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

Awake Tracheal Intubation Is Associated with Fewer Adverse Events in Critical Care Patients than Anaesthetised Tracheal Intubation

BACKGROUND

Tracheal intubation in critical care is a high-risk procedure requiring significant expertise and airway strategy modification. We hypothesise that awake tracheal intubation is associated with a lower incidence of severe adverse events compared to standard tracheal intubation in critical care patients.

METHODS

Records were acquired for all tracheal intubations performed from 2020 to 2022 for critical care patients at a tertiary hospital. Each awake tracheal intubation case, using a videolaryngoscope with a hyperangulated blade (McGrath® MAC X-Blade), was propensity matched with two controls (1:2 ratio; standard intubation videolaryngoscopy (VL) and direct laryngoscopy (DL) undergoing general anaesthesia). The primary endpoint was the incidence of adverse events, defined as a mean arterial pressure of <55 mmHg (hypotension), SpO2 < 80% (desaturation) after sufficient preoxygenation, or peri-interventional cardiac arrest.

RESULTS

Of the 135 tracheal intubations included for analysis, 45 involved the use of an awake tracheal intubation. At least one adverse event occurred after tracheal intubation in 36/135 (27%) of patients, including awake 1/45 (2.2%; 1/1 hypotension), VL 10/45 (22%; 6/10 hypotension and 4/10 desaturation), and DL 25/45 (47%; 10/25 hypotension, 12/25 desaturation, and 3/25 cardiac arrest; p < 0.0001).

CONCLUSIONS

In this retrospective observational study of intubation practices in critical care patients, awake tracheal intubation was associated with a lower incidence of severe adverse events than anaesthetised tracheal intubation.

The new prognostic factor in pre-intubation follow-up of critically ill patients: integrated pulmonary index monitoring

OBJECTIVE

The objective of this study was to identify the integrated pulmonary index in the follow-up of non-intubated critically ill patients in the emergency department and its efficacy in deciding on advanced airway application in comparison with the Glasgow Coma Scale.

METHODS

This is a prospective, single-center, methodological study. In our study, we recorded the demographic characteristics, Glasgow Coma Scale, and the integrated pulmonary index of 90 patients with respiratory failure who were followed up in the emergency department between June 1, 2019 and September 1, 2019, and we compared the results of Glasgow Coma Scale and integrated pulmonary index in making the endotracheal intubation decision.

RESULTS

Endotracheal intubation was applied to 30% of the 90 patients included in the study. The area under the curve was calculated as 0.906 for integrated pulmonary index and 0.860 for Glasgow Coma Scale in predicting endotracheal intubation. There was no significant difference between the area under the curves of integrated pulmonary index and Glasgow Coma Scale. According to the best cutoff values determined in the estimation of endotracheal intubation, sensitivity was 74.07% and specificity was 95.24% for integrated pulmonary index, and sensitivity was 74.07% and specificity was 85.71% for Glasgow Coma Scale.

CONCLUSION

The integrated pulmonary index monitoring provides an objective evaluation in the follow-up of critically ill patients with spontaneous breathing in the emergency department and is predictive in deciding on timely endotracheal intubation.

Tongue retraction using a McIvor blade improves airway condition during fiberoptic intubation: a randomized controlled trial

Airway clearance is crucial for successful fiberoptic intubation. We hypothesized that tongue retraction using a McIvor blade could facilitate fiberoptic intubation. This randomized clinical trial aimed to compare intubation time and airway condition between the jaw thrust maneuver and tongue retraction with the McIvor blade during fiberoptic intubation. Ninety-four adult patients scheduled for elective surgery were randomly assigned to one of two groups. During fiberoptic intubation, airway clearance was secured by applying the jaw-thrust maneuver (J group) or by tongue retraction using the McIvor blade (M group). We assessed the total intubation time, number of attempts for tube advancement, and airway clearance at the soft palate and epiglottis levels. The total intubation time was significantly shorter in the M group than in the J group (p = 0.035). The number of attempts to advance the tube was significantly lower in the M group (p = 0.033). Airway clearance at the soft palate level was significantly better in the M group than in the J group (p = 0.027). Retracting the tongue with the McIvor blade demonstrated a better condition for fiberoptic intubation and shortened total intubation time compared with the jaw-thrust maneuver.Clinicalregistiration: CRIS; http://cris.nih.go.kr (KCT0002392) registered 28/07/2017.

A quasi-experimental study of fresh oxygen flow on patients' oxygen reserve during mask-assisted ventilation under general anesthesia induction

Background

To compare the effect of different amounts of fresh oxygen flow on oxygen reserve in patients undergoing general anesthesia.

Methods

Seventy-two patients were enrolled in this quasi-experimental study. Patients were randomly divided into experimental groups with a fresh oxygen flow of 1 L/min, 2 L/min, 4 L/min, and 8 L/min (denoted as G1, G2, G3, and G4, respectively) for 2 min of mask-assisted ventilation. Safe apnea time (SAT) was the primary endpoint; SAT was defined as the time from the cessation of ventilation to the time the patient's pulse oxygen saturation (SpO2) decreased to 90%. Ventilation indicators such as end-tidal oxygen concentration (EtO2), end-tidal carbon dioxide partial pressure (EtCO2), SpO2, and carbon dioxide (CO2) elimination amount, during mask-assisted ventilation, were the secondary endpoints.

Results

The SAT of G1, G2, G3, and G4 were 305.1 ± 97.0 s, 315 ± 112.5 s, 381.3 ± 118.6 s, and 359 ± 104.4 s, respectively (p > 0.05). The EtO2 after 2 min of mask-assisted ventilation in groups G1, G2, G3, and G4 were 69.7 ± 8.8%, 75.2 ± 5.0%, 82.5 ± 3.3%, and 86.8 ± 1.5%, respectively (p < 0.05). Also, there was a moderate positive correlation between the fresh oxygen flow and EtO2 (correlation coefficient r = 0.52, 95% CI 0.31-0.67, p < 0.0001). The CO2 elimination in the G1 and G2 groups was greater than that in the G4 group (p < 0.05). There was no significant difference in other indicators among the groups (all p > 0.05).

Conclusion

The amount of fresh oxygen flow during mask-assisted ventilation was positively correlated with EtO2. Also, even though there was no significant difference, the patients' oxygen reserves increased with the increase in fresh oxygen flow.

Development and validation of a regression model with nomogram for difficult video laryngoscopy in Chinese population: a prospective, single-center, and nested case-control study

Background

Airway management failure is associated with increased perioperative morbidity and mortality. Airway-related complications can be significantly reduced if difficult laryngoscopy is predicted with high accuracy. Currently, there are no large-sample studies on difficult airway assessments in Chinese populations. An airway assessment model based on the Chinese population is urgently needed to guide airway rescue strategy.

Methods

This prospective nested case-control study took place in a tertiary hospital in Shanghai, China. Information on 10,549 patients was collected, and 8,375 patients were enrolled, including 7,676 patients who underwent successful laryngoscopy and 699 patients who underwent difficult laryngoscopy. The baseline characteristics, medical history, and bedside examinations were included as predictor variables. Laryngoscopy was defined as 'successful laryngoscopy' based on a Cormack-Lehane Grades of 1-2 and as 'difficult laryngoscopy' based on a Cormack-Lehane Grades of 3-4. A model was developed by incorporating risk factors and was presented in the form of a nomogram by univariate logistic regression, least absolute shrinkage and selection operator, and stepwise logistic regression. The main outcome measures were area under the curve (AUC), sensitivity, and specificity of the predictive model.

Result

The AUC value of the prediction model was 0.807 (95% confidence interval [CI]: 0.787-0.828), with a sensitivity of 0.730 (95% CI, 0.690-0.769) and a specificity of 0.730 (95% CI, 0.718-0.742) in the training set. The AUC value of the prediction model was 0.829 (95% CI, 0.800-0.857), with a sensitivity of 0.784 (95% CI, 0.73-0.838) and a specificity of 0.722 (95% CI, 0.704-0.740) in the validation set.

Conclusion

Our model had accurate predictive performance, good clinical utility, and good robustness for difficult laryngoscopy in the Chinese population.

Videolaryngoscopy in critical care and emergency locations: moving from debating benefit to implementation

The recently published INTUBE study subanalysis and DEVICE trial findings both demonstrate a clear benefit of videolaryngoscopy over direct laryngoscopy in facilitating tracheal intubation of patients in the emergency department and ICU. We consider the increasing evidence supporting the use of videolaryngoscopy, the possible reasons behind its relatively slow adoption into clinical practice, and the potential role of the hyperangulated videolaryngoscope blade. We discuss the significance of improved first-pass tracheal intubation success in reducing the overall risk of complications in critically ill patients. Additionally, we address the need for specific training in videolaryngoscopy in order to maximise patient benefit, and propose that adequate training and rehearsal opportunities in videolaryngoscopy can only be realised by widespread and regular use wherever the clinical setting.

