The causes of difficult tracheal intubation and preoperative assessments in different age groups

Impact of Radiotherapy on Endotracheal Intubation Quality Metrics in Patients with Esophageal Cancer: A Challenge for Advanced Airway Management?

(1) Background: Currently, no data are available in the literature investigating the influence of radiotherapy (RT) on endotracheal intubation success in patients with esophageal cancer. This study aims to evaluate the impact of RT on endotracheal intubation quality metrics in patients with esophageal cancer. (2) Methods: Patients with esophageal cancer who underwent RT followed by surgery between 2012 and 2023 at the University Hospital Heidelberg, Germany, were retrospectively analyzed. (3) Results: Fifty-five patients, predominantly males 65.5% with a mean age of 64 years, were enrolled. Overall, 81.8% of the patients had an ASA class of III, followed by 27.2% ASA II. The mean prescribed cumulative total dose to the primary tumor and lymph node metastasis was 48.2 Gy with a mean single dose of 1.8 Gy. The mean laryngeal total dose was 40.0 Gy. Direct laryngoscopy was performed in 80.0% of cases, followed by 12.1% videolaryngoscopy, and 7.2% required fiberoptic intubation. Overall, 96.4% of patients were successfully intubated on the first attempt. (4) Conclusions: It has been demonstrated that post-RT effects can increase the risk of airway management difficulties and complications. The results of our study did not indicate any evidence of impaired advanced airway management in patients with esophageal cancer who had undergone RT.

Can chin-nape circumference and the ratio of neck circumference to chin-nape circumference predict difficult mask ventilation or difficult intubation in obese patients?

We aimed to evaluate the success of the ratio of chin-nape circumference (CNC) and neck circumference (NC) to CNC in predicting difficult mask ventilation (DMV) or difficult intubation (DI). Eighty-seven obese patients (body mass index ≥ 30) were evaluated between September 15, 2019 and September 15, 2020. Mallampati score, mouth opening, upper lip bite test, distance between incisors, thyromental distance (TMD), sternomental distance (SMD), and thyromental height were recorded. NC and CNC were measured in a neutral position. The ratio of NC to TMD and the ratio of NC to CNC were calculated. Mask ventilation was graded according to the method described by Han et al (Grade 3 or 4 equals DMV). DI assessment was performed using the intubation difficulty scale (IDS, IDS < 5 equals easy intubation, IDS ≥ 5 equals DI). Logistic regression analysis was performed to identify the variables thought to be effective in DMV and DI. Receiver operating characteristic curves were generated for each parameter considered effective. DMV was found in 17.2% (n = 15) of the patients included in the study, and DI was found in 16.1% (n = 14). The relationship between DMV and age, male gender, obstructive sleep apnea syndrome, NC, ratio of NC to TMD, ratio of NC to SMD, ratio of NC to CNC, and CNC was significant. Male gender and NC >45.5 cm were independent risk factors for DMV. The relationship between DI and distance between incisors, NC, ratio of NC to TMD, ratio of NC to SMD, and CNC was significant. A distance between the incisors < 4.85 cm and a NC > 41.5 cm were found to be independent risk factors for DI. CNC may predict DMV and DI in obese patients. The ratio of NC to CNC may predict DMV in obese patients.

Effect of COVID-19 on the incidence of postintubation laryngeal lesions

Background

Critically ill patients intubated in the intensive care unit experience prolonged intubation leading to increased frequency of laryngeal injuries. This study aimed to demonstrate a suspected increase in vocal fold injury in patients who were intubated with COVID-19 as compared with patients intubated for other reasons.

Methods

A retrospective review of medical records was performed to identify patients examined using flexible endoscopic evaluation of swallowing exams. The study included 25 patients with COVID-19 and 27 without COVID-19 at Baylor Scott & White Medical Center in Temple, Texas. Various injuries were evaluated, ranging from granulation tissue to vocal cord paralysis. Severe lesions were those causing clinically significant airway obstruction or requiring operative intervention. The incidence of laryngeal injury in patients intubated for COVID-19 was then compared with that of patients intubated for other reasons.

Results

The increased presence of severe injury in COVID-positive patients appeared clinically significant but was not statistically significant (P = 0.06). Interestingly, patients who received pronation therapy had 4.6 times the odds of more severe injury compared with patients who did not (P = 0.009).

Conclusion

Lower thresholds for performing flexible laryngoscopy on postintubated patients who are proned may allow for earlier intervention and reduce morbidity in an already at-risk population.

