The unanticipated difficult airway with recommendations for management

Determinants of difficult laryngoscopy based on upper airway indicators: a prospective observational study

BACKGROUND

The main cause of anesthesia-related deaths is the failure to manage difficult airways. Difficult laryngoscopic exposure is a major cause of unsuccessful management of difficult airways. Inadequate preoperative airway assessment hinders the clinical management of difficult airways cases, emphasizing the critical need for accurate identification of difficult airways. Currently, no definitive and reliable indicators are available to predict a difficult airway. Our study aims to predict laryngoscope exposure risk factors by combining ultrasonically measured upper airway anatomic parameters with physical examination indicators.

METHODS

Patients aged 18 to 75 years, classified as American Standards Association (ASA) I-III, and scheduled for elective general anesthesia with endotracheal intubation were included. All patients received the upper airway and ultrasonographic measurements. After anesthesia induction, laryngoscope exposure was analyzed using the Cormack-Lehane grading system, with Grades III and IV as indicative of difficult laryngoscopy. Univariate and multivariate logistic regression analyses were performed to identify reliable indicators for predicting difficult laryngoscopy. Receiver Operating Characteristic (ROC) curve analysis was utilized to assess the predictive performance of each indicator.

RESULTS

A total of 1120 patients finished the study, with 710 cases found in Grade I laryngoscopic exposure group, 360 cases in Grade II group, and 50 cases in Grade III group. There was no case observed in Grade IV group, thereby resulting in an incidence of difficult laryngoscopy of 4.46%. Univariate logistic regression analysis revealed that several parameters including age, Body Mass Index (BMI), neck circumference, neck mobility, snoring intensity, as well as ultrasound measurements of the pre-epiglottic space and thyromental distance were identified as significant risk factors for difficult laryngoscopy (P < 0.05). Among these, BMI, and neck circumference exhibited notable predictive value, with Area Under The Curve (AUC) values of 0.746 (95%CI 0.649-0.842) and 0.732 (95%CI 0.638-0.827), respectively. Neck mobility was also identified as an independent risk factor for predicting difficult laryngoscopy (P = 0.009) in multivariate logistic regression analysis, with an AUC of 0.672 (0.562-0.782) in the ROC curve.

CONCLUSIONS

Our findings revealed a direct correlation between difficult laryngoscopy and age, BMI, neck circumference, neck mobility, snoring intensity, as well as ultrasound measurements of the pre-epiglottic space and thyromental distance. Furthermore, neck mobility was identified as an independent predictive factor.

TRIAL REGISTRATION

The trial was registered prior to patient enrollment at clinicaltrials.gov (register no. ChiCTR2100053826, Date of registration: November 30, 2021).

Using a Disposable Flexible Fiberoptic Scope as a Bougie for Difficult Intubation

In this case report, we describe two difficult intubations in which an endotracheal tube was threaded over a fiberoptic bronchoscope that was acting as a bougie. Our patients initially presented with limited neck extension, narrow mouth opening, and restricted view of the glottic region. A fiberoptic bronchoscope was guided through while the patient was oxygenated through a laryngeal mask. After the scope provided an unrestricted view of the vocal cords, the digital module was removed by cutting the fiberoptic thread, and an endotracheal tube was passed through. After proper confirmation of the endotracheal tube position, the intubation was deemed successful and thereby, we share our experience with the novel technique. This technique may potentially improve critical patient outcomes whether in trauma or an unexpectedly difficult intubation.

Ultrasound-Guided Airway Evaluation: Is It a Game Changer for Predicting Difficult Endotracheal Intubation?

INTRODUCTION

Airway ultrasound has recently promised to be a valuable addition to preoperative airway assessment tools. This study was undertaken to determine the efficacy of ultrasound-guided measurement of soft tissue thickness (STT) at various levels of the anterior neck in predicting difficult airways in an eastern Indian population.

OBJECTIVE

 The primary objective was to find out the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of anterior neck soft tissue thickness at the level of the hyoid (STT-Hyoid) and vocal cords (STT-VC), distance from the skin to the epiglottis midway (DSEM), and the ratio of the depth of the pre-epiglottic space (Pre-E) to the distance from the epiglottis to the mid-point of the vocal cords (E-VC). The secondary objective was to develop a scoring system using these parameters.

MATERIALS AND METHODS

One hundred eighty-eight patients aged 18-65 years who received general anesthesia and endotracheal intubation for surgery were included in the study. Anterior neck soft tissue thickness measurements were done preoperatively using ultrasound. The actual difficulty of the airway was graded by the anesthesiologist while performing endotracheal intubation using the intubation difficulty scale (IDS).

RESULTS

The incidence of a difficult airway (IDS > 5) was 9.04%. The STT-Hyoid and STT-VC had a moderate correlation with IDS. The DSEM and Pre-E/E-VC ratios had a weak correlation with IDS. For difficult airway prediction, the cutoff points of STT-Hyoid and STT-VC were 7.95 mm and 24.25 mm, respectively. The combined cutoff measurements of STT-Hyoid and STT-VC (29.95 mm) were better predictors of difficult airway.

CONCLUSION

Preoperative airway ultrasound examination measuring the soft tissue thickness at the hyoid and vocal cord levels is an effective modality in predicting a difficult airway. However, further studies are needed to validate this finding in populations of varied ethnicity and demographic distribution.

A quantitative study of airway ultrasound in predicting difficult laryngoscopy: A prospective study

PURPOSE

As common clinical screening tests cannot effectively predict a difficult airway, and unanticipated difficult laryngoscopy remains a challenge for physicians. We herein used ultrasound to develop some point-of-care predictors for difficult laryngoscopy.

METHODS

This prospective observational study included 502 patients who underwent laryngoscopy and a detailed sonographic assessment. Patients under 18 years old, or with maxillofacial deformities or fractures, limited mouth opening, limited neck movement or history of neck surgery were excluded from the study. Laryngoscopic views of all patients were scored and grouping using the modified Cormack-Lehane (CL) scoring system. The measurements acquired comprised tongue width, the longitudinal cross-sectional area of the tongue, tongue volume, the mandible-hyoid bone distance, the hyoid bone-glottis distance, the mandible-hyoid bone-glottis angle, the skin-thyrohyoid membrane distance, the glottis-superior edge of the thyroid cartilage distance (DGTC), the skin-hyoid bone distance, and the epiglottis midway-skin distance. ANOVA and Chi-square were used to compare differences between groups. Logistic regression was used to identify risk factors for difficult laryngoscopy and it was visualized by receiver operating characteristic curves and nomogram. R version 3.6.3 and SPSS version 26.0 were used for statistical analyses.

RESULTS

Difficult laryngoscopy was indicated in 49 patients (CL grade Ⅲ - Ⅳ) and easy laryngoscopy in 453 patients (CL grade Ⅰ - Ⅱ). The ultrasound-measured mandible-hyoid bone-glottis angle and DGTC significantly differed between the 2 groups (p < 0.001). Difficult laryngoscopy was predicted by an area under the curve (AUC) of 0.930 with a threshold mandible-hyoid bone-glottis angle of 125.5° and by an AUC of 0.722 with a threshold DGTC of 1.22 cm. The longitudinal cross-sectional area of the tongue, tongue width, tongue volume, the mandible-hyoid distance, and the hyoid-glottis distance did not significantly differ between the groups.

CONCLUSION

Difficult laryngoscopy may be anticipated in patients in whom the mandible-hyoid bone-glottis angle is smaller than 125.5° or DGTC is larger than 1.22 cm.

Prediction of difficult laryngoscopy / difficult intubation cases using upper airway ultrasound measurements in emergency department: a prospective observational study

INTRODUCTION

Difficult laryngoscopy and intubation are serious problems among critically ill patients in emergency department (ED) so utility of a rapid, accurate and noninvasive method for predicting of these patients are necessary. Ultrasonography has been recently used in this regard and this study was conducted to investigate the correlation of some introduced upper airway ultrasound parameters with difficult laryngoscopy / difficult intubation in patients referred to the ED.

METHOD

In this prospective observational study all patients ≥ 18-year-old who had an indication for rapid sequence intubation (RSI) were included. Ultrasound parameters including Hyoid Bone Visibility (HBV), Distance from Skin to Hyoid Bone (DSHB), Distance from Skin to Vocal Cords (DSVC), Distance from Skin to Thyroid Isthmus (DSTI), and Distance between Arytenoids Cartilages (DBAC) were measured in all cases. The patients underwent RSI and thereafter the patients' baseline characteristics, Cormack-Lehane grade, number of attempted laryngoscopy were recorded in a pre-prepared check list and compared with measured ultrasound parameters. The "difficult laryngoscopy" was defined as Cormack-Lehane classification grades III/IV; and need for more than 3 intubation attempts was considered as "difficult intubation".