A prospective observational study of recall of discomfort on tracheal extubation after general anaesthesia

Background

Tracheal extubation is a critical stage in the management of general anaesthesia during which serious complications may occur. Immediately before extubation, patients often exhibit signs that suggest that they are awake and experiencing discomfort. There is concern that patients may retain such memories of the extubation process. However, previous studies have not examined patient recall of extubation in detail. We therefore investigated the frequency of recall of discomfort during extubation, as well as first orientation to place, and other recollections upon emerging from general anaesthesia.

Methods

In a prospective observational study, 818 patients were interviewed during routine post-anaesthesia rounds on the day after general anaesthesia. The primary outcome was the proportion of patients recalling discomfort during extubation. The secondary outcome was the location of orientation to place upon emerging from general anaesthesia.

Results

Recall of discomfort during extubation was uncommon, at 1.1% (n=9; 95% confidence interval [CI]: 0.5-2.1%). Only 3.1% of patients recalled the extubation process at all (n=25; 95% CI: 2.0-4.5%). The first orientation to place was most commonly in transit to a ward, in 41% of cases (n=337; 95% CI: 38-45%).

Conclusions

Recall of discomfort during extubation appears to be rare, and the great majority of patients may not retain any memory of the extubation process. This information may be used to reassure patients and guide extubation practices for anaesthetists.

Clinical trial registration

UMIN Clinical Trials Registry (UMIN000046136).

Current practice pattern among anaesthesiologists for difficult airway management: A nationwide cross-sectional survey

Background and Aims

The practice patterns for airway management vary among anaesthesiologists, depending on various setups and geographical divides. This survey assessed practice patterns in unanticipated difficult intubation and cannot intubate or cannot ventilate (CICV) situations/complete ventilation failure among Indian anaesthesiologists'.

Methods

A validated questionnaire of 22 items related to practice preferences for airway management among anaesthesiologists was sent to Indian Society of Anaesthesiologists members online through Google Forms and distributed manually to delegates in continuing medical education programme.

Results

A total of 535 responses were obtained and analysed. In unanticipated difficult laryngoscopy and intubation, the order of preference for alternative airway devices was video laryngoscope (VL, 60.1%), intubating laryngeal mask airway/laryngeal mask airway (23.5%), fibreoptic bronchoscope (13.5%) and optical stylets (1.2%). Advanced difficult airway devices were unavailable in most nursing homes and government non-teaching hospitals. Seventy per cent of respondents experienced CICV situations at least once, most during head and neck surgeries. In CICV situations, the order of choice for the front-of-neck airway access was cricothyroidotomy (CT) by narrow bore cannula (48.9%), tracheostomy by the surgeon (30%), Seldinger CT (12.5%), open surgical CT (5.4%) and scalpel bougie CT (3.2%).

Conclusion

The VL was the most preferred airway rescue device in unanticipated difficult intubation, and intravenous catheter cricothyroidotomy was the most selected technique in CICV situations.

Upper airway angle and glottic height: a prospective cohort to evaluate two new features for airway prediction

BACKGROUND

Predicting difficult direct laryngoscopies remains challenging and improvements are needed in preoperative airway assessment. We conceived two new tests (the upper airway angle and the glottic height) and assessed their association with difficult direct laryngoscopies as well as their predictive performance.

METHODS

A prospective cohort was conducted with 211 patients undergoing general anesthesia for surgical procedures. We assessed the association between difficult laryngoscopies and modified Mallampati Test (MMT), Upper Lip Bite Test (ULBT), Mandibular Length (ML), Neck Circumference (NC), Mouth Opening (MO), Sternomental Distance (SMD), Thyromental Distance (TMD), Upper Airway Angle (UAA), and Glottic Height (GH). We also estimated their predictive values.

RESULTS

Difficult laryngoscopy was presented by 12 patients (5.7%). Six tests were significantly associated with difficult laryngoscopies and their area under the ROC curve, and 95% CIs were as follows: UAA = 88.82 (81.86-95.78); GH = 86.43 (72.67-100); ML = 83.75 (72.77-94.74); NC = 79.17 (64.98-93.36); MO = 65.58 (45.13-86.02); and MMT = 77.89 (68.37-87.41).

CONCLUSION

We have found two new features (the UAA and the GH) to be significantly associated with the occurrence of difficult direct laryngoscopies. They also presented the best predictive performance amongst the nine evaluated tests in our cohort of patients. We cannot ensure, however, these tests to be superior to other regularly used bedside tests based on our estimated 95% CIs.

Preoperative airway ultrasound assessment in the sniffing position: a prospective observational study

BACKGROUND

Clinical airway screening tests intend to predict difficult airways, but none have a high predictive value. Recent systematic reviews correlate ultrasound with difficult laryngoscopy. This study aimed primarily to correlate ultrasound measurements of anatomical upper airway structures in the sniffing position with difficult direct laryngoscopy. The secondary aim was to observe gender-based differences.

METHODS

This prospective, cross-sectional, single-center observational study included 209 patients requiring general anesthesia for elective surgery. Preoperatively, we performed six clinical airway assessments and three ultrasound measurements, which were the Distance from Skin to the Hyoid Bone (DSHB), to the Epiglottis (DSE), and to the anterior commissure of the vocal cords (DSAC) in a sniffing position. Benumof's criteria for the "best view at the first attempt" for direct laryngoscopy assessed the difficulty of laryngoscopy.

RESULTS

The distance from skin to the epiglottis was the best predictor of direct difficult laryngoscopy (defined as Cormack-Lehane grade ≥ 2b) with a minimum thickness cut-off at 2.70 ± 0.19 cm (sensitivity 91.3%; specificity 96.9%). The skin to the hyoid bone distance cut-off was 1.41 ± 0.30 cm with moderate correlation (sensitivity 80.4%; specificity 60.1%). No correlation was found for the distance to the anterior commissure of the vocal cords. In women compared to men, the skin to the epiglottis distance was more sensitive (92.3% vs. 90.9%) and specific (98.8% vs. 95.2%).

CONCLUSIONS

DSE in the sniffing position is the most reliable parameter for preoperative airway ultrasound assessment in the Caucasian population, with higher sensitivity and specificity in women, and might be considered as an independent predictor for direct difficult laryngoscopy.

Comparison of Clinical Performance of C-MAC Video Laryngoscope Guided vs Blind Placement of I-Gel® in Paediatric Patients: A Randomized Controlled Open-Label Trial

Objective

Placement of the supraglottic airway devices under direct vision has been shown to decrease the incidence of malposition in adults. This study was designed to compare the clinical performance of C-MAC guided and blind placement of i-gel® in paediatric patients.

Methods

The present prospective, randomized controlled study was conducted on 102 paediatric patients scheduled to undergo elective infraumbilical surgeries under general anaesthesia. Patients were randomly divided into group "B" (blind) and group "C" (C-MAC) based on the technique used for placement of i-gel®. The primary objective of the study was to compare the incidence of malposition based on the fiberoptic bronchoscope (FOB) score of the glottic view. Oropharyngeal leak pressure (OPLP), hemodynamic parameters, and insertion characteristics (time taken to insert and the number of attempts) were secondary objectives. Categorical data were presented as ratio or percentage and continuous data were presented as mean ± standard deviation or median [95% confidence interval (CI)].

Results

The incidence of malposition (Brimacombe score 1 or 2) was significantly lower in group C compared to group B (7.8% vs 49% respectively) (P < 0.001); implying a relative risk reduction of 2.42 (95% CI 1.72 to 3.40) with C-MAC. On FOB assessment, the median (interquartile range) Brimacombe score was significantly better in group C [4 (4-4)] compared to group B [3 (2-3)] (P < 0.001). The OPLP was significantly higher in group C compared to group B. Other insertion characteristics were comparable in both the study groups.

Conclusion

Compared to blind placement, C-MAC guided placement ensures proper alignment of i-gel® with periglottic structures and proper functioning of i-gel®.

Geometric morphometrics and machine learning from three-dimensional facial scans for difficult mask ventilation prediction

Background

Unanticipated difficult mask ventilation (DMV) is a potentially life-threatening event in anesthesia. Nevertheless, predicting DMV currently remains a challenge. This study aimed to verify whether three dimensional (3D) facial scans could predict DMV in patients scheduled for general anesthesia.

Methods

The 3D facial scans were taken on 669 adult patients scheduled for elective surgery under general anesthesia. Clinical variables currently used as predictors of DMV were also collected. The DMV was defined as the inability to provide adequate and stable ventilation. Spatially dense landmarks were digitized on 3D scans to describe sufficient details for facial features and then processed by 3D geometric morphometrics. Ten different machine learning (ML) algorithms, varying from simple to more advanced, were introduced. The performance of ML models for DMV prediction was compared with that of the DIFFMASK score. The area under the receiver operating characteristic curves (AUC) with its 95% confidence interval (95% CI) as well as the specificity and sensitivity were used to evaluate the predictive value of the model.

