Carin A. Hagberg

practice Guidelines for Management of the Difficult airway An Updated Report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway

RACTICE Guidelines are systematically developed recommendations that assist the practitioner and patient in making decisions about health care. These recommendations may be adopted, modified, or rejected according to clinical needs and constraints and are not intended to replace local institutional policies. In addition, Practice Guidelines developed by the American Society of Anesthesiologists (ASA) are not intended as standards or absolute requirements, and their use cannot guarantee any specific outcome. Practice Guidelines are subject to revision as warranted by the evolution of medical knowledge, technology, and practice. They provide basic recommendations that are supported by a synthesis and analysis of the current literature, expert and practitioner opinion, open-forum commentary, and clinical feasibility data. This document updates the “Practice Guidelines for Management of the Difficult Airway: An Updated Report by

Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue

In 50 morbidly obese patients, we quantified the soft tissue of the neck from the skin to the anterior aspect of the trachea at the vocal cords using ultrasound. Thyromental distance, mouth opening, limited neck mobility, modified Mallampati score, abnormal upper teeth, neck circumference and sleep apnoea were assessed as predictors of difficult laryngoscopy. Of the nine (18%) cases of difficult laryngoscopy, seven (78%) had a history of obstructive sleep apnoea, compared with two of the 41 patients (5%) in whom laryngoscopy was easy (p < 0.001). Patients in whom laryngoscopy was difficult had more pretracheal soft tissue (mean (SD) 28 (2.7) mm vs. 17.5 (1.8) mm; p < 0.001) and a greater neck circumference (50 (3.8) vs. 43.5 (2.2) cm; p < 0.001). None of the other predictors correlated with difficult laryngoscopy. We conclude that an abundance of pretracheal soft tissue at the level of the vocal cords is a good predictor of difficult laryngoscopy in obese patients.

Risk factors assessment of the difficult airway: An Italian survey of 1956 patients

Over the last decade, there has been a heightened awareness and an increase in the amount of literature being published on recognition and prediction of the difficult airway. During the preoperative evaluation of the airway, a thorough history and physical specifically related to the airway should be performed. Various measurements of anatomic features and noninvasive clinical tests can be performed to enhance this assessment. In this study we correlated the Mallampati modified score and several other indexes with the laryngoscopic view to identify anatomical and clinical risk factors related to the difficult airway. We prospectively collected data on 1956 consecutive patients scheduled to receive general anesthesia requiring endotracheal intubation for elective surgery. The Mallampati classification versus the Cormack-Lehane (C-L) linear correlation index was 0.904. A Mallampati Class 3 correlated with a C-L Grade 2 (0.94), whereas a Mallampati Class 4 correlated with a C-L Grade 3 (0.85) and a C-L Grade 4 (0.80). Operator evaluation, performed by a simplified tracheal intubation difficulty scale, showed a linear correlation of 0.96 compared with the C-L groups. Although there is a correlation between oropharyngeal volume and difficult intubation, the Mallampati score by itself is insufficient for predicting difficult endotracheal intubation.

Difficult airway management practice patterns among anesthesiologists practicing in the United States: have we made any progress?

STUDY OBJECTIVE To determine the extent instruction and practice in the use of airway devices and techniques varies among anesthesiologists practicing in the United States. DESIGN Survey questionnaire. SETTING University medical center. MEASUREMENTS Questionnaires were completed by American-trained anesthesiologists who attended the 1999 American Society of Anesthesiologists (ASA) Annual Meeting. Data collected included demographics, education, skills with airway devices/techniques, management of clinical difficult airway scenarios, and the use of the ASA Difficult Airway Algorithm. MAIN RESULTS 1) DEMOGRAPHICS: 452 questionnaires were correctly completed; 62% attending anesthesiologists, 70% <50 years, 81% males, 44% from academic institutions, 63% >10 years of practice, 81% night duty, 77% board certified. 2) Education: 71% had at least one educational modality: difficult airway rotation, workshops, conferences, books, and simulators. 3) Skills: Miller blade 61%, Bullard laryngoscope 32%, LMA 86%, Combitube 43%, bougie 43%, exchangers 47%, cuffed oropharyngeal airway (COPA) 34%, retrograde 41%, transtracheal needle jet ventilation 34%, cricothyrotomy 21%, fiberoptics 59%, and blind nasal intubation 78%. The average reported use of special airway devices/techniques was 47.5%. 4) Management choices: failed intubation/ventilation: LMA (81%) and for all other situations: fiberoptic intubation. Use of ASA Difficult Airway Algorithm in clinical practice (86%). CONCLUSION Fiberoptic intubation and the LMA are most popular in management of the difficult airway.

A Randomized Controlled Trial Comparing the ProSeal™ Laryngeal Mask Airway with the Laryngeal Tube Suction in Mechanically Ventilated Patients

Background:The ProSeal™ Laryngeal Mask Airway (PLMA) (Laryngeal Mask Company, Henley-on-Thames, United Kingdom) is a new laryngeal mask with a modified cuff designed to improve its seal and a drain tube for gastric tube placement. Similarly, the Laryngeal Tube Suction (LTS) (VBM Medizintechnik Gmbh, Sulz a.N, Germany) is a new laryngeal tube that also has an additional channel for gastric tube placement. This study compared the placement and functions of these two devices. Methods:One hundred fifty patients undergoing general anesthesia for elective surgery were randomly allocated to the PLMA (n = 75) or LTS (n = 75). Oxygenation and ventilation, ease of insertion, fiberoptic view, oropharyngeal leak pressure, ventilatory data, ease of gastric tube insertion, and postoperative airway morbidity were determined. Results:After successful insertion of the devices in 96% of patients with the PLMA and in 94.4% with the LTS it was possible to maintain oxygenation, ventilation, and respiratory mechanics during the entire duration of surgery. Successful first and second attempt insertion rates were 57 patients (76%) and 15 patients (20%), respectively, for the PLMA and 60 patients (80%) and 11 patients (14.6%), respectively, for the LTS. Airway placement was unsuccessful with the PLMA in three patients and with the LTS in four patients. Time to achieve an effective airway was 36 ± 24 s with the PLMA versus 34 ± 25 s with the LTS. Gastric tube insertion was possible in 97.3% of patients with the PLMA and in 96% with the LTS. Conclusions:With respect to both physiologic and clinical function, the PLMA and LTS are similar and either device can be used to establish a safe and effective airway in mechanically ventilated anesthetized adult patients.