RESULTS

One hundred and twenty-three patients (52% male) were included of whom 10 patients (8.1%) were categorized as difficult laryngoscopy cases; and just 4 (3.3%) cases underwent more than 3 laryngoscopy attempts who considered as difficult intubation cases. The mean age of the patients in non-difficult and difficult intubation groups were 69.2 ± 15.16 and 68.77 ± 17.37 years, respectively (p > 0.05). There was no significant relationship between difficult laryngoscopy and HBV (p = 0.381) but has significant correlation with difficult intubation (p = 0.004). The DSHB had a significant correlation with difficult laryngoscopy (p = 0.002) but its correlation with difficult intubation was not significant (p = 0.629). The DSVC and DSTI had a significant relationship with both difficult laryngoscopy (p = 0.003 and p = 0.001), and difficult intubation (p = 0.025 and p = 0.001). The DBAC had not significant correlation neither with the difficult laryngoscopy (p = 0.142), nor with difficult intubation (p = 0.526).

CONCLUSION

The findings showed that ultrasound parameters including soft tissue DSHB, DSVC and DSTI could be proper predictors of difficult laryngoscopy. Also, HBV, DSVC and DSTI may be proper predictors for difficult intubation. But DBAC was not useful in this regard.

Development and Internal Validation of a Prediction Model for Difficult Laryngoscopy Using Ultrasound-Derived Factor in Comatose Patients

OBJECTIVES

The distance from skin to the hyoid bone (DSHB) and skin to the anterior commissure of vocal cords (DSAC) are reliable parameters for pre-operative airway ultrasound assessment in awake patients and can be assessed in comatose patients. This study aimed to inspect its feasibility and accuracy in predicting difficult laryngoscopy for comatose patients.

METHODS

A prospective cohort study included patients with a Glasgow Coma Scale (GCS) of ≤8 who underwent emergency tracheal intubation between November 2019 and August 2020. The outcome was difficult laryngoscopy and classified according to the Cormack-Lehane grading.

RESULTS

A total of 151 patients were included in the study. Fifty-two (34.4%) patients were categorized as having difficult laryngoscopy. The DSHB add DSAC (hereinafter referred to as the "DSBAC") was superior to either parameter alone in the predictive performance, and the optimal cut-off value was 1.90. To optimize the predictive value, DSBAC (adjusted odds ratio [OR]: 7.76; 95% confidence interval [CI]: 2.88-20.94; P < .001), GCS (adjusted OR: 1.39; 95% CI: 3.93-26.28; P = .039), mandibular retraction (adjusted OR: 8.20; 95% CI: 1.92-35.09; P = .005) and edentulous (adjusted OR: 4.23; 95% CI: 1.40-12.80; P = .011) were included in a multivariable model and constructed a nomogram. Discrimination and calibration statistics were satisfactory, with C-index above 0.80 from both model development and internal validation.

CONCLUSIONS

Ultrasound-derived factor, DSBAC, can be easily assessed and help predict difficult laryngoscopy among comatose patients. A simple nomogram including only four clinical items exhibited excellent discrimination performance and was useful when comatose patients underwent emergency tracheal intubation.

Emergent use of tube tip in pharynx technique in “cannot intubate cannot oxygenate” situation: A case report

BACKGROUND

A “cannot intubate, cannot oxygenate (CICO)” situation is a life-threatening condition that requires emergent management to establish a route for oxygenation to prevent oxygen desaturation. In this paper, we describe airway management in a patient with an extended parotid tumor that invaded the airways during CICO using the endotracheal tube tip in the pharynx (TTIP) technique.

CASE SUMMARY

A 43-year-old man was diagnosed with parotid tumor for > 10 years. Computed tomography and nasopharyngeal fiberoptic examination revealed a substantial mass from the right parotid region with a deep extension through the lateral pharyngeal region to the retropharyngeal region and obliteration of the nasopharynx to the oropharynx. Tumor excision was arranged. However, we encountered CICO during anesthesia induction. An endotracheal tube was used as an emergency supraglottic airway device (TTIP) to ventilate the patient in a CICO situation where other tools such as laryngeal mask airway or mask ventilation were not suitable for this complicated and difficult airway. The patient did not experience desaturation despite sudden loss of definite airway. During tracheostomy, the pulse oximetry remained 100% with our technique of ventilating the patient. The arterial blood gas analysis revealed PaCO₂ 35.7 mmHg and PaO₂ 242.5 mmHg upon 50% oxygenation afterward.

CONCLUSION

Using an endotracheal tube as a supraglottic airway device, patients may have increased survival without experiencing life-threatening desaturation.

Non-invasive ventilation for preoxygenation before general anesthesia: a systematic review and meta-analysis of randomized controlled trials

Background and objectives

Preoxygenation is crucial for providing sufficient oxygen reservoir to a patient before intubation and enables the extension of the period between breathing termination and critical desaturation (safe apnoea time). Conventionally, face mask ventilation is used for preoxygenation. Non-invasive ventilation is a new preoxygenation method. The study objective was to compare the outcomes of non-invasive ventilation and face mask ventilation for preoxygenation.

Method

PubMed, Embase, Cochrane Library, and the ClinicalTrials.gov registry were searched for eligible studies published from database inception to September 2021. Individual effect sizes were standardized, and a meta-analysis was conducted using random effects models to calculate the pooled effect size. Inclusion criteria were randomised controlled trials of comparing the outcomes of non-invasive ventilation or face mask ventilation for preoxygenation in patients scheduled for surgeries. The primary outcome was safe apnea time, and the secondary outcomes were post-operative complications, number of patients who achieved the expired O₂ fraction (FeO₂) after 3 min of preoxygenation, minimal SpO₂ during tracheal intubation, partial pressure of oxygen in the arterial blood (PaO₂) and partial pressure of carbon dioxide (PaCO₂) after preoxygenation, and PaO₂ and PaCO₂ after tracheal intubation.

Results

13 trials were eligible for inclusion in this study. Significant differences were observed in safe apnoea time, number of patients who achieved FeO₂ 90% after preoxygenation for 3 min, and PaO₂ and PaCO₂ after preoxygenation and tracheal intubation. Only in the non-obese subgroup, no significant difference was observed in safe apnoea time (mean difference: 125.38, 95% confidence interval: − 12.26 to 263.03).

Conclusion

Non-invasive ventilation appeared to be more effective than conventional methods for preoxygenation. We recommend non-invasive ventilation based on our results.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01842-y.

Predictive Value of Modified Mallampati Test and Upper Lip Bite Test Concerning Cormack and Lehane's Laryngoscopy Grading in the Anticipation of Difficult Intubation: A Cross-Sectional Study at a Tertiary Care Hospital, Bhubaneswar, India

Background and objective

Many tests are at hand to predict difficult intubation preoperatively to prevent morbidity and mortality of unanticipated difficult intubation. The present study was conducted to evaluate and compare the efficacy of the modified Mallampati test (MMT) and upper lip bite test (ULBT) to foresee difficult intubation.

Materials and methods

After obtaining written informed consent, this prospective comparative observational study was conducted on 225 patients scheduled for elective surgery under general endotracheal anesthesia. Preoperative MMT and ULBT were performed. MMT Grade III, IV, and ULBT Grade IV were regarded as predictors of difficult intubation. The laryngoscopic view was graded as per Cormack and Lehane's laryngoscopic grading after induction of anesthesia by an experienced anesthesiologist ignorant of preoperative airway evaluation. Patients with Cormack and Lehane Class III and IV were regarded as difficult intubation. Sensitivity, specificity, and positive and negative predictive values of MMT and ULBT were computed. Agreement between two tests with the Cormack Lehane test was determined by the Kappa coefficient.

Results

In our research, the occurrence of difficult intubation was found to be 10.2% (23 cases of difficult intubation out of 225 patients). In our analysis, we found the sensitivity (95.5% vs. 95.4%), specificity (54.8% vs 50.0%), positive predictive value (91.6% vs 93.1%), and negative predictive value (39.1% vs 39.1%) were almost comparable between modified Mallampati test and upper lip bite test. Kappa coefficient for the upper lip bite test (0.492) was slightly higher as compared to modified Mallampati scoring (0.454), but both the values are highly statistically significant (p-value <0.001).

Conclusion

Both the upper lip bite test and modified Mallampati test are comparable with each other and since the upper lip bite test is easy to perform bedside test we recommend it to be used alone or in collaboration with other tests in assessing difficult airways.

First-pass Success Rate and Number of Attempts Required for Intubation in Anticipated Difficult Airway: Comparison between Macintosh and Channeled King Vision Video Laryngoscopes

Background and Aims

Video laryngoscopy has been shown to improvise Cormack-Lehane grading and rate of successful tracheal intubation and is now incorporated in most of the difficult airway guidelines. Since there is scarce literature regarding the use of channeled blade of King Vision video laryngoscope (KVVL) in anticipated difficult intubation, we planned to undertake this randomized control trial to assess the performance of channeled blade of KVVL and Macintosh laryngoscope in patients with anticipated difficult intubation.

Design and Setting

This prospective randomized study was conducted in a tertiary care hospital.

Materials and Methods

Patients fulfilling the inclusion criteria were randomly assigned equally to the KVVL group or Macintosh group. The primary outcome of the study was intubation success in the first attempt and number of attempts required for intubation, and the secondary outcomes were Cormack-Lehane grading and time required to intubate in both the groups.

Results

The first-pass success of intubation was 88.6% in the KVVL group and 76.5% in the Macintosh group (P = 0.035). The second attempt of intubation was required in 11.4% and 20.6% of patients in the KVVL and Macintosh groups, respectively. Cormack Lehane Grade I was achieved in 100% of patients of the KVVL group as compared to 29.4% of patients in the Macintosh group. Moreover, the difference was statistically significant (P = 0.035). The mean duration of intubation was prolonged in the KVVL group as compared to the Macintosh group, and the difference was statistically significant (P = 0.04).

Conclusion

The channeled blade of KVVL had a higher first-pass success rate and required fewer attempts to intubate when used in patients with anticipated difficult intubation. Further, the KVVL was found to be significantly better than the Macintosh laryngoscope in terms of Cormack-Lehane grading, but the time taken to intubate the trachea was more in the KVVL group.

Comparative Evaluation of C-MAC Videolaryngoscope with Macintosh Direct Laryngoscope in Patients with Normal Airway Predictors

Background

Video laryngoscopes (VL) assist in securing the airway faster and more accurately in difficult airways. However, data regarding its usefulness in patients with normal airways are sparse.

Aim

We designed this study to compare the ease and success of endotracheal intubation between C-MAC and Macintosh direct laryngoscope (DL) in adult patients with no anticipated airway difficulty.

Settings and Design

The design involves prospective randomized case - control study.

Subjects and Methods

One hundred and twenty adult patients with predicted normal airway were randomized into two groups and were intubated using VL (C-MAC VL) and DL (Macintosh DL), respectively. The Cormack-Lehane (CL) grade, time taken for intubation, attempts taken (number), and need for laryngeal maneuvers or stylets were recorded and analyzed for statistical significance.

Results

Thirty-eight patients in the DL group and 48 patients in the VL group had CL I view, 20 patients in the DL group and 16 patients in the VL group had CL II, and two patients in the DL group had CL III view. None of the patients in Group VL had CL III view. In seven out of 60 cases in the DL group, difficulty was experienced during insertion of the laryngoscope blade as compared to two cases out of 60 in the VL group. The mean time taken for intubation was lesser in Group DL (28.48 s) as compared to 39.3 s in Group VL. Nine patients in Group DL and 16 patients in Group VL required external laryngeal manipulation. Stylets were used, in seven patients in group DL and in 11 patients in group VL.

Conclusions

In patients with a predicted normal airway, C-MAC provides a better glottic view compared to Macintosh DL. Time taken for intubation using the C-MAC video laryngoscope was more. However, success rates on the first attempt at endotracheal intubation and the number of intubation attempts with either laryngoscope were similar.

Comparison of emergency airway management techniques in the performance of emergent Cricothyrotomy

Introduction

Emergent cricothyrotomy (EC) is a rare and lifesaving procedure to secure a difficult airway when other methods have failed. Many techniques have been discussed in the literature. This study aimed to identify major techniques used to perform EC in a regional trauma center and evaluate outcomes associated with the techniques.

Methods

Patients who underwent EC at Arrowhead Regional Medical Center between 1-1-2009 and 1-1-2019 were reviewed for eligibility for this study. Patients’ data were extracted from the trauma database. Chi-square tests were conducted to assess the difference on variables between the techniques.

Results

A total of 51 (0.17%) of these patients required EC and were included in the database. The two most prevalent techniques were the scalpel-bougie-tube (SBT) and the surgical cricothyrotomy technique (SCT). More than half (n = 27, 52.9%) of the cohort received the SBT. There was no statistically significant difference between the two techniques with regards to demographic variables, including age (p = 0.7528), injury severity score (ISS, p = 0.896), gender (p = 0.3709), and race (p = 0.8935). However, the SCT group had a statistically higher Glasgow Coma Scale (GCS) than the SBT group (p = 0.0036). There was no statistically significant difference in mortality or complications between these two groups (p = 0.2172 for mortality).

Discussion

Two techniques of EC were identified as preferred techniques. Both procedures were successful in securing an emergency airway, noting a difference in the time to completion of the two techniques. Given the rarity of the procedure, practitioners may choose the method based on their training and the availability of appropriate instruments.

Association between Successful Palpation of the Cricothyroid Membrane and the 3-3-2 Rule for Predicting Difficult Airway in Female Patients Undergoing Non-Neck Surgery: A Prospective Observational Cohort Study

Background: Prediction of difficult airway is important for airway management in patients undergoing surgery. The assessment of airway structures and establishment of protective airway strategies are essential to improve patient safety. However, the association between successful palpation of the cricothyroid membrane and airway predictions has not been fully elucidated in patients undergoing surgery. We investigated this in female patients undergoing non-neck surgery. Methods: A total of 68 female patients were enrolled in this prospective observational cohort study between January 2021 and June 2021 at Eunpyeong St. Mary’s Hospital, College of Medicine, Catholic University of Korea, Seoul, Republic of Korea. Exclusion criteria were male patients and those with neck pathology or neck surgery. The assessment of difficult airway was performed before the induction of anesthesia and was defined by one of the following conditions: inter-incisor distance < 3 fingerbreadths, hyoid-to-mental distance < 3 fingerbreadths, and thyroid-to-hyoid distance < 2 fingerbreadths (the “3-3-2 rule”). The accuracy of palpable identification of the cricothyroid membrane was confirmed by ultrasonography (US). The patients were divided into the non-difficult airway (NDA) group (n = 30) and the difficult airway (DA) group (n = 30). Results: The two groups were comparable in terms of age, but the DA group had higher body mass index (BMI). In airway assessment, 9 patients showed inter-incisor distance < 3 fingerbreadths, 3 patients showed hyoid-to-mental distance < 3 fingerbreadths, and 24 patients showed thyroid-to-hyoid distance < 2 fingerbreadths in the DA group. The rate of successful palpation of the cricothyroid membrane was higher in the patients without than in those with difficult airway variables. Conclusions: Patients with a positive 3-3-2 rule showed a poor palpability of cricothyroid membrane.

Comparisons of Videolaryngoscopes for Intubation Undergoing General Anesthesia: Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

Background: The efficacy and safety of videolaryngoscopes (VLs) for tracheal intubation is still conflicting and changeable according to airway circumstances. This study aimed to compare the efficacy and safety of several VLs in patients undergoing general anesthesia. Methods: Medline, EMBASE, and the Cochrane Library were searched until 13 January 2020. The following VLs were evaluated compared to the Macintosh laryngoscope (MCL) by network meta-analysis for randomized controlled trials (RCTs): Airtraq, Airwayscope, C-MAC, C-MAC D-blade (CMD), GlideScope, King Vision, and McGrath. Outcome measures were the success and time (speed) of intubation, glottic view, and sore throat (safety). Results: A total of 9315 patients in 96 RCTs were included. The highest-ranked VLs for first-pass intubation success were CMD (90.6 % in all airway; 92.7% in difficult airway) and King Vision (92% in normal airway). In the rank analysis for secondary outcomes, the following VLs showed the highest efficacy or safety: Airtraq (safety), Airwayscope (speed and view), C-MAC (speed), CMD (safety), and McGrath (view). These VLs, except McGrath, were more effective or safer than MCL in moderate evidence level, whereas there was low certainty of evidence in the intercomparisons of VLs. Conclusions: CMD and King Vision could be relatively successful than MCL and other VLs for tracheal intubation under general anesthesia. The comparisons of intubation success between VLs and MCL showed moderate certainty of evidence level, whereas the intercomparisons of VLs showed low certainty evidence.

Frequency and Risk Factors for Difficult Intubation in Women Undergoing General Anesthesia for Cesarean Delivery: A Multicenter Retrospective Cohort Analysis

BACKGROUND

Estimates for the incidence of difficult intubation in the obstetric population vary widely, though prior studies reporting rates of difficult intubation in obstetrics are older and limited by smaller samples. The goals of this study were to provide a contemporary estimate of the frequency of difficult and failed intubation in women undergoing general anesthesia for cesarean delivery and to elucidate risk factors for difficult intubation in women undergoing general anesthesia for cesarean delivery.

METHODS

This is a multicenter, retrospective cohort study utilizing the Multicenter Perioperative Outcomes Group database. The study population included women aged 15-44 undergoing general anesthesia for cesarean delivery between 2004 and 2019 at one of 45 medical centers. Co-primary outcomes included the frequencies of difficult and failed intubation. Difficult intubation was defined as Cormack-Lehane view ≥3, intubation attempts ≥3, rescue fiberoptic intubation, rescue supraglottic airway, or surgical airway. Failed intubation was defined as any attempt at intubation without successful endotracheal tube placement. Rates of difficult and failed intubation were assessed. Several patient demographic, anatomical, and obstetric factors were evaluated for potential associations with difficult intubation.

RESULTS

We identified 14,748 cases of cesarean delivery performed under general anesthesia. There were 295 cases of difficult intubation, with a frequency of 1:49 (95% CI: 1:55, 1:44) (n=14,531). There were 18 cases of failed intubation, with a frequency of 1:808 (95% CI: 1:1,276, 1:511) (n=14,537). Factors with the highest point estimates for the odds of difficult intubation included increased body mass index, Mallampati score III or IV, small hyoid to mentum distance, limited jaw protrusion, limited mouth opening, and cervical spine limitations.

CONCLUSIONS

In this large, multi-center, contemporary study of over 14,000 general anesthetics for cesarean delivery, we observed an overall risk of difficult intubation of 1:49 and a risk of failed intubation of 1:808. Most risk factors for difficult intubation were non-obstetric in nature. These data demonstrate that difficult intubation in obstetrics remains an ongoing concern.

Comparison of Airway Ultrasound Indices and Clinical Assessment for the Prediction of Difficult Laryngoscopy in Elective Surgical Patients: A Prospective Observational Study

Background:

Ultrasound is evolving as a probable tool in airway assessment. The upper airway is a superficial structure and has sonographically identifiable structures which makes it ideal for evaluation with the ultrasound.

Aims:

The aim of this study was to evaluate the role of skin to hyoid and skin to thyrohyoid membrane distance in prediction of difficult laryngoscopy.

Settings and Design:

This is a prospective observational study included 150 patients aged 18–60 years of American Society of Anesthesiologists Physical Status I and II scheduled to undergo surgery under general anesthesia requiring laryngoscopy and endotracheal intubation.

Materials and Methods:

The modified Mallampati score, mouth opening, mentohyoid distance, thyromental distance were noted. Skin to hyoid bone distance and skin to thyrohyoid membrane distance were measured by ultrasound. Patients were clubbed retrospectively into easy and difficult laryngoscopy groups on the basis of Cormack Lehane grading, and the characteristics of both groups were compared.

Statistical Analysis:

Statistical Package for the Social Sciences, Version 23 was used for statistical analysis. Independent samples t-test was used to compare the means between difficult and easy laryngoscopy patients. Diagnostic accuracy of the significant (P < 0.05) variables between difficult and easy laryngoscopy patients was calculated using receiver operating characteristics curve in terms of their area under curve. Appropriate cutoff values (with corresponding sensitivity, specificity, and overall accuracy) were also identified.

Results:

Out of 150 patients, 13 (8.7%) were identified as difficult laryngoscopy whereas 137 patients (91.3%) were identified as easy laryngoscopy. The demographics of both groups were comparable. Mentohyoid distance, skin to hyoid bone distance, and skin to thyrohyoid distance were statistically different between easy and difficult laryngoscopy patients, with lower mentohyoid distance and higher skin to hyoid bone distance and skin to thyrohyoid distance in difficult laryngoscopy patients. Diagnostic accuracy of the mentohyoid distance (70.3%) was slightly superior to skin to hyoid bone distance (67.1%) and skin to thyrohyoid distance (68.1%).

Conclusion:

Ultrasound measurements of skin to hyoid bone and skin to thyrohyoid membrane distance fail to eclipse clinical parameters in accurately predicting a difficult laryngoscopy.

Efficacy of stylet angulation at the holding position during tracheal intubation with a videolaryngoscope: a randomized controlled trial

The aim of this randomized controlled trial was to determine the efficacy of stylet angulation at the holding position during tracheal intubation with a McGRATH MAC videolaryngoscope. Patients were randomized to a group for intubation without stylet angulation at the holding position (non-angulation group) and to a group for intubation with stylet angulation at the holding position (angulation group). The primary outcome was the time for placement of the tracheal tube. Sixty patients were analyzed. The mean (standard deviation) times for tube placement were 21.3 (5.6) s in the non-angulation group and 16.9 (3.8) s in the angulation group (P < 0.001). The scores of operator's perception of difficulty in tube delivery, number of attempts for tube delivery, and degrees of extension, abduction, internal rotation of the right upper arm and extension of the right wrist during tube placement in the angulation group were significantly smaller than those in the non-angulation group (P < 0.001, P = 0.002, P < 0.001, P < 0.001, P < 0.001, P < 0.001, respectively). Our results suggest that stylet angulation at the holding position improves maneuverability of the tracheal tube and enables easy, smooth, and swift tube placement during tracheal intubation with a McGRATH MAC videolaryngoscope.

Difficult intubation and anesthetic management in an adult patient with undiagnosed congenital tracheal stenosis: a case report

In the operating room, unanticipated difficult intubation can occur and anesthesiologists can experience challenging situations. Undiagnosed tracheal stenosis caused by congenital factors, trauma, tumors, or post-intubation injury, can make advancing the endotracheal tube difficult. We present an adult patient in whom we were unable to pass an endotracheal tube into the trachea. This was caused by undiagnosed congenital mid-tracheal stenosis with complete tracheal rings. When faced with an unanticipated difficult airway, the anesthesiologist needs to comprehend the results of preoperative evaluations. If an unusual situation (e.g., congenital tracheal stenosis) occurs, active cooperation with other departments should be considered.

Factors and Economic Outcomes Associated with Documented Difficult Intubation in the United States

Purpose

Establishing good mechanical ventilation is a critical component and prerequisite to a wide range of surgical and medical interventions. Yet difficulties in intubating patients, and a variety of associated complications, are well documented. The economic burden resulting from difficult intubation (DI), however, is not well understood. The current study examines the economic burden of documented DI during inpatient surgical admissions and explores factors that are associated with DI.

Patients and Methods

Using data from the Premier Healthcare Database, adult patients with inpatient surgical admissions between January 1, 2016 and December 31, 2018 were selected. International Classification of Diseases, Tenth Edition, Clinical Modification (ICD-10-CM) diagnosis codes were used to classify the patients into matched cohorts of DI and non-DI patients.

Results

Patients in the DI group have mean inpatient costs and intensive care unit (ICU) costs that are substantially higher than patients without difficult intubations ($14,468 and $4,029 higher, respectively). Mean hospital length of stay and ICU length of stay were 3.8 days and 2.0 days longer, respectively (all p<0.0001, except ICU cost p=0.0001) in the DI group. Obesity, other chronic conditions, and larger hospital size were significantly associated with DI.

Conclusion

DI is associated with higher average cost and longer average length of stay.

Awareness among anesthesia residents pertaining to various intubation techniques in craniofacial surgery: A questionnaire study

Aim:

This study was intended to evaluate the knowledge and clinical skill of anesthesia residents pertaining to various intubation techniques employed in craniofacial surgery.

Materials and Methods:

A cross-sectional survey research design was employed in this study. A self-administered questionnaire survey was used to validate the knowledge and clinical skill of anesthesia residents pertaining to various intubation techniques employed in craniofacial surgery. In this regard, a preliminary study with a convenience sample of 156 anesthesia residents studying in various medical institutions across South India was conducted so as to assess the knowledge and clinical skill of anesthesia residents pertaining to various intubation techniques employed in craniofacial surgery. This study, while limited in sample size, benefits the craniofacial surgeons and anesthetists as target readers to assess the knowledge and clinical skill of anesthesia residents pertaining to various intubation techniques employed in craniofacial surgery

Results:

The results of this study reveal that majority of the anesthesia residents encountered craniofacial surgery during their residency period. However, only 19.87% have performed various intubation techniques that are employed in craniofacial surgery. Nearly 38.46% of the participants felt that blind awake intubation is the most difficult intubation technique to employ in the head-and-neck region and requires expertise. Nearly 78.84% of the participants felt that special training is required for handling craniofacial surgical cases under general anesthesia.

Conclusion:

The results of this study reveal that there is a dearth of knowledge and clinical exposure among anesthesia residents regarding various intubation techniques employed in craniofacial surgery. Educational and quality improvement initiatives in various intubation techniques could enhance anesthesia residents' knowledge and clinical exposure in managing various craniofacial surgical cases.

Utilization of apnea-hypopnea index as a novel predictive factor for difficult mask ventilation in the Chinese population under general anesthesia

Purpose

Difficult mask ventilation (DMV) is a potentially life-threatening situation that can arise during anesthesia. However, most clinical predictors of DMV are based on European and US populations. On the other hand, most predictive models consist of multiple factors and complicated assessments. Since obstructive sleep apnea (OSA) is among the most important risk factors associated with DMV, the apnea-hypopnea index (AHI) may play an important role in determining patient risk.The purpose of this study was to investigate the relationship between DMV and AHI, and to determine preoperative risk factors for DMV in Chinese patients.

Methods

A prospective cohort trial enrolled patients scheduled for elective surgery. After obtaining informed consent, patient demographic information was collected, and patients were tested with pre-operative polysomnography. The anesthesiologist who managed the airway graded the mask ventilation. The difficult mask ventilation was defined as the mask ventilation provided by an unassisted anesthesiologist without oral airway or other adjuvant. A logistic regression model was used to analyze the association between AHI and DMV.

Results

A total of 159 patients were analyzed. For both primary and secondary outcomes, the unadjusted and adjusted odds ratio for DMV showed significant increases by 5 AHI units. AHI, age, and the Mallampati classification were found to be independent predictive factors for DMV.

Conclusions

AHI is associated with DMV as a novel independent risk factor in Chinese patients. Along with age and Mallampati classification, AHI should be included in establishing a superior predictive strategy for DMV screening.

Trial registration

Chinese Clinical Trial Registry ChiCTR-DDD-17013076

Comparison of videolaryngoscopy and direct laryngoscopy for tracheal intubation in obstetrics: a mixed-methods systematic review and meta-analysis

PURPOSE

The incidence of difficult and failed intubation is higher in obstetrical patients than in the general population because of anatomic and physiologic changes in pregnancy. Videolaryngoscopy improves the success rate of intubation and reduces complications when compared with direct laryngoscopy in adults; however, it is not known whether this extends to obstetrical surgery. The aim of this study was to examine the efficacy, efficiency, and safety of videolaryngoscopy compared with direct laryngoscopy in obstetrics.

SOURCE

Central, CINAHL, Embase, MEDLINE and Web of Science databases were searched from inception to 27 May 2020 with no restrictions. Inclusion criteria included randomized-controlled trials (RCTs), observational studies, case series, and case reports that reported the application of videolaryngoscopy to intubate the trachea in pregnant patients having general anesthesia.

PRINCIPAL FINDINGS

Overall, four RCTs with 428 participants, nine observational studies, and 35 case reports/series with 100 participants were included. On meta-analysis of three trials, the co-primary outcomes of first-attempt success rate (risk ratio, 1.02; 95% confidence intervals [CI], 0.98 to 1.06; P = 0.29; I2 = 0%) and time to tracheal intubation (mean difference, 1.20 sec; 95% CI, -6.63 to 9.04; P = 0.76; I² = 95%) demonstrated no difference between videolaryngoscopy and direct laryngoscopy in parturients without difficult airways. Observational studies and case reports underline the role of videolaryngoscopy as a primary choice when difficulty with tracheal intubation is expected or as a rescue modality in difficult or failed intubations.

CONCLUSIONS

Evidence for the utility of videolaryngoscopy continues to evolve but supports its increased adoption in obstetrics where videolaryngoscopes should be immediately available for use as a first-line device.

TRIAL REGISTRATION

PROSPERO (CRD42020189521); registered 6 July 2020.

Canadian Airway Focus Group updated consensus-based recommendations for management of the difficult airway: part 1. Difficult airway management encountered in an unconscious patient

PURPOSE

Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the literature on airway management has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This first of two articles addresses difficulty encountered with airway management in an unconscious patient.

SOURCE

Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians, were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence was lacking, statements are based on group consensus.

FINDINGS AND KEY RECOMMENDATIONS

Most studies comparing video laryngoscopy (VL) with direct laryngoscopy indicate a higher first attempt and overall success rate with VL, and lower complication rates. Thus, resources allowing, the CAFG now recommends use of VL with appropriately selected blade type to facilitate all tracheal intubations. If a first attempt at tracheal intubation or supraglottic airway (SGA) placement is unsuccessful, further attempts can be made as long as patient ventilation and oxygenation is maintained. Nevertheless, total attempts should be limited (to three or fewer) before declaring failure and pausing to consider "exit strategy" options. For failed intubation, exit strategy options in the still-oxygenated patient include awakening (if feasible), temporizing with an SGA, a single further attempt at tracheal intubation using a different technique, or front-of-neck airway access (FONA). Failure of tracheal intubation, face-mask ventilation, and SGA ventilation together with current or imminent hypoxemia defines a "cannot ventilate, cannot oxygenate" emergency. Neuromuscular blockade should be confirmed or established, and a single final attempt at face-mask ventilation, SGA placement, or tracheal intubation with hyper-angulated blade VL can be made, if it had not already been attempted. If ventilation remains impossible, emergency FONA should occur without delay using a scalpel-bougie-tube technique (in the adult patient). The CAFG recommends all institutions designate an individual as "airway lead" to help institute difficult airway protocols, ensure adequate training and equipment, and help with airway-related quality reviews.

George J. A prospective randomised simulation trial comparing our novel AIR-BOX to standard airway equipment storage modalities

Background

There is little evidence guiding equipment handling during emergency endotracheal intubations (EEI). Available evidence and current practice are either outdated, anecdotal or focused on difficult—not emergency—intubation. In this study, we describe and evaluate our equipment handling unit: the AIR-BOX.

Methods

This is a proof-of-concept, prospective, randomised simulation trial. A convenience sample of 50 airway course participants voluntarily underwent randomisation: 21 to the AIR-BOX group, 14 to the intubation box group, and 15 to the crash cart group. The volunteers were asked to intubate a manikin using the equipment from the storage unit of their randomisation. Outcome measures included time-to-readiness, time-to-intubation, first-pass success, and subjective operator experience.

Results

The mean time-to-readiness was 67.2 s with the AIR-BOX, 84.6 s with the intubation box, and 115 s with the crash cart. The mean time-to-intubation was 105 s with the AIR-BOX, 127 s with the intubation box and 167 s with the crash cart. A statistically significant difference was achieved between the AIR-BOX and the crash cart. No statistically significant difference was found between the three groups with regard to first-pass success or the time between intubation readiness and intubation.

Conclusions

This study supports the AIR-BOX as a viable tool that can improve and simplify access to emergency intubating equipment. It also opens doors for multiple future innovations that can positively impact equipment handling practices. Future studies can focus on assessing whether applying the AIR-BOX will yield a clinically significant impact on patient outcomes.

Evaluation of retrograde intubation with different doses of dexmedetomidine infusion: A randomised controlled trial

Background

Retrograde intubation is one of the well-described and alternative methods of difficult airway management. It requires effective sedation and patient preparation. Study was done to evaluate intubating conditions during retrograde guided intubation with two different doses of dexmedetomidine.

Methods

This prospective randomized double blind parallel group trial was planned on 60 patients with difficult airway. Patients were divided in two groups to receive either dexmedetomidine 1.0 μg/kg (Group A) or dexmedetomidine 1.5 μg/kg (Group B) by intravenous (IV) route. The Modified Observer Assessment Awareness and Sedation (OAA/S) was measured as primary outcome and ease of intubation, facial grimace score, cough severity, hemodynamic response, patient recall and discomfort were assessed as secondary outcome during awake retrograde intubation.

Results

Groups were comparable in terms of demographic and baseline parameters. OAA/S (P = 0.001), cough severity (P < 0.001), facial grimace score (P < 0.001), grading of discomfort during procedure (P < 0.001) and recall of procedure scale (P = 0.038) were found significantly better/lower in Group B as compared to Group A. Hemodynamic parameters were better in Group B and showed significant difference during the retrograde intubation. However, ease of intubation scale, intubating time and complications were not significantly different (P > 0.05) between the two groups.

Conclusion

Retrograde intubation can be easily learned and performed with minimal complications. Dexmedetomidine in a dose of 1.5 μg/kg IV is optimum and safe for retrograde intubation with clinically manageable side effects.

Effectiveness of four ultrasonographic parameters as predictors of difficult intubation in patients without anticipated difficult airway

Background

Predicting difficult intubation (DI) is a key challenge, as no single clinical predictor is sufficiently valid to predict the outcome. We evaluated the effectiveness of four upper airway ultrasonographic parameters in predicting DI. The validity of the models using combinations of ultrasonography-based parameters was also investigated.

Methods

This prospective, observational, double-blinded cohort trial enrolled 1,043 surgical patients classified as American Society of Anesthesiologists physical status I–III without anticipated difficult airway. Preoperatively, their tongue thickness (TT), invisibility of hyoid bone (VH), and anterior neck soft tissue thickness from the skin to thyrohyoid membrane (ST) and hyoid bone (SH) were measured by sublingual and submandibular ultrasonography. The logistic regression, Youden index, and receiver operator characteristic analysis results were reported.

Results

Overall, 58 (5.6%) patients were classified as DI. The TT, SH, ST, and VH had accuracies of 78.4%, 85.0%, 84.7%, and 84.9%, respectively. The optimal values of TT, SH, and ST for predicting DI were > 5.8 cm (sensitivity: 84.5%, specificity: 78.1%, AUC: 0.880), > 1.4 cm (sensitivity: 81%, specificity: 85.2%, AUC: 0.898) and > 2.4 cm (sensitivity: 75.9%, specificity: 85.2%, AUC: 0.885) respectively. VH had a sensitivity and specificity of 72.4% and 85.6% (AUC: 0.790). The AUC values of the five models (with combinations of three or four parameters) ranged from 0.975–0.992. ST and VH had a significant impact on the individual models.

Conclusions

SH had the best accuracy. Individual parameters showed limited validity. The model including all four parameters offered the best diagnostic value.

A comparison of difficult intubation documentation practices with existing guidelines in the advent of video laryngoscopy

STUDY OBJECTIVE

To assess whether anesthesia providers' interpretations of a difficult intubation are consistent with current guidelines and explore possible explanations for any observed discrepancy including video laryngoscopy usage.

DESIGN

A retrospective data analysis of tracheal intubation records from the electronic health record of a large healthcare system in the United States from January to June 2018.

SETTING

General anesthesia encounters that involved a tracheal intubation in the operating rooms and non-operating room areas, including procedural areas, medical/surgical floors, and intensive care units.

PATIENTS

Records for 30,072 adult patients (33,142 cases) were identified for analysis. Patient age ranged from 18 to 100 and ASA physical status from I to V.

INTERVENTIONS

None.

MEASUREMENTS

The magnitude and direction of disagreement regarding intubation difficulty was estimated by examining anesthesiologist documentation vs. the American Society of Anesthesiologists guideline definitions. Any explanations for disagreement provided by clinicians were also analyzed. Furthermore, the association between video laryngoscopy and odds of disagreement was assessed.

MAIN RESULTS

While documentation of intubation difficulty in over 95% of records was consistent with current definitions, disagreement occurred in 1.6% of cases using the number of attempts definition (N = 31,964) and in 4.6% of cases using the Cormack-Lehane grade definition (N = 25,407). Some of the most frequently identified explanations clinicians gave in these cases of disagreement included the use of video laryngoscopy (used to explain documented difficult and easy intubations), clinician experience level, and the use of airway assist devices. Video laryngoscopy use was associated with greater odds of disagreement between anesthesiologist documentation and guideline definitions.

CONCLUSIONS

A review of electronic anesthesia records suggests that clinicians inconsistently interpret and document difficult intubations in light of current guideline definitions and that video laryngoscopy usage appears to be associated, albeit not necessarily independently, with a greater discrepancy between anesthesiologist documentation and guideline definitions.

Comparison of the new flexible tip bougie catheter and standard bougie stylet for tracheal intubation by anesthesiologists in different difficult airway scenarios: a randomized crossover trial

Background

Incidence of difficult endotracheal intubation ranges between 3 and 10%. Bougies have been recommended as an airway adjunct for difficult intubation, but reported success rates are variable. A new generation flexible tip bougie appears promising but was not investigated so far. We therefore compared the new flexible tip with a standard bougie in simulated normal and difficult airway scenarios, and used by experienced anesthesiologists.

Methods

We conducted a observational, randomized, cross-over simulation study. Following standardized training, experienced anesthesiologists performed endotracheal intubation using a Macintosh blade and one of the bougies in six different airway scenarios in a randomized sequence: normal airway, tongue edema, pharyngeal obstruction, manual cervical inline stabilization, cervical collar stabilization, cervical collar stabilization and pharyngeal obstruction. Overall success rate with a maximum of 3 intubation attempts was the primary endpoint. Secondary endpoints included number of intubation attempts, time to intubation and dental compression.

Results

Thirty-two anesthesiologist participated in this study between January 2019 and May 2019. Overall success rate was similar for the flexible tip bougie and the standard bougie. The flexible tip bougie tended to need less intubation attempts in more difficult airway scenarios. Time to intubation was less if using the flexible tip bougie compared to the standard bougie. Reduced severity of dental compression was noted for the flexible tip bougie in difficult airway scenarios except cervical collar stabilization.

Conclusion

In this simulation study of normal and difficult airways scenarios, overall success rate was similar for the flexible tip and standard bougie. Especially in more difficult airway scenarios, less intubation attempts, and less optimization maneuvers were needed if using the flexible tip bougie.

Trial registration

clinicaltrials.gov Identifier: NCT03733158. 7th November 2018.

Methodological quality and transparency of clinical practice guidelines for difficult airway management using the appraisal of guidelines research & evaluation II instrument: A systematic review

BACKGROUND

Complications arising from airway management represent an important cause of morbidity and mortality. Clinical practice guidelines (CPGs) are systematically created documents that summarise knowledge and assist the delivery of high-quality medical care by identifying evidence that supports best clinical care.

OBJECTIVE

Using the Appraisal of Guidelines for Research & Evaluation II instrument, we aimed to evaluate the methodological rigour and transparency of unanticipated difficult airway management CPGs in adults.

DESIGN

Using PUBMED without language restrictions, we identified eligible CPGs between 1 January 1996 and 30 June 2019. All versions of a CPG were included as independent guidelines to assess improvements over time or the methodological limitations of each version. CPGs-related obstetrics or paediatrics or the management extubation in cases of difficult airway were excluded.

RESULTS

Fourteen CPGs were included. Of the six domains suggested by the Appraisal of Guidelines for Research & Evaluation II instrument, 'applicability' had the lowest score (23%) and 'scope and objectives' had the highest score (88%). The remaining domains (stakeholder involvement, editorial independence, rigour of development and clarity of presentation) had scores ranging between 56 and 81%. Overall, the highest scored CPG was the Difficult Airway Society 2015.

CONCLUSION

Future updates of CPGs for difficult airway management in adults and severely ill patients should consider more emphasis on the applicability of their recommendations to real clinical practice.

Description and comparison of the performance of the upper lip bite test, the ratio of height to thyromental distance and other methods of preoperative airway assessment in a Nigerian population – a pilot study

Background: The ability to reliably predict difficult intubation can prevent airway related adverse outcomes. The upper lip bite test (ULBT) and ratio of height to thyromental distance (RHTMD) are airway predictive tests that have been evaluated in Caucasian populations with promising results. This study determined the test performance of the ULBT and RHTMD and compared with commonly employed predictive tests (modified Mallampati [MMT], thyromental distance [TMD] and inter-incisor gap [IIG]) in adult Nigerians. Methods: This was a cross-sectional study. Two hundred and sixteen consecutive, consenting ASA I-III patients presenting for surgery and planned for general anaesthesia with endotracheal intubation over a six month period in our teaching hospital, had all five airway assessment tests (ULBT, RHTMD, MMT, TMD and IIG) assessed preoperatively. The Cormack and Lehane grading was used to determine easy or difficult visualisation of the larynx (EVL or DVL). Sensitivity, specificity, predictive values and likelihood ratios of the tests were determined. Results: The sensitivities, specificities, positive and negative predictive values and positive and negative likelihood ratios respectively for the tests were: ULBT (11.8%, 99.0%, 50.0%, 92.9%, 11.71 and 0.89), RHTMD (35.3%, 92.5%, 28.6%, 94.4%, 4.68 and 0.70), TMD (29.4%, 97.5%, 50.0%, 94.2%, 11.71 and 0.72), MMT (52.9%, 86.4%, 25.0%, 95.6%, 3.90 and 0.54), and IIG (11.8%, 97.0%, 25.0%, 92.8%, 3.90 and 0.91). Conclusion: The modified Mallampati test had the highest sensitivity in this study, however all the tests evaluated showed only low to moderate sensitivity. The ULBT and RHTMD had low sensitivities in this population. However, based on the high positive likelihood ratios of the ULBT and the TMD, whenever positive, these tests do show a high probability of DVL and these two tests would probably perform similarly in this population. Anthropometric differences may account for differences in performance of preoperative airway assessment tests in various populations.

LeHeR, a simple novel approach for difficult airway in non-trauma patients

Managing the difficult airway presents a great challenge to anaesthesiologists and emergency physicians. Although there are many methods and scoring systems available to predict and anticipate difficult airway, the dictum in emergency airway is to always expect the unexpected. We have encountered a novel simple method of improving laryngoscopic view in difficult airway. We report four cases of difficult airway encountered in our district hospital from November 2017 to December 2018, in which intubation was performed using a simple manoeuvre called supine left head rotation (LeHeR). In all these cases, LeHeR manoeuvre has proven to be successful after more than a single attempt at intubation using various methods. The manoeuvre improves drastically the laryngoscopic view of Cormack-Lehane from 3B and 4 to 1 and 2.

Difficult airway management algorithms: a directed review

The primary aim of this study was to identify, describe and compare the content of existing difficult airway management algorithms. Secondly, we aimed to describe the literature reporting the implementation of these algorithms. A directed search across three databases (MEDLINE, Embase and Scopus) was performed. All articles were screened for relevance to the research aims and according to pre-determined exclusion criteria. We identified 38 published airway management algorithms. Our results show that most facemask employ a four-step process as represented by a flow chart, with progression from tracheal intubation, facemask ventilation and supraglottic airway device use, to a rescue emergency surgical airway. The identified algorithms are overwhelmingly similar, yet many use differing terminology. The frequency of algorithm publication has increased recently, yet adherence and implementation outcome data remain limited. Our results highlight the lack of a single algorithm that is universally endorsed, recognised and applicable to all difficult airway management situations.

Advancing emergency airway management practice and research

Emergency airway management is one of the vital resuscitative procedures undertaken in the emergency department (ED). Despite its clinical and research importance in the care of critically ill and injured patients, earlier studies have documented suboptimal intubation performance and high adverse event rates with a wide variation across the EDs. The optimal emergency airway management strategies remain to be established and their dissemination to the entire nation is a challenging task. This article reviews the current published works on emergency airway management with a focus on the use of airway management algorithms as well as the importance of first‐pass success and systematic use of rescue intubation strategies. Additionally, the review summarizes the current evidence for each of the important airway management processes, such as assessment of the difficult airway, preparation (e.g., positioning and oxygenation), intubation methods (e.g., rapid sequence intubation), medications (e.g., premedications, sedatives, and neuromuscular blockades), devices (e.g., direct and video laryngoscopy and supraglottic devises), and rescue intubation strategies (e.g., airway adjuncts and rescue intubators), as well as the airway management in distinct patient populations (i.e., trauma, cardiac arrest, and pediatric patients). Well‐designed, rigorously conducted, multicenter studies that prospectively and comprehensively characterize emergency airway management should provide clinicians with important opportunities for improving the quality and safety of airway management practice. Such data will not only advance research into the determination of optimal airway management strategies but also facilitate the development of clinical guidelines, which will, in turn, improve the outcomes of critically ill and injured patients in the ED.

Preparation for and Management of “Failed” Laryngoscopy and/or Intubation

An airway manager’s primary objective is to provide a path to oxygenation. This can be achieved by means of a facemask, a supraglottic airway, or a tracheal tube. If one method fails, an alternative approach may avert hypoxia. We cannot always predict the difficulties with each of the methods, but these difficulties may be overcome by an alternative technique. Each unsuccessful attempt to maintain oxygenation is time lost and may incrementally increase the risk of hypoxia, trauma, and airway obstruction necessitating a surgical airway. We should strive to optimize each effort. Differentiation between failed laryngoscopy and failed intubation is important because the solutions differ. Failed facemask ventilation may be easily managed with an supraglottic airway or alternatively tracheal intubation. When alveolar ventilation cannot be achieved by facemask, supraglottic airway, or tracheal intubation, every anesthesiologist should be prepared to perform an emergency surgical airway to avert disaster.

Predictive Values of Preoperative Tests for Difficult Laryngoscopy and Intubation in Adult Patients at Tikur Anbessa Specialized Hospital

Introduction

The significance of difficult or failed tracheal intubation following induction is a well-recognized cause of morbidity and mortality in anesthetic practice. Nevertheless, the need to predict potentially difficult tracheal intubation has received a little attention. During routine anesthesia, the incidence of difficult tracheal intubation has been estimated at 1.5%–8% of general anesthetics. Difficulties in intubation have been associated with serious complications, such as brain damage or death, particularly when failed intubation has occurred. Occasionally, in a patient with a difficult airway, the anesthetist is faced with the situation where mask ventilation proves difficult or impossible. This is one of the most critical emergencies that may be faced in the practice of anesthesia. If the anesthetist can predict which patients are likely to prove difficult to intubate, he/she may reduce the risks of anesthesia considerably. In Ethiopia, there are no data on the magnitude of difficult laryngoscopic tracheal intubation and no standard guidelines for preoperative tests. The main concern of this study was to provide information on the magnitude of difficult laryngoscopic intubation and to determine valuable preoperative tests to predict difficult laryngoscopy and intubation in patients with apparently normal airways which can help anesthetists to improve preoperative airway assessment and contribute to decrease anesthesia-related morbidity and mortality.

Objective

The main objective of this study was to assess the magnitude and predictive values of preoperative tests for difficult laryngoscopy and intubation, among surgical patients who underwent elective surgery under general anesthesia with endotracheal intubation in Tikur Anbessa Hospital from February 1 to March 30, 2016.

Study Design

A facility-based cross-sectional study design was used.

Result

In this study, we found the magnitude of difficult laryngoscopy and intubation as 13.6% and 5%, respectively. 33.3% of patients with difficult laryngoscopy were found to be difficult for intubation. Mallampati test, interincisor distance, and thyromental distance were identified to be good preoperative tests to predict difficult laryngoscopic intubation when used in combination.

Recommendation

We recommend anesthesia professionals to use combination of MMC/TMD/IID for their routine preoperative airway assessment.

Airway Management Equipment in a Metropolitan Region: An Audit

Difficult airway equipment containers are commonly found in operating rooms, but the availability of airway equipment beyond that environment is unknown. Using the Difficult Airway Society (U.K.) and American Society of Anesthesiologists’ guidelines, we conducted an inspection audit of airway equipment at all anaesthetic sites in our region. Staff knowledge about the equipment was assessed and feedback was provided to each site.

Eighteen of the 42 sites had an airway container. Equipment for an unexpected difficult intubation, according to the guidelines, was deficient at all sites. Equipment to detect oesophageal intubation was inadequate. Locations remote from the operating suite lacked emergency invasive airway equipment and were, on average, a 4.3 minute walk from the nearest appropriate equipment. Two clinics had no emergency invasive airway equipment. Half of the airway containers with check lists had items missing. One third of the items with an expiry date were expired. Quality control and implementation of airway guidelines could rectify these deficiencies. Anaesthesia organisations should be encouraged to publish detailed equipment guidelines.

C-MAC® video-laryngoscope assisted removal of pediatric upper airway foreign body via apneic technique: Two case reports

C-MAC® video-laryngoscope is often used by anesthetists in difficult intubation scenarios primarily in adults. Using this C-MAC® device in two of our pediatric cases, we successfully removed the laryngeal foreign body, while the anesthetist provided the apneic technique. A systematic review of PubMed and Google Scholar for similar cases was conducted. We found only one such case report of pediatric airway foreign body removal via video-laryngoscope in the English literature. The use of this high-quality, magnified video-laryngoscope in children in an emergency scenario is often not adequately applied. This procedure provides continuous real-time visualization to both the operating surgeon as well as the anesthetist in respect to the airway and thereby reduces the chance of any untoward complications. Here, we present two interesting case reports of C-MAC® video-laryngoscope assisted removal of laryngeal foreign body via apneic technique with spontaneous ventilation performed on two different children in our facility. Both these children had clinical symptoms of upper airway obstruction with fluctuating stridor simulating croup or asthma.

Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation: a Cochrane Systematic Review

Difficulties with tracheal intubation commonly arise and impact patient safety. This systematic review evaluates whether videolaryngoscopes reduce intubation failure and complications compared with direct laryngoscopy in adults. We searched CENTRAL, MEDLINE, Embase and clinicaltrials.gov up to February 2015, and conducted forward and backward citation tracking. We included randomized controlled trials that compared adult patients undergoing laryngoscopy with videolaryngoscopy or Macintosh laryngoscopy. We did not primarily intend to compare individual videolaryngoscopes. Sixty-four studies (7044 participants) were included. Moderate quality evidence showed that videolaryngoscopy reduced failed intubations (Odds Ratio (OR) 0.35, 95% Confidence Interval (CI) 0.19-0.65) including in participants with anticipated difficult airways (OR 0.28, 95% CI 0.15-0.55). There was no evidence of reduction in hypoxia or mortality, but few studies reported these outcomes. Videolaryngoscopes reduced laryngeal/airway trauma (OR 0.68, 95% CI 0.48-0.96) and hoarseness (OR 0.57, 95% CI 0.36-0.88). Videolaryngoscopy increased easy laryngeal views (OR 6.77, 95% CI 4.17-10.98) and reduced difficult views (OR 0.18, 95% CI 0.13-0.27) and intubation difficulty, typically using an 'intubation difficulty score' (OR 7.13, 95% CI 3.12-16.31). Failed intubations were reduced with experienced operators (OR 0.32, 95% CI 0.13-0.75) but not with inexperienced users. We identified no difference in number of first attempts and incidence of sore throat. Heterogeneity around time for intubation data prevented meta-analysis. We found evidence of differential performance between different videolaryngoscope designs. Lack of data prevented analysis of impact of obesity or clinical location on failed intubation rates. Videolaryngoscopes may reduce the number of failed intubations, particularly among patients presenting with a difficult airway. They improve the glottic view and may reduce laryngeal/airway trauma. Currently, no evidence indicates that use of a videolaryngoscope reduces the number of intubation attempts or the incidence of hypoxia or respiratory complications, and no evidence indicates that use of a videolaryngoscope affects time required for intubation.

