubation attempts, and the surgery was postponed. In this case, the patient failed to recall any previous difficulties with anesthesia. The preanesthetic history, chest radiography, and spirometry failed to reveal the patient's tracheal stenosis under the vocal cords. The difficulty grade of direct laryngoscopy was not described; passing the endotracheal tube was impossible due to the unusual trachea. A full view of the larynx was obtained using direct laryngoscopy and the GlideScope®. Considering these two articles, we need to keep in mind that neither the use of VL nor achievement of a laryngeal view guarantees intubation success. Accurately predicting a difficult airway remains as a cornerstone of airway management. Furthermore, considering the recognized associations between a difficult airway and patient characteristics, the patient's medical history may help to predict a difficult airway [3,12]. To avoid airway complications, anesthesiologists should be proficient in the use of a wide range of anesthetic airway techniques and alternative intubation tools and should know how to manage a failed airway, including when and how they will wake the patient in cases of difficulty [1]. In addition, for follow-up care, the anesthesiologist should inform the patient of the airway difficulty that was encountered. A written report that describes the difficult airway, including the apparent reasons for difficulty, how the intubation was finally accomplished, and the implications for future care, is recommended [3]. In conclusion, anesthesiologists should determine a strategy for a difficult intubation. They should assemble a team that can assist one another and make prompt decisions, use the most familiar and skilled tool, and record the findings in detail.

The reflective intubation manoeuvre increases success rate in moderately difficult direct laryngoscopy: A prospective case-control study.

Reflective intubation is a recently described technique to facilitate tracheal intubation. The aim of the study was to assess success rate of reflective intubation in patients undergoing tracheal intubation and to correlate its application with laryngeal visibility. A prospective case-control study. Operating theatre suite of a university hospital. One hundred randomly selected patients undergoing elective surgery who required tracheal intubation as part of standard anaesthesia care. All patients underwent an initial intubation attempt using conventional direct laryngoscopy. Successfully intubated patients formed group E (easy), and the remaining patients underwent a single reflective intubation attempt. Patients with successful reflective intubation formed group M (moderate). The remaining patients underwent tracheal intubation using a suitable alternative intubation technique (group D, difficult). Primary outcomes were the success rate and time to successful intubation. Laryngeal visibility scores, changes in arterial oxygen saturation and incidence of sore throat were secondary outcomes. Forty-six patients underwent successful tracheal intubation using conventional laryngoscopy (group E), 42 patients presented moderate difficulty (group M) and 12 patients required alternative intubation techniques (group D). Reflective intubation was successful in 78% of patients in the 'noneasy' subgroup, but was unsuccessful in 22%. Intubation times were 9 ± 3 (group E), 15 ± 9 (group M) and 46 ± 38 s (group D). Oxygen saturation was comparable in all patients. Sore throat occurred significantly more often in group D. Reflective intubation proved to be successful in moderately difficult intubation conditions (Cormack and Lehane classes 2 and 3a). Reflective intubation represents a very useful first-line methodological extension of direct laryngoscopic tracheal intubation.

New assembled video laryngoscope: a study on efficacy and cost-effectiveness

Video laryngoscopes have been introduced in recent years as an alternative choice to facilitate tracheal intubation. Difficulties with tracheal intubation are mostly caused by difficult direct laryngoscopy with impaired view to the vocal cords. Many endoscopic intubation laryngoscopes have been designed to visualize the vocal cords around the corner looking through a proximal viewfinder. Although they are useful devices, they have limitations for doing direct laryngoscopy and are very expensive, hence they are not used for routine tracheal intubation.

English

Although uncommon, and rarely reported, esophageal perforation has significant medical and legal consequences. Upper aero digestive tract injury can result in severe complications like pneumothorax, pneumonia, retropharyngeal abscess, retrosternal abscess, mediastinitis etc. Such patients have very poor outcome especially if there is a delay in diagnosis and treatment. Our patient sustained a laceration of the upper esophagus associated with subcutaneous emphysema after a difficult direct laryngoscopy and failed intubation. The importance of prompt diagnosis and treatment in the event of this rare complication and the different causative factors are discussed. KEYWORDS: Esophageal laceration, endotracheal Intubation, subcutaneous emphysema. INTRODUCTION: Aero-digestive tract injury during general anesthesia is a significant source of morbidity for patients and a source of liability for anesthesiologists. Karen B. Domino et al 1 analysed the ASA Closed Claims database which showed that most claims for esophageal injuries were for esophageal perforation (n= 43 of 48 esophageal injuries, 90%). Sixty-two percent (n= 30) of all esophageal injuries were associated with difficult intubation (P <0.001 compared with all other sites combined.). In addition, esophageal injuries involved a significantly greater proportion of females (P <0.001) and patients older than 60 yr of age (P<0.001) compared with other sites combined. Esophageal injuries were more severe than all other types of airway injury combined, with 9 (19%)

Use of airtraq optical laryngoscope for naso-tracheal intubation in anaesthetized patients

Reported is a case of successful Nasotracheal intubation using Airtraq optical laryngoscope in a patient of fracture zygomatic arch with cervical spine injury. The patient had predicted difficult direct laryngoscopy with restricted mouth opening.

Defining and developing expertise in tracheal intubation using a GlideScope(®) for anaesthetists with expertise in Macintosh direct laryngoscopy: an in-vivo longitudinal study.

Although videolaryngoscopy can provide excellent views of the laryngeal structures as both the primary method of tracheal intubation and as a rescue technique for difficult direct laryngoscopy, the existing literature is inadequate to define expertise or even competence. We observed the performance of nine trainees during 890 intubations, with an additional 72 intubations performed by expert anaesthetists used as a control group. Univariate and multivariate mixed-effects logistic regression models were applied to detect potential predictors of successful intubation and define the number of intubations necessary for a trainee to achieve expertise (>90% probability of optimal performance). Optimal performance was predicted by single laryngoscope insertion (p<0.001) and a Cormack and Lehane grade-1 view (p<0.001), and not by normal lifting force applied to the device (p=0.15), with expertise reached after 76 attempts. These results indicate that expertise in videolaryngoscopy requires prolonged training and practice.

Elective use of supraglottic airway devices for primary airway management in children with difficult airways

Supraglottic airways (SGAs) have an established role in airway management of difficult airways in both adults and children. However, there are limited data regarding the use of SGAs for primary airway management in children. The aim of this study is to assess the success rates and adverse events related to the use of SGAs for primary airway management during anaesthesia in children with difficult airways. A retrospective analysis of SGA use for primary airway management in the difficult airway population in a single centre over a 4-yr period was performed. Difficult airway was defined as either a history of difficult direct laryngoscopy (a documented Cormack and Lehane Grade 3 or greater and the need for an alternate device to direct laryngoscopy for successful tracheal intubation), a history of difficult mask ventilation, or both. The difficult airway condition, patient characteristic data, type and length of procedure, type and size of SGA placed, number of attempts for successful device placement, success/failure associated with the device during anaesthetic maintenance, and complications were recorded. A total of 77,272 children received general anaesthesia in a free-standing paediatric institution. Four hundred and fifty-nine patients were reported to have a difficult airway. Of those, 109 received general anaesthesia and an SGA for primary management, meeting the inclusion criteria for this study during a 4-yr period. An SGA was successfully used in 96% of these patients. In four patients, an alternative airway was needed. SGAs can be effectively utilized for airway maintenance in the paediatric difficult airway population.

A Comparative Trial of the GlideScope® Video Laryngoscope to Direct Laryngoscope in Children With Difficult Direct Laryngoscopy and an Evaluation of the Effect of Blade Size

Lee, Ji-Hyun; Park, Yong-Hee; Byon, Hyo-Jin; Han, Woong-Ki; Kim, Hee-Soo; Kim, Chong-Sung; Kim, Jin-Tae Author Information