Results

The incidence of DMV was 35/669 (5.23%). The logistic regression (LR) model performed best among the 10 ML models. The AUC of the LR model was 0.825 (95% CI, 0.765-0.885). The sensitivity and specificity of the model were 0.829 (95% CI, 0.629-0.914) and 0.733 (95% CI, 0.532-0.819), respectively. The LR model demonstrated better predictive performance than the DIFFMASK score, which obtained an AUC of 0.785 (95% CI, 0.710-0.860) and a sensitivity of 0.686 (95% CI, 0.578-0.847). Notably, we identified a significant morphological difference in the mandibular region between the DMV group and the easy mask ventilation group.

Conclusion

Our study indicated a distinct morphological difference in the mandibular region between the DMV group and the easy mask ventilation group. 3D geometric morphometrics with ML could be a rapid, efficient, and non-invasive tool for DMV prediction to improve anesthesia safety.

Left Head Rotation as an Alternative to Difficult Tracheal Intubation: Randomized Open Label Clinical Trial

BACKGROUND

Tracheal intubation is a life-saving intervention, and optimizing the patient's head and neck position for the best glottic view is a crucial step that accelerates the procedure. The left head rotation maneuver has been recently described as an innovative alternative to the traditional sniffing position used for tracheal intubation with marked improvement in glottic visualization.

OBJECTIVE

This study compared the glottic view and intubating conditions in the sniffing position versus left head rotation during direct laryngoscopy.

METHODS

This randomized, open-label clinical trial enrolled 52 adult patients admitted to Baguio General Hospital and Medical Center from September 2020 to January 2021 for an elective surgical procedure requiring tracheal intubation under general anesthesia. Intubation was done using a 45° left head rotation in the experimental group (n=26), while the control group (n=26) was intubated using the conventional sniffing position. Glottic visualization and intubation difficulty with the two procedures were assessed using the Cormack-Lehane grade and Intubation Difficulty Scale, respectively. Successful intubation is measured by observing a capnographic waveform in the end-tidal CO2 monitor after placement of the endotracheal tube.

RESULTS

There was no statistically significant difference in the Cormack-Lehane grade, with 85% (n=44) of patients classified under grades 1 (n=11 and n=15) and 2 (n=11 and n=7) in the left head rotation and sniffing position groups, respectively. In addition, there were no statistically significant differences in the Intubation Difficulty Scale scores of patients intubated with left head rotation or sniffing position; 30.7% (n=8) of patients in both groups were easily intubated, while 53.8% (n=14) in left head rotation and 57.6% (n=15) in sniffing position groups were intubated with slight difficulty. Similarly, there were no significant differences between the 2 techniques in any of the 7 parameters of the Intubation Difficulty Scale, although numerically fewer patients required the application of additional lifting force (n=7, 26.9% vs n=11, 42.3%) or laryngeal pressure (n=3, 11.5% vs n=7, 26.9%) when intubated with left head rotation. The intubation success rate with left head rotation was 92.3% versus 100% in the sniffing position, but this difference was not statistically significant.

CONCLUSIONS

Left head rotation produces comparable laryngeal exposure and intubation ease to the conventional sniffing position. Therefore, left head rotation may be an alternative for patients who cannot be intubated in the sniffing position, especially in hospitals where advanced techniques such as video laryngoscopes and flexible bronchoscopes are unavailable, as is the case in this study. However, since our sample size was small, studies with a larger study population are warranted to establish the generalizability of our findings. In addition, we observed inadequate familiarity among anesthesiologists with the left head rotation technique, and the intubation success rate may improve as practitioners attain greater technical familiarization.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial Number (ISRCTN)ISRCTN23442026; https://www.isrctn.com/ISRCTN23442026.

Glidescope Video Laryngoscopy in Patients with Severely Restricted Mouth Opening-A Pilot Study

BACKGROUND

An inter-incisor gap <3 cm is considered critical for videolaryngoscopy. It is unknown if new generation GlideScope Spectrum™ videolaryngoscopes with low-profile hyperangulated blades might facilitate safe tracheal intubation in these patients. This prospective pilot study aims to evaluate feasibility and safety of GlideScopeTM videolaryngoscopes in severely restricted mouth opening.

METHODS

Feasibility study in 30 adults with inter-incisor gaps between 1.0 and 3.0 cm scheduled for ENT or maxillofacial surgery. Individuals at risk for aspiration or rapid desaturation were excluded.

RESULTS

The mean mouth opening was 2.2 ± 0.5 cm (range 1.1-3.0 cm). First attempt success rate was 90% and overall success was 100%. A glottis view grade 1 or 2a was achieved in all patients. Nasotracheal intubation was particularly difficult if Magill forceps were required (n = 4). Intubation time differed between orotracheal (n = 9; 33 (25; 39) s) and nasotracheal (n = 21; 55 (38; 94) s); p = 0.049 intubations. The airway operator's subjective ratings on visual analogue scales (0-100) revealed that tube placement was more difficult in individuals with an inter-incisor gap <2.0 cm (n = 10; 35 (29; 54)) versus ≥2.0 cm (n = 20; 20 (10; 30)), p = 0.007, while quality of glottis exposure did not differ.

CONCLUSIONS

GlidescopeTM videolaryngoscopy is feasible and safe in patients with severely restricted mouth opening if given limitations are respected.

Expanding scope of Kirkpatrick model from training effectiveness review to evidence-informed prioritization management for cricothyroidotomy simulation

Modified Kirkpatrick model has been adopted to evaluate training effectiveness by 6 categories, including activity accounting (training objectives/success in organization change) at Level-0, reaction (satisfaction) at Level-1, learning (acquisition of surgical airway skills) at Level-2, behavior (post-training change in personal strengths) at Level-3, result (organizational or clinical outcomes) at Level-4, and Return on Investment (ROI) or Expectation (ROE) (monetary and societal values following training and other quality and safety related measures) at Level-5. The purpose of this hospital-based prospective observational study was twofold: i) To evaluate potential impacts on monetary and societal values and successful organization change following implementation of advanced Cricothyroidotomy simulator and standardized curriculum in healthcare simulation training, ii) To inform decisions of resource allocation by reviewing overall values and prioritization strategies for i) general surgeon/emergency physician ii) with seniority >5 years and iii) prior porcine training experience based on findings at Kirkpatrick Level-0, Level-4, and Level-5. Seventy doctors and 10 nurses completed Cricothyroidotomy training and follow-up questionnaires within 2021/22. All training usability scoring measured by Scales of Emergency Surgical Airway Simulator (SESAS-17) achieved over 4 out of 5 (Level-4) with effects in favor of emergency physicians or general surgeons (p < .5), regardless of seniority and prior training experience. Success in organization change (Level-0) and cost-effectiveness (Level-5) were hypothetically established using theoretical framework of Gleicher's formula and Roger's Diffusion of Innovation Theory. Overall training effectiveness, in terms of advantage in usability, cost-benefits and successful organizational changes, provided sound evidence to support continuous investment of new curriculum and innovative simulator and "Surgeon-and-emergency-physician-first" policy when it comes to resources allocation strategies for Cricothyroidotomy training. [ACGME competencies: Practice Based Learning and Improvement, Systems Based Practice.].

Are we talking about practice? A randomized study comparing simulation-based deliberate practice and mastery learning to self-guided practice

OBJECTIVES

Simulation-based technical skills training is now ubiquitous in medicine, particularly for high acuity, low occurrence (HALO) procedures. Mastery learning and deliberate practice (ML + DP) are potentially valuable educational methods, however, they are resource intensive. We sought to compare the effect of deliberate practice and mastery learning versus self-guided practice on skill performance of the rare, life-saving procedure, a bougie-assisted cricothyroidotomy (BAC).

METHODS

We conducted a multi-center, randomized study at five North American emergency medicine (EM) residency programs. We randomly assigned 176 EM residents to either the ML + DP or self-guided practice groups. Three blinded airway experts independently evaluated BAC skill performance by video review before (pre-test), after (post-test) and 6-12 months (retention) after the training session. The primary outcome was post-test skill performance using a global rating score (GRS). Secondary outcomes included performance time and skill performance at the retention test.

RESULTS

Immediately following training, GRS scores were significantly higher as mean performance improved from pre-test, (22, 95% CI = 21-23) to post-test (27, 95% CI = 26-28), (p < 0.001) for all participants. However, there was no difference between the groups on GRS scores (p = 0.2) at the post-test or at the retention test (p = 0.2). At the retention test, participants in the ML + DP group had faster performance times (66 s, 95% CI = 57-74) compared to the self-guided group (77 s, 95% CI = 67-86), (p < 0.01).

CONCLUSIONS

There was no significant difference in skill performance between groups. Residents who received deliberate practice and mastery learning demonstrated an improvement in skill performance time.

Retention of emergency cricothyroidotomy skills: A multicenter randomized controlled trial

Objectives

Emergency cricothyroidotomy is the final approach to establishing a secure airway. The procedure is acute and highly infrequent, making it difficult to achieve and maintain competence in the clinic. Simulation-based training in emergency cricothyroidotomy is effective but it is unknown how often training should be repeated to maintain skills. This study aimed to assess novices' retention of technical skills in emergency cricothyroidotomy after completing SBT.

Methods

Novices in emergency cricothyroidotomy completed a structured, simulation-based training program and were randomized to retention tests after 1, 3, or 6 months. Participants completed two emergency cricothyroidotomy tests at end-of-training and follow-up retention testing. Test performances were video recorded and evaluated by two experienced blinded raters using a structured assessment tool. Differences in the performances and the pass/fail rates were analyzed.

Results

Eighty-two medical students from two different Danish universities were included from April 2021 to February 2022. Paired t-tests showed skills decay significantly after 1 month (mean loss 6.7 points, p < 0.001). The mean loss of points, representing the difference in global score points, from the end-of-training to retention test was 6.7 points (95% confidence interval [CI] 4.5-8.8) for the 1-month group, 8.2 points (95% CI 5.8-10.0) for the 3-months group, and 9.9 points (95% CI 8.1-11.7) for the 6-months group. Six participants in both the 1-month group (23.1%) and the 3-month group (24%) passed the first retention test, but no one in the 6-months group had a passing performance.

Conclusions

Novices' technical skills performance in emergency cricothyroidotomy decay significantly already after 1 month. This initial loss of skill seems to be stable until 3 months, after which there is a further significant loss of skills. Recurring training should be implemented for the benefit of patient safety and outcomes.

Consensus Guidelines for Perioperative Care for Emergency Laparotomy Enhanced Recovery After Surgery (ERAS®) Society Recommendations Part 2-Emergency Laparotomy: Intra- and Postoperative Care

BACKGROUND

This is Part 2 of the first consensus guidelines for optimal care of patients undergoing emergency laparotomy (EL) using an Enhanced Recovery After Surgery (ERAS) approach. This paper addresses intra- and postoperative aspects of care.

METHODS

Experts in aspects of management of high-risk and emergency general surgical patients were invited to contribute by the International ERAS® Society. PubMed, Cochrane, Embase, and Medline database searches were performed for ERAS elements and relevant specific topics. Studies on each item were selected with particular attention to randomized clinical trials, systematic reviews, meta-analyses, and large cohort studies and reviewed and graded using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. Recommendations were made on the best level of evidence, or extrapolation from studies on elective patients when appropriate. A modified Delphi method was used to validate final recommendations. Some ERAS® components covered in other guideline papers are outlined only briefly, with the bulk of the text focusing on key areas pertaining specifically to EL.

RESULTS

Twenty-three components of intraoperative and postoperative care were defined. Consensus was reached after three rounds of a modified Delphi Process.

CONCLUSIONS

These guidelines are based on best available evidence for an ERAS® approach to patients undergoing EL. These guidelines are not exhaustive but pull together evidence on important components of care for this high-risk patient population. As much of the evidence is extrapolated from elective surgery or emergency general surgery (not specifically laparotomy), many of the components need further evaluation in future studies.

Learning curve for flexible bronchoscope-guided orotracheal intubation for anesthesiology residents: A cumulative sum analysis

BACKGROUND

Endotracheal intubation with a flexible bronchoscope is a well-recognized airway management technique that anesthesiologists must master. Skill acquisition and knowledge must reach an appropriate level before trainees perform independent practice on patients. There are a paucity of evidence-based outcome measures of trainee competence in performing flexible bronchoscopy. The objectives of this study were to 1) construct a learning curve for flexible bronchoscope-guided orotracheal intubation for anesthesiology residents using the CUSUM method and 2) determine the number of procedures required to achieve proficiency.

METHODS

This study included 12 first-year anesthesiology residents with no previous experience with flexible bronchoscopic intubation. Trainees attended theoretical and simulation training and performed flexible bronchoscope-guided orotracheal intubation in adult patients with normal airways under general anesthesia. Number of intubation attempts, intubation success rate, time to intubation, and incidence of dental and mucosal injuries were recorded. The cumulative sum (CUSUM) method was used to evaluate the learning curve of flexible bronchoscope-guided orotracheal intubation.

RESULTS

Trainees performed flexible bronchoscope-guided orotracheal intubation on 364 patients. First-attempt intubation success occurred in 317 (87.1%) patients. Second-attempt intubation success occurred in 23 (6.3%) patients. Overall, the flexible bronchoscope-guided orotracheal intubation success rate was 93.4% (range, 85.3% to 100%). The mean number of orotracheal intubation procedures per trainee was 31 ± 5 (range, 23 to 40). All trainees crossed the lower decision boundary (H0) after 15.1 ± 5.6 procedures (range, 8 to 25 procedures). There was a significant decrease in median intubation time [39s (IQR: 30, 50) vs. 76s (IQR: 54, 119)] (P < 0.001) after crossing the lower decision boundary (H0) compared to before. There were no dental, mucosa, arytenoid or vocal cord trauma events associated with intubation.

CONCLUSIONS

Learning curves constructed with CUSUM analysis showed that all trainees (anesthesiologist residents) included in this study achieved competence (intubation success rates ≥ 80%) in flexible bronchoscope-guided orotracheal intubation. Trainees needed to perform 15 (range, 8 to 25) procedures to achieve proficiency. There was wide variability between trainees.

TRIAL REGISTRATION

Trial registration: Chinese Clinical Trial Register, ChiCTR 2000032166.

Anatomical morphometry for Cricothyrotomy puncture and incision

PURPOSE

Emergency surgical airway securing techniques include cricothyrotomy, puncture, and incision. While the instruments used for these methods vary in size, no index of laryngeal morphology exists to guide instrument selection. Therefore, we measured the morphology of the cricothyroid ligament in Japanese individuals and assessed its correlations with height.

METHODS

This retrospective study used 61 anatomical practice specimens. The cricothyroid ligament of the laryngeal area was dissected, and a frontal image was recorded. Next, images of the midsagittal sections of the larynx and trachea were recorded. The width and height of the cricothyroid ligament were measured from the frontal images, and the depth of the larynx and the angle to the lower edge of the cricothyroid plate were measured from the mid-sagittal cross-sectional images. The height was estimated from the tibial lengths of the specimens and statistically analyzed for correlations. 　 RESULTS: The width and depth were significantly greater in males. Overall, there was a slight correlation between the results of each laryngeal measurement and estimated height for all items.

CONCLUSION

The morphology of cricothyrotomy revealed that the width and depth of the laryngeal area varied according to sex. Moreover, the results also showed a correlation with the estimated height. Thus, it is important to predict the morphology of the laryngeal area and cricothyroid ligament by considering factors such as patient sex, weight, and height.

Anaesthetic nurse specialist role in perioperative anaesthetic management of patients who are morbidly obese

This integrative literature review examined the role of an anaesthetic nurse specialist (ANS) in the perioperative anaesthetic nursing management of morbidly obese patients associated with elective orthopaedic surgery. The responsibility of the ANS is to provide high-quality perioperative anaesthetic care to ensure patient safety. Morbid obesity is increasing globally, with significant implications for healthcare delivery, care and treatment, including perioperative care. The Association of Anaesthetists of Great Britain and Ireland emphasises that the perioperative management of these patients presents significant organisational and practical issues. However, there are limited data or guidelines on whether surgeons, anaesthetists and nurses routinely take special precautions in managing morbidly obesity patients undergoing elective orthopaedic operative procedures. The authors carried out a search of databases, followed by an integrated literature review and synthesis of 11 studies. The main findings revealed significant clinical challenges and resource requirements for perioperative anaesthetic management of this patient group. Recommendations are made to prepare for and manage these surgical patients, from preoperative assessment to postoperative care.

Ease of Intubation with McGrath Videolaryngoscope and Incidence of Adverse Events During Tracheal Intubation in COVID-19 Patients: A Prospective Observational Study

Background

Tracheal intubation in critically ill patients remains high-risk despite advances in equipment, technique, and clinical guidelines. Many patients with COVID-19 were in respiratory distress and required intubation that is considered an aerosol-generating procedure (AGP). The transition to videolaryngoscopy as a routine first line option throughout anesthetic and ICU practice has been reported. We evaluated the ease of intubation, success rate, use of accessory maneuvers and adverse outcomes during and 24 hours after intubation with the McGrath videolaryngoscope.

Methods

This was a prospective, observational single center study conducted at non-operating room locations that included all adults (>18 years old) with suspected or confirmed COVID-19 infection and were intubated by McGrath videolaryngoscope. The anesthesiologist performed tracheal intubation were requested to fill online data collection form. A co-investigator was responsible to coordinate daily with assigned consultants for COVID intubation and follow up of patients at 24 hours after intubation.

Results

A total of 105 patients were included in our study. Patients were predominantly male (n=78; 74.3%), their COVID status was either confirmed (n=97, 92.4%) or suspected (n=8, 7.6%). Most were intubated in the COVID ward (n=59, 56.2%) or COVID ICU (n=23, 21.9%). The overall success rate of intubation with McGrath in the first attempt was 82.9%. The glottic view was either full (n=85, 80.95%), partial (n=16, 15.24%) or none (n=4, 3.81%). During intubation, hypoxemia occurred in 18.1% and hypotension in 16.2% patients. Within 24 hours of intubation, pneumothorax occurred in 1.9%, cardiac arrest and return of spontaneous circulation in 6.7% and mortality in 13.3% of patients.

