[Evaluation and management of expected or unexpected difficult airways: adopting practice guidelines]

A new score for airway assessment using clinical and ultrasound parameters

Background

Over the last few years, ultrasonography has been introduced as the fifth pillar to patient's bedside physical examination. Clinical assessments aim to screen and look for airway difficulties to predict difficult intubations, but none have demonstrated a significant predictive capacity. Recent systematic reviews have established a correlation between ultrasound imaging and difficult direct laryngoscopy. The primary objective of this study was to determine whether the utilization of ultrasonography to examine the upper airway could accurately predict difficult direct laryngoscopy.

Methods

This is a prospective observational study including 102 adult patients that required general anesthesia for elective surgery. Preoperatively, clinical airway assessments were performed. Data such as Mallampati-Samsoon grade (MS), upper lip bite test (ULBT), thyromental (TMD) and sternomental distance (SMD), cervical circumference (CC) and the Arné risk index were collected. Ultrasound evaluation was taken at five different levels in two planes, parasagittal and transverse. Therefore, the following measurements were registered: distance from skin to hyoid bone (DSHB), distance from skin to thyrohyoid membrane (DSTHM), distance from skin to epiglottis (DSE), distance from skin to thyroid cartilage (DSTC) and distance from hyoid bone and thyroid cartilage (DHBTC). Patients were divided into two groups based on the difficulty to perform direct laryngoscopy, according to Cormack-Lehane (C-L) classification. Grades I and II were classified as easy laryngoscopy and grades III or IV as difficult. Logistic regression models and the Receiver Operating Characteristic (ROC) curve was employed to determine the diagnostic precision of ultrasound measurements to distinguish difficult laryngoscopy (DL).

Results

The following risk score for DL was obtained, DSTHM ≥ 1.60 cm (2 points), DSTC ≥ 0.78 cm (3 points) and gender (2 points for males). The score can range from 0 to 7 points, and showed and AUC (95% CI) of 0.84 (0.74-0.95). A score of 5 points or higher indicates a 34-fold increase in the risk of finding DL (p = 0.0010), sensitivity of 91.67, specificity of 75.56, positive predictive value of 33.33, and negative predictive value of 98.55.

Conclusion

The use of ultrasonography combined with classic clinical screening tests are useful tools to predict difficult direct laryngoscopy.

Recommendations for the evaluation and management of the anticipated and non-anticipated difficult airway of the Societat Catalana d'Anestesiologia, Reanimació i Terapèutica del Dolor, based on the adaptation of clinical practice guidelines and expert consensus

The Airway Division of the Catalan Society of Anaesthesiology, Intensive Care and Pain Management (SCARTD) presents its latest guidelines for the evaluation and management of the difficