Difficult laryngoscopy made easy with a "BURP"

Preoperative bedside test indicators as predictors of difficult video laryngoscopy in obese patients: a prospective observational study

Purpose

The aim of this study was to identify factors associated with difficult video laryngoscopy in obese patients.

Methods

A total of 579 obese patients undergoing elective laparoscopic weight loss surgery were intubated with a single-lumen endotracheal tube using a video laryngoscopy under general anesthesia, and the patients were divided into two groups based on the Cormack-Lehane classification (difficult video laryngoscopy defined as ≥ 3): the easy video laryngoscopy group and the difficult video laryngoscopy group. Record the general condition of the patient, bedside testing indicators related to the airway, Cormack-Lehane classification during intubation, and intubation failure rate.

Results

The findings of this study show that the incidence of difficult video laryngoscopy in obese patients is 4.8%. Multivariate logistic regression analysis indicated that body mass index was significantly associated with difficult video laryngoscopy (OR = 1.082, 95% CI [1.033-1.132], P < 0.001).

Conclusion

For Chinese obese patients without known difficult airways, the incidence of difficult video laryngoscopy is 4.8%. Body mass index is associated factors for the occurrence of difficult video laryngoscopy, with an increased risk observed as body mass index rise.

To compare the efficacy of the between-the-fingers grip with the conventional pen-holding grip to hold an endotracheal tube for orotracheal intubation: A randomised controlled trial

Background and Aims

Correctly holding the endotracheal tube (ETT) is essential for successful tracheal intubation. The study's primary objective was to compare the between-the-fingers grip with the conventional pen-holding grip regarding the number of attempts required for orotracheal intubation and usage of external aids.

Methods

Three hundred patients undergoing elective surgeries under general anaesthesia were randomised according to the method to hold the ETT to Group C (conventional grip) and Group M (modified, between-the-fingers grip) during oro-tracheal intubation. A designated anaesthetist blinded to the groups performed laryngoscopy in all the patients, and difficult Cormack-Lehane grade 3b and 4 (n = 24) were excluded. Then, the group was revealed to the anaesthetist, and intubation was done accordingly; the number of attempts, use of backward upward rightward pressure (BURP), and time taken were noted. The sample size was estimated using the software G*Power version 3.1.9.2. Statistical Package for Social Sciences, version 23 (SPSS-23, IBM, Chicago, USA) was used for data analysis.

Results

Single-attempt intubation was comparable between the groups (99.3% versus 97.2%, P = 0.197). In contrast, the external assistance as BURP (0.75% versus 6.99%, P = 0.009) and the time taken for intubation (P = 0.008) were reduced in group M significantly.

Conclusion

The between-the-fingers grip seems as effective as the standard grip to hold the ETT during intubation. However, it proved to be better as it can reduce the requirement for external assistance in BURP.

The effect of mandibular advancement for mandibular deficiency dentofacial deformities on laryngeal grade and intubation difficulty: a preliminary study

OBJECTIVE

The purpose of this study was to evaluate mandibular advancement for cases of mandibular deficiency with changes in vocal cord grade and intubation difficulty at subsequent surgery requiring intubation.

STUDY DESIGN

This retrospective case series included patients with a diagnosis of mandibular deficiency (Class II skeletal dentofacial deformity) who underwent mandibular advancement surgery (T1) followed by a subsequent surgery (T2) which required intubation. The primary predictor variable was mandibular advancement. The primary outcome variable was the change in laryngeal grade-Cormack and Lehane-after mandibular advancement. A secondary outcome was intubation difficulty after mandibular advancement.

RESULTS

Eight patients were included in the study. At T1, the average laryngeal grade was 1.6. There was 1 difficult intubation. The average time to T2 was 9 months. At T2, all patients were intubated on their first attempt, and all had a Cormack-Lehane Grade I view of the vocal cords. There were no difficult intubations at T2. Analysis showed a significant association between mandibular advancement and laryngeal grade at T2 (P = .03; 95% CI 0.07-1.13).

CONCLUSIONS

This preliminary investigation found an association between mandibular advancement for cases of mandibular and improved laryngeal grade at subsequent intubation without any difficult intubations.

Change in glottic view during intubation using a KoMAC videolaryngoscope: A retrospective analysis

Intubation with videolaryngoscopy has become popular in various clinical settings. However, despite the use of a videolaryngoscope, difficult intubation still exists and intubation failure has been reported. This retrospective study assessed the efficacy of the 2 maneuvers in improving the glottic view during videolaryngoscopic intubation. The medical records of patients who underwent videolaryngoscopic intubation and whose glottal images were stored in electronic medical charts were reviewed. The videolaryngoscopic images were divided into 3 categories according to the applied optimization techniques as follows: conventional method, with the blade tip located in the vallecular; backward-upward-rightward pressure (BURP) maneuver; and epiglottis lifting maneuver. Four independent anesthesiologists scored the visualization of the vocal folds using the percentage of glottic opening (POGO, 0-100%) scoring system. A total of 128 patients with 3 laryngeal images were analyzed. The glottic view was the most improved in the epiglottis lifting maneuver among all the techniques. The median POGO scores were 11.3, 36.9, and 63.1 in the conventional method, BURP, and epiglottis lifting maneuver, respectively (P < .001). There were significant differences in the distribution of POGO grades according to the application of BURP and epiglottis lifting maneuvers. In the POGO grades 3 and 4 subgroups, the epiglottis lifting maneuver was more effective than the BURP maneuver in improving the POGO score Inadequate visualization of the vocal folds occurred even when intubation was performed using a videolaryngoscope. The application of optimization maneuvers, such as BURP and epiglottis lifting by the blade tip, could improve the glottic view.

Cricoid Pressure: Contradictory Evidence Regarding a Standard Practice

The purpose of applying cricoid pressure is to prevent pulmonary aspiration of regurgitated gastric contents during airway management in mask-ventilated patients who are at risk of aspiration. Providers may apply cricoid pressure during induction and intubation if they expect a difficult intubation or if the patient has a high risk for regurgitation. Although the application of cricoid pressure has been accepted as a standard practice worldwide, controversy persists because pulmonary aspiration can occur even when cricoid pressure is applied. The perioperative nurse should have thorough knowledge of the anatomy of the upper respiratory and gastrointestinal tracts, be able to demarcate the surface landmarks of the neck, and be skilled in applying cricoid pressure properly and safely. This article discusses cricoid pressure in the context of safe airway management as well as the perioperative nurse's role as an assistant to the anesthesia professional when applying cricoid pressure.

The effects of backward, upward, rightward pressure maneuver for intubation using the OptiscopeTM: a retrospective study

BACKGROUND

The OptiscopeTM and the backward, upward, rightward pressure (BURP) maneuver are widely used in clinical practice because the BURP maneuver facilitates intubation by improving visualization of the larynx. However, the effect of the BURP maneuver is unclear when using the OptiscopeTM. Therefore, we retrospectively investigated the effect of the BURP maneuver on intubation using the OptiscopeTM.

METHODS

Sixty-eight patients intubated with the OptiscopeTM were enrolled. We used the BURP maneuver in Group A (n = 33) and the conventional maneuver (which does not use the BURP maneuver) in Group B (n = 35). BURP application status was a binary variable representing whether the BURP maneuver was used during the intubation. A multiple linear regression analysis was performed to assess the effects of the BURP application status on intubation time controlling for body mass index, preoperative dental injury status, obstructive sleep apnea history, thyromental distance, sternomental distance, interincisor distance, history of neck rotation restriction, and Mallampati classification.

RESULTS

There was no difference in the intubation time between the two groups. According to the regression model (R2 = 0.308, P = 0.007), the BURP maneuver (Group A) decreased the intubation time by 6.089 seconds (95% confidence interval 1.303-10.875, P = 0.014) compared to Group B.

Laryngoscopic view after application of manual in-line stabilization – A comparison with early morning sniffing position in the same patient

Background:

The application of manual in-line stabilization (MILS) for minimizing spinal cord injury is known to increase difficulty in airway management.

Aim:

The study aims to assess the change in Modified Cormack–Lehane (CL) laryngoscopic view with the application of MILS from the early morning sniffing position (EMSP) in adult patients.

Setting and Design:

This was a prospective, interventional, self-controlled study conducted on 220 patients aged 18–65 years, belonging to the American Society of Anesthesiologists Physical Status Class I or II, having a normal airway, and scheduled for elective surgery under general anesthesia.

Materials and Methods:

After inducing general anesthesia, MILS was applied to the patient's neck, and a Modified CL view of the vocal cords was recorded under direct laryngoscopy. The view was again noted after applying backward-upward-rightward pressure (BURP). MILS and BURP were released. The view was obtained again with and without BURP in EMSP.

Statistical Analysis:

Normality of data was tested by Kolmogorov–Smirnov test. Wilcoxon ranked-sum test for quantitative variables and Chi-square test for qualitative variables were used.

Results:

On application of MILS, the majority of patients had Modified CL Grade 3a (121 patients) and 3b (53 patients) views. The majority of patients had Modified CL Grade 1 (114 patients) and 2a (71 patients) views on placing in EMSP. These findings were statistically significant (P < 0.0001). Consequent to the placement of BURP upon MILS, patients with lower CL Grade views (2b: 101 patients) were significantly higher (P < 0.0001) in comparison with MILS alone.

Conclusion:

In patients with a normal airway, MILS leads to a significantly greater incidence of higher grades of laryngoscopic views in comparison to EMSP. Use of BURP after MILS causes significantly less incidence of higher grades of laryngoscopic view when compared with MILS alone. All patients requiring MILS should be considered to be a difficult airway, and hence, preparation should be done accordingly.

Creation of an artificial intelligence model for intubation difficulty classification by deep learning (convolutional neural network) using face images: an observational study

Background

Tracheal intubation is the gold standard for securing the airway, and it is not uncommon to encounter intubation difficulties in intensive care units and emergency rooms. Currently, there is a need for an objective measure to assess intubation difficulties in emergency situations by physicians, residents, and paramedics who are unfamiliar with tracheal intubation. Artificial intelligence (AI) is currently used in medical imaging owing to advanced performance. We aimed to create an AI model to classify intubation difficulties from the patient’s facial image using a convolutional neural network (CNN), which links the facial image with the actual difficulty of intubation.

Methods

Patients scheduled for surgery at Yamagata University Hospital between April and August 2020 were enrolled. Patients who underwent surgery with altered facial appearance, surgery with altered range of motion in the neck, or intubation performed by a physician with less than 3 years of anesthesia experience were excluded. Sixteen different facial images were obtained from the patients since the day after surgery. All images were judged as “Easy”/“Difficult” by an anesthesiologist, and an AI classification model was created using deep learning by linking the patient’s facial image and the intubation difficulty. Receiver operating characteristic curves of actual intubation difficulty and AI model were developed, and sensitivity, specificity, and area under the curve (AUC) were calculated; median AUC was used as the result. Class activation heat maps were used to visualize how the AI model classifies intubation difficulties.

Results

The best AI model for classifying intubation difficulties from 16 different images was generated in the supine-side-closed mouth-base position. The accuracy was 80.5%; sensitivity, 81.8%; specificity, 83.3%; AUC, 0.864; and 95% confidence interval, [0.731-0.969], indicating that the class activation heat map was concentrated around the neck regardless of the background; the AI model recognized facial contours and identified intubation difficulties.

Conclusion

This is the first study to apply deep learning (CNN) to classify intubation difficulties using an AI model. We could create an AI model with an AUC of 0.864. Our AI model may be useful for tracheal intubation performed by inexperienced medical staff in emergency situations or under general anesthesia.

Clinical Issues-May 2021

Surgical technologists inserting urinary catheters Key words: surgical technologist (ST), urinary catheter insertion, catheter-associated urinary tract infection (CAUTI), task delegation, competency. Assisting the anesthesia professionals with cricoid pressure Key words: cricoid pressure, Sellick maneuver, airway, induction, aspiration. Perioperative care of the patient with a corn food allergy Key words: corn allergy, dextrose, anaphylaxis, derivatives, food allergy.

Difficult airway predictors were associated with decreased use of neuromuscular blocking agents in emergency airway management: a retrospective cohort study in Thailand

Background

It is recommended that difficult airway predictors be evaluated before emergency airway management. However, little is known about how patients with difficult airway predictors are managed in emergency departments. We aimed to explore the incidence, management and outcomes of patients with difficult airway predictors in an emergency department.

Methods

We conducted a retrospective study using intubation data collected by a prospective registry in an academic emergency department from November 2017 to October 2018. Records with complete assessment of difficult airway predictors were included. Two categories of predictors were analyzed: predicted difficult intubation by direct laryngoscopy and predicted difficult bag-mask ventilation. The former was evaluated based on difficult external appearance, mouth opening and thyromental distance, Mallampati score, obstruction, and limited neck mobility as in the mnemonic “LEMON”. The latter was evaluated based on difficult mask sealing, obstruction or obesity, absence of teeth, advanced age and reduced pulmonary compliance as in the mnemonic “MOANS”. The incidence, management and outcomes of patients with these difficult airway predictors were explored.

Results

During the study period, 220 records met the inclusion criteria. At least 1 difficult airway predictor was present in 183 (83.2%) patients; 57 (25.9%) patients had at least one LEMON feature, and 178 (80.9%) had at least one MOANS feature. Among patients with at least one difficult airway predictor, both sedation and neuromuscular blocking agents were used in 105 (57.4%) encounters, only sedation was used in 65 (35.5%) encounters, and no medication was administered in 13 (7.1%) encounters. First-pass success was accomplished in 136 (74.3%) of the patients. Compared with patients without predictors, patients with positive LEMON criteria were less likely to receive neuromuscular blocking agents (OR 0.46 (95% CI 0.24–0.87), p = 0.02) after adjusting for operator experience and device used. There were no significant differences between the two groups regarding glottic view, first-pass success, or complications. The LEMON criteria poorly predicted unsuccessful first pass and glottic view.

Conclusions

In emergency airway management, difficult airway predictors were associated with decreased use of neuromuscular blocking agents but were not associated with glottic view, first-pass success, or complications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12873-021-00434-2.

Evaluation of the relationship between airway measurements with ultrasonography and laryngoscopy in newborns and infants

BACKGROUND

A difficult laryngoscopy in young children can be a stressful situation for the pediatric anesthetist. In recent years, several measurements have been used to obtain difficult laryngoscopy markers in children. However, there is no prospective study in which ultrasonography is expected to be used for this purpose, particularly in the newborn and infant age groups.

GOALS

In this study, our goal was to evaluate the relationship between the preoperative airway assessment tools and the difficult laryngoscopic view in neonates and infants.

METHODS

Our study included newborns and infants undergoing elective surgery requiring intubation under general anesthesia. The following measurements were recorded the following: patients' age, body mass index, thyromental distance, mandibular length, the distance between the lip corner and ipsilateral ear tragus, and the transverse length (measured by hand with sign-middle-ring fingers side by side). In the thyromental distance measurement, the "thyroid notch" was determined by ultrasonography. Glottic structures appearing during laryngoscopy were graded according to the Cormack-Lehane Classification.

RESULTS

Of the 150 patients included in the study, 36 were female, and 92% were under the age of one. The incidence of difficult laryngoscopic views was 8% in the age groups studied, and the frequency of difficult laryngoscopic views in the newborn age group was 14.3%. The relationship between airway assessment tools and the Cormack-Lehane Classification scores was statistically significant. The negative predictive value was high for all values.

CONCLUSIONS

The risk of a difficult laryngoscopy increases in children under the age of one. The preoperative airway assessment tools and body mass index had acceptable negative predictive values. We believe that all measurements could be used as markers for difficult laryngoscopy in newborns and infants.

The "BURP" maneuver improves the glottic view during laryngoscopy but remains a difficult procedure

Objective

We investigated the “BURP” maneuver’s effect on the association between difficult laryngoscopy and difficult intubation, and predictors of a difficult airway.

Methods

Adult patients who underwent general anesthesia and tracheal intubation from September 2016 to May 2018 were included. The “BURP” maneuver was performed when glottic exposure was classified as Cormack–Lehane grade 3 or 4, suggesting difficult laryngoscopy. The thyromental distance, modified Mallampati score, and interincisor distance were assessed before anesthesia.

Results

Among this study’s 2028 patients, the “BURP” maneuver decreased difficult laryngoscopies from 428 (21.1%) to 124 (6.1%) cases and increased the difficult intubation to difficult laryngoscopy ratio from 53/428 (12.4%) to 52/124 (41.9%). For laryngoscopies classified as difficult without the “BURP” maneuver, the area under the curve (AUC) of the thyromental distance, modified Mallampati score, and interincisor distance was 0.60, 0.57, and 0.66, respectively. In difficult laryngoscopies using the “BURP” maneuver, the AUC of the thyromental distance, modified Mallampati score, and interincisor distance was 0.71, 0.67, and 0.76, respectively.

Conclusions

The “BURP” maneuver improves the laryngoscopic view and assists in difficult laryngoscopies. Compared with difficult laryngoscopies without the “BURP” maneuver, those with the “BURP” maneuver are more closely associated with difficult intubations and are more predictable.

Trial registration:www.chictr.org.cn identifier: ChiCTR-ROC- 16009050.

Comparison of a Novel Cadaver Model (Fix for Life) With the Formalin-Fixed Cadaver and Manikin Model for Suitability and Realism in Airway Management Training

BACKGROUND

Manikins are widely used in airway management training; however, simulation of realism and interpatient variability remains a challenge. We investigated whether cadavers embalmed with the novel Fix for Life (F4L) embalmment method are a suitable and realistic model for teaching 3 basic airway skills: facemask ventilation, tracheal intubation, and laryngeal mask insertion compared to a manikin (SimMan 3G) and formalin-fixed cadavers.

METHODS

Thirty anesthesiologists and experienced residents ("operators") were instructed to perform the 3 airway techniques in 10 F4L, 10 formalin-fixed cadavers, and 1 manikin. The order of the model type was randomized per operator. Primary outcomes were the operators' ranking of each model type as a teaching model (total rank), ranking of the model types per technique, and an operator's average verbal rating score for suitability and realism of learning the technique on the model. Secondary outcomes were the percentages of successfully performed procedures per technique and per model (success rates in completing the respective airway maneuvers). For each of the airway techniques, the Friedman analysis of variance was used to compare the 3 models on mean operator ranking and mean verbal rating scores.

RESULTS

Twenty-seven of 30 operators (90%) performed all airway techniques on all of the available models, whereas 3 operators performed the majority but not all of the airway maneuvers on all models for logistical reasons. The total number of attempts for each technique was 30 on the manikin, 292 in the F4L, and 282 on the formalin-fixed cadavers. The operators' median total ranking of each model type as a teaching model was 1 for F4L, 2 for the manikin and, 3 for the formalin-fixed cadavers (P < .001). F4L was considered the best model for mask ventilation (P = .029) and had a higher mean verbal rating score for realism in laryngeal mask airway insertion (P = .043). The F4L and manikin did not differ significantly in other scores for suitability and realism. The formalin-fixed cadaver was ranked last and received lowest scores in all procedures (all P < .001). Success rates of the procedures were highest in the manikin.

CONCLUSIONS

F4L cadavers were ranked highest for mask ventilation and were considered the most realistic model for training laryngeal mask insertion. Formalin-fixed cadavers are inappropriate for airway management training.

Comparing the Ease of Mask Ventilation, Laryngoscopy, and Intubation in Supine and Lateral Position in Infants with Meningomyelocele

Background

The biggest anesthetic challenge in infants with thoracolumbar /sacral meningomyelocele is securing the airway. For securing the airway, most of the anesthesiologist's practices supine position with doughnut or head ring placed around the swelling to prevent rupture, which has got disadvantages like risk of rupture, infection and damage to neural structure. Left lateral position has been recommended previously for tracheal intubation in post-tonsillectomy hemorrhage. Several studies have shown successful ventilation in lateral position using laryngeal mask airway and intubation using video laryngoscopes.

Aims and Objectives

Primary objective is to compare the time taken for intubation, number of attempts required for intubation. Secondary objective is to compare ease of mask ventilation, Cormack Lehane grading and Backwards Upward Rightwards Pressure [BURP] manoeuvre.

Materials and Methods

A comparative, prospective randomized, controlled trial of 60 infants undergoing thoracolumbar/sacral meningomylocele repair. Infants were allocated to one of two groups of 30 patients each, by computer-generated randomization into Group S: mask ventilation, laryngoscopy and intubation in supine position and Group L: mask ventilation, laryngoscopy and intubation in lateral position.

Statistical Methods

Chi-square/Fisher Exact test was used to find the significance of study parameters on categorical scale between two or more groups.

Results

Mean intubation time of sixteen seconds were clinically acceptable and comparable in each of the two positions P = 0.145. Ten patients in the left lateral position, eight patients in the supine position required second intubation attempts before the airway was secured. Only 8.3% of our patients required third intubation attempts.

Conclusion

Anesthesiologist should pay more attention to the safety and quality of mask ventilation, laryngoscopy and intubation in meningomylocele infants. Both supine and lateral position were comparable.

Reliability of the thyromental height test for prediction of difficult visualisation of the larynx: A prospective external validation

Background and Aims:

Thyromental height (TMH) has been reported to be useful for prediction of difficult visualisation of the larynx (DVL), defined as Cormack--Lehane (C&L) grade III or IV. The aim of this study was to compare the diagnostic accuracy of the TMH test for DVL with that of other clinically used tests in Japanese patients.

Methods:

Six hundred and nine surgical patients undergoing endotracheal intubation under general anaesthesia were enrolled in this prospective observational study. TMH, thyromental distance (TMD), and Samsoon and Young's modified Mallampati (MMT) tests were performed in all patients. The C&L grades for the laryngoscopic view with and without external backward, upward, rightward pressure (BURP) were determined by designated airway assessors. The cutoff value for the TMH test was calculated using receiver-operating characteristic (ROC) curve analysis. The sensitivity, specificity, positive predictive value, accuracy, positive likelihood ratio, and area under the ROC curve (AUROC) for each predictive test were calculated and compared.

Results:

ROC curve analysis indicated that 54 mm is the optimal cutoff value for the TMH test. However, both this value and the conventional cutoff value of 50 mm, which has been reported as having good diagnostic accuracy in the literature, had poor diagnostic accuracy. The AUROC for the TMH test was 0.631 without BURP and 0.592 with BURP; these values were not superior to those for the TMD test or MMT.

Conclusion:

The TMH test is not a good predictor of DVL in Japanese patients.

Do Difficult Airway Techniques Predispose Obese Patients to Bronchospasm?

Objective

The existing evidence separately correlates morbid obesity with difficult intubation and bronchospasm. However, there is a lack of data on whether anaesthesia provider manipulations during difficult intubation contribute to an increased ratio of bronchospasm in these patients.

Methods

This is a retrospective analysis of data prospectively taken from 50 morbidly obese patients involved in a previously published study. A possible difficult intubation was preoperatively investigated by recording the following specific physical examination indices: Mallampati and Cormack-Lehane (CL) classifications, cervical spine mobility (CSM), thyromental distance (Td) and patients' ability to open their mouth (mouth opening). Bronchospasm was clinically detected by auscultation and confirmed by measuring peak airway pressures during mechanical ventilation. The Kruskal-Wallis H test was used for data analysis, followed by the Mann-Whitney U test as applicable.

Results

Different physical examination prognostic indices, including Mallampati and CL scales (p<0.001; the CSM excluded -p=0.790), showed that they are related to difficult intubation. Bronchospasm not attributable to difficult intubation was observed in six obese patients.

Conclusion

Patients with morbid obesity constitute an increased relative risk group as far as difficult intubation is concerned, particularly if preoperative findings support a relationship between the two variables examined. In our study, difficult intubation and the concomitant use of special equipment and manipulations did not contribute to an increased rate of bronchospasm in obese patients, but in view of the lack of data, a large number of more sophisticated studies are required to elucidate such an assumption.

Correlation of Neck Circumference with Difficult Mask Ventilation and Difficult Laryngoscopy in Morbidly Obese Patients: an Observational Study

PURPOSE

Mask ventilation and laryngoscopy can be challenging in morbidly obese patients because of excessive fat tissue. There are studies suggesting that neck circumference is associated with difficult mask ventilation, difficult laryngoscopy, and difficult intubation. The primary aim of our study is to evaluate predictive value of neck circumference for difficult mask ventilation and difficult laryngoscopy in female and male morbidly obese patients separately.

METHODS

This observational cross-sectional study was performed in the period between March 2015 and December 2015. One hundred and twenty (37 male and 83 female) patients undergoing elective surgery were included. Neck circumference, BMI, Mallampati scores, neck movements, dentition, upper lip bite test, breast, thorax, waist, hip circumferences, mouth opening, and sternomental and thyromental distances were evaluated preoperatively. Mask ventilation was graded using four-grade classification. Laryngoscopy was evaluated by Cormack Lehane score.

RESULTS

The incidence of difficult mask ventilation was 13.5% in male and 3.6% in female patients. Mouth opening ≤ 6.5 cm and inadequate flexion were found as significant predictors for difficult mask ventilation in male patients. The incidence of difficult laryngoscopy was 10.8% in male and 4.8% in female patients. Mallampati score > II was found as a significant predictor for difficult laryngoscopy in both male and female patients. Sternomental distance ≤ 16 cm and inadequate flexion were also significant predictors for difficult laryngoscopy in male patients. Neck circumference was not found statistically significant predictor for difficult mask ventilation and laryngoscopy in morbidly obese patients in our study.

CONCLUSION

Neck circumference is not a statistically significant predictor for difficult mask ventilation and laryngoscopy in morbidly Turkish obese male and female patients.

CLINICAL TRIALS REGISTRATION NUMBER

NCT02589015.

The Addition of a Head Rotation When the Ramped Position Fails to Provide Good Laryngeal Visualization: A Preliminary Study

Although several studies have reported that the ramped position (torso and head elevated) significantly improves laryngoscopic view, in our experience, the ramped position fails to provide good laryngeal visualization in some cases. When the ramped position failed to provide good laryngeal visualization, we added a head rotation in order to improve laryngeal visualization in 62 patients. The method significantly improved laryngeal visualization and did not cause laryngeal disturbances postoperatively.

Clinical Impact of External Laryngeal Manipulation During Laryngoscopy on Tracheal Intubation Success in Critically Ill Children

OBJECTIVES

External laryngeal manipulation is a commonly used maneuver to improve visualization of the glottis during tracheal intubation in children. However, the effectiveness to improve tracheal intubation attempt success rate in the nonanesthesia setting is not clear. The study objective was to evaluate the association between external laryngeal manipulation use and initial tracheal intubation attempt success in PICUs.

DESIGN

A retrospective observational study using a multicenter emergency airway quality improvement registry.

SETTING

Thirty-five PICUs within general and children's hospitals (29 in the United States, three in Canada, one in Japan, one in Singapore, and one in New Zealand).

PATIENTS

Critically ill children (< 18 years) undergoing initial tracheal intubation with direct laryngoscopy in PICUs between July 1, 2010, and December 31, 2015.

MEASUREMENTS AND MAIN RESULTS

Propensity score-matched analysis was performed to evaluate the association between external laryngeal manipulation and initial attempt success while adjusting for underlying differences in patient and clinical care factors: age, obesity, tracheal intubation indications, difficult airway features, provider training level, and neuromuscular blockade use. External laryngeal manipulation was defined as any external force to the neck during laryngoscopy. Of the 7,825 tracheal intubations, the initial tracheal intubation attempt was successful in 1,935/3,274 intubations (59%) with external laryngeal manipulation and 3,086/4,551 (68%) without external laryngeal manipulation (unadjusted odds ratio, 0.69; 95% CI, 0.62-0.75; p < 0.001). In propensity score-matched analysis, external laryngeal manipulation remained associated with lower initial tracheal intubation attempt success (adjusted odds ratio, 0.93; 95% CI, 0.90-0.95; p < 0.001).

CONCLUSIONS

External laryngeal manipulation during direct laryngoscopy was associated with lower initial tracheal intubation attempt success in critically ill children, even after adjusting for underlying differences in patient factors and provider levels. The indiscriminate use of external laryngeal manipulation cannot be recommended.

Cricoid Pressure Controversies

Since cricoid pressure was introduced into clinical practice, controversial issues have arisen, including necessity, effectiveness in preventing aspiration, quantifying the cricoid force, and its reliability in certain clinical entities and in the presence of gastric tubes. Cricoid pressure–associated complications have also been alleged, such as airway obstruction leading to interference with manual ventilation, laryngeal visualization, tracheal intubation, placement of supraglottic devices, and relaxation of the lower esophageal sphincter. This review synthesizes available information to identify, address, and attempt to resolve the controversies related to cricoid pressure. The effective use of cricoid pressure requires that the applied force is sufficient to occlude the esophageal entrance while avoiding airway-related complications. Most of these complications are caused by excessive or inadequate force or by misapplication of cricoid pressure. Because a simple-to-use and reliable cricoid pressure device is not commercially available, regular training of personnel, using technology-enhanced cricoid pressure simulation, is required. The current status of cricoid pressure and objectives for future cricoid pressure–related research are also discussed.

All India Difficult Airway Association 2016 guidelines for the management of unanticipated difficult tracheal intubation in adults

The All India Difficult Airway Association (AIDAA) guidelines for management of the unanticipated difficult airway in adults provide a structured, stepwise approach to manage unanticipated difficulty during tracheal intubation in adults. They have been developed based on the available evidence; wherever robust evidence was lacking, or to suit the needs and situation in India, recommendations were arrived at by consensus opinion of airway experts, incorporating the responses to a questionnaire sent to members of the AIDAA and the Indian Society of Anaesthesiologists. We recommend optimum pre-oxygenation and nasal insufflation of 15 L/min oxygen during apnoea in all patients, and calling for help if the initial attempt at intubation is unsuccessful. Transnasal humidified rapid insufflations of oxygen at 70 L/min (transnasal humidified rapid insufflation ventilatory exchange) should be used when available. We recommend no more than three attempts at tracheal intubation and two attempts at supraglottic airway device (SAD) insertion if intubation fails, provided oxygen saturation remains ≥ 95%. Intubation should be confirmed by capnography. Blind tracheal intubation through the SAD is not recommended. If SAD insertion fails, one final attempt at mask ventilation should be tried after ensuring neuromuscular blockade using the optimal technique for mask ventilation. Failure to intubate the trachea as well as an inability to ventilate the lungs by face mask and SAD constitutes 'complete ventilation failure', and emergency cricothyroidotomy should be performed. Patient counselling, documentation and standard reporting of the airway difficulty using a 'difficult airway alert form' must be done. In addition, the AIDAA provides suggestions for the contents of a difficult airway cart.

Airway management: the difficult airway

Maintenance of a patent airway to allow ventilation with high concentration oxygen is an essential procedure during the resuscitation of all trauma patients. A range of equipment is available to help achieve and maintain a clear airway, with endotracheal intubation remaining the gold standard. However, in trauma patients attempts at intubation are often impeded by the presence of associated injuries and the application of devices to immobilize the cervical spine. In the situation of ‘can’t ventilate, can’t intubate’ a surgical airway can be life-saving while expert help is sought. Recently, new devices, in particular the laryngeal mask airway and Combitube®, have gained recognition as having a role in difficult airway management when other methods have failed, thereby reducing the need for surgical intervention. This paper presents an overview of the currently accepted methodology of managing the difficult airway in the trauma patient.

A comparison between the GlideScope® classic and GlideScope® direct video laryngoscopes and direct laryngoscopy for nasotracheal intubation

DESIGN

Prospective, randomized, clinical trial.

SETTING

University hospital operation room.

PATIENTS

104 patients scheduled for elective dental or maxillofacial surgery were randomized to two groups: GlideScope® classic (GSc) and GlideScope® direct (GSd).

INTERVENTIONS

We compared the video laryngoscopes GSc and GSd with each other and with direct laryngoscopy (DL) for nasotracheal intubation with regard to visualization of the glottis, intubation success rate, and required time for and ease of intubation. The aim of the study was to determine whether the use of the video monitor alone reduced the difficulty of nasotracheal intubation, and also to investigate whether the GSc, with its blade designed for difficult airways, had an additional advantage over the video-assisted Macintosh blade (GSd). In both groups the investigators first performed laryngoscopy using the GSd blade, first with the monitor concealed and then with it visible. In the GSd group the tube was then inserted into the trachea with the video monitor screen visible. In the GSc group, the GSd blade was exchanged for the GSc blade, which was then used when inserting the tube with the screen visible.

RESULTS

The success rates and the times required for the video-assisted nasotracheal intubation did not differ significantly between the groups. A better view was obtained more often in the GSc group. In both groups there was a significant difference between direct laryngoscopy and the video-assisted intubation technique. Overall, using the video monitor improved the C-L scores by one grade in 52% and by two grades in 11% of the patients.

CONCLUSIONS

Video laryngoscopes increase the ease of nasotracheal intubation. The GSc blade might provide a better view of the laryngeal structures in case of a difficult airway than the GSd blade. Video laryngoscopy per se gives a better view of the glottis than direct laryngoscopy.

Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics

The Obstetric Anaesthetists' Association and Difficult Airway Society have developed the first national obstetric guidelines for the safe management of difficult and failed tracheal intubation during general anaesthesia. They comprise four algorithms and two tables. A master algorithm provides an overview. Algorithm 1 gives a framework on how to optimise a safe general anaesthetic technique in the obstetric patient, and emphasises: planning and multidisciplinary communication; how to prevent the rapid oxygen desaturation seen in pregnant women by advocating nasal oxygenation and mask ventilation immediately after induction; limiting intubation attempts to two; and consideration of early release of cricoid pressure if difficulties are encountered. Algorithm 2 summarises the management after declaring failed tracheal intubation with clear decision points, and encourages early insertion of a (preferably second-generation) supraglottic airway device if appropriate. Algorithm 3 covers the management of the 'can't intubate, can't oxygenate' situation and emergency front-of-neck airway access, including the necessity for timely perimortem caesarean section if maternal oxygenation cannot be achieved. Table 1 gives a structure for assessing the individual factors relevant in the decision to awaken or proceed should intubation fail, which include: urgency related to maternal or fetal factors; seniority of the anaesthetist; obesity of the patient; surgical complexity; aspiration risk; potential difficulty with provision of alternative anaesthesia; and post-induction airway device and airway patency. This decision should be considered by the team in advance of performing a general anaesthetic to make a provisional plan should failed intubation occur. The table is also intended to be used as a teaching tool to facilitate discussion and learning regarding the complex nature of decision-making when faced with a failed intubation. Table 2 gives practical considerations of how to awaken or proceed with surgery. The background paper covers recommendations on drugs, new equipment, teaching and training.

Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults

These guidelines provide a strategy to manage unanticipated difficulty with tracheal intubation. They are founded on published evidence. Where evidence is lacking, they have been directed by feedback from members of the Difficult Airway Society and based on expert opinion. These guidelines have been informed by advances in the understanding of crisis management; they emphasize the recognition and declaration of difficulty during airway management. A simplified, single algorithm now covers unanticipated difficulties in both routine intubation and rapid sequence induction. Planning for failed intubation should form part of the pre-induction briefing, particularly for urgent surgery. Emphasis is placed on assessment, preparation, positioning, preoxygenation, maintenance of oxygenation, and minimizing trauma from airway interventions. It is recommended that the number of airway interventions are limited, and blind techniques using a bougie or through supraglottic airway devices have been superseded by video- or fibre-optically guided intubation. If tracheal intubation fails, supraglottic airway devices are recommended to provide a route for oxygenation while reviewing how to proceed. Second-generation devices have advantages and are recommended. When both tracheal intubation and supraglottic airway device insertion have failed, waking the patient is the default option. If at this stage, face-mask oxygenation is impossible in the presence of muscle relaxation, cricothyroidotomy should follow immediately. Scalpel cricothyroidotomy is recommended as the preferred rescue technique and should be practised by all anaesthetists. The plans outlined are designed to be simple and easy to follow. They should be regularly rehearsed and made familiar to the whole theatre team.

Perioperative management of 19 infants undergoing glossopexy (tongue-lip adhesion) procedure: a retrospective study

BACKGROUND

Glossopexy (tongue-lip adhesion) is a procedure in which the tongue is anchored to the lower lip and mandible to relieve the upper airway obstruction mainly in infants with Pierre Robin sequence. Infants suffering from severe upper airway obstruction and feeding difficulties due to glossoptosis are the candidates for this procedure and are predicted to demonstrate difficult airway and difficult intubation.

METHODS

We retrospectively examined the perioperative management of 19 infants undergoing glossopexy procedure at our institution from 1992 to 2010.

RESULTS

Out of 19 patients, Pierre Robin sequence was diagnosed in 17, Treacher Collins syndrome in 1, and Stickler syndrome in 1. In all of them, inhalation anesthesia was induced with a nasopharyngeal tube in place. Nine patients underwent fiberoptic intubation. After surgery, 12 patients were extubated in the operating room and 11 of them required a nasopharyngeal tube to keep the airway open. Seven patients left the operating room with the trachea intubated. Two patients received tracheostomy at the age of 2 months. Seventeen patients underwent release of tongue-lip adhesion coincidentally with the palate repair at 7-14 months of age. For this surgery, no one required fiberoptic intubation.

CONCLUSIONS

The airway of these patients should be managed carefully not only before but also after the operation. A nasopharyngeal tube was effective in maintaining the upper airway patency during anesthesia induction and before and after operation.

Angular change in the line of vision to the larynx: implications for determining the laryngoscopic view

BACKGROUND

We measured the angular change from the line of vision to the larynx around the upper incisors under defined laryngoscopic forces and investigated its association with the laryngoscopic view.

METHODS

Laryngoscopy was performed under general anesthesia with muscle paralysis in male patients with a difficult laryngoscopy (DLG, n = 11) and in male patients matched for age and body mass index with an easy laryngoscopy (ELG, n = 11). A Macintosh blade #3 was used for the procedure. The line of vision was marked on lateral photographs during laryngoscopy by simultaneously delineating two straight lines: a line from the upper incisors to the lowest surface of the laryngoscope blade and a line from the upper incisors to the thyroid notch. The angle difference, defined as the angle between those two lines, was measured at laryngoscopic forces of 10-50 N.

RESULTS

The angle difference was significantly greater in the DLG than in the ELG at 50 N [median, 18.0° (range, 16.5-21.0°) vs 12.0° (12.0-13.5°), respectively; P < 0.001] and at lower forces (10-40 N; P ≤ 0.001). A higher Cormack-Lehane grade was associated with a greater angle difference at 50 N (P < 0.001).

CONCLUSIONS

Compared with ELG, DLG is associated with a larger angle difference, i.e., a larger gap between the underside of the blade and the thyroid notch at all laryngoscopic forces (10-50 N). The concept of angle difference, based on the angular change in the line of vision around the upper incisors, may provide a new approach to understanding DLG. This study was registered with the Clinical Research Information Service, registration number KCT0000433.

Preanesthetic assessment data do not influence the time for tracheal intubation with Airtraq™ video laryngoscope in obese patients

PURPOSE

this study investigated the influence of anatomical predictors on difficult laryngoscopy and orotracheal intubation in obese patients by comparing Macintosh and Airtraq™ laryngoscopes.

METHODS

from 132 bariatric surgery patients (body mass index ≥ 35 kgm(-1)), cervical perimeter, sternomental distance, interincisor distance, and Mallampati score were recorded. The patients were randomized into two groups according to whether a Macintosh (n=64) or an Airtraq™ (n=68) laryngoscope was used for tracheal intubation. Time required for intubation was the first outcome. Cormack-Lehane score, number of intubation attempts, the Macintosh blade used, any need for external tracheal compression or the use of gum elastic bougie were recorded. Intubation failure and strategies adopted were also registered.

RESULTS

intubation failed in two patients in the Macintosh laryngoscope group, and these patients were included as worst cases scenario. The intubation times were 36.9+22.8s and 13.7+3.1s for the Macintosh and Airtraq™ laryngoscope groups (p<0.01), respectively. Cormack-Lehane scores were also lower for the Airtraq™ group. One patient in the Macintosh group with intubation failure was quickly intubated with the Airtraq™. Cervical circumference (p<0.01) and interincisor distance (p<0.05) influenced the time required for intubation in the Macintosh group but not in the Airtraq™ group.

CONCLUSION

in obese patients despite increased neck circumference and limited mouth opening, the Airtraq™ laryngoscope affords faster tracheal intubation than the Macintosh laryngoscope, and it may serve as an alternative when conventional laryngoscopy fails.

Thyromental height: a new clinical test for prediction of difficult laryngoscopy

BACKGROUND

The incidence of difficult laryngoscopy is reported in the range of 1.5% to 20%. We hypothesized that there is a close association between the occurrence of difficult laryngoscopy and the height between the anterior borders of the mentum and thyroid cartilage, while the patient lies supine with her/his mouth closed. We have termed this the "thyromental height test" (TMHT). Our aim in this study was to determine its utility in predicting difficult laryngoscopy.

METHODS

Three hundred fourteen consecutive male and female patients aged ≥ 16 years scheduled to undergo general anesthesia were invited to participate. Airway assessments were performed with the modified Mallampati test, thyromental distance and sternomental distance, and TMHT in the preoperative clinic. Afterward, Cormack and Lehane grade of laryngoscopy views was assessed during intubation. The laryngoscopist was unaware of airway assessments. As a primary end point, the validity and prediction indexes for the TMHT were calculated. Calculation of validity indexes for the 3 other methods of airway assessment was a secondary objective of this study.

RESULTS

The optimal sensitivity and specificity values were in the range of 47.46 to 51.02 mm. To facilitate clinical application, a cutoff value equal to 50 mm was chosen. TMHT was more accurate than the other tests (all P < 0.0001).

CONCLUSIONS

The TMHT appears to be a more accurate predictor of difficult laryngoscopy than the existing anatomical measurements.

Emergency airway management: common ventilation techniques

Maintaining a patient's airway and facilitating breathing are the main priorities during any emergency situation in which breathing is compromised. The key to safe management of an airway is thorough assessment, primarily to ensure the airway is patent. In an emergency situation, a bag-valve-mask may be the most effective way to assist ventilation. If ventilation is required for prolonged periods in an emergency situation, then endotracheal intubation should be performed. This involves the placement of a cuffed, endotracheal tube in the trachea, through which ventilation is maintained. Each tracheal intubation event should be anticipated as a potentially difficult intubation. Longer term ventilatory support may be achieved by the use of mechanical ventilators, which are designed to assist the movement of gases (air) into and out of a patient's lungs, while minimising the work and effort of breathing. This article provides nurses with an overview of the techniques and equipment that is most often used within emergency and intensive care units to maintain the patency of a patient's airway and provide ventilatory support.

Endotracheal intubation under local anesthesia and sedation in an infant with difficult airway

Management of the difficult airway in an infant is a challenge for the anesthesiologist. A 10-month-old infant presented to an otolaryngologist with nasopharyngeal mass since birth, which had increased rapidly in size in the last 1 month and was hanging through the cleft palate into the oropharynx. The infant was scheduled for excision of the nasopharyngeal mass through a maxillary approach and the tongue mass through an oral approach under general anesthesia. This case report describes endotracheal intubation performed successfully under sedation and local anesthesia in an infant with a nasal mass protruding through the cleft palate into the oropharynx.

Incidence of difficult intubation in intensive care patients: analysis of contributing factors

Difficulties in endotracheal intubation increase morbidity and mortality in intensive care patients. We studied the problem in surgical intensive care patients with the aim of risk reduction. Patients intubated in the intensive care unit were evaluated. The intubations were performed or supervised by anaesthetists following the algorithm valid at the time of the study. Fifty percent of the 198 intubations were performed by specialist anaesthetists, 41.5% by anaesthesia trainees and 8.5% by surgical trainees. The initial attempt was by direct laryngoscopy (n=173), flexible fibrescope (n=8) or blind nasal technique (n=17). When direct laryngoscopy failed (n=7), intubation was accomplished with an intubating laryngeal mask airway (n=5), Frova stylet (n=1) or fibrescope (n=1). Thirty percent were rated as easy, 47% as moderately easy and 23% as difficult. Difficult intubations were associated with a higher incidence of anatomic anomalies, difficult bag-mask ventilation and severe oxygen desaturation. Every intubation in the ICU setting should be considered potentially difficult. The existing algorithm should be modified to incorporate the American Society of Anesthesiologists difficult airway algorithm adapted to the needs of the intensive care unit. A training program for alternative methods of airway management for difficult intubations should be established.

A randomised, controlled crossover comparison of the C-MAC videolaryngoscope with direct laryngoscopy in 150 patients during routine induction of anaesthesia

BACKGROUND

The C-MAC® (Karl Storz, Tuttlingen, Germany) has recently been introduced as a new device for videolaryngoscopy guided intubation. The purpose of the present study was to compare for the first time the C-MAC with conventional direct laryngoscopy in 150 patients during routine induction of anaesthesia.

METHODS

After approval of the institutional review board and written informed consent, 150 patients (ASA I-III) with general anaesthesia were enrolled. Computer-based open crossover randomisation was used to determine the sequence of the three laryngoscopies: Conventional direct laryngoscopy (HEINE Macintosh classic, Herrsching, Germany; blade sizes 3 or 4; DL group), C-MAC size 3 (C-MAC3 group) and C-MAC size 4 (C-MAC4 group) videolaryngoscopy, respectively. After 50 patients, laryngoscopy technique in the C-MAC4 group was changed to the straight blade technique described by Miller (C-MAC4/SBT).

RESULTS

Including all 150 patients (70 male, aged (median [range]) 53 [20-82] years, 80 [48-179] kg), there was no difference of glottic view between DL, C-MAC3, C-MAC4, and C-MAC4/SBT groups; however, worst glottic view (C/L 4) was only seen with DL, but not with C-MAC videolaryngoscopy. In the subgroup of patients that had suboptimal glottic view with DL (C/L≥2a; n = 24), glottic view was improved in the C-MAC4/SBT group; C/L class improved by three classes in 5 patients, by two classes in 2 patients, by one class in 8 patients, remained unchanged in 8 patients, or decreased by two classes in 1 patient. The median (range) time taken for tracheal intubation in the DL, C-MAC3, C-MAC4 and C-MAC4/SBT groups was 8 sec (2-91 sec; n = 44), 10 sec (2-60 sec; n = 37), 8 sec (5-80 sec; n = 18) and 12 sec (2-70 sec; n = 51), respectively.

CONCLUSIONS

Combining the benefits of conventional direct laryngoscopy and videolaryngoscopy in one device, the C-MAC may serve as a standard intubation device for both routine airway management and educational purposes. However, in patients with suboptimal glottic view (C/L≥2a), the C-MAC size 4 with straight blade technique may reduce the number of C/L 3 or C/L 4 views, and therefore facilitate intubation. Further studies on patients with difficult airway should be performed to confirm these findings.

Proposal for the management of the unexpected difficult pediatric airway

The incidence of unanticipated difficult or failed airway in otherwise healthy children is rare, and routine airway management in pediatric patients is easy in experienced hands. However, difficulties with airway management in healthy children are not infrequent in nonpediatric anesthetists and are a main reason for pediatric anesthesia-related morbidity and mortality. Clear concepts and strategies are, therefore, required to maintain oxygenation and ventilation in children. Several complicated algorithms for the management of the unanticipated difficult adult and pediatric airway have been proposed, but a simple structured algorithm for the pediatric patient with unanticipated difficult airway is missing. This paper proposes a simple step-wise algorithm for the unexpected difficult pediatric airway based on an adult Difficult Airway Society (DAS) protocol, discusses the role of recently introduced airway devices, and suggests a content of a pediatric airway trolley. It is intended as an easy to memorize and a practical guide for the anesthetist only occasionally involved in pediatric anesthesia care as well as a call to stimulate discussion about the management of the unanticipated difficult pediatric airway.

Cricoid pressure and laryngeal manipulation in 402 pre-hospital emergency anaesthetics: essential safety measure or a hindrance to rapid safe intubation?

OBJECTIVES

This is the first study to look at the effects of cricoid pressure/laryngeal manipulation on the laryngeal view and intubation success in the emergency or pre-hospital environment. Cricoid pressure is applied in the hope of reducing the incidence of aspiration. However the technique has never been evaluated in a randomized trial and may adversely affect laryngeal view. In order to improve intubating conditions cricoid pressure may be released and the larynx manipulated into a more favourable position.

METHODS

We carried out a prospective observational study to evaluate the effects of cricoid pressure and laryngeal manipulation on laryngeal view in our physician led pre-hospital trauma service.

RESULTS

402 patients were included over a 16-month period. We intubated 98.8% patients on the first or second attempt. In 61 intubations (in 55 patients, 13.6%) the larynx required manipulation to facilitate intubation. In 22 intubations cricoid pressure was removed with the laryngeal view improving in 50%. Bimanual laryngeal manipulation was used in 25 intubations and the larynx better visualised in 60% of these. Backwards upwards rightwards pressure was applied to the larynx in 14 intubations and the laryngeal view improved in 64%. Two patients regurgitated when cricoid pressure was released. Both had prolonged periods of bag valve mask ventilation and difficult intubations.

DISCUSSION

The results suggest that cricoid pressure should be removed if the laryngeal view obtained is not sufficient to allow immediate intubation. Further manipulation of the larynx is likely to improve the chances of successful tracheal tube placement.