Needle Cricothyroidotomy by Intensive Care Paramedics

Objective:

Cricothyroidotomy is an advanced airway procedure for critically ill or injured patients. In Victoria, Australia, intensive care paramedics (ICPs) perform needle cricothyroidotomy utilizing the proprietary QuickTrach II (QTII) device. Recently, an Ambulance Victoria (AV) institutional change in workflow included pre-puncture surgical incision to assist in successful placement. This review aims to explore whether a surgical pre-incision prior to the insertion of the device improved overall procedural success rates of needle cricothyroidotomy using the QTII.

Methods:

This was a retrospective review of all patients who received a needle cricothyroidotomy by ICPs from May 1, 2015 through September 15, 2020. Data and patient care records were sourced from the AV data warehouse.

Results:

A total of 27 patients underwent a needle cricothyroidotomy with the mean age of patients being 50.2 years. Most cricothyroidotomies were performed using the QuickTrach II kit (92.6%). Prior to modification of the QTII procedure, front-of-neck access (FONA) success was 50.0%; however, this improved to 82.4% after the procedures recent update. The overall success rate of all paramedic-performed needle cricothyroidotomy during the study period was 74.1% (n = 20).

Conclusions:

This review demonstrates that propriety devices such as the QTII device achieve a low success rate for a FONA intervention. Despite the low frequency of this procedure, ICPs with extensive training and regular maintenance can perform needle cricothyroidotomy using scalpel assistance with a reasonable success rate. But when compared to the broader literature, success rate using a more straightforward technique such as a surgical cricothyroidotomy technique is likely going to be higher.

Predicting difficult airway intubation in thyroid surgery using multiple machine learning and deep learning algorithms

Background

In this paper, we examine whether machine learning and deep learning can be used to predict difficult airway intubation in patients undergoing thyroid surgery.

Methods

We used 10 machine learning and deep learning algorithms to establish a corresponding model through a training group, and then verify the results in a test group. We used R for the statistical analysis and constructed the machine learning prediction model in Python.

Results

The top 5 weighting factors for difficult airways identified by the average algorithm in machine learning were age, sex, weight, height, and BMI. In the training group, the AUC values and accuracy and the Gradient Boosting precision were 0.932, 0.929, and 100%, respectively. As for the modeled effects of predicting difficult airways in test groups, among the models constructed by the 10 algorithms, the three algorithms with the highest AUC values were Gradient Boosting, CNN, and LGBM, with values of 0.848, 0.836, and 0.812, respectively; In addition, among the algorithms, Gradient Boosting had the highest accuracy with a value of 0.913; Additionally, among the algorithms, the Gradient Boosting algorithm had the highest precision with a value of 100%.

Conclusion

According to our results, Gradient Boosting performed best overall, with an AUC >0.8, an accuracy >90%, and a precision of 100%. Besides, the top 5 weighting factors identified by the average algorithm in machine learning for difficult airways were age, sex, weight, height, and BMI.

Multivariable prediction models for difficult direct laryngoscopy: Systematic review and literature metasynthesis

CONTEXT

The difficult airway is an important scenario in anaesthesia due to the impact of its potential complications, and the difficulty in predicting its presence in current clinical practice.

METHODS

Systematic review of articles in English and Spanish retrieved from MEDLINE (Ovid), LILACS and EMBASE up to March 2018. The search strategy was defined by the authors. The reviewers uploaded the studies to specially designed tables in order to qualitatively analyse the results of each paper.

RESULTS

A total of 3602 studies were identified. Thirty-four of these were included in the qualitative review. The most commonly used definition of difficulty was the Cormack-Lehane 3 or 4 classification, with a weighted mean incidence of 7.23%. The most relevant finding was the methodological weaknesses in obtaining these scales.

CONCLUSIONS

Available prediction models show limited discrimination, and weaknesses were detected in the methodology used to develop these prediction rules.

Textural properties and muscle activities during mastication of normal and ultrasonically softened sticky rice aimed for consumers with swallowing disorder: A pilot study

Ultrasonication was used to develop softer sticky rice for elder adults. Textural properties of original sticky rice (oSR) and ultrasonically modified sticky rice (mSR) were determined. In addition, jaw muscle activities during mastication of both oSR and mSR were investigated. Twenty-seven healthy elderly subjects, age 68.9 ± 7.6 years, were asked to masticate both types of sticky rice in random sequence for three times with a 5-min rest between each test. Activities of bilateral masseter and suprahyoid muscles were recorded. Root mean square (RMS) and mastication duration were analyzed. After mastication trials, subjects were asked to rate preference and softness of the samples. mSR exhibited significantly lower hardness than oSR, while cohesiveness and adhesiveness values of the two samples were not significantly different. Interestingly, all the muscle activities were not significantly different between masticating oSR and mSR, whereas the number of chewing cycles while chewing the mSR was larger. However, 92% of the subjects preferred mSR and felt that it was softer. mSR may therefore be regarded as having potential for elder people who have difficulty masticating hard solid foods based on its lower hardness and higher level of preference compared to oSR.