Conclusion

These results illustrate the ease and utility of the McGrath videolaryngoscope for tracheal intubation in COVID-19 patients. Its disposable blade is of significant value in protectin during tracheal intubation.

Post-induction hypotension with remimazolam versus propofol in patients routinely administered angiotensin axis blockades: a randomized control trial

BACKGROUND

Certain routine medication could result in post-induction hypotension (PIH), such as angiotensin axis blockades, which are frequently administered as a first-line therapy against hypertension. Remimazolam is reportedly associated with lesser intraoperative hypotension than propofol. This study compared the overall incidence of PIH following remimazolam or propofol administration in patients managed by angiotensin axis blockades.

METHODS

This single-blind, parallel-group, randomized control trial was conducted in a tertiary university hospital in South Korea. Patients undergoing surgery with general anesthesia were considered for enrollment if the inclusion criteria were met: administration of an angiotensin converting enzyme inhibitor or angiotensin receptor blocker, 19 to 65 years old, American Society of Anesthesiologists physical status classification ≤ III, and no involvement in other clinical trials. The primary outcome was the overall incidence of PIH, defined as a mean blood pressure (MBP) < 65 mmHg or decrease by ≥ 30% of the baseline MBP. The time points of measurement were baseline, just before the initial intubation attempt, and 1, 5, 10, and 15 min following intubation. The heart rate, systolic and diastolic blood pressures, and bispectral index were also recorded. Groups P and R included patients administered propofol and remimazolam, respectively, as an induction agent.

RESULTS

A total of 81 patients were analyzed, of the 82 randomized patients. PIH was less frequent in group R than group P (62.5% versus 82.9%; t value 4.27, P = 0.04, adjusted odds ratio = 0.32 [95% confidence interval 0.10-0.99]). The decrease in the MBP from baseline was 9.6 mmHg lesser in group R than in group P before the initial intubation attempt (95% confidence interval 3.3-15.9). A similar trend was observed for systolic and diastolic blood pressures. No severe adverse events were observed in either group.

CONCLUSION

Remimazolam results in less frequent PIH than propofol in patients undergoing routine administration of angiotensin axis blockades.

TRIAL REGISTRATION

This trial was retrospectively registered on Clinical Research Information Service (CRIS), Republic of Korea (KCT0007488). Registration date: 30/06/2022.

The EUPEMEN (EUropean PErioperative MEdical Networking) Protocol for Bowel Obstruction: Recommendations for Perioperative Care

Mechanical bowel obstruction is a common symptom for admission to emergency services, diagnosed annually in more than 300,000 patients in the States, from whom 51% will undergo emergency laparotomy. This condition is associated with serious morbidity and mortality, but it also causes a high financial burden due to long hospital stay. The EUPEMEN project aims to incorporate the expertise and clinical experience of national clinical specialists into development of perioperative rehabilitation protocols. Providing special recommendations for all aspects of patient perioperative care and the participation of diverse specialists, the EUPEMEN protocol for bowel obstruction, as presented in the current paper, aims to provide faster postoperative recovery and reduce length of hospital stay, postoperative morbidity and mortality rate.

Comparing the Scalpel-Bougie-Tube Emergency Front-of-Neck Airway (eFONA) Technique on Conventional Manikins and Ovine Larynges: Evaluating Cost, Realism, and Performance in Anaesthetic Trainees

Background Emergency front-of-neck airway (eFONA) is a crucial life-saving procedure in "cannot intubate, cannot oxygenate" (CICO) situations. It is essential to teach and maintain eFONA skills for healthcare providers, especially anesthesiologists. This study aims to assess the effectiveness of cost-effective ovine larynx models compared to conventional manikins in teaching eFONA using the scalpel-bougie-tube technique to a group of anaesthesia novices and newly appointed anaesthetic Fellows. Methods and study design The study was conducted at Walsall Manor Hospital, a district general hospital in the Midlands, UK. Participants underwent a pre-survey to assess familiarity with FONA and the ability to perform a laryngeal handshake. After a lecture and demonstration, participants performed two consecutive emergency cricothyrotomies on both ovine models and conventional manikins, followed by a post-survey to assess their confidence in performing eFONA and rate their experience using sheep larynges. Results The training session significantly improved the participants' ability to perform a laryngeal handshake and their confidence in performing eFONA. The majority of participants rated the ovine model higher in terms of realism, difficulty with penetration, difficulty in recognising landmarks, and difficulty in performing the procedure. Additionally, the ovine model was more cost-effective compared to conventional manikins. Conclusion Ovine models provide a more realistic and cost-effective alternative to conventional manikins for teaching eFONA using the scalpel-bougie-tube technique. The use of these models in routine airway teaching enhances the practical skill set of anaesthesia novices and newly appointed anaesthetists, better preparing them for CICO situations. However, further training with objective assessment methods and larger samples is needed to corroborate these findings.

High-flow oxygen therapy versus facemask preoxygenation in anticipated difficult airway management (PREOPTI-DAM): an open-label, single-centre, randomised controlled phase 3 trial

Background

Difficult airway management remains a critical procedure with life-threatening adverse events. Current guidelines suggest high-flow therapy by nasal cannulae (HFNC) as a preoxygenation device in this setting. However, there is an evidence gap to support this recommendation.

Methods

The PREOPTI-DAM study is an open-label, single-centre, randomised controlled phase 3 trial done at Nantes University Hospital, France. Patients were aged 18-90 years with one major or two minor criteria of anticipated difficult airway management, and requiring intubation for scheduled surgery, were eligible. Patients with body mass index >35 kg/m² were excluded. Patients were randomly allocated (1:1) to receive 4-min preoxygenation by HFNC or facemask. Randomisation was stratified according to the intubation strategy (laryngoscopic versus fiberoptic intubation). The primary outcome was the incidence of oxygen desaturation ≤94% or of bag-mask ventilation during intubation. The primary and safety analyses included the intention to treat population. This trial is registered with ClinicalTrials.gov (NCT03604120) and EudraCT (2018-A00434-51).

Findings

From September 4 2018 to March 31 2021, 186 patients were enrolled and randomly assigned. One participant withdrew consent and 185 (99.5%) were included in the primary analysis (HFNC, N = 95; Facemask, N = 90). The incidence of the primary outcome was not significantly different between the HFNC and the facemask groups, respectively 2 (2%) versus 7 (8%); adjusted difference, -5.6 [95% confidence interval (CI), -11.8 to 0.6], P = 0.10. In the HFNC group, 76 patients (80%) versus 53 (59%) in the facemask group, reported good or excellent intubation experiences; adjusted difference 20.5 [95% CI, 8.3-32.8], P = 0.016. Comparing HFNC with facemask, severe complication occurred in 22 (23%) versus 27 (30%) patients (P = 0.29), and moderate complication in 14 (15%) versus 18 (20%) patients (P = 0.35). No death or cardiac arrest occurred during the study.

Interpretation

Compared with facemask, HFNC did not significantly reduce the incidence of desaturation ≤94% or bag-mask ventilation during anticipated difficult intubation but the trial was underpowered to rule out a clinically significant benefit. Patient satisfaction was improved with HFNC.

Funding

Nantes University Hospital and Fisher & Paykel Healthcare.

Comparison of silicone double-lumen tube and polyvinyl chloride single-lumen tube in fiberoptic tracheal intubation on a difficult airway model: a randomized controlled non-inferiority trial

The management of patients with history or suspicion of difficult intubation can be challenging, especially in surgical procedures requiring one-lung ventilation. The ease of insertion of silicone double lumen tube (DLT) have previously been shown to be comparable to polyvinyl single lumen tube (SLT) in fiberoptic bronchoscope (FOB) tracheal intubation. Hence, in difficult airway situation, we hypothesized that the performance of insertion of silicone DLT would also be non-inferior to polyvinyl SLT in FOB intubation. We used a neck collar to mimic patients with difficult airway. 80 patients who required one-lung ventilation were enrolled in a prospective, randomized, non-inferiority trial. Patients were randomly allocated to the DLT or SLT groups (SLT with bronchial blocker). Neck collar was supplied to all patients before FOB intubation. The time of insertion for FOB, railroading, tracheal intubation, and total procedure were measured. The difficulty of railroading was evaluated in 4 grades. In the DLT group, the railroading was significantly shorter and easier comparing to the SLT group. The total procedure was also simpler and faster in the DLT group. While simulated difficult airways may not fully replicate actual difficult airways, we suggest that fiberoptic intubation with silicone DLT could be a feasible first-line option for patients with expected difficult airways requiring lung separation, unless the size of the DLT relative to the patient's airway is problematic.Trial registration: NCT03392766.

Comparing nasopharyngeal apnoeic oxygenation at 18 l/min to preoxygenation alone in obese patients - A randomised controlled study

STUDY OBJECTIVE

Investigate a low-cost, nasopharyngeal apnoeic oxygenation technique, establish its efficacy, and compare it to preoxygenation only in an obese population. The study's hypothesis was that nasopharyngeal apnoeic oxygenation at 18 l.min^-1 would significantly prolong safe apnoea time compared to preoxygenation alone.

DESIGN

Randomised controlled study.

SETTING

Theatre complex of a resource constrained hospital.

PATIENTS

30 adult, obese (BMI ≥ 35 kg.m^-2) patients presenting for elective surgery. Patients with limiting cardio-respiratory disease, suspected difficult airway, risk of aspiration, and that were pregnant, were excluded. Patients were allocated by block randomisation in a 1:2 ratio to a preoxygenation-only (No-AO) and an intervention group (NPA-O₂).

INTERVENTIONS

All patients were preoxygenated to an Et-O2 > 80%, followed by a standardised induction. The intervention group received oxygen at 18 l.min^-1 via the nasopharyngeal catheter intervention. The desaturation process was documented until an SpO₂ of 92% or 600 s was reached.

MEASUREMENTS

Baseline demographic and clinical characteristics were collected. The primary outcome was safe apnoea time, defined as the time taken to desaturate to an SpO₂ of 92%. Secondary outcomes were rate of carbon dioxide accumulation and factors affecting the risk of desaturation.

MAIN RESULTS

The study was conducted in a morbidly obese population (NoAO = 41,1 kg.m^-2; NPA-O₂ = 42,5 kg.m^-2). The risk of desaturation was signifantly lower in the intervention group (Hazzard Ratio = 0,072, 95% CI[0,019-0,283]) (Log-Rank test, p < 0.001). The median safe apnoea time was significantly longer in the intervention group (NoAO = 262 s [IQR 190-316]; NPA-O₂ = 600 s [IQR 600-600]) (Mann-Whitney-U test, p < 0.001). The mean rate of CO₂ accumalation was significantly slower in the intervention group (NoAO = 0,47 ± 0,14 kPa.min^-1; NPA-O₂ = 0,3 ± 0,09 kPa.min^-1) (t-test, p = 0.003). There were no statistically significant risk factors associated with an increased risk of desaturation found.

CONCLUSIONS

Nasopharyngeal apnoeic oxygenation at 18 l/min prolongs safe apnoea time, compared to preoxygenation alone, and reduces the risk of desaturation in morbidly obese patients.

CLINICAL TRIAL REGISTRATION

PACTR202202665252087; WC/202004/007.

Pre-operative ultrasound prediction of difficult airway management in adult patients: A systematic review of clinical evidence

BACKGROUND

Predicting a difficult airway, including difficult laryngoscopy, intubation or mask ventilation, is paramount in peri-operative management. As clinical predictors are only partially reliable, ultrasound-based measurements might be useful in evaluating anterior neck fat tissues depth.

OBJECTIVES

The aim of this systematic review is to report clinical evidence on pre-operative ultrasound as a predictor of difficult laryngoscopy, difficult intubation or difficult mask ventilation.

DESIGN

A systematic review of randomised controlled trials and observational studies.

DATA SOURCES

The MEDLINE, EMBASE and Google Scholar databases were queried from inception until 28 February 2022.

ELIGIBILITY CRITERIA

Studies involving adult patients who had undergone orotracheal intubation after evaluation with airways ultrasound were considered suitable. Exclusion criteria were a clinical history of difficult airways, cancer or trauma, pregnancy, supraglottic airway devices, video-laryngoscopy. Parameters were classified by reporting their accuracy in discriminating 'difficult' vs. 'not difficult' laryngoscopy, intubation or mask ventilation.

RESULTS

Thirty-one observational studies were included and a total of 41 single parameters and 12 different combinations of clinical and ultrasound parameters were reported. The distance from skin to epiglottis midway with neutral position of head and neck, the distance from hyoid bone to skin surface with a neutral position of head and neck and the hyomental distance extended/neutral ratio are the most associated with difficult laryngoscopy or difficult intubation. A combination of clinical and ultrasound parameters (a modified Mallampati score, the distance from the skin to the epiglottis midway with neutral position of the head and neck, and the USED-MSH score) showed high accuracy. Only two studies reported the role of ultrasound in predicting difficult mask ventilation: the distance from hyoid bone to skin surface with neutral position of head and neck, the thickness of the base of the tongue with hyperextension of the head, and the hyomental distance with hyperextension of the head and active subluxation of the mandible are the parameters with the highest correlation.

CONCLUSIONS

The use of ultrasound parameters might be useful in predicting difficult laryngoscopy or difficult intubation. Several ultrasound parameters and combinations have been associated with difficult laryngoscopy or difficult intubation prediction. The use of scores combining clinical predictors and ultrasound measures are very promising. Data on difficult mask ventilation are scarce and the role of ultrasound is still controversial. Future studies are needed.

CLINICAL TRIAL REGISTRATION

CRD42021250574.

Five Decades of Trauma Anesthesiology

We present a brief history of the scientific and educational development of trauma anesthesiology. Key milestones from the past 50 years are noted, as well as the current standing of the subspecialty and prospects for the future.

[Cricothyrotomy : Data situation, guidelines and techniques for the definitive surgical airway]

Cricothyrotomy represents the final approach to secure the airway, in the course of which less invasive measures have failed. It can also primarily be carried out to establish a secure airway. This is essential to protect the patient from a significant hypoxia. This is a cannot ventilate-cannot oxygenate (CVCO) situation, which presumably all colleagues in emergency intensive care medicine and anesthesia have already been confronted with. Evidence-based algorithms for the management of a difficult airway and CVCO have been established. If oxygenation using an endotracheal tube, an extraglottic airway device or bag-valve mask ventilation all fail, the airway must be surgically secured, i.e. using cricothyrotomy. The prevalence of the CVCO situation in a prehospital setting is ca. 1%. No valid prospective randomized in vivo studies have been carried with respect to the question of the best method.

A randomized controlled trial comparing three supraglottic airway devices used as a conduit to facilitate tracheal intubation with flexible bronchoscopy

PURPOSE

Once difficult ventilation and intubation are declared, guidelines suggest the use of a supraglottic airway (SGA) as a rescue device to ventilate and, if oxygenation is restored, subsequently as an intubation conduit. Nevertheless, few trials have formally studied recent SGA devices in patients. Our objective was to compare the efficacy of three second-generation SGA devices as conduits for bronchoscopy-guided endotracheal intubation.

METHODS

In this prospective, single-blinded three-arm randomized controlled trial, patients with an American Society of Anesthesiologists Physical Status of I-III undergoing general anesthesia were randomized to bronchoscopy-guided endotracheal intubation using AuraGain™, Air-Q® Blocker, or i-gel® devices. We excluded patients with contraindications to an SGA or drugs and who were pregnant or had a neck, spine, or respiratory anomaly. The primary outcome was intubation time, measured from SGA circuit disconnection to CO2 measurement. Secondary outcomes included ease, time, and success of SGA insertion; success of intubation on first attempt; overall intubation success; number of attempts to intubate; ease of intubation; and ease of SGA removals.

RESULTS

One hundred and fifty patients were enrolled from March 2017 to January 2018. Median intubation times were similar across the three groups (Air-Q Blocker, 44 sec; AuraGain, 45 sec; i-gel, 36 sec; P = 0.08). The i-gel was faster to insert (i-gel: 10 sec; Air-Q Blocker, 16 sec; AuraGain, 16 sec; P < 0.001) and easier to insert (Air-Q Blocker vs i-gel, P = 0.001; AuraGain vs i-gel, P = 0.002). Success of SGA insertion, success of intubation, and number of attempts were similar. The Air-Q Blocker was easier to remove than the i-gel (P < 0.001).

CONCLUSION

All three second-generation SGA devices performed similarly regarding intubation. Despite minor benefits of the i-gel, clinicians should select their SGA based on clinical experience.

STUDY REGISTRATION

ClinicalTrials.gov (NCT02975466); registered on 29 November 2016.

Conventional versus video-assisted laryngoscopy for perioperative endotracheal intubation (COVALENT) - a randomized, controlled multicenter trial

BACKGROUND

Data on the routine use of video-assisted laryngoscopy in peri-operative intubations are rather inconsistent and ambiguous, in part due to small populations and non-uniform outcome measures in past trials. Failed or prolonged intubation procedures are a reason for relevant morbidity and mortality. This study aims to determine whether video-assisted laryngoscopy (with both Macintosh-shaped and hyperangulated blades) is at least equal to the standard method of direct laryngoscopy with respect to the first-pass success rate. Furthermore, validated tools from the field of human factors will be applied to examine within-team communication and task load during this critical medical procedure.

METHODS

In this randomized, controlled, three-armed parallel group design, multi-centre trial, a total of more than 2500 adult patients scheduled for perioperative endotracheal intubation will be randomized. In equally large arms, video-assisted laryngoscopy with a Macintosh-shaped or a hyperangulated blade will be compared to the standard of care (direct laryngoscopy with Macintosh blade). In a pre-defined hierarchical analysis, we will test the primary outcome for non-inferiority first. If this goal should be met, the design and projected statistical power also allow for subsequent testing for superiority of one of the interventions. Various secondary outcomes will account for patient safety considerations as well as human factors interactions within the provider team and will allow for further exploratory data analysis and hypothesis generation.

