Magnitude and Predisposing Factors of Difficult Airway during Induction of General Anaesthesia.
ABSTRACT: To assess magnitude and predisposing factors of difficult airway during induction of general anaesthesia.Hospital based cross sectional study carried out to determine the incidence of difficult mask ventilation, difficult laryngoscopy (Cormack and Lehane III and IV), difficult intubation (IDS ≥ 5), and failed intubation. The association between each predisposing factor and airway parameters with components of difficult airway is investigated with binary logistic regression. Sensitivity, specificity, positive and negative predictive value of the test, and odds ratio with 95% confidence interval were calculated to determine the association between independent and dependent variable.The incidence of difficult laryngoscopy, difficult intubation, and failed intubation are 12.3%, 9%, and 0.005%, respectively. Mouth opening < 30 mm and Mallampati classes III and IV are the most sensitive tests and second high specific test next to combination of tests to predict difficult intubation and laryngoscopy (P value < 0.001). Unrestricted multiple attempt without alternative airway techniques resulted in exponential increase in desaturation episodes and further difficulty of airway management (P value < 0.001).Mallampati classes III and IV, mouth opening ≤ 30 mm, jaw slide grade C, attempt > 3, and ineffective alternative technique have increased predictability value of difficult airway.
Project description:The diagnostic validity of clinical airway assessment tests for predicting difficult laryngoscopy in patients requiring endotracheal intubation were evaluated using receiver operating characteristic (ROC) curve analysis and a grey zone approach.In this prospective observational study, patients were evaluated during a pre-anaesthetic visit. Predictive airway assessment tests (i.e. Modified Mallampati [MMT] classification; upper lip bite test [ULBT]; mouth opening; sternomental distance; thyromental distance [TMD]; neck circumference; neck mobility; height to thyromental distance [HT/TMD]; neck circumference-to-thyromental distance [NC/TMD]) were performed on each patient and LEMON, Naguib, and MACOCHA scores were also calculated. In addition, laryngeal images were acquired and assessed for percentage of glottic opening (POGO) scores. A POGO score of zero was categorized as difficult laryngoscopy.The incidence of difficult laryngoscopy was 14.4% (35/243). Although seven predictive airway assessments (i.e. MMT classification, ULBT, mouth opening, HT/TMD, NC/TMD, and the LEMON and Naguib models) predicted difficult laryngoscopy by ROC analyses, a grey zone approach showed that the parameters were inconclusive in approximately 70% of patients. From all the tests, the HT/TMD ratio showed the highest sensitivity (80.0%) and ULBT had the highest specificity (95.2%).Using the grey zone approach, all predictive airway assessment tests showed large inconclusive zones which may explain previous inconsistent results in the prediction of difficult laryngoscopy. Our results suggest that the usefulness of clinical airway evaluation tests for predicting difficult laryngoscopy remains controversial.ClinicalTrials.gov (NCT01719848).
Project description:Introduction:The significance of difficult or failed tracheal intubation following induction is a well-recognized cause of morbidity and mortality in anesthetic practice. Nevertheless, the need to predict potentially difficult tracheal intubation has received a little attention. During routine anesthesia, the incidence of difficult tracheal intubation has been estimated at 1.5%-8% of general anesthetics. Difficulties in intubation have been associated with serious complications, such as brain damage or death, particularly when failed intubation has occurred. Occasionally, in a patient with a difficult airway, the anesthetist is faced with the situation where mask ventilation proves difficult or impossible. This is one of the most critical emergencies that may be faced in the practice of anesthesia. If the anesthetist can predict which patients are likely to prove difficult to intubate, he/she may reduce the risks of anesthesia considerably. In Ethiopia, there are no data on the magnitude of difficult laryngoscopic tracheal intubation and no standard guidelines for preoperative tests. The main concern of this study was to provide information on the magnitude of difficult laryngoscopic intubation and to determine valuable preoperative tests to predict difficult laryngoscopy and intubation in patients with apparently normal airways which can help anesthetists to improve preoperative airway assessment and contribute to decrease anesthesia-related morbidity and mortality. Objective:The main objective of this study was to assess the magnitude and predictive values of preoperative tests for difficult laryngoscopy and intubation, among surgical patients who underwent elective surgery under general anesthesia with endotracheal intubation in Tikur Anbessa Hospital from February 1 to March 30, 2016. Study Design:A facility-based cross-sectional study design was used. Result:In this study, we found the magnitude of difficult laryngoscopy and intubation as 13.6% and 5%, respectively. 33.3% of patients with difficult laryngoscopy were found to be difficult for intubation. Mallampati test, interincisor distance, and thyromental distance were identified to be good preoperative tests to predict difficult laryngoscopic intubation when used in combination. Recommendation:We recommend anesthesia professionals to use combination of MMC/TMD/IID for their routine preoperative airway assessment.
Project description:BACKGROUND:Predicting difficult intubation is of high clinical interest. METHODS:237 patients aged ?18 years were included in the study. Preoperative airway evaluation included: Mallampati test, thyromental distance, sternomental distance and thyromental height test. During direct laryngoscopy Cormack & Lehane classification was graded. We calculated the ROC AUC, sensitivity and specificity for thyromental height test as a primary end point of our study. RESULTS:Only thyromental height test and Cormack-Lehane scale proved significant on occurrence of difficult intubation. The optimal sensitivity and specificity values of thyromental height test were met with a cut off value of 50 mm. With 1 mm increase in thyromental height test, risk of difficult intubation decreased by 7%. CONCLUSION:Thyromental height test is a simple, easy to perform and non-invasive test to predict difficult intubation in patients scheduled for elective double lumen tube intubation during thoracic surgical procedures. With 1 mm above 50 mm increase in thyromental height test the risk of difficult intubation decreased by 7%. TRIAL REGISTRATION:Clinicaltrials.gov Identifier: NCT02988336.
Project description:Failed intubation in obstetrics remains the most common cause of death directly related to anesthesia. Neck circumference has been shown to be a predictor for difficult intubation in morbidly obese patients. The aim of this study was to determine an optimal cutoff point of neck circumference for prediction of difficult intubation in obstetric patients.Ninety-four parturients scheduled for cesarean section under general anesthesia were included in the study. Preoperative airway assessment and neck circumference were measured. Difficult intubation was the primary outcome according to the intubation difficulty scale (IDS), intubation reported difficult if the IDS score was ≥5.Univariate analysis showed that Mallampati score and neck circumference were positive predictors for difficult intubation (P = 0.005 and P = 0.011, respectively). Mouth opening, thyromental distance, sternomental distance, and the hyomental distance ratio were not useful predictors (P = 0.68, P = 0.87, P = 0.48, and P = 0.27, respectively). Logistic regression for the Mallampati score and neck circumference negative results as independent predictors of difficult intubation in obstetric (P = 0.53). Sensitivity analysis showed that neck circumference of 33.5 cm is the cutoff point to detect difficult intubation with 100% sensitivity (95% confidence interval [CI]: 69.2-100) and 50% specificity (95% CI: 38.9-61.1). The area under the curve for neck circumference was 0.746 (95% CI: 0.646-0.830) with a positive predictive value of 19.2 (95% CI: 9.6-32.5), a negative predicative value of 100 (95% CI: 91.6-100), and a P < 0.0001.In obstetric patients, a neck circumference ≥33.5 cm is a sensitive predictor for difficult intubation.
Project description:Objective. Evaluation of C-MAC PM® in combination with a standard Macintosh blade size 3 in direct and indirect laryngoscopy and D-Blade® in indirect laryngoscopy in a simulated difficult airway. Primary outcome was defined as the best view of the glottic structures. Secondary endpoints were subjective evaluation and assessment of the intubation process. Methods. Prospective monocentric, observational study on 48 adult patients without predictors for difficult laryngoscopy/tracheal intubation undergoing orthopedic surgery. Every participant preoperatively received a cervical collar to simulate a difficult airway. Direct and indirect laryngoscopy w/o the BURP maneuver with a standard Macintosh blade and indirect laryngoscopy w/o the BURP maneuver using D-Blade® were performed to evaluate if blade geometry and the BURP maneuver improve the glottic view as measured by the Cormack-Lehane score. Results. Using a C-MAC PM® laryngoscope, D-Blade® yielded improved glottic views compared with the Macintosh blade used with either the direct or indirect technique. Changing from direct laryngoscopy using a Macintosh blade to indirect videolaryngoscopy using C-MAC PM® with D-Blade® improved the Cormack-Lehane score from IIb, III, or IV to I or II in 31 cases. Conclusion. The combination of C-MAC PM® and D-Blade® significantly enhances the view of the glottis compared to direct laryngoscopy with a Macintosh blade in patients with a simulated difficult airway. Trial Registration Number. This trial is registered under number NCT03403946.
Project description: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.
Project description:BACKGROUND:Existing difficult airway prediction tools are not practical for emergency intubation and do not incorporate physiological data. The HEAVEN criteria (Hypoxaemia, Extremes of size, Anatomic challenges, Vomit/blood/fluid, Exsanguination, Neck mobility) may be more relevant for emergency rapid sequence intubation (RSI). METHODS:A retrospective analysis included air medical RSI patients. A checklist was used to assess HEAVEN criteria prior to RSI, and Cormack-Lehane (CL) laryngoscopic view was recorded for the first intubation attempt. The incidence of a difficult (CL III/IV) laryngoscopic view as well as failure to intubate on first attempt with and without oxygen desaturation were determined for each of the HEAVEN criteria and total number of HEAVEN criteria. In addition, the association between HEAVEN criteria and both laryngoscopic view and intubation performance were quantified using multivariate logistic regression for direct laryngoscopy (DL) and video laryngoscopy (VL) configured with a Macintosh #4 non-hyperangulated blade. RESULTS:A total of 5137 RSI patients over 24 months were included. Overall intubation success was 97%. A CL III/IV laryngoscopic view was reported in 25% of DL attempts and 15% of VL attempts. Each of the HEAVEN criteria and total number of HEAVEN criteria were associated with both CL III/IV laryngoscopic view and failure to intubate on the first attempt with and without oxygen desaturation for both DL and VL. These associations persisted after adjustment for multiple co-variables including the other HEAVEN criteria. CONCLUSION:The HEAVEN criteria may be useful to predict laryngoscopic view and intubation performance for DL and VL during emergency RSI.
Project description:Background:The rigid tube for laryngoscopy is an instrument used in ENT, for inspecting the larynx and its vicinity. We used it to facilitate intubation, in ENT patients. Methods:Twenty patients attending for surgery were included for study. Group 1 (n=10) had no airway pathology but at least two predictors of an anatomically difficult airway. Group 2 (n=10) had an obstructing airway pathology. After anesthesia induction, classical laryngoscopy was performed, and intubation grade registered. Using the retromolar approach the rigid tube advanced slowly, the epiglottis was lifted, and the vocal cords were visualized. The bougie was introduced through the rigid tube into the trachea, the rigid tube was extracted, and the intubating tube was placed in the trachea, over the bougie. Results:The mean (SD) maneuver duration was 59.4 (18.2) sec. The Cormack-Lehane view of the glottis at classical laryngoscopy was poor in four patients in Group 1 and six patients in Group 2. The lowest desaturation was 82%. No complications other than sore throat were noted. Conclusion:The rigid tube for laryngoscopy is a useful tool for intubation in ENT patients. We noticed an advantage against classical intubation in patients with base of tongue carcinoma, reduced mouth opening and protruding upper incisors with this instrument.
Project description:BACKGROUND:Obstetric dfficult airway is a leading cause of maternal morbidity and mortality. The laryngeal mask airway (LMA) is often used as a rescue airway device after failed intubation, however, little is known about predictors of difficult LMA insertion, particularly in obstetrics. Since Mallampati scores of III/IV has been associated with difficult tracheal intubation, our present study aims to investigate if Mallampati score (MP) could predict airway outcomes for LMA use in obstetrics. METHODS:This prospective cohort study was performed at a single-center: Quanzhou Women's and Children's Hospital, Fujian Province, China. Five hundred and eighty-four parturients undergoing elective cesarean section under general anesthesia were recruited. The primary outcome was time to effective ventilation, and secondary outcomes included first attempt insertion success, seal pressure, ventilation and hemodynamic parameters, occurrence of clinical aspiration, and maternal and fetal outcomes. RESULTS:The parturients were classified into two groups based on MP of III/IV (High MP: 61) versus I/II (Low MP: 523). BMI was higher in the High MP group than in the Low MP group (mean (SD) 29.3 (7.0) vs 26.8 (3.1), p < 0.0001). There was no difference in maternal age, ASA status and gestational age. There was similar time to effective ventilation (mean (SD) High MP: 14.9 (4.5) vs Low MP: 15.7 (4.4) seconds, p = 0.2172), and first attempt success rate, seal pressure, and peak airway pressure. No clinical aspiration was noted. The incidence of blood on SLMA was higher in the High MP group than in Low MP (4 (6.6%) vs 4 (0.8%), p = 0.001). There was no difference in sore throat, voice hoarseness, maternal satisfaction and fetal outcomes. CONCLUSION:High MP was not associated with reduced SLMA airway outcomes in cesarean section under general anesthesia, but may increase the risk of blood found on SLMA upon removal. TRIAL REGISTRATION:This study was registered at http://www.clinicaltrials.gov , identifier: NCT02026882 , retrospectively registered. Date of registration: December 31, 2013.
Project description:BACKGROUND:Abnormal laryngeal structures are likely to be associated with a difficult laryngoscopy procedure. Currently, laryngeal structures can be measured by ultrasonography, however, little research has been performed on the potential role of ultrasound on the evaluation of a difficult laryngoscopy. The present study investigated the value of laryngeal structure measurements for predicting a difficult laryngoscopy. OBJECTIVE:The main objective of this study was to explore the value of laryngeal structure measurements for predicting a difficult laryngoscopy. METHODS:Two hundred and eleven adult patients (over 18?years old) were recruited to undergo elective surgery under general anesthesia via endotracheal intubation. Ultrasound was utilized to measure the distance between the skin and thyroid cartilage (DST), the distance between the thyroid cartilage and epiglottis (DTE), and the distance between the skin and epiglottis (DSE) in the parasagittal plane. These metrics were then investigated as predictors for classifying a laryngoscopy as difficult vs easy, as defined by the Cormack and Lehane grading scale. RESULTS:Multivariate logistic regression showed that the DSE, but not DST or DTE, was significantly related to difficult laryngoscopies. Specifically, a DSE???2.36?cm predicted difficult laryngoscopies with a sensitivity and specificity of 0.818 (95% CI: 0.766-0.870) and 0.856 (95% CI: 0.809-0.904). Furthermore, when combining the best model constructed of other indicators (i.e. sex, body mass index, modified Mallampati test) to predict the difficult laryngoscopy, the AUC reached 93.28%. CONCLUSION:DSE is an independent predictor of a difficult laryngoscopy; a DSE cutoff value of 2.36?cm is a better predictor of a difficult laryngoscope than other ultrasound or physiological measurements for predicting a difficult laryngoscope. Nevertheless, it's more valuable to apply the best model of this study, composed of various physiological measurements, for this prediction purpose.