Multivariable prediction models for difficult direct laryngoscopy: Systematic review and literature metasynthesis

CONTEXT

The difficult airway is an important scenario in anaesthesia due to the impact of its potential complications, and the difficulty in predicting its presence in current clinical practice.

METHODS

Systematic review of articles in English and Spanish retrieved from MEDLINE (Ovid), LILACS and Embase up to March 2018. The search strategy was defined by the authors. The reviewers uploaded the studies to specially designed tables in order to qualitatively analyse the results of each paper.

RESULTS

A total of 3602 studies were identified. Thirty-four of these were included in the qualitative review. The most commonly used definition of difficulty was the Cormack-Lehane3 or 4 classification, with a weighted mean incidence of 7.23%. The most relevant finding was the methodological weaknesses in obtaining these scales.

CONCLUSIONS

Available prediction models show limited discrimination, and weaknesses were detected in the methodology used to develop these prediction rules.

Study comparing different airway assessment tests in predicting difficult laryngoscopy: A prospective study in geriatric patients

Background and Aims

Limited studies are available comparing diagnostic accuracy of various airway predictors in geriatric patients. We conducted this study with primary aim to evaluate and validate the predictive value of 'standard airway predictors' like modified Mallampati test, thyromental distance (TMD), sternomental distance, neck movement (NM), mouth opening (MO), dentition and 'new airway predictors' like upper lip bite test (ULBT), ratio of height to thyromental distance and thyromental height test (TMHT) for predicting difficult laryngoscopy in geriatric patients.

Methods

This prospective, observational study was conducted on 140 patients above 65 years of age of either sex, scheduled for elective surgery under general anaesthesia requiring endotracheal intubation. The age, weight, height, body mass index (BMI) and airway parameters were recorded. The laryngoscopic view was assessed by modified Cormack-Lehane scale. Standard formulae were used to calculate validity indexes.

Results

The incidence of difficult larygoscopy found in our study was 25%. The mean age of our study population was 69.37 ± 4.23 years. TMD exhibited the highest sensitivity (80%) and negative predictive value (NPV) (91.86%) as compared to other studied airway predictors. The positive predictive value (PPV) of ULBT was 100%. Moreover, ULBT exhibited highest accuracy (82.14%) and odds ratio (86.88) and high specificity (91.30%) for predicting difficult laryngoscopy in geriatric patients. NM and TMHT also exhibited high accuracy (77.85%, 77.14%) and PPV (59.09%, 52.94%).

Conclusions

TMD and ULBT both showed good predictive value in diagnosing difficult laryngoscopy in geriatric patients. Furthermore, NM and TMHT also exhibited higher diagnostic accuracy in predicting difficult airway in these patients.

Factors affecting the risk of SARS-CoV-2 transmission to anesthesiologists performing endotracheal intubation in patients with SARS-CoV-2

BACKGROUND

In this study, we estimated the predictive factors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in anesthesiologists performing endotracheal intubation in patients with confirmed SARS-CoV-2.

METHOD

We analyzed data from a survey conducted by the Chinese Society of Anesthesiology Task Force on Airway Management on endotracheal intubation in 98 patients with SARS-CoV-2 confirmed through nucleic acid testing and chest computed tomography. The multivariate logistic model with stepwise selection was used for selecting the predictive factors significantly associated with SARS-CoV-2 infection in the corresponding anesthesiologists.

RESULTS

SARS-CoV-2 prevalence in the corresponding anesthesiologists was 20.41% after intubation in patients with SARS-CoV-2. Univariate analysis indicated that intubation for elective treatment, intubation in an operating room or isolation ward, and routine rapid induction with continuous positive-pressure ventilation (PPV) for intubation were associated with a lower SARS-CoV-2 risk in the anesthesiologists. Multivariate analysis revealed that intubation for elective treatment was associated with a significantly decreased SARS-CoV-2 risk (adjusted odds ratio [aOR] = 0.28, 95% confidence interval [CI]: 0.14-0.68, P < 0.0001), and coughing by patients during endotracheal intubation was associated with a significantly increased SARS-CoV-2 risk (aOR = 1.70, 95% CI: 1.39-2.97, P = 0.0404) in the anesthesiologists.