The Incidence of Class “zero” Airway and the Impact of Mallampati Score, Age, Sex, and Body Mass Index on Prediction of Laryngoscopy Grade

IMPLICATIONS In an earlier study we proposed the addition of a new airway class, zero (visualization of the epiglottis), to the four classes of the modified Mallampati classification. In this prospective study, 764 surgical patients were assessed with regard to their airway class (including class zero), laryngoscopy grade, and the effect of the airway class and other predictors on the laryngoscopy grade.

Instruction of airway management skills during anesthesiology residency training

BACKGROUND Difficult airway management is a critical aspect of anesthesiology training and practice. A survey was conducted of American anesthesia residency programs to determine the prevalence of a specific airway rotation and its curriculum. METHODS A questionnaire was sent by both e-mail and fax to all 132 directors of American anesthesiology residency programs. RESULTS Of the 132 programs surveyed, 79 (60%) responded. Of the responders, 26 programs (33%) have a difficult airway rotation. The rotation was offered throughout the years of clinical training in 13 (49%) of the programs and was of 1-week duration in 16 (61%) of these programs who had a rotation. Formal instruction was administered before the rotation in 18 (69%) of the programs. Instruction was usually performed on surgical patients in 22 (85%) of the program, ASA status I and II patients in 20 (77%) of the programs, and taught by selected faculty in 20 (78%) of the programs. There was a 2- to 5-minute time limitation or a number of maximum attempts when using any of these devices in 16 (62%) programs. There was a case number requirement regarding the use of the devices in 5 (19%) of the programs. Residents were evaluated by both skills testing and written evaluation in 63% of these programs. DISCUSSION Of the programs with an airway rotation, the flexible fiberoptic bronchoscope and the laryngeal mask airway represent the most frequently used devices, excluding the standard laryngoscopes. There is minimum emphasis on more invasive techniques. Traditional methods of instruction continue to be utilized more frequently than nontraditional methods.

An Evaluation of the Laryngeal Tube ® During General Anesthesia Using Mechanical Ventilation

The Laryngeal Tube® is a new supraglottic ventilatory device for airway management. It has been developed to secure a patent airway during either spontaneous or mechanical ventilation. In this study, we sought to determine the effectiveness of the Laryngeal Tube for primary airway management during routine surgery with mechanical ventilation. One-hundred-seventy-five subjects classified as ASA physical status I and II, scheduled for elective surgery, were included in the study. After the induction of general anesthesia and insertion of a Size 4 Laryngeal Tube, measurements of oxygen saturation, end-tidal CO2 and isoflurane concentration, and breath-by-breath spirometry data were obtained every 5 min throughout surgery. The lungs were ventilated with volume-controlled mechanical ventilation. The number of attempts taken to insert the Laryngeal Tube and the insertion time were recorded. In 96.6% of patients, it was possible to maintain oxygenation, ventilation, and respiratory mechanics by using mechanical ventilation throughout the surgical procedure. The results of this study suggest that the Laryngeal Tube is an effective and safe airway device for airway management in mechanically ventilated patients during elective surgery. IMPLICATIONS: In 96.6% of patients intubated with the Laryngeal Tube®, it was possible to maintain oxygenation, ventilation, and respiratory mechanics during mechanical ventilation.

Awake insertion of the Bonfils Retromolar Intubation Fiberscope in five patients with anticipated difficult airways.

Traditionally, an awake intubation is performed by flexible fiberoptic laryngoscopy. However, many new devices have been developed to assist anesthesiologists with both routine and difficult airway management, one of which is the Bonfils Retromolar Intubation Fiberscope. This device may be more beneficial than the flexible fiberoptic laryngoscope since it can readily navigate through soft tissue and physically lift airway structures, is more affordable, durable, and easier to clean. This case series demonstrates successful use of the Bonfils Scope in five patients for awake orotracheal intubation with anticipated difficult airways.

Submental intubation: a literature review

A literature review was performed to analyse the evidence supporting submental intubation and to aid in the development of a new airway algorithm in craniofacial surgery patients. A systematic search of Pub Med, OVID, the Cochrane Database and Google Scholar between January 1984 and April 2011 was performed. Measured variables included the outcome, complications, publishing specialty journal and method of intubation including technique modifications, indications for the procedure, devices utilized and the total procedure time to complete the submental intubation. Of the 842 patient cases from 41 articles represented in the review, the success rate was 100%. Minor complications were reported in 60 patients and included superficial skin infections (N=23), damage to the tube apparatus (N=10), fistula formation (N=10), right mainstem bronchus tube dislodgement/obstruction (N=5), hypertrophic scarring (N=3), accidental extubation in paediatric patients (N=2), excessive bronchial flexion (N=2), lingual nerve paresthesia (N=1), venous bleeding (N=2), mucocele (N=1), and dislodgement of the throat pack sticker in the submental wound (N=1). The average reported time to complete a submental intubation was 9.9 min. Submental intubation is a safe, effective and time efficient method for securing an airway when increased surgical exposure or restoration of occlusion is a priority.