The difficult airway with recommendations for management--part 2--the anticipated difficult airway

Depth to the airway lumen at the level of the cricothyroid membrane measured by ultrasound

BACKGROUND

Knowing the likely depth to the airway before emergency cricothyroidotomy may improve success in cases where it cannot be measured. Our aim was to measure the depth to the airway at the cricothyroid membrane by ultrasound in a large group of adult patients.

METHOD

Prospective, observational study in two centres, Oxford and Gloucester. Patients presenting for a large variety of surgical operations were studied. Patients under 18 years; pregnant; critically ill; had a history of neck surgery were not included. Ultrasound examination was performed pre-operatively while participants lay supine with their head and neck extended, with light transducer pressure. We measured depth to the airway lumen in mm; age; weight; height and sex.

RESULTS

In total 352 patients were studied. We found that depth to the airway lumen strongly correlated with weight (r = 0.855, P < 0.001) and to a lesser extent body mass index (r = 0.781, P < 0.001). Statistical analysis produced an equation to predict upper 95% CI of depth to the airway from the patient's weight: Depth to the airway lumen in mm = (0.13 × weight in kg) + 0.86.

CONCLUSIONS

If ultrasound measurement is not possible before emergency cricothyroidotomy, the clinician could use our results to predict the depth to the airway by using the patient's weight. If the upper 95% CI were used as the depth of incision, it would enter the airway in 39 out of 40 patients of that weight, without damage to posterior structures in those with a shallower airway.

A comparison of two doses of ketamine with dexmedetomidine for fiberoptic nasotracheal intubation

Background and Aims:

Flexible fiber-optic intubation is considered to be the gold standard for management of difficult airway. Fiber-optic intubation does require effective sedation and blunting of airway reflexes for which various drug regimens have been utilized in the past. In a quest to find the noble drug combination, we combined ketamine and dexmedetomidine in two different doses, to evaluate the clinical efficacy and safety profile of ketamine and dexmedetomidine for fiber-optic intubation.

Materials and Methods:

This prospective randomized study was conducted in 72 patients of 20–50 years’ age group of either sex with the American Society of Anesthesiologists Physical Status I and II with difficult airway. We compared two doses of ketamine 20 mg (Group I) and 40 mg (Group II) with a common dose of dexmedetomidine at 1 μg/kg body weight, given as an infusion over 10 min (a solution of 50 ml with normal saline). Sedation scores, hemodynamic variables in terms of blood pressure, heart rate (HR), and oxygen saturation were studied along with 24-h postoperative patient discomfort and recall of procedure.

Results:

Group II patients showed less variation from their baseline values in terms of HR (ranged between 0.73% and 4.75%) and mean arterial pressure (ranged between 0% and 3.97%) in comparison to Group I HR (ranged between 0.09% and 9.81%) and mean pressures (ranged between 0.3% and 10.38%). Discomfort during procedure (P < 0.001) and recall of procedure scale (P = <0.001) were found significantly better/lower in Group II as compared to Group I.

Conclusion:

Ketamine 40 mg in comparison to 20 mg with dexmedetomidine provides better hemodynamic conditions with better tolerance and lower recall to the fiber-optic intubation.

Acute Awake Fiberoptic Intubation in the ICU in a Patient with Limited Mouth Opening and Hypoxemic Acute Respiratory Failure

The incidence and survival of patients with head-and-neck cancer have been on the increase for decades. Following surgery or radiation therapy, complications such as difficult airways may evolve. These difficult airways may be unique and not manageable with conventional intubation methods as well as video laryngoscopes. Acute awake fiberoptic intubation may be a feasible option also for urgent emergency airway management of known difficult airways. The “cannot intubate–cannot oxygenate” (CI–CO) situation has to be avoided at all costs, since emergency cricothyrotomy has a fail ratio of more than 50% when performed by an anesthesiologist.

A clinical prediction rule to identify difficult intubation in children with Robin sequence requiring mandibular distraction osteogenesis based on craniofacial CT measures

BACKGROUND

Airway management is challenging in children with Robin sequence (RS) requiring mandibular distraction osteogenesis (MDO). We derived and validated a prediction rule to identify difficult intubation before MDO for children with RS based on craniofacial computed tomography (CT) images.

METHOD

This was a retrospective study of 69 children with RS requiring MDO from November 2016 to June 2018. Multiple CT imaging parameters and baseline characteristic (sex, age, gestational age, body mass index [BMI]) were compared between children with normal and difficult intubation according to Cormack-Lehane classification. A clinical prediction rule was established to identify difficult intubation using group differences in CT parameters (eleven distances, six angles, one section cross-sectional area, and three segment volumes) and clinicodemographic characteristics. Predictive accuracy was evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

The overall incidence of difficult intubation was 56.52%, and there was no significant difference in sex ratio, age, weight, height, BMI, or gestational age between groups. The distance between the root of the tongue and posterior pharyngeal wall was significantly shorter, the bilateral mandibular angle shallower, and the cross-sectional area at the epiglottis tip smaller in the difficult intubation group. A clinical prediction rule based on airway cross-sectional area at the tip of the epiglottis was established. Area > 36.97 mm² predicted difficult intubation while area < 36.97 mm² predicted normal intubation with 100% sensitivity, 62.5% specificity, 78.6% positive predictive value, and 100% negative predictive value (area under the ROC curve = 0.8125).

CONCLUSION

Computed tomography measures can objectively evaluate upper airway morphology in patients with RS for prediction of difficult intubation. If validated in a larger series, the measures identified could be incorporated into airway assessment tools to guide treatment decisions. This was a retrospective study and was granted permission to access and use these medical records by the ethics committee of Guangzhou Women and Children's Medical Center.

TRIALS REGISTRATION

Registration No. ChiCTR1800018252, NaZhang, Sept 7 2018.

Difficult Airway Society guidelines for awake tracheal intubation (ATI) in adults

Awake tracheal intubation has a high success rate and a favourable safety profile but is underused in cases of anticipated difficult airway management. These guidelines are a comprehensive document to support decision making, preparation and practical performance of awake tracheal intubation. We performed a systematic review of the literature seeking all of the available evidence for each element of awake tracheal intubation in order to make recommendations. In the absence of high‐quality evidence, expert consensus and a Delphi study were used to formulate recommendations. We highlight key areas of awake tracheal intubation in which specific recommendations were made, which included: indications; procedural setup; checklists; oxygenation; airway topicalisation; sedation; verification of tracheal tube position; complications; management of unsuccessful awake tracheal intubation; post‐tracheal intubation management; consent; and training. We recognise that there are a range of techniques and regimens that may be effective and one such example technique is included. Breaking down the key practical elements of awake tracheal intubation into sedation, topicalisation, oxygenation and performance might help practitioners to plan, perform and address complications. These guidelines aim to support clinical practice and help lower the threshold for performing awake tracheal intubation when indicated.

The management of unanticipated difficult airways in children of all age groups in anaesthetic practice - the position paper of an expert panel

Children form a specific group of patients, as there are significant differences between children and adults in both anatomy and physiology. Difficult airway may be unanticipated or anticipated. Difficulties encountered during intubation may cause hypoxia, hypoxic brain injury and, in extreme situations, may result in the patient’s death. There are few paediatric difficult-airway guidelines available in the current literature, and some of these have significant limitations. This position paper, intended for unanticipated difficult airway, was elaborated by the panel of specialists representing the Polish Society of Anaesthesiology and Intensive Care as well as the Polish Neonatal Society. It covers both elective intubation and emergency situations in children in all age groups. An integral part of the paper is an algorithm. The paper describes in detail all stages of the algorithm considering some modification in specific age groups, i.e. neonates.

Ultrasonographic identification of the cricothyroid membrane in a patient with a difficult airway as a result of cervical hematoma caused by hemophilia: a case report

Background

Surgical cricothyroidotomy is a last resort in patients with an anticipated difficult airway, but without any guarantee of success. Identification of the cricothyroid membrane may be the key to successful cricothyrotomy. Ultrasonographic identification of the cricothyroid membrane has been reported to be more useful than the conventional palpation technique. However, ultrasonographic identification techniques are not yet fully characterized.

Case presentation

A 28-year-old man with hemophilia and poor adherence to medication. He was brought to the emergency department with a large cervical hematoma and respiratory difficulty. An otolaryngologist decided to insert a tracheal tube to maintain his airway. However, emergent laryngoscopy indicated an anticipated difficult airway. A backup plan that included awake intubation by the anesthesiologists and surgical cricothyroidotomy by an otolaryngologist was devised. The cricothyroid membrane could not be identified by palpation but was detected by ultrasonographic identification with a longitudinal approach. Awake fiberoptic intubation was successfully performed.

Conclusions

In this case, the cricothyroid membrane could be identified using the longitudinal approach but not the transverse approach. It may be ideal to know which ultrasound technique can be applied for each patient.

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.

Will This Patient Be Difficult to Intubate?: The Rational Clinical Examination Systematic Review

IMPORTANCE

Recognizing patients in whom endotracheal intubation is likely to be difficult can help alert physicians to the need for assistance from a clinician with airway training and having advanced airway management equipment available.

OBJECTIVE

To identify risk factors and physical findings that predict difficult intubation.

DATA SOURCES

The databases of MEDLINE and EMBASE were searched from 1946 to June 2018 and from 1947 to June 2018, respectively, and the reference lists from the retrieved articles and previous reviews were searched for additional studies.

STUDY SELECTION

Sixty-two studies with high (level 1-3) methodological quality that evaluated the accuracy of clinical findings for identifying difficult intubation were reviewed.

DATA EXTRACTION AND SYNTHESIS

Two authors independently abstracted data. Bivariate random-effects meta-analyses were used to calculate summary positive likelihood ratios across studies or univariate random-effects models when bivariate models failed to converge.

RESULTS

Among the 62 high-quality studies involving 33 559 patients, 10% (95% CI, 8.2%-12%) of patients were difficult to intubate. The physical examination findings that best predicted a difficult intubation included a grade of class 3 on the upper lip bite test (lower incisors cannot extend to reach the upper lip; positive likelihood ratio, 14 [95% CI, 8.9-22]; specificity, 0.96 [95% CI, 0.93-0.97]), shorter hyomental distance (range of <3-5.5 cm; positive likelihood ratio, 6.4 [95% CI, 4.1-10]; specificity, 0.97 [95% CI, 0.94-0.98]), retrognathia (mandible measuring <9 cm from the angle of the jaw to the tip of the chin or subjectively short; positive likelihood ratio, 6.0 [95% CI, 3.1-11]; specificity, 0.98 [95% CI, 0.90-1.0]), and a combination of physical findings based on the Wilson score (positive likelihood ratio, 9.1 [95% CI, 5.1-16]; specificity, 0.95 [95% CI, 0.90-0.98]). The widely used modified Mallampati score (≥3) had a positive likelihood ratio of 4.1 (95% CI, 3.0-5.6; specificity, 0.87 [95% CI, 0.81-0.91]).

CONCLUSIONS AND RELEVANCE

Although several simple clinical findings are useful for predicting a higher likelihood of difficult endotracheal intubation, no clinical finding reliably excludes a difficult intubation. An abnormal upper lip bite test, which is easily assessed by clinicians, raises the probability of difficult intubation from 10% to greater than 60% for the average-risk patient.

The Difficult Airway Trolley: A Narrative Review and Practical Guide

Death and severe morbidity attributable to anesthesia are commonly associated with failed difficult airway management. When an airway emergency develops, immediate access to difficult airway equipment is critical for implementation of rescue strategies. Previously, national expert consensus guidelines have provided only limited guidance for the design and setup of a difficult airway trolley. The overarching aim of the current work was to create a dedicated difficult airway trolley (for patients>12 years old) for use in anesthesia theatres, intensive care units, and emergency departments. A systematic literature search was performed, using the PubMed, Embase, and Google Scholar search engines. Based on evidence presented in 11 national or international guidelines, and peer-reviewed journals, we present and outline a difficult airway trolley organized to accommodate sequential progression through a four-step difficult airway algorithm. The contents of the top four drawers correspond to specific steps in the airway algorithm (A = intubation, B = oxygenation via a supraglottic airway device, C = facemask ventilation, and D = emergency invasive airway access). Additionally, specialized airway equipment may be included in the fifth drawer of the proposed difficult airway trolley, thus enabling widespread use. A logically designed, guideline-based difficult airway trolley is a vital resource for any clinician involved in airway management and may aid the adherence to difficult airway algorithms during evolving airway emergencies. Future research examining the availability of rescue airway devices in various clinical settings, and simulation studies comparing different types of difficult airway trolleys, are encouraged.

Predictive value of quick surgical airway assessment for trauma (qSAT) score for identifying trauma patients requiring surgical airway in emergency room

Background

A surgical airway is usually unpredictable in trauma patients. The aim of this study was to develop a predictable scoring system to determine the need for a surgical airway by using a database from a large multicenter trauma registry.

Methods

We obtained data from the nationwide trauma registry in Japan for adult blunt trauma patients who were intubated in the emergency department. Based on a multivariate logistic regression analysis in the development cohort, the Quick Surgical Airway Assessment for Trauma (qSAT) score was defined to predict the need for a surgical airway. The association of the qSAT with surgical airway was validated in the validation cohort.

Results

Between 2004 and 2014, 17,036 trauma patients were eligible. In the development phase (n = 8129), the qSAT score was defined as the sum of the three binary components, including male sex, presence of a facial injury, and presence of a cervical area injury, for a total score ranging from 0 to 3. In the validation cohort (n = 8907), the proportion of patients with a surgical airway markedly increased with increasing qSAT score (0 points, 0.5%; 1 point, 0.9%; 2 points, 3.5%; 3 points, 25.0%; P <  0.001). Multivariate analysis revealed that qSAT score was an independent predictor of surgical airway (adjusted OR, 3.19 per 1 point increase; 95% CI, 2.47–4.12; P <  0.0001). The qSAT score of ≥1 had a had a good sensitivity of 86.8% for predicting the requirement for surgical airway; while qSAT score of 3 had a good specificity of 99.9% in ruling out the need for surgical airway.

Conclusions

The qSAT score could be assessed simply using only information present upon hospital arrival to identify patients who may need a surgical airway. The utilize of qSAT score in combination with repeated evaluations on physical finding could improve outcomes in trauma patients.

Emergency front-of-neck airway by ENT surgeons and residents: A dutch national survey

Objectives

ENT surgeons and anesthesiologists work closely together in managing challenging airway cases. Sharing knowledge, experiences, and expectations interdisciplinary is essential in order to facilitate decision‐making and adequate management in emergency front‐of‐neck airway cases.

Methods

A survey was performed, to analyze level of experience, technique of preference, training, knowledge of material and protocols, and self‐efficacy scores of Dutch ENT surgeons and residents in performing an urgent or emergency front‐of‐neck airway.

Results

Within one year (January 2014–2015), 25.7% of the 257 respondents had performed an urgent or emergency front‐of‐neck airway. Of all reported emergency front‐of‐neck airways (N = 30), 80% were managed by tracheotomy. In future emergency front‐of‐neck airway cases, 74% stated cricothyrotomy would be their technique of preference. The majority would choose an uncuffed large‐bore cannula technique. Post‐academic hands‐on training was attended by 42% of respondents. Self‐efficacy scores were highest for surgical tracheotomy, and higher when trained or experienced. In case of an emergency scenario, 8.6% would not perform a front‐of‐neck airway themselves. The main reasons for reluctance to start in general were lack of experience and lack of training. Reported items for improvement were mainly the development of a protocol and training.

Conclusion

The chance of encountering an airway emergency scenario requiring front‐of‐neck airway is realistic. There is inconsistency between advised technique, technique of preference and technique actually performed by ENT surgeons. This study shows that there is both a need and desire for improvement in training and organization of care. Interdisciplinary guidelines and education is needed and could eventually safe lives.

Level of evidence

5

Videolaryngoscopy versus fiberoptic bronchoscope for awake intubation - a systematic review and meta-analysis of randomized controlled trials

Background

Awake intubation with videolaryngoscopy (VL) is a novel method that is drawing more and more attention as an alternative to awake intubation with fiberoptic bronchoscope (FOB). This meta-analysis is designed to determine the performance of VL compared to the FOB for awake intubation.

Methods

The Cochrane Central Register of Controlled Trials, PubMed, Embase, and Web of science were searched from database inception until October 30, 2017. Randomized controlled trials comparing VL and FOB for awake intubation were selected. The primary outcome was the overall success rate. Rev-Man 5.3 software was used to perform the pooled analysis and assess the risk of bias for each eligible study. The GRADE system was used to assess the quality of evidence for all outcomes.

Results

Six studies (446 patients) were included in the review for data extraction. Pooled analysis did not show any difference in the overall success rate by using VL and FOB (relative risk [RR], 1.00; P=0.99; high-quality evidence). There was no heterogeneity among studies (I²=0). Subgroup analyses showed no differences between two groups through nasal (RR, 1.00; P=1.00; high-quality evidence) and oral intubations (RR, 1.00; P=0.98; high-quality evidence). The intubation time was shorter by using VL than by using FOB (mean difference, −40.4 seconds; P<0.01; low-quality evidence). There were no differences between groups for other outcomes (P>0.05).

Conclusion

For awake intubation, VL with a shorter intubation time is as effective and safe as FOB. VL may be a useful alternative to FOB.

[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.

Do Difficult Airway Techniques Predispose Obese Patients to Bronchospasm?

Objective

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

Methods

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

Results

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

Conclusion

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

Ultrasound as an Assessment Method in Predicting Difficult Intubation: A Prospective Clinical Study

Objective

Aim of the study is to predict the difficulty in intubation preoperatively using ultrasonography.

Methods

One hundred and thirty-seven patients underwent ultrasound followed by surgery under general anesthesia. A experienced radiologist examined the airway and performed measurements of specific airway parameters: visualization of hyoid bone, visualization of vocal cords through thyroid cartilage, visualization of epiglottis, distance from base of tongue to hyoid bone, distance of hyomental region distance of thyrohyoid region, distance between skin and fat pad thickness to thyroid cartilage, thickness of submental region, distance from epiglottis to skin (above hyoid), and visualization of cricothyroid membrane. After performing ultrasound, patient was presented for surgery. An experienced anesthesiologist who is associated with this study did all the laryngoscopy and intubation.

Results

We were able to visualize all relevant anatomical structures in all the participants using ultrasound. The receiver operating characteristic curve analysis results showed that hyomental is ≤ 1.09 (P value < 0.01) to classify difficult in intubation.

Conclusion

The study shows that ultrasound can reliably image all the airway structures. This study suggests that hyomental distance is a more valid criterion in predicting difficult intubation. Further, case control study is needed for assessing the ease of intubation.

Temporal Trends in Difficult and Failed Tracheal Intubation in a Regional Community Anesthetic Practice

Background

When tracheal intubation is difficult or unachievable before surgery or during an emergent resuscitation, this is a critical safety event. Consensus algorithms and airway devices have been introduced in hopes of reducing such occurrences. However, evidence of improved safety in clinical practice related to their introduction is lacking. Therefore, we selected a large perioperative database spanning 2002 to 2015 to look for changes in annual rates of difficult and failed tracheal intubation.

Methods

Difficult (more than three attempts) and failed (unsuccessful, requiring awakening or surgical tracheostomy) intubation rates in patients 18 yr and older were compared between the early and late periods (pre- vs. post-January 2009) and by annual rate join-point analysis. Primary findings from a large, urban hospital were compared with combined observations from 15 smaller facilities.

Results

Analysis of 421,581 procedures identified fourfold reductions in both event rates between the early and late periods (difficult: 6.6 of 1,000 vs. 1.6 of 1,000, P &lt; 0.0001; failed: 0.2 of 1,000 vs. 0.06 of 1,000, P &lt; 0.0001), with join-point analysis identifying two significant change points (2006, P = 0.02; 2010, P = 0.03) including a pre-2006 stable period, a steep drop between 2006 and 2010, and gradual decline after 2010. Data from 15 affiliated practices (442,428 procedures) demonstrated similar reductions.

Conclusions

In this retrospective assessment spanning 14 yr (2002 to 2015), difficult and failed intubation rates by skilled providers declined significantly at both an urban hospital and a network of smaller affiliated practices. Further investigations are required to validate these findings in other data sets and more clearly identify factors associated with their occurrence as clues to future airway management advancements.

Ultrasound-guided identification of the cricothyroid membrane in a patient with a difficult airway: a case report

BACKGROUND

Surgical cricothyroidotomy is considered to be the last resort for management of the difficult airway. A major point for a successful surgical cricothyroidotomy is to identify the location of the cricothyroid membrane.

CASE PRESENTATION

We encountered a patient with progressive respiratory distress who was anticipated to have a difficult airway due to a large neck abscess. We prepared for both awake intubation and surgical cricothyroidotomy. The cricothyroid membrane could not be identified by palpation, but was readily identified using ultrasound.

CONCLUSION

Ultrasound-guided identification of the cricothyroid membrane may be useful in a patient with a difficult airway due to neck swelling.

Difficult Airway Characteristics Associated with First-Attempt Failure at Intubation Using Video Laryngoscopy in the Intensive Care Unit

RATIONALE

Video laryngoscopy has overcome the need to align the anatomic axes to obtain a view of the glottic opening to place a tracheal tube. However, despite this advantage, a large number of attempts are unsuccessful. There are no existing data on anatomic characteristics in critically ill patients associated with a failed first attempt at laryngoscopy when using video laryngoscopy.

OBJECTIVES

To identify characteristics associated with first-attempt failure at intubation when using video laryngoscopy in the intensive care unit (ICU).

METHODS

This is an observational study of 906 consecutive patients intubated in the ICU with a video laryngoscope between January 2012 and January 2016 in a single-center academic medical ICU. After each intubation, the operator completed a data collection form, which included information on difficult airway characteristics, device used, and outcome of each attempt. Multivariable regression models were constructed to determine the difficult airway characteristics associated with a failed first attempt at intubation.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences in sex, age, reason for intubation, or device used between first-attempt failures and first-attempt successes. First-attempt successes more commonly reported no difficult airway characteristics were present (23.9%; 95% confidence interval [CI], 20.7-27.0% vs. 13.3%; 95% CI, 8.0-18.8%). In logistic regression analysis of the entire 906-patient database, blood in the airway (odds ratio [OR], 2.63; 95% CI, 1.64-4.20), airway edema (OR, 2.85; 95% CI, 1.48-5.45), and obesity (OR, 1.59; 95% CI, 1.08-2.32) were significantly associated with first-attempt failure. Data collection on limited mouth opening and secretions began after the first 133 intubations, and we fit a second logistic model to examine cases in which these additional difficult airway characteristics were collected. In this subset (n = 773), the presence of blood (OR, 2.73; 95% CI, 1.60-4.64), cervical immobility (OR, 3.34; 95% CI, 1.28-8.72), and airway edema (OR, 3.10; 95% CI, 1.42-6.70) were associated with first-attempt failure.

CONCLUSIONS

In this single-center study, presence of blood in the airway, airway edema, cervical immobility, and obesity are associated with higher odds of first-attempt failure, when intubation was performed with video laryngoscopy in an ICU.

Obstructive sleep apnea as a risk factor associated with difficult airway management - A narrative review

STUDY OBJECTIVE

The association between obstructive sleep apnea (OSA) and difficult airway had been studied in various clinical trials but the relationship between the two conditions has not been clearly established. The objective of this narrative review is to determine if OSA is a risk factor associated with difficult airway.

DESIGN

The OVID Medline in process, Medline (vis Pub Med), EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Web of Science and SCOPUS were searched up to April 2016 using specific keywords. Inclusion criteria were: [1] airway management in patients with a diagnosis of OSA, [2] comparison of airway management between OSA and non-OSA patients, [3] publications or abstracts in the English language. The incidence of difficult airway between OSA and non-OSA patients was compared using Chi-square analysis or Fisher's exact test.

