Cormack-Lehane Classification Research Articles

Using temporomandibular joint mobility to predict difficult tracheal intubation

The aim of this prospective study was to determine the reliability of temporomandibular joint (TMJ) mobility measurements for predicting difficult intubation. To evaluate the accuracy in predicting difficult intubation by TMJ mobility measurement, 762 patients requiring general anesthesia with tracheal intubation for elective surgery were enrolled in this prospective, observational, single-blind study. Maximum mouth opening, right-left jaw excursion, and degrees of protraction were determined with a digital inclinometer. Incisor gap was measured using a vernier caliper during full mouth opening. After induction of anesthesia using a standard protocol, the patient's grade of laryngeal view by Cormack-Lehane classification was documented by an anesthesiologist. We found that the degrees of protraction and incisor gap in the easy intubation group were significantly higher than those in the difficult intubation group. The incisor gap was found to be more sensitive (88.37%) and more specific (95.71%) than protraction degrees (58.14% and 59.76%, respectively). The results revealed that measurements of the incisor gap and degrees of protraction may be useful routine screening tests for preoperative prediction of difficult intubation.

CobraPLUS and Cookgas air-Q versus Fastrach for blind endotracheal intubation: a randomised controlled trial

CobraPLUS and Cookgas air-Q are supraglottic airways expected to allow safe ventilation as well as reliable blind intubation. In a prospective, controlled trial, we hypothesised that quality of ventilation and success rate of blind endotracheal intubation of these new devices would be superior to the Fastrach intubating laryngeal mask airway (ILMA). When blind intubation failed the quality of fibrescope-guided intubation was investigated. To allow identification of those patients in whom blind intubation would be difficult, we investigated the predictive value of currently used predictors for ease of endotracheal intubation. One hundred and eighty adult patients with documented BMI, Mallampati score, Cormack-Lehane classification, interincisor gap and thyromental distance were randomised into three groups according to the device used. Ventilation conditions were rated as excellent, good or difficult. When blind intubation failed, fibrescope-guided intubation conditions were rated as well. Statistical analysis was performed by a χ-test. The quality of ventilation was excellent for all devices. Three patients in the CobraPLUS group and two patients in the ILMA and the Cookgas groups needed a slight reposition. Blind intubation through the CPLA was successful in 47%, through the Cookgas in 57%, whereas the Fastrach group had a success rate of 95%. Fibreoptic intubation was possible in all but one patient. None of the registered scores and measures allowed prediction of difficult blind intubation. All devices appeared to be safe airways. The Fastrach ILMA proved to be a reliable facilitator for blind intubation. CobraPLUS and Cookgas air-Q allowed an easy fibrescopic intubation. Failed blind intubations could not be predicted by the used parameters.

Comparison of Succinylcholine and Rocuronium for First-attempt Intubation Success in the Emergency Department

The objective was to determine the effect of paralytic type and dose on first-attempt rapid sequence intubation (RSI) success in the emergency department (ED). This was a retrospective evaluation of information collected prospectively in a quality improvement database between July 1, 2007, and October 31, 2008. Information regarding all intubations performed in a tertiary care ED was recorded in this database. All RSI performed using succinylcholine or rocuronium were included. Logistic regression was used to analyze the effect of paralytic type and dosing, as well as age, sex, body mass index, physician experience, device type, and presence of difficult airway predictors on first attempt RSI success. A total of 327 RSI were included in the final analyses. All patients received etomidate as the induction sedative and were successfully intubated. Of these, 113 and 214 intubations were performed using succinylcholine and rocuronium, respectively. The rate of first-attempt intubation success was similar between the succinylcholine and rocuronium groups (72.6% vs. 72.9%, p=0.95). Median doses used for succinylcholine and rocuronium were 1.65 mg/kg (interquartile range [IQR]=1.26-1.95 mg/kg) and 1.19 mg/kg (IQR=1-1.45 mg/kg), respectively. In the univariate logistic regression analyses, variables predictive of first-attempt intubation success were laryngeal view (more success if Grade 1 or 2 compared to Grade 3 or 4 of the Cormack-Lehane classification, odds ratio [OR] =55.18, 95% confidence interval [CI]=18.87 to 161.39), intubation device (less success if direct laryngoscopy, OR=0.57, 95% CI=0.34 to 0.96), and presence of a difficult airway predictor (OR=0.55, 95% CI=0.31 to 0.99). In the multivariate analysis, the only variable predictive of first-attempt intubation success was laryngeal view. Succinylcholine and rocuronium are equivalent with regard to first-attempt intubation success in the ED when dosed according to the ranges used in this study.

MALLAMPATI TEST AS A PREDICTOR OF LARYNGOSCOPIC VIEW

To determine the accuracy of the modified Mallampati test for predicting difficult tracheal intubation. A cross-sectional, clinical, observational, non-blinded study. A quality analysis of anesthetic care. Operating theatres and department of anesthesiology in a university hospital. Following the local ethics committee approval and patients' informed consent to anesthesia, all adult patients (> 18 yrs) presenting for any type of non-emergency surgical procedures under general anesthesia requiring endotracheal intubation were enrolled. Prior to anesthesia, Samsoon and Young's modification of the Mallampati test (modified Mallampati test) was performed. Following induction, the anesthesiologist described the laryngoscopic view using the Cormack-Lehane scale. Classes 3 or 4 of the modified Mallampati test were considered a predictor of difficult intubation. Grades 3 or 4 of the Cormack-Lehane classification of the laryngoscopic view were defined as impaired glottic exposure. The sensitivity, specificity, positive and negative predictive value, relative risk, likelihood ratio and accuracy of the modified Mallampati test were calculated on 2x2 contingency tables. Of the total 1,518 patients enrolled, 48 had difficult intubation (3.2%). We failed to detect as many as 35.4% patients in whom glottis exposure during direct laryngoscopy was inadequate (sensitivity 0.646). Compared to the original article by Mallampati, we found lower specificity (0.824 vs. 0.995), lower positive predictive value (0.107 vs. 0.933), higher negative predictive value (0.986 vs. 0.928), lower likelihood ratio (3.68 vs. 91.0) and accuracy (0.819 vs. 0.929). When used as a single examination, the modified Mallampati test is of limited value in predicting difficult intubation.

Alternative devices for difficult airway in prehospital settings

Introduction: The management of airway in prehospital setting has a lot of special considerations such the patient's position, the environment, the family or the patient per se. The purpose is calculating the use of alternative device for management of difficult airway in prehospital settings. Methods: A prospective study based record of the information of all the endotracheal intubations. The inclusion criteria were all persons 18 age older who need endotracheal intubation. We register age, sex, Cormack-lehane Classification, cause of intubation, access to patient, intubation attempts, use of alternative devices and final status (dead or alive). We defined difficult airway with more than 3 attempts to perform the intubation. Results: Median age 62 (SD 17.6). Sex male 62.9%, female 37.1%. The endotracheal intubation's cause were: cardiological 4.5%, traumatic 7%, neurological 17.1%, cardiac arrest 63.3% and others 8%. The Cormack-lehane classification were grade 1 28.2%, grade 2 25.1%, grade 3 24.1% and grade 4 22.6%. The intubation's attempts were 1 in 50% of cases, 2 in 26.5%, 3 in 18% and 4 or more in 5.5%. 23.5% of difficult airway in our series. In 22.2% of the cases were used alternative devices. The patient's access were good in 56.3% of cases. The final status were dead in 55.5% and alive in 44.5%. We found statically significance among difficult airway and Cormack-lehane classification, access to the patient but not with final patient's status. Conclusions: We estimate 22.2% of difficult airway in our series. We used alternative devices in 23.5% of cases. The access to the patient and the Cormack-lehane classification has statically association with the difficult airway.

Airway Scope Versus Macintosh Laryngoscope in Patients With Simulated Limitation of Neck Movements

Tracheal intubation in patients with suspected neck injuries should achieve two contradicting goals-sufficient laryngeal exposure and the least cervical spine movement. Because the former involves displacements of the cervical vertebrae, intubation under immobilization is widely performed today to prevent exacerbation of spinal code injuries. The unique curving blade of the Airway Scope (AWS) is designed to fit the oropharyngeal anatomy. A camera at the tip of the blade displays the view of the larynx, but unlike the direct laryngoscope, it needs no line-of-sight of the oral, pharyngeal, and tracheal axis. Our purpose is to determine whether AWS could be a suitable airway device for the intubation of patients with potential neck injury. Thirty-six patients scheduled for surgery were randomly assigned to undergo intubation using either AWS or Macintosh laryngoscope (MLS). After general anesthetic induction, the patient's head was set in a neutral position, and an appropriately sized semi-rigid neck collar was placed. Measurements include intubation time, number of attempts, success rate, Cormack-Lehane classification, airway optimization maneuver, Intubation Difficulty Scale scores, and complications. Intubation time proved no statistical significance (mean ± SD, AWS, 62.9 seconds ± 26.0 seconds, MLS, 55.6 seconds ± 26.0 seconds; p = 0.42). AWS scored less in Cormack-Lehane classification (median [range], AWS I [I-I], MLS IIIa [I-IIIb]; p < 0.0001), required fewer additional airway optimization maneuvers (p = 0.0003), and scored less in Intubation Difficulty Scale scores (AWS 0 [0-1], MLS 2 [0-5]; p < 0.0001). In neck-immobilized patients using semi-rigid cervical collars, AWS improves laryngeal exposure and facilitates tracheal intubation. AWS may be a suitable intubation device for trauma patients.

Cormack–Lehane classification revisited

BackgroundThe Cormack–Lehane (CL) classification is broadly used to describe laryngeal view during direct laryngoscopy. This classification, however, has been validated by only a few studies reporting inconclusive data concerning its reliability. This discrepancy between widespread use and limited evidence prompted us to investigate the knowledge about the classification among anaesthesiologists and its intra- and inter-observer reliability. MethodsOne hundred and twenty interviews were performed at a major European anaesthesia congress. Participants were interviewed about their general knowledge on grading systems to classify laryngeal view during laryngoscopy and were subsequently asked to define the grades of the CL classification. Inter- and intra-observer reliabilities were tested in 20 anaesthesiologists well familiar with the CL classification, who performed 100 laryngoscopies in a full-scale patient simulator. ResultsAlthough 89% of interviewed subjects claimed to know a classification to describe laryngeal view during laryngoscopy, 53% were able to name a classification. When specifically asked about the CL classification, 74% of the interviewed subjects stated to know this classification, whereas 25% could define all four grades correctly. In the simulator-based part of the study, inter-observer reliability was fair with a κ coefficient of 0.35 and intra-observer reliability was poor with a κ of 0.15. ConclusionsThe CL classification is poorly known in detail among anaesthesiologists and reproducibility even in subjects well familiar with this classification is limited.

Difficulties with Gum Elastic Bougie Intubation in an Academic Emergency Department

Background The difficulties with gum elastic bougie (GEB) use in the emergency department (ED) have never been studied prospectively. Objectives To determine the most common difficulties associated with endotracheal intubation using a GEB in the ED. Methods We conducted a prospective, observational study of GEB practices in our two affiliated urban EDs with a 3-year residency training program and an annual census of 150,000 patients. Laryngoscopists performing a GEB-assisted intubation completed a structured data form after laryngoscopy, recording patient characteristics, grade of laryngeal view (using the modified Cormack-Lehane classification), reason for GEB use, and problems encountered. Data were analyzed using standard statistical methods and 95% confidence intervals. Results A GEB was used for 88 patients. The overall success rate was 70/88 (79.6%; 95% confidence interval [CI] 71.1–88.0%). The GEB failure rate of the first laryngoscopist was 25/88 (28.4%; 95% CI 21.0–40.3%), with the two most common reasons being: inability to insert the bougie past the hypopharynx in 13 (52%; 95% CI 32.4–71.6%) and inability to pass the endotracheal tube over the bougie in six (24%; 95% CI 7.3–40.7). Conclusions The GEB is a helpful rescue airway device, but emergency care providers should be aware that failure rates are relatively high at a teaching institution.

Inter- and intra-observer reliability of the Cormack-Lehane classification

Inter- and intra-observer reliability of the Cormack-Lehane classification

Changes in three-dimensional computer tomography images of upper airway in patients with difficult tracheal intubation

Objective To evaluate the changes in three-dimensional computer tomography (3DCT) images of upper airway in patients with difficult tracheal intubation and provide theoretical evidence for predicting the difficult tracheal intubation. Methods Seventeen ASA Ⅰ or Ⅱ male patients, 25-60 yr old, height 165-185 era, weight 55-110 kg, body mass index 19-33 kg/m2, scheduled for elective surgery under general anesthesia, were studied. The airway condition was evaluated with Mallampati classification and Willsan score system in all patients before the operation. The patients underwent 3DCT scanning under 2 different statuses: with or without tongue protruding while opening his mouth maximally. The volume of the oropharyngeal cavity (Va1, Va2) andtongue body (Vt1, Vt2), and area of the oropharyngeal cavity (Aa1, Aa2) and tongue body (At1, At2) in the coronal position were measured before and during tongue protruding. The midline sagittal images of the upper airway were made on computer to measure the direct laryngoscope angle and vertical distance between the mandible and hyoid (MHD). Awake blind tracheal intubation was performed in all patients. The exposure of the glottis was performed after anesthesia induction and evaluated with Cormack-Lehane classification. The patients were divided into non-difficult intubation group (group NDI, Cormack-Lehane grade Ⅰ or Ⅱ) and difficult intubation group (group DI, Cormack-Lehane grade Ⅲ or Ⅳ) according to Cormack-Lehane classification. Results There were 8 patients in group NDI, and 9 patients in group DI. There was no significant difference in the indices before tongue protruding between group DI and NDI (P>0.05). Va2, Va1 - Va1, Aa2, Aa1 - Aa2, and At1- At2 weresignificanfly smaller, MHD was significantly longer and Va1,/Vt1- Va2/Vt2was significantly larger in group DI than in group NDI (P < 0.05 or 0.01). Va2 and Aa2 were significantly smaller than Va1 and Aa1 in group DI respectively (P < 0.05). Conclusion The changes in 3DCT images of the upper airway in patients with difficult tracheal intubation are mainly presented as smaller volume and area of the oropharyngeal cavity, larger difference value of the ratio of cavity volume to tongue volume and prolonged MHD. Key words: Airway obstruction; Tomography, spiral computed

An Evaluation of the Rapid Airway Management Positioner in Obese Patients Undergoing Gastric Bypass or Laparoscopic Gastric Banding Surgery

A new positioning device, the Rapid Airway Management Positioner (RAMP, Airpal Inc., Center Valley, PA) was evaluated to determine if there was an improvement in either mask ventilation, direct laryngoscopy, or both with the use of the RAMP in this patient population. Fifty-one morbidly obese patients (BMI > 35kg/m(2)) undergoing elective bariatric surgery were enrolled. Ventilation and laryngoscopy was performed in the neutral and head-elevated laryngoscopy position (HELP). Direct laryngoscopy was performed noting the glottic view according to the Cormack-Lehane classification (Samsoon and Young, Anesthesiology 42:487, 1987). Mask ventilation was then recommenced. The HELP, or "ramped," position was achieved by inflating the RAMP, which was placed underneath the patient prior to entering the OR. Once proper HELP position was achieved, a second laryngoscopy was performed followed by endotracheal intubation. Two main outcomes were noted in the neutral and HELP positions: (1) laryngoscopic view and (2) ease of ventilation. The inflated ramped position provided greater ease of ventilation as compared to the neutral position (p = 0.0003). There was also a significant improvement in the glottic view in the ramped position (p = 0.04). Ease of intubation was perceived to be severely difficult among two, and overall use of the positioning device was found to be difficult among seven of the residents. The RAMP effectively positions morbidly obese patients in the HELP position. Ease of ventilation and laryngoscopic view were both improved with its use in this patient population.

The timing of tracheal Intubation with rocuronium relaxation based on neuro-muscular monitoring

Objective To investigate the timing of tracheal intubafion with rocuronium relaxation based on neuro-muscular monitoring.Methods One hundred and twenty patients undergoing elective laparoseopic cholecystectomy were randomly divid-ed into two groups(n=60).Tracheal intubation performed 60 s after a bolus dose of 0.9 mg/kg rocuronium(group A)or at maximal T1 depression based on neuromuscular monitoring (group B).Glottic exposure and intubation condition were evaluated with Cormack-Lehane classification and Cooper's score,respectively.HR,SBP and time to maximal T1 depression Were record-ed during induction.Hoarseness and sore throat were observed in first postoperative day.Results Time to maximal T1 de-pression after rocuronium injection was(66.0±18.1)s (95%confidence interval 30.2 s-101.8 s).Coopor's score and Cormack's classification in group B was superior to that in group A(P<O.05).HR and SBP increased significantly after tracheal intuba-tion(P<0.05)in both groups,with more increasing extent in group A(P<0.05).The incidence of hoarseness was comparable between both groups.with higher incidence of sore throat in group A than in group B(P<O.05).Conclusion Neuro-muscular monitoring enables to get better intubation condition.More than 101.8 s after a bolus dose of 0.9 mg/kg rocu.Fonium may be the ideal time for tracheal intubation. Key words: Neuro-musealar monitoring; Rocumnium; Intubation condition; Glottic exposure

Left-molar approach for direct laryngoscopy: is it easy?

For direct laryngoscopy, we compared midline and left-molar approaches with respect to ease of intubation, using a Macintosh blade. We investigated the relationship between failure of the left-molar approach and preoperative risk factors for difficult intubation. With local ethics committee approval, 200 consecutive adult, nonpregnant patients were included in the study. The demographic data, body mass index, Mallampati modified score, interincisor gap, and mentohyoid and thyromental distances were measured preoperatively. First, the Macintosh blade was inserted using the midline approach, and then optimal external laryngeal manipulation (OELM) was applied. Second, the blade was inserted using the left-molar approach. The glottic views were assessed according to the Cormack-Lehane classification before and after OELM in both approaches. In cases where tracheal intubation failed with the left-molar approach, the midline approach was applied again and endotracheal intubation took place. The grade I glottic view obtained using the midline approach without OELM did not change in 94.3% of the patients with the left-molar approach without OELM; in addition, the grade II glottic view improved to grade I in 52.8% of the patients with the same technique (P < 0.001). Although the number of patients with a grade I or II glottic view in the left-molar approach was 197, only 37 patients could be intubated using the left-molar approach. In addition, 59.5% of them were intubated at the second attempt with the left-molar approach, while the incidence of a second attempt was 1.2% with the midline approach (P < 0.001). There was no correlation between the preoperative risk factors for difficult intubation and failure of the left-molar approach. Difficulty in the insertion of the endotracheal tube limits the efficacy of the left-molar approach. It is not possible to predict the failure of intubation with the left-molar approach by considering the preoperative risk factors.

Comparison of Intubation Success of Video Laryngoscopy Versus Direct Laryngoscopy in the Difficult Airway Using High-Fidelity Simulation

A number of devices, including video laryngoscopy, are used to aid in managing difficult airways. The goal of this study was to compare timing and success of video laryngoscopy to standard laryngoscopic intubation using a simulation mannequin in normal and difficult airway scenarios. Residents and attending physicians of a PGY 2-4 emergency medicine residency program participated. A single, high-fidelity simulation mannequin was used. Each participant received an in-service on the video laryngoscope (GlideScope). Three airway settings were used: standard, decreased neck mobility, and tongue edema. Participants intubated with a Macintosh blade and video laryngoscope in each scenario, and graded the best view achieved using the Cormack-Lehane classification. Outcome measures included time to view the vocal cords, time to intubation, grading of view, and intubation success or failure. Institutional Review Board approval was obtained. Fifty-two participants were enrolled. Participants successfully intubated the mannequin faster using the Macintosh blade in both the normal and neck immobility settings (9.4 seconds faster, 95% CI 3.2-15.7, P = 0.004, 16.1 seconds faster, 95% CI 3.6-28.7, P = 0.01). In the tongue edema setting, however, video laryngoscopy provided a better grade view of the cords, a higher success rate of viewing the cords at time of intubation (50% vs. 12%), and a higher rate of successful intubations (83% vs. 23%). The GlideScope also significantly reduced the time needed to view the cords (89 seconds reduction, 95% CI 54.4-123.7, P < 0.0001) and intubate (131.3 seconds reduction, 95% CI 99.1-163.6, P< 0.0001) for the tongue edema setting. In the most difficult airway case, tongue edema, the video laryngoscope provided an enhanced view of the cords using less time, increased intubation success, and decreased the time to intubation.

Predictors of difficult intubation – a simple approach

Background: A common cause of anaesthesia related morbidity and mortality is difficult or failed intubation. A lot of studies have attempted to create a score or mathematical model to predict difficult intubation accurately without much success. Many of them consider all predictive parameters as equal. This study attempts to rank the predictors of difficult intubation without creating complicated mathematical models.Methods: Modified mallampati class, degree of head extension, mento-hyoid distance, thyromental distance, interincisor gap, forward movement of the mandible and indirect laryngoscopy were assessed in 498 patients scheduled for elective surgery. Grading of glottis exposure on direct laryngoscopy was done based on CormackLehane classification. Logistic regression analysis was done to identify factors that were significantly associated with difficult glottis exposure (Grades 3 & 4). The predictors were ranked according to the ‘odds’ derived from regression analysis.Results: Direct laryngoscopy was difficult in 40 patients (8%). Indirect laryngoscopy was excluded from the analysis in view of poor patient cooperation in a large number of patients (13%). Degree of head extension, Mento-hyoid distance of < 4 cm and modified Mallampati class 3&4 were found to have significant association with difficult glottic exposure . These predictors could be ranked in the same order based on ‘odds’ ratio (11, 3.4, and 2.5 respectively) calculated from logistic regression analysis.Conclusion: Patients with restricted head movement have much higher ‘odds’ of having a difficult glottic exposure at direct laryngoscopy, followed by those with decreased mentohyoid distance and higher modified mallampati class.

Success of the Gum Elastic Bougie as a Rescue Airway in the Emergency Department

The gum elastic bougie (GEB) is a rescue airway device commonly found in the emergency department (ED). However, data documenting its efficacy are lacking in the emergency medicine literature. To determine the success rate of endotracheal intubation using a GEB and the reliability of "palpable clicks" and "hold-up" in the ED setting. The GEB was introduced at our two affiliated urban EDs with a 3-year residency training program and an annual census of 150,000. Physicians were trained in the use of the GEB before initiation of the study. Over the course of 1 year, we conducted a prospective, observational study of GEB practices in the ED. The study population included all adult patients on whom intubation was attempted with a GEB. All emergency physicians attempting intubation completed a structured data form after laryngoscopy, recording patient characteristics, grade of laryngeal view (using the modified Cormack-Lehane classification), and presence of "palpable clicks" and "hold-up." Indications for GEB use in our ED include a difficult or rescue airway and for training purposes. Data were analyzed using standard statistical methods and 95% confidence intervals. In our study period, there were 26 patients on whom intubation was attempted with a GEB. The overall success rate was 20/26 (76.9%; 95% confidence interval [CI] 60.7-93.1%). Among cases where the GEB was used for training purposes (all grade 1 or 2a laryngeal view), six of seven (85.7%) intubations were successful. When the GEB was used for clinically indicated purposes, 14 of 19 (73.7%; 95% CI 53.9-93.5%) intubations were successful. Palpable clicks were appreciated in 11/20 successful intubations (sensitivity 55.0%; 95% CI 33.2-76.8%); there was one false positive (specificity 80%; 95% CI 40.9-98.2%). Of 20 successful intubations, hold-up was deferred in five cases; of 15 remaining cases, hold-up was appreciated in 5/15 (sensitivity 33.3%; 95% CI 9.5-57.2%); there were no false positives (specificity 100%; 95% CI 60.7-100%). In our ED setting, the GEB had a success rate of 73.7% when utilized as a rescue airway after failed attempts. The characteristics of "palpable clicks" and "hold-up" were unreliable.

Comparison of the Upper Lip Bite Test with Measurement of Thyromental Distance for Prediction of Difficult Intubations

The upper lip bite test (ULBT) introduced in 2003 is a simple method for predicting difficult intubations. According to this test, the higher a patient can bite the upper lip with the lower incisors, the lower the risk of difficult intubation. Given the necessity for evaluation and re-evaluation of a newer predictive method, this study was conducted to compare the ULBT with another method for difficult airway prediction, the measurement of thyromental distance (TMD). In this prospective, observational, single-blind study, 350 patients who required inhaled general anesthesia with endotracheal intubation for elective surgery were enrolled for evaluation of the accuracy in predicting difficult intubation by TMD measurement and ULBT. In the ULBT, the capacity of biting the upper lip is categorized into three classes: class I, a patient is able to raise the lower incisors above the vermilion line; class II, a patient is able to bite the upper lip below the vermilion line; and class III, a patient is unable to bite the upper lip. After induction of anesthesia with a standard protocol, the patient's grade of laryngeal view by the Cormack-Lehane classification was documented by an anesthesiologist with at least 3 years' experience who was unaware of prior evaluations. A TMD equal to or less than 4 cm and a class III ULBT were considered to be predictive of difficult intubation. A Cormack-Lehane class III or IV was considered a difficult intubation. Only 20 (5.7%) of the patients were considered to have difficult intubations. Sensitivity, specificity, positive and negative predictive values, and accuracy were 70%, 93.3%, 39%, 98.1%, and 92.6%, respectively, for the ULBT, and 55%, 88%, 22%, 97%, and 86.3%, respectively, for TMD. Specificity and positive predictive value were found to be significantly higher for the ULBT than for TMD (p < 0.05). The sensitivity, negative predictive value, and accuracy were not significantly different between the two methods. The findings suggest that the sensitivity of the ULBT and TMD for predicting difficult intubations may not be significantly different, but the specificity of the ULBT is significantly higher. The positive predictive value of the ULBT was significantly higher than that of TMD, signifying that a positive ULBT is more predictive of a difficult airway than is a positive TMD.

Anestesia general en pacientes con discapacidad intelectual sometidos a cirugía dental

To describe the anesthetic technique used, the evaluation of airway patency, and the perioperative complications in patients with lower than average intelligence (mentally disabled) who are administered general anesthesia for dental surgery. We carried out a prospective, descriptive, comparative study of mentally disabled ASA 2-3 patients. The patients were distributed in 2 groups: mild to moderate mental disability and severe to very severe mental disability. Induction was via intravenous or inhaled anesthesia depending on availability of venous access. Maintenance was with sevoflurane in oxygen and air at variable concentrations in order to maintain a bispectral index (BIS) between 40 and 60. Statistical comparisons were based on the chi2 test, the log-rank test and the t test. Forty-seven patients were enrolled. The anesthetic technique maintained hemodynamic stability in both groups. No statistically significant differences were found in Mallampati classification, Cormack-Lehane classification, or level of disability. The incidence of complications was higher in the group with more severe disability; the most common complication was difficult tracheal intubation. Bradycardia was the most common complication in the group with mild to moderate mental disability. The anesthetic technique used in this study proved to be safe and effective in this type of patient. A higher degree of mental disability led to less effective examination of the airway and more difficult direct laryngoscopy. BIS was as effective for monitoring in this population as it is in the general population.

Laryngoscopies in the Obese: Predicting Problems and Optimizing Visualization

This pilot study was designed to 1) identify predictors of difficult laryngeal exposure in obese patients, 2) develop strategies for efficient intubation and intraoperative visualization of the glottis, and 3) devise perioperative protocols for difficult laryngoscopies. We undertook a retrospective study over a 1-year period of 14 consecutive patients with a body mass index of more than 30 kg/M2 who underwent elective direct laryngoscopy under general anesthesia. Measurements of height, weight, neck circumference, Mallampati score, and Cormack-Lehane classification of the airway were recorded. Problems encountered during anesthesia induction and emergence were also noted. The laryngologist recorded on a visual analog scale the degree of difficulty encountered in obtaining a binocular stereoscopic view and magnification, illumination, and suspension. Anatomic challenges during difficult laryngoscopy included decreased neck extension, redundant folds of tissue in the oropharynx and hypopharynx, and upper airway collapsibility. Overall, there was an association between the incidence of difficult laryngeal exposure and the Cormack-Lehane score (r = .57; p = .03), but the Mallampati score was of limited utility to the laryngologist. Neck size in female patients correlated with the Cormack-Lehane score (p = .02). Neither weight nor body mass index were predictive of a difficult laryngeal exposure. Straight blade laryngoscopes with a distal flange allowed greater depth of insertion and provided the best visualization of the glottis. An appropriate clinical examination may help predict a difficult airway. However, further studies are warranted to fully characterize the anatomic predictors of a difficult laryngeal exposure.

Nasotracheal intubation: look before you leap

Nasotracheal intubation is frequently used for airway management during maxillofacial surgery. Complications such as haemorrhage occur more frequently with this route of intubation than with the orotracheal route. This case report describes a male patient aged 51 yr who developed severe epistaxis after the tube had passed the nares. As an additional complication laryngoscopy and endotracheal intubation failed because of difficult airway (Cormack-Lehane grade 4). Attempts using an intubating laryngeal mask airway and a Bonfils intubating fibrescope did not succeed. The airway was finally managed by cricothyroidotomy. A modified sequence of nasotracheal intubation is proposed to avoid similar life-threatening complications.