CONCLUSION

Endotracheal intubation for elective treatments, intubation in an operating room or isolation ward, and routine rapid induction with continuous PPV for patients with confirmed SARS-CoV-2 are associated with a lower risk of SARS-CoV-2 transmission in practicing anesthesiologists, and coughing by patients during intubation increases the risk.

Association of advanced age with intubation-related adverse events in the emergency department: a multicentre prospective observational study

BACKGROUND

While the older population accounts for an increasing proportion of emergency department (ED), little is known about intubation-related adverse events in this high-risk population. We sought to determine whether advanced age is associated with a higher risk of intubation-related adverse events in the ED.

METHODS

This is an analysis of data from a prospective, 15-centre, observational study-the second Japanese Emergency Airway Network (JEAN-2) study. The current analysis included adult (aged ≥18 years) patients who underwent intubation in the ED between 2012 and 2018. The primary exposure was age (18-39, 40-64, 65-74, 75-84 and ≥85 years). The primary outcome was overall intubation-related adverse events during or immediately after an intubation. Adverse events were further categorised into major (hypotension, hypoxaemia, oesophageal intubation, cardiac arrest, dysrhythmia and death) and minor (endobronchial intubation, oesophageal intubation with early recognition, dental/lip trauma, airway trauma and regurgitation) adverse events. We constructed multivariable logistic regression models adjusting for seven potential confounders with generalised estimating equations that account for patients clustering within the ED.

RESULTS

Among 9714 patients eligible for the analysis, 15% were aged ≥85 years, and 16% had adverse events. In the unadjusted models, advanced age was not significantly associated with the risk of overall adverse events. In the adjusted models, the association was significant (adjusted OR 1.41 in age ≥85 years (95% CI, 1.09 to 1.81) compared with age 18-39 years). Specifically, older patients had a significantly higher risk of major adverse events (adjusted OR in age ≥85 years 2.65 (95% CI, 1.78 to 3.94)), which was driven by the association of advanced age with an increased risk of hypotension (adjusted OR in ≥85 years, 5.69 (95% CI, 3.13 to 10.37)). By contrast, advanced age was not associated with minor adverse events.

CONCLUSION

Based on the data from a prospective multicentre study, advanced age was associated with higher risks of major adverse events.

Mallampati test with phonation, tongue protrusion and supine position is most correlated with Cormack-Lehane test

Many modified Mallampati tests have been developed to date. Samsoon's modified Mallampati test (standard Mallampati test) is currently widely used. We newly designed seven types of assessment protocol of Mallampati test, in addition to standard Mallampati test. In this study, we studied the correlation between eight types of protocol (standard and seven alternative protocols) of Mallampati test and Cormack-Lehane test. We newly designed assessment protocols as new Mallampati test. These are different protocols depending on the presence or absence of phonation, those of protrusion of tongue, and sitting position or supine position. The oropharyngeal structures visualized by these eight types of Mallampati test for total of 145 patients undergoing dental oral surgery were evaluated. The scores derived via eight types of Mallampati test were recorded. The influence of phonation, tongue protrusion and body position on Mallampati test score was analyzed, respectively. The relationships between eight types of Mallampati test and Cormack-Lehane test were analyzed. Tongue protrusion, phonation and sitting position tended to lower the score of Mallampati test (p < 0.001, respectively). The standard Mallampati test was not correlated with Cormack-Lehane test. In the new Mallampati tests, assessment protocol with tongue protrusion, phonation and sitting position, that with tongue protrusion and supine position, or that with tongue protrusion, phonation and supine position were significantly correlated with Cormack-Lehane test, respectively. (p = 0.020, p = 0.007 and p = 0.004, respectively). The standard Mallampati test did not correlate with Cormack-Lehane test. Mallampati test with phonation, tongue protrusion and supine position were most correlated with Cormack-Lehane test.

Accuracy of thyromental height test for predicting difficult intubation in elderly

BACKGROUND

Studies of the accuracy of different airway tests are lacking in elderly. We evaluated and compared the accuracy of thyromental height in predicting difficult intubation in relation to the other traditional airway tests in elderly.

METHODS

We included 120 patients aged ≥ 65 years scheduled for general anesthesia with tracheal intubation. Thyromental height, modified Mallampati test, thyromental distance and sternomental distance were evaluated. Cormack-Lehane grade > 2 was considered difficult laryngoscopy. Difficult tracheal intubation was considered if successful intubation required more than 2 attempts. The accuracy of different tests in predicting difficult intubation and difficult laryngoscopy were evaluated through area under receiver operating characteristic (AUROC) curves. Univariate and multivariate analyses were conducted to identify risk factors for difficult intubation and difficult laryngoscopy.

RESULTS

Our cohort had a mean age of 71(7) years. We encountered difficult laryngoscopy in 15/120 (12%) patients, difficult intubation in 20/120 (17%) patients, and failed laryngoscopy requiring alternative methods for securing the airway in 3/120 (3%) patients. For predicting difficult intubation, thyromental height and modified Mallampati test showed the highest accuracy AUROC (95% confidence interval): 0.9 (0.83-0.95), cut-off value ≤ 5.9 cm, and AUROC (95% confidence interval): 0.89 (0.82-0.94), cut-off value > 2, respectively. Low thyromental height and high modified Mallampati test were the only independent risk factors for difficult laryngoscopy and difficult intubation.

CONCLUSION

In elderly scheduled for elective procedure, both thyromental height and modified Mallampati tests showed good accuracy in predicting difficult intubation and difficult laryngoscopy, whilst thyromental distance and sternomental distance were poor predictors.

Surgeon-performed intubation in awake patients utilising an anterior commissure laryngoscope with bougie: a retrospective case series

Objective

This retrospective case series examined the outcomes of surgeon-performed intubation using the anterior commissure rigid laryngoscope and bougie in adults with a difficult airway, including awake patients.

Methods

This study comprised a series of adult patients who underwent surgeon-performed intubation over a 10-year period. They were identified by a records search for the Current Procedural Terminology (‘CPT’) code 31500 – ‘intubation by surgeon’.

Results

Forty-nine intubations performed in the operating theatre were reviewed. Intubation performed by the surgeon using the rigid anterior commissure laryngoscope was successful in 47 of the cases (96 per cent). Over half of the patients had experienced failed intubation attempts with other methods by other providers prior to the surgeon performing direct laryngoscopy. Twenty intubations were performed without paralytics and with the patient awake.

Conclusion

In properly selected adults who need an urgent, secure airway in the operating theatre, surgeon-performed anterior commissure laryngoscopic intubation using a bougie should be considered a safe, reliable procedure. In most cases, this procedure can be performed in selected patients whilst awake, with sedation.

Airway physical examination tests for detection of difficult airway management in apparently normal adult patients

BACKGROUND

The unanticipated difficult airway is a potentially life-threatening event during anaesthesia or acute conditions. An unsuccessfully managed upper airway is associated with serious morbidity and mortality. Several bedside screening tests are used in clinical practice to identify those at high risk of difficult airway. Their accuracy and benefit however, remains unclear.

OBJECTIVES

The objective of this review was to characterize and compare the diagnostic accuracy of the Mallampati classification and other commonly used airway examination tests for assessing the physical status of the airway in adult patients with no apparent anatomical airway abnormalities. We performed this individually for each of the four descriptors of the difficult airway: difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation, and failed intubation.

SEARCH METHODS

We searched major electronic databases including CENTRAL, MEDLINE, Embase, ISI Web of Science, CINAHL, as well as regional, subject specific, and dissertation and theses databases from inception to 16 December 2016, without language restrictions. In addition, we searched the Science Citation Index and checked the references of all the relevant studies. We also handsearched selected journals, conference proceedings, and relevant guidelines. We updated this search in March 2018, but we have not yet incorporated these results.

SELECTION CRITERIA

We considered full-text diagnostic test accuracy studies of any individual index test, or a combination of tests, against a reference standard. Participants were adults without obvious airway abnormalities, who were having laryngoscopy performed with a standard laryngoscope and the trachea intubated with a standard tracheal tube. Index tests included the Mallampati test, modified Mallampati test, Wilson risk score, thyromental distance, sternomental distance, mouth opening test, upper lip bite test, or any combination of these. The target condition was difficult airway, with one of the following reference standards: difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation, and failed intubation.

DATA COLLECTION AND ANALYSIS

We performed screening and selection of the studies, data extraction and assessment of methodological quality (using QUADAS-2) independently and in duplicate. We designed a Microsoft Access database for data collection and used Review Manager 5 and R for data analysis. For each index test and each reference standard, we assessed sensitivity and specificity. We produced forest plots and summary receiver operating characteristic (ROC) plots to summarize the data. Where possible, we performed meta-analyses to calculate pooled estimates and compare test accuracy indirectly using bivariate models. We investigated heterogeneity and performed sensitivity analyses.

MAIN RESULTS

We included 133 (127 cohort type and 6 case-control) studies involving 844,206 participants. We evaluated a total of seven different prespecified index tests in the 133 studies, as well as 69 non-prespecified, and 32 combinations. For the prespecified index tests, we found six studies for the Mallampati test, 105 for the modified Mallampati test, six for the Wilson risk score, 52 for thyromental distance, 18 for sternomental distance, 34 for the mouth opening test, and 30 for the upper lip bite test. Difficult face mask ventilation was the reference standard in seven studies, difficult laryngoscopy in 92 studies, difficult tracheal intubation in 50 studies, and failed intubation in two studies. Across all studies, we judged the risk of bias to be variable for the different domains; we mostly observed low risk of bias for patient selection, flow and timing, and unclear risk of bias for reference standard and index test. Applicability concerns were generally low for all domains. For difficult laryngoscopy, the summary sensitivity ranged from 0.22 (95% confidence interval (CI) 0.13 to 0.33; mouth opening test) to 0.67 (95% CI 0.45 to 0.83; upper lip bite test) and the summary specificity ranged from 0.80 (95% CI 0.74 to 0.85; modified Mallampati test) to 0.95 (95% CI 0.88 to 0.98; Wilson risk score). The upper lip bite test for diagnosing difficult laryngoscopy provided the highest sensitivity compared to the other tests (P < 0.001). For difficult tracheal intubation, summary sensitivity ranged from 0.24 (95% CI 0.12 to 0.43; thyromental distance) to 0.51 (95% CI 0.40 to 0.61; modified Mallampati test) and the summary specificity ranged from 0.87 (95% CI 0.82 to 0.91; modified Mallampati test) to 0.93 (0.87 to 0.96; mouth opening test). The modified Mallampati test had the highest sensitivity for diagnosing difficult tracheal intubation compared to the other tests (P < 0.001). For difficult face mask ventilation, we could only estimate summary sensitivity (0.17, 95% CI 0.06 to 0.39) and specificity (0.90, 95% CI 0.81 to 0.95) for the modified Mallampati test.

AUTHORS' CONCLUSIONS

Bedside airway examination tests, for assessing the physical status of the airway in adults with no apparent anatomical airway abnormalities, are designed as screening tests. Screening tests are expected to have high sensitivities. We found that all investigated index tests had relatively low sensitivities with high variability. In contrast, specificities were consistently and markedly higher than sensitivities across all tests. The standard bedside airway examination tests should be interpreted with caution, as they do not appear to be good screening tests. Among the tests we examined, the upper lip bite test showed the most favourable diagnostic test accuracy properties. Given the paucity of available data, future research is needed to develop tests with high sensitivities to make them useful, and to consider their use for screening difficult face mask ventilation and failed intubation. The 27 studies in 'Studies awaiting classification' may alter the conclusions of the review, once we have assessed them.

Encountering unexpected difficult airway: relationship with the intubation difficulty scale

Background

An unexpected difficult intubation can be very challenging and if it is not managed properly, it may expose the encountered patient to significant risks. The intubation difficulty scale (IDS) has been used as a validated method to evaluate a global degree of intubation difficulty. The aims of this study were to evaluate the prevalence and characteristics of unexpected difficult intubation using the IDS.

Methods

We retrospectively reviewed 951 patients undergoing elective surgery in a single medical center. Patients expected to have a difficult intubation or who had history of difficult intubation were excluded. Each patient was assessed by the IDS scoring system with seven variables. Total prevalence of difficult intubation and the contributing individual factors were further analyzed.

Results

For the 951 patients, the difficult intubation cases presenting IDS > 5 was 5.8% of total cases (n = 55). The prevalence of Cormack-Lehane Grade 3 or 4 was 16.2% (n = 154). Most of the difficult intubation cases were managed by simple additional maneuvers and techniques such as stylet application, additional lifting force and laryngeal pressure.

Conclusions

Unexpected difficult airway was present in 5.8% of patients and most was managed effectively. Among the components of IDS, the Cormack-Lehane grade was most sensitive for predicting difficult intubation.

Assessment before airway management

It is wise to plan and prepare for the unexpected difficult airway. Although it is essential to take a history and examine every patient prior to airway management, preoperative anticipation of a difficult airway occurs in only 50% of patients subsequently found to have a difficult airway. Bedside screening tests lack accuracy. The modified Mallampati test and the measurement of thyromental distance are unreliable for prediction of difficult tracheal intubation. Knowledge of risk factors for various airway management techniques may help when devising an airway management plan.

Airway management by physician-staffed Helicopter Emergency Medical Services - a prospective, multicentre, observational study of 2,327 patients

Background

Despite numerous studies on prehospital airway management, results are difficult to compare due to inconsistent or heterogeneous data. The objective of this study was to assess advanced airway management from international physician-staffed helicopter emergency medical services.

Methods

We collected airway data from 21 helicopter emergency medical services in Australia, England, Finland, Hungary, Norway and Switzerland over a 12-month period. A uniform Utstein-style airway template was used for collecting data.

Results

The participating services attended 14,703 patients on primary missions during the study period, and 2,327 (16 %) required advanced prehospital airway interventions. Of these, tracheal intubation was attempted in 92 % of the cases. The rest were managed with supraglottic airway devices (5 %), bag-valve-mask ventilation (2 %) or continuous positive airway pressure (0.2 %). Intubation failure rates were 14.5 % (first-attempt) and 1.2 % (overall). Cardiac arrest patients showed significantly higher first-attempt intubation failure rates (odds ratio: 2.0; 95 % CI: 1.5-2.6; p < 0.001) compared to non-cardiac arrest patients. Complications were recorded in 13 %, with recognised oesophageal intubation being the most frequent (25 % of all patients with complications). For non-cardiac arrest patients, important risk predictors for first-attempt failure were patient age (a non-linear association) and administration of sedatives (reduced failure risk). The patient’s sex, provider’s intubation experience, trauma type (patient category), indication for airway intervention and use of neuromuscular blocking agents were not risk factors for first-attempt intubation failure.

Conclusions

Advanced airway management in physician-staffed prehospital services was performed frequently, with high intubation success rates and low complication rates overall. However, cardiac arrest patients showed significantly higher first-attempt failure rates compared to non-cardiac arrest patients. All failed intubations were handled successfully with a rescue device or surgical airway.

Trial registration

Study registration: www.clinicaltrials.govNCT01502111. Registered 22 December 2011.

Comparing ease of intubation in obese and lean patients using intubation difficulty scale

Background:

Difficult tracheal intubation contributes to significant morbidity and mortality during induction of anesthesia. There are divided opinions regarding ease of intubation in obese patients. Moreover, the definition of difficult intubation is not uniform; hence we have use the Intubation Difficulty Scale (IDS) to find the incidence of difficult intubation in obese patients.

Aims:

The primary aim of the following study is to find out the incidence of difficult intubation in obese and lean patients using IDS and secondary aim is to assess the performance of bedside screening tests to predict difficult intubation, mask ventilation and laryngoscopy in obese and lean patients.

Materials and Methods:

A prospective, observational cohort study of 200 patients requiring general anesthesia were categorized into 100 each based on body mass index (BMI) into lean (BMI <25 kg/m²) and obese (BMI ≥25 kg/m²) groups. IDS score ≥5 was termed as difficult intubation. Pre-operative airway assessment included Mallampati score, mouth opening, neck circumference (NC), upper lip bite test, thyromental distance, sternomental distance (SMD) and head neck mobility. Patients having difficulty in mask ventilation and laryngoscopy was recorded.

Results:

Over all in 200 patients the incidence of difficult intubation was 9%. Obese patients were slightly more difficult to intubate than lean (11% vs. 7%, P = 0.049). Age >40 years, NC >35 cm, SMD <12.5 cm and restricted head neck mobility were factors which were associated with IDS ≥5. Multivariate analysis revealed SMD <12.5 cm to predict difficult intubation in obese patients. Obese patients were difficult to mask ventilate (6% vs. 1%, P = 0.043). There was no difference regarding grading of laryngoscopy between the two groups.

Conclusion:

Obese patients are difficult to mask ventilate and intubate. During intubation of obese patients who is more than 40 years age and SMD <12.5 cm, it is preferable to have a second skilled anesthesiologist.

The effect of aging on pulmonary function: implications for monitoring and support of the surgical and trauma patient

Age-related anatomic, physiologic, and immunologic changes to the pulmonary system, as well as a high prevalence of chronic pulmonary diseases, puts the geriatric patient at an especially high risk for postoperative pulmonary complications. Successful perioperative respiratory care of the geriatric patient relies on careful risk assessment and optimization of pulmonary function and support. The success of such efforts aimed at preventing and/or mitigating pulmonary complications in the geriatric patient depends on a thorough, individualized, yet standardized and evidence-based approach to the care of every patient.

Lingual traction to facilitate fiber-optic intubation of difficult airways: a single-anesthesiologist randomized trial

PURPOSE

Flexible fiber-optic bronchoscope-guided orotracheal intubation is a valuable technique with demonstrated benefits in the management of difficult airways. Despite its popularity with anesthesia providers, the technique is not fail-safe and airway-related complications secondary to failed intubation attempts remain an important problem. We sought to determine the effect of incorporating lingual traction on the success rate of fiber-optic bronchoscope-guided intubation in patients with anticipated difficult airways.

METHODS

In this prospective, randomized, cohort study, we enrolled 91 adult patients with anticipated difficult airways scheduled for elective surgery to undergo fiber-optic bronchoscope-guided orotracheal intubation alone or with lingual traction by an individual anesthesiologist after induction of general anesthesia and neuromuscular blockade. A total of 78 patients were randomized: 39 patients to the fiber-optic bronchoscope-guided intubation with lingual traction group and 39 patients to the fiber-optic bronchoscope-guided intubation alone group. The primary endpoint was the rate of successful first attempt intubations. The secondary outcome was sore throat grade on post-operative day 1.

RESULTS

Fiber-optic intubation with lingual traction compared to fiber-optic intubation alone resulted in a higher success rate (92.3 vs. 74.4 %, χ (2) = 4.523, p = 0.033) and greater odds for successful first attempt intubation (OR 4.138, 95 % CI 1.041-16.444, p = 0.044). Sore throat severity on post-operative day 1 was not significantly different but trended towards worsening grades with lingual traction.

CONCLUSIONS

In this study, lingual traction was shown to be a valuable maneuver for facilitating fiber-optic bronchoscope-guided intubation in the management of patients with anticipated difficult airways.

Validation of modified Mallampati test with addition of thyromental distance and sternomental distance to predict difficult endotracheal intubation in adults

Background and Aims:

Intubation is often a challenge for anaesthesiologists. Many parameters assist to predict difficult intubation. The present study was undertaken to assess the validity of different parameters in predicting difficult intubation for general anaesthesia (GA) in adults and effect of combining the parameters on the validity.

Methods:

The anaesthesiologist assessed oropharynx of 135 adult patients. Modified Mallampati test (MMT) was used and the thyromental distance (TMD) and sternomental distances (SMD) for each of the patients were also measured. The Cormack and Lehane laryngoscopic grading was assessed following laryngoscopy. The validity parameters such as sensitivity, specificity, false positive and negatives values, positive and negative predictive values were calculated. The effect of combining different measurements on the validity was also studied. Univariate analysis was performed using the parametric method.

Results:

The study group comprised of 135 patients. The sensitivity and specificity of MMT were 28.6% and 93%, respectively. The TMD (<6.5 CM) had sensitivity and specificity of 100% and 75.8%, respectively. The SMD (<12.5 CM) had sensitivity and specificity of 91% and 92.7%, respectively. Combination of MMT grading and TMD and SMD measurements increased the validity (sensitivity of 100% and specificity of 92.7%).

Conclusion:

MMT had high specificity. The validity of combination of MMT, SMD and TMD as compared to MMT alone was very high in predicting difficult intubation in adult patients. All parameters should be used in assessing an adult patient for surgery under GA.

Risk Factors for Perioperative Airway Difficulty and Evaluation of Intubation Approaches Among Patients With Benign Goiter

Objective:

The objective was to determine patient and gland characteristics associated with difficult intubation in patients undergoing thyroidectomy for goiter and to assess different methods of intubation in these patients.

Methods:

This study was an IRB-approved, retrospective chart review of 112 consecutive patients undergoing hemithyroidectomy or total thyroidectomy for thyroid goiter from 2009-2012 at an academic tertiary care facility in Bronx, New York. Patient demographics, thyroid gland characteristics (gland weight and nodule size), presence of preoperative symptoms (dyspnea, dysphagia, and hoarseness), and radiographical findings (tracheal compression, tracheal deviation, and substernal extension of the thyroid gland) were recorded. Anesthesia records were reviewed for method of intubation, as well as success or failure of intubation attempts.

Results:

Nineteen patients (17.0%) were men and 93 (83.0%) were women. The age of the patients included in the study ranged from 14 to 86 years with a mean ± SD age of 53.5 ± 14.7 years. Difficult intubation was noted with 13 (11.6%) patients. Only patient age was significantly associated with difficult intubation. The mean age of patients with airway difficulty was 60.7 ± 3.7 years compared to 52.1 ± 1.5 years in those who did not experience airway difficulty ( P = .04). No other reviewed risk factors were found to be significantly associated with difficult intubation. Fiberoptic intubation (FOI) was used in 38 patients and difficult intubation occurred in 18.4% (7/38). Direct laryngoscopy with transoral intubation (LTOI) was used in 58 patients, in whom 3.4% (2/58) experienced a difficult intubation. FOI was aborted 6 times and LTOI was subsequently successful in each of these cases.

Conclusions:

Our results suggest that benign nodular goiter disease does not pose significant challenges to intubation in our patient cohort. The technique of intubation deviated from the initial plan several times in the FOI group, whereas LTOI was ultimately successful in every case. Our data suggest that the role of fiberoptic intubation for patients with large goiters should be further refined.