MAIN RESULTS

Ten studies were included in the final review. Overall, the incidence of difficult tracheal intubation was higher in OSA patients versus non-OSA patients [56/386 (14.5%) vs. 69/897 (7.7%); P=0.0002]. OSA patients also have a higher incidence of difficult mask ventilation [115/4626 (2.5%) vs. 471/64,684 (0.7%); P<0.0001]. Compared to non-OSA patients, OSA was not associated with difficulty in the use of a supraglottic airway (SGA) device [10/663 (1.5%) vs. 162/15,171 (1.1%); P=0.38]. No studies compared difficult surgical airway in OSA and non-OSA patients.

CONCLUSIONS

OSA was found to be a risk factor associated with difficult tracheal intubation and difficult mask ventilation. There was no association between OSA and difficult SGA use.

Infrared Red Intubation System (IRRIS) guided flexile videoscope assisted difficult airway management

BACKGROUND

Tracheal intubation with a flexible scope is a cornerstone technique in patients with severely difficult airways, but may fail. We report on a technique, Infrared Red Intubation System (IRRIS), that seems to facilitate the identification of the glottis.

METHODS

The IRRIS is placed over the patient's cricothyroid membrane and emits blinking infrared light through the patient's skin into the subglottic space. When a flexible videoscope (one that does not filter infrared light) is introduced into the airway, it will display this as a blinking white light emerging from the glottis, retrograde transillumination, showing the pathway to the trachea. We have introduced this as an adjunct when managing our patients with difficult airways. We describe the technique and retrospectively report on the first ten patients where it was used.

RESULTS

All ten patients had significant pathology in the airway, radiation therapy, predictors for difficult intubation and/or morbid obesity. In all cases the blinking light was visible during the flexible endoscopy and provided unambiguous identification of the glottis, from a distance. The blinking nature of the light from the IRRIS helped to distinguish it from the reflections in the mucosa that inevitably arise when the mucosa is hit by the light from the flexible scope itself.

CONCLUSION

The addition of the IRRIS technique to intubation with flexible videoscopes may be a tool that will make intubation of the most difficult airways easier and may be of special help to the clinician who only rarely uses flexible videoscopes for tracheal intubation.

Guidelines and algorithms for managing the difficult airway

The difficult airway constitutes a continuous challenge for anesthesiologists. Guidelines and algorithms are key to preserving patient safety, by recommending specific plans and strategies that address predicted or unexpected difficult airway. However, there are currently no "gold standard" algorithms or universally accepted standards. The aim of this article is to present a synthesis of the recommendations of the main guidelines and difficult airway algorithms.

Perioperative management of a patient with Coffin-Lowry syndrome complicated by severe obesity: A case report and literature review

RATIONALE

Coffin-Lowry syndrome (CLS) is a rare inherited disease with specific clinical features, such as mental retardation, facial dysmorphism, and cardiac abnormality. In particular, the characteristic facial features of CLS, including retrognathia and large tongue, are associated with difficult ventilation and/or intubation, which is a serious problem of anesthesia management. However, case reports on anesthesia management of CLS are very limited as there are only two published English reports till date. In this case report, we discuss anesthetic and postoperative considerations in patients with CLS, focusing on difficult airway management, and summarize past reports including some Japanese articles.

PATIENT CONCERNS

A 25-year-old man with CLS was planning to undergo laminectomy because of progressive quadriplegia caused by calcification of the yellow ligament. We suspected difficulty in airway management because of several factors in his facial features, short thyromental and sternomental distances in computed tomography, severe obesity, and sleep apnea syndrome.

DIAGNOSES

Difficult airway was suspected. However, because of mental retardation, awake intubation was considered difficult.

INTERVENTIONS

We selected bronchofiberscope-guided nasotracheal intubation, maintaining spontaneous breathing under moderate sedation with a propofol target-controlled infusion.

OUTCOMES

Airway management was safely performed during anesthesia induction.

LESSONS

In many patients with CLS, difficult intubation was reported, and sedation or slow induction maintaining spontaneous breathing was mainly selected for anesthesia induction. Spontaneous breathing should be maintained during anesthesia induction in case of CLS patients.