DISCUSSION

This randomized controlled trial will provide a solid base of data in a field where reliable evidence is of major clinical importance. With thousands of endotracheal intubations performed every day in operating rooms around the world, every bit of performance improvement translates into increased patient safety and comfort and may eventually prevent significant burden of disease. Therefore, we feel confident that a large trial has the potential to considerably benefit patients and anaesthetists alike.

TRIAL REGISTRATION

ClincalTrials.gov NCT05228288.

PROTOCOL VERSION

1.1, November 15, 2021.

Human factors in anaesthesia: a narrative review

Healthcare relies on high levels of human performance, as described by the 'human as the hero' concept. However, human performance varies and is recognised to fall in high-pressure situations, meaning that it is not a reliable method of ensuring safety. Other safety-critical industries embed human factors principles into all aspects of their organisations to improve safety and reduce reliance on exceptional human performance; there is potential to do the same in anaesthesia. Human factors is a broad-based scientific discipline which aims to make it as easy as possible for workers to do things correctly. The human factors strategies most likely to be effective are those which 'design out' the chance of an error or adverse event occurring. When errors or adverse events do happen, barriers are in place to trap them and reduce the risk of progression to patient and/or worker harm. If errors or adverse events are not trapped by these barriers, mitigations are in place to minimise the consequences. Non-technical skills form an important part of human factors barriers and mitigation strategies and include: situation awareness; decision-making; task management; and team working. Human factors principles are not a substitute for proper investment and appropriate staffing levels. Although applying human factors science has the potential to save money in the long term, its proper implementation may require investment before reward can be reaped. This narrative review describes what is known about human factors in anaesthesia to date.

Pro-Con Debate: Videolaryngoscopy Should Be Standard of Care for Tracheal Intubation

In this Pro-Con commentary article, we discuss whether videolaryngoscopy (VL) should be the standard of care for tracheal intubation. Dr Aziz makes the case that VL should be the standard of care, while Dr Berkow follows with a challenge of that assertion. In this debate, we explore not only the various benefits of VL, but also its limitations. There is compelling evidence that VL improves first-pass success rates, reduces the risk of intubation failure and esophageal intubation, and has benefits in the difficult airway patient. But VL is not without complications and does not possess a 100% success rate. In the case of failure, it is important to have back-up plans for airway management. While transition of care from direct laryngoscopy (DL) to VL may result in improved airway management outcomes, the reliance on VL may degrade other important clinical skills when they are needed most. If VL is adapted as the standard of care, airway managers may no longer practice and retain competency in other airway techniques that may be required in the event of VL failure. While cost is a barrier to broad implementation of VL, those costs are normalizing. However, it may still be challenging for institutions to secure purchase of VL for every intubating location, as well as back-up airway devices. As airway management care increasingly transitions from DL to VL, providers should be aware of the benefits and risks to this practice change.

Implementing human factors in anaesthesia: guidance for clinicians, departments and hospitals: Guidelines from the Difficult Airway Society and the Association of Anaesthetists: Guidelines from the Difficult Airway Society and the Association of Anaesthetists

Human factors is an evidence-based scientific discipline used in safety critical industries to improve safety and worker well-being. The implementation of human factors strategies in anaesthesia has the potential to reduce the reliance on exceptional personal and team performance to provide safe and high-quality patient care. To encourage the adoption of human factors science in anaesthesia, the Difficult Airway Society and the Association of Anaesthetists established a Working Party, including anaesthetists and operating theatre team members with human factors expertise and/or interest, plus a human factors scientist, an industrial psychologist and an experimental psychologist/implementation scientist. A three-stage Delphi process was used to formulate a set of 12 recommendations: these are described using a 'hierarchy of controls' model and classified into design, barriers, mitigations and education and training strategies. Although most anaesthetic knowledge of human factors concerns non-technical skills, such as teamwork and communication, human factors is a broad-based scientific discipline with many other additional aspects that are just as important. Indeed, the human factors strategies most likely to have the greatest impact are those related to the design of safe working environments, equipment and systems. While our recommendations are primarily provided for anaesthetists and the teams they work with, there are likely to be lessons for others working in healthcare beyond the speciality of anaesthesia.

Automated location of orofacial landmarks to characterize airway morphology in anaesthesia via deep convolutional neural networks

BACKGROUND

A reliable anticipation of a difficult airway may notably enhance safety during anaesthesia. In current practice, clinicians use bedside screenings by manual measurements of patients' morphology.

OBJECTIVE

To develop and evaluate algorithms for the automated extraction of orofacial landmarks, which characterize airway morphology.

METHODS

We defined 27 frontal + 13 lateral landmarks. We collected n=317 pairs of pre-surgery photos from patients undergoing general anaesthesia (140 females, 177 males). As ground truth reference for supervised learning, landmarks were independently annotated by two anaesthesiologists. We trained two ad-hoc deep convolutional neural network architectures based on InceptionResNetV2 (IRNet) and MobileNetV2 (MNet), to predict simultaneously: (a) whether each landmark is visible or not (occluded, out of frame), (b) its 2D-coordinates (x,y). We implemented successive stages of transfer learning, combined with data augmentation. We added custom top layers on top of these networks, whose weights were fully tuned for our application. Performance in landmark extraction was evaluated by 10-fold cross-validation (CV) and compared against 5 state-of-the-art deformable models.

RESULTS

With annotators' consensus as the 'gold standard', our IRNet-based network performed comparably to humans in the frontal view: median CV loss L=1.277·10^-3, inter-quartile range (IQR) [1.001, 1.660]; versus median 1.360, IQR [1.172, 1.651], and median 1.352, IQR [1.172, 1.619], for each annotator against consensus, respectively. MNet yielded slightly worse results: median 1.471, IQR [1.139, 1.982]. In the lateral view, both networks attained performances statistically poorer than humans: median CV loss L=2.141·10^-3, IQR [1.676, 2.915], and median 2.611, IQR [1.898, 3.535], respectively; versus median 1.507, IQR [1.188, 1.988], and median 1.442, IQR [1.147, 2.010] for both annotators. However, standardized effect sizes in CV loss were small: 0.0322 and 0.0235 (non-significant) for IRNet, 0.1431 and 0.1518 (p<0.05) for MNet; therefore quantitatively similar to humans. The best performing state-of-the-art model (a deformable regularized Supervised Descent Method, SDM) behaved comparably to our DCNNs in the frontal scenario, but notoriously worse in the lateral view.

CONCLUSIONS

We successfully trained two DCNN models for the recognition of 27 + 13 orofacial landmarks pertaining to the airway. Using transfer learning and data augmentation, they were able to generalize without overfitting, reaching expert-like performances in CV. Our IRNet-based methodology achieved a satisfactory identification and location of landmarks: particularly in the frontal view, at the level of anaesthesiologists. In the lateral view, its performance decayed, although with a non-significant effect size. Independent authors had also reported lower lateral performances; as certain landmarks may not be clear salient points, even for a trained human eye.

Equivalence of the top-down manoeuvre and bottom-up manoeuvre in speed and accuracy of identifying the cricothyroid membrane: a prospective randomised cross-over study

BACKGROUND

Accurate identification of the cricothyroid membrane is crucial for successful cricothyrotomy; however, a manoeuvre that helps identify it both accurately and quickly remains unclear. The effectiveness of the so-called 'bottom-up manoeuvre' has never been investigated. This study aimed to examine whether the bottom-up manoeuvre is as rapid and accurate as the conventional 'top-down manoeuvre' at identifying the cricothyroid membrane.

METHODS

This study was a prospective randomised cross-over trial conducted at an academic medical centre between 2018 and 2019. Fifth-year medical students participated. The students were trained in the use of either the top-down manoeuvre or the bottom-up manoeuvre first. Each student subsequently performed the technique once on a volunteer. The students were then taught and practiced the other manoeuvre as well. The accuracy of cricothyroid membrane identification and the time taken by successful participants only were measured and compared between the manoeuvres using equivalence tests with two one-sided tests.

RESULTS

A total of 102 medical students participated in this study and there was no missing data. The accuracy of identification and time required for success were similar between the top-down manoeuvre and the bottom-up manoeuvre (65.7% vs. 70.6%, taking 13.8 s [interquartile range (IQR): 9.4-17.5] vs. 15.5 s [IQR: 11.5-19.9], respectively). The success rate was statistically equivalent (rate difference, 4.9%; 90% confidence interval [CI], -5.8 to 15.6; equivalence margin, -20.0 to 20.0). The time required for success was also statistically equivalent (median difference, 1.7 s; 90% CI, -0.2 to 3.3; equivalence margin, -4.0 to 4.0).

CONCLUSION

Among students first trained in both manoeuvres for identifying the cricothyroid membrane, the speed and accuracy of identification were similar between those using the bottom-up manoeuvre and those using the top-down manoeuvre.

A multicentre randomised controlled trial of the McGrath Mac videolaryngoscope versus conventional laryngoscopy

Before completion of this study, there was insufficient evidence demonstrating the superiority of videolaryngoscopy compared with direct laryngoscopy for elective tracheal intubation. We hypothesised that using videolaryngoscopy for routine tracheal intubation would result in higher first-pass tracheal intubation success compared with direct laryngoscopy. In this multicentre randomised trial, 2092 adult patients without predicted difficult airway requiring tracheal intubation for elective surgery were allocated randomly to either videolaryngoscopy with a Macintosh blade (McGrath) or direct laryngoscopy. First-pass tracheal intubation success was higher with the McGrath (987/1053, 94%), compared with direct laryngoscopy (848/1039, 82%); absolute risk reduction (95%CI) was 12.1% (10.9-13.6%). This resulted in a relative risk (95%CI) of unsuccessful tracheal intubation at first attempt of 0.34 (0.26-0.45; p < 0.001) for McGrath compared with direct laryngoscopy. Cormack and Lehane grade ≥ 3 was observed more frequently with direct laryngoscopy (84/1039, 8%) compared with McGrath (8/1053, 0.7%; p < 0.001) No significant difference in tracheal intubation-associated adverse events was observed between groups. This study demonstrates that using McGrath videolaryngoscopy compared with direct laryngoscopy improves first-pass tracheal intubation success in patients having elective surgery. Practitioners may consider using this device as first choice for tracheal intubation.

Scalpel cricothyrotomy versus punctured cricothyrotomy in the context of the CICO crisis. A systematic review and Meta-analysis

IMPORTANCE

The preferential use of a scalpel (SCT) or puncture techniques (PCT) for cricothyrotomy remains a controversial topic.

OBJECTIVE

We performed a systematic review and meta-analysis comparing puncture cricothyrotomy with scalpel cricothyrotomy using overall success rate, first-time success rate, and time taken to perform the procedure as the primary outcome together with complications as a secondary outcome.

EVIDENCE REVIEW

Pubmed databases, EMBASE databases, MEDLINE, Google Scholar, and Cochrane Central Register of Controlled Trials, from 1980 to October 2022.

FINDINGS

A total of 32 studies were included in the systematic review and meta-analysis. It also showed that PCT was close to SCT in terms of overall success rate (82.2% vs. 82.6%, Odd Ratios OR = 0.91, [95%CI: 0.52-1.58], p = 0.74) as well as first-performance success rate (62.9% vs. 65.3%, OR = 0.52, [0.22-1.25], p = 0.15). PCT does not compare favorably with SCT in terms of required time for the procedure (the mean time required for PCT versus SCT incision in the intervention groups was 0.34 standard deviations higher (Mean Difference MD = 17.12, [3.37-30.87], p = 0.01) as well as complications (21.4% vs. 15.1%, Relative Risk RR = 1.49, [0.80-2.77], p = 0.21).

CONCLUSIONS AND RELEVANCE

The results show that SCT has an advantage over PCT in terms of time required for the procedure, while there is no difference in overall success rate, first-time success rate after training, and complications. The superiority of SCT may be the result of fewer and more reliable procedural steps. However, the level of evidence is low (GRADE).

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.

Risk patterns of consecutive adverse events in airway management: a Bayesian network analysis

BACKGROUND

Minor adverse airway events play a pivotal role in the safety of airway management. Changes in airway management strategies can reduce such events, but the broader impact on airway management remains unclear.

METHODS

Minor, frequently occurring adverse airway events were audited before and after implementation of changes to airway management strategies. We used two Bayesian networks to examine conditional probabilities of subsequent airway events and to compute the likelihood of certain events given that certain previous events occurred.

RESULTS

Independent of sex, age, and American Society of Anesthesiologists physical status, targeted changes to airway management strategies reduced the risk of a first event. Obese patients were an exception, in whom no risk reduction was achieved. Frequently occurring event sequences were identified, for example the most likely event to follow difficult bag-mask ventilation was a Cormack-Lehane grade ≥3, with a risk of 14.3% (95% credible interval [CI], 11.4-17.2%). An impact of the targeted changes was detected on the likelihood of some event sequences, for example the likelihood of no consecutive event after a tracheal tube-related event increased from 43.3% (95% CI, 39.4-47.6%) to 56.4% (95% CI, 52.0-60.5%).

CONCLUSIONS

Identification of risk patterns and typical structures of event sequences provides a clinically relevant perspective on airway incidents. It further provides a means to quantify the impact of targeted airway management changes. These targeted changes can influence some event sequences, but overall, the benefit results from the cumulative effect of improvements in multiple events. Targeted airway management changes with knowledge of risk patterns and event sequences can potentially further improve patient safety in airway management.

CLINICAL TRIAL REGISTRATION

NCT02743767.

High-Flow Nasal Cannula for Apneic Oxygenation in Obese Patients for Elective Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Obese patients desaturate rapidly during the apneic period after induction of anesthesia for elective surgery. Administration of oxygen using high-flow nasal cannulae (HFNCs) may prevent desaturation in nonobese patients compared to facemask (FM) preoxygenation. The aim of this meta-analysis was to compare the effectiveness of HFNC to FM preoxygenation techniques in reducing preintubation desaturation in obese patients undergoing elective surgery.

METHODS

This study protocol was registered on PROSPERO (CRD42022309391). Adult studies that compared HFNC and FM preoxygenation in obese patients requiring general anesthesia for elective surgery were included. The primary outcome was desaturation resulting in oxygen saturation of <92% from induction of anesthesia until intubation. Secondary outcomes included the lowest arterial oxygen content before intubation expressed in mm Hg, safe apnea time expressed in seconds, the lowest oxygen saturation before intubation expressed as a percentage, patient-reported discomfort, the need for rescue ventilation, and the incidence of aspiration of gastric contents during intubation. Risk of bias was assessed using the Cochrane Collaboration tool. Certainty was assessed following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

Six studies including 351 participants were eligible for analysis. There was no difference in odds of oxygen desaturation <92% between HFNC and FM (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.15-1.63; P = .24). The HFNC group had a significantly longer safe apnea time (mean difference [MD], -124.20 with 95% CI, -200.47 to -47.93; P = .001). There was no difference between HFNC and FM in the lowest arterial oxygen content (MD, -23.90; 95% CI, -88.64 to 40.85; P = .47) and the lowest peripheral oxygenation saturation (MD, -0.47 with 95% CI, -5.07 to 4.12; P = .84). HFNC had a lower odd of discomfort than FM (OR, 0.13; 95% CI, 0.03-0.52; P = .004). There was no difference in the odds of aspiration of gastric contents between HFNC and FM (OR, 0.33; 95% CI, 0.01-8.21; P = .50). The risk of bias for our primary and secondary outcomes was low. The GRADE assessment for our primary outcome indicated a low level of certainty. For secondary outcomes, the GRADE assessment indicated a very low certainty for all outcomes except for patient discomfort, which was indicated as a moderate level of certainty.

CONCLUSIONS

There may be no difference between HFNC and FM preoxygenation in preventing oxygen desaturation <92% or the lowest oxygen saturation before intubation. Preparation remains important to prevent and manage desaturation during induction of obese patients.

Pre-intubation ventilation device for bearded patients: prospective, randomized, crossover trial in anesthetized patients

Having a beard is an independent predictor of difficult ventilation by face mask. This study evaluates the efficacy of a novel intra-oral Bag-Valve-Guedel Adaptor (BVGA) in anaesthetized bearded patients. Patients with ASA score 1-2, scheduled for elective surgery, were recruited for this prospective, crossover trial. Beard length was categorized as < 0.5 cm, 0.5-1 cm, 1-5 cm, or > 5 cm. Patients were ventilated by attending anesthesiologists using the BVGA and a facemask (both with a Guedel oral airway). End-tidal CO₂ (EtCO₂) and expiratory tidal volume (TV) were recorded as was the number of hands required for the procedure. The primary outcome was the difference between BVGA and Facemask. Sixty-one patients were enrolled. Of these, 38 had beards, and 23 were without beards or with beards < 0.5 cm length. In bearded patients, ventilation with the BVGA was superior to the face mask by EtCO₂ and non-inferior by TV (BVGA-vs-Mask, mean [95% CI]: EtCO₂ [mmHg], 33.0 [31.6, 34.3]-vs-27.2 [25.5, 28.8], p < 0.001; TV [ml∙kg^-1 IBW], 8.1 [7.4, 8.9]-vs-6.9 [6.0, 7.7], p = 0.11). The BVGA was found to be superior to the face mask by EtCO₂ across all beard lengths (p ≤ 0.001), but by TV only for the longest beard group (p = 0.009). After securing the BVGA, ventilation was possible without hands in 74% of the cases - clearly impossible with the facemask (p ≤ 0.001). The BVGA is more effective and more convenient than the facemask in anaesthetized bearded patients. A follow-up study is underway to test whether replacing the face mask with the BVGA will improve effectiveness and ease of pre-intubation field ventilation by less-experienced, first responders.