Ultrasound measurement of anterior neck soft tissue and tongue thickness to predict difficult laryngoscopy - An observational analytical study

Background and Aims:

Airway ultrasound is an emerging tool to predict difficult laryngoscopy. This study aimed to determine the utility of ultrasound measurement of the anterior soft tissue neck thickness at the level of hyoid, thyrohyoid membrane and thickness of tongue to predict difficult laryngoscopy and compare them with clinical parameters for airway assessment.

Methods:

The distance from skin to hyoid bone, skin to the thyrohyoid membrane in neutral and sniffing position and maximum tongue thickness was measured by ultrasound and correlated with Cormack Lehane (CL) laryngoscope view in 310 adult surgical patients. Receiver operating characteristic curve was plotted and the area under the curve was calculated for each parameter. The sensitivity and specificity of ultrasound-guided parameters were compared with clinical parameters like the inter-incisor gap, modified Mallampatti classification, thyromental, sternomental distance and neck circumference.

Results:

Incidence of difficult laryngoscopy (CL grade-III and IV) was 11.3%. A significant difference was observed in the ultrasound parameters between the easy and difficult laryngoscopy (P-value = 0.001). Sensitivity and specificity to predict difficult airway was 69.6% and 77% for tongue thickness, 68% and 73% for the skin to hyoid bone distance in a neutral position and found to be higher than clinical parameters.

Conclusion:

The ultrasound measurements of soft tissue thickness of the anterior neck and tongue thickness along with the clinical assessment of airway can be useful in predicting difficult laryngoscopy.

[Management of the difficult airway : Overview of the current guidelines]

Several national airway task forces have recently updated their recommendations for the management of the difficult airway in adults. Routinely responding to airway difficulties with an algorithm-based strategy is consistently supported. The focus is increasingly not on tools and devices but more on good planning, preparation and communication. In the case of anticipated airway difficulties the airway should be secured when the patient is awake with maintenance of spontaneous ventilation. Unaltered a flexible bronchoscopic intubation technique is advised as a standard of care in such patients. The importance of maintenance of oxygenation is emphasized. Face mask ventilation and the use of supraglottic devices are recommended if unexpected airway difficulties occur. Face mask ventilation may be facilitated and optimised by early administration of neuromuscular blocking agents. If required, in not fastened patients threatened by acute hypoxia, carefully applied and pressure-controlled ventilation may ensure sufficient oxygenation until the airway is secured. Apnoeic oxygen techniques are recommended in high-risk patients and to relieve the time pressure of falling oxygen saturation during decision-making processes. The early use of video laryngoscopy is advised for endotracheal intubation in the case of failed direct laryngoscopy or if intubation is expected to be difficult. For the coverage of cannot intubate-cannot oxygenate scenarios, second generation supraglottic devices and invasive airway access are advocated. The discussion regarding the optimal technique for emergency invasive airway access is still in progress. In the case of uncontrollable respiratory deterioration and progressive hypoxia, the algorithm must be consistently executed and without delay due to ineffective activities (straightforward strategy). Although there is no evidence to support the selection of a particular approach, the importance and the need for a defined airway concept/algorithm in any anesthesia department is fostered. Simplicity and clarity are essential for recall under stressful and time-sensitive conditions. The algorithm should be adapted to local conditions and preferences and devices should be limited to a definite number. The acquisition and maintenance of expertise by education and training is demanded.

Is obstructive sleep apnea associated with difficult airway? Evidence from a systematic review and meta-analysis of prospective and retrospective cohort studies

BACKGROUND

Difficult airway management and obstructive sleep apnea may contribute to increased risk of perioperative morbidity and mortality. The objective of this systematic review and meta-analysis (SRMA) is to evaluate the evidence of a difficult airway being associated with obstructive sleep apnea (OSA) patients undergoing surgery.

METHODS

The standard databases were searched from 1946 to April 2017 to identify the eligible articles. The studies which included adult surgical patients with either suspected or diagnosed obstructive sleep apnea must report at least one difficult airway event [either difficult intubation (DI), difficult mask ventilation (DMV), failed supraglottic airway insertion or difficult surgical airway] in sleep apnea and non-sleep apnea patients were included.

RESULTS

Overall, DI was 3.46-fold higher in the sleep apnea vs non-sleep apnea patients (OSA vs. non-OSA: 13.5% vs 2.5%; OR 3.46; 95% CI: 2.32-5.16, p <0.00001). DMV was 3.39-fold higher in the sleep apnea vs non-sleep apnea patients (OSA vs. non-OSA: 4.4% vs 1.1%; OR 3.39; 95% CI: 2.74-4.18, p <0.00001). Combined DI and DMV was 4.12-fold higher in the OSA vs. non-OSA patients (OSA vs. non-OSA: 1.1% vs 0.3%; OR 4.12; 95% CI: 2.93-5.79, p <0.00001). There was no significant difference in the supraglottic airway failure rates in the sleep apnea vs non-sleep apnea patients (OR: 1.34; 95% CI: 0.70-2.59; p = 0.38). Meta-regression to adjust for various subgroups and baseline confounding factors did not impact the final inference of our results.

CONCLUSION

This SRMA found that patients with obstructive sleep apnea had a three to four-fold higher risk of difficult intubation or mask ventilation or both, when compared to non-sleep apnea patients.

Effectiveness and Safety of a Novel Approach for Management of Patients with Potential Difficult Mask Ventilation and Tracheal Intubation: A Multi-center Randomized Trial

Background:

Patients with potential difficult mask ventilation (DV) and difficult intubation (DI) are often managed with awake intubation, which can be stressful for patients and anesthesiologists. This prospective randomized study evaluated a new approach, fast difficult airway evaluation (FDAE). We hypothesized that the FDAE approach would reduce the need for awake intubation.

Methods:

After obtaining informed consent, 302 patients with potential DV/DI undergoing elective surgeries were randomly assigned to the FDAE group (Group E) and the control group (Group C). In Group E, patients were gradually sedated, and adequacy of manual mask ventilation during spontaneous breathing was assessed at various sedation levels. Awake intubation was applied in those with inadequate mask ventilation. In Group C, DI was evaluated under local anesthesia. However, the care team could intubate under general anesthesia if the vocal cords were visible. The primary outcome was the rate of awake intubations in both groups and the induction efficiency assessed by the induction time. The secondary outcome was the incidence of serious complications.

Results:

The rate of awake intubation was significantly lower in Group E than that in Group C (5.81% vs. 36.05%, χ² = 42.3, P < 0.001). The induction time was much shorter in Group E than in Group C (11.85 ± 4.82 min vs. 18.71 ± 7.85 min, t = 5.39, P < 0.001). There was no significant difference in the incidence of intubation related complications between the two groups. Patients in Group E had a much lower incidence of recall (9.68% vs. 44.90%, χ² = 47.68, P < 0.001) of the induction process and higher satisfaction levels than patients in Group C (t = 15.36, P < 0.001).

Conclusions:

The FDAE significantly reduces the need for awake intubation and improves the efficiency of the intubation process without comprising safety in patients with potential difficult mask ventilation and DI.

Trial Registration:

No. ChiCTR-TRC-11001418; http://www.gctr.org/cn/proj/show.aspx?proj=1562.

Video Laryngoscopy or Macintosh Laryngoscopy: Which One Is More Successful in Patients With Bilateral Mandibular Fractures?

PURPOSE

Successful intubation is challenging in patients with bilateral mandibular fractures. The aim of this study was to compare the video laryngoscope (VL) with the Macintosh laryngoscope (ML) for intubation of patients with bilateral mandibular fractures.

MATERIALS AND METHODS

In this randomized controlled trial study, patients who had bilateral mandibular fractures (angle or subcondylar) were studied. Patients were randomly assigned to 1 of 2 groups using computerized randomization. Laryngoscopy was performed by the ML in group 1 and the VL in group 2. Intubation device (ML or VL) was the predictive factor of the study and age, maximum mouth opening (MMO), incisor fracture, and gender were the variables. Intubation time and successful intubation at the first attempt were the study outcomes. Independent t test was applied to compare intubation time, MMO, and age between the 2 groups.

RESULTS

Seventy-eight patients were studied (40 in group 1 and 38 in group 2). Mean intubation time was 33.02 ± 9.68 seconds in group 1 and 39.16 ± 7.40 seconds in group 2. Comparison of the data showed a significant difference between the 2 groups (P = .002). Twenty-four patients in group 1 and 31 in group 2 were successfully intubated at the first attempt. There was a significant difference in the number of successful or failed intubation attempts between the 2 groups (P = .03).

CONCLUSION

According to the present findings, use of the VL increased the first-attempt success rate of intubation in patients with bilateral mandibular fractures. Time of intubation could be longer when using the VL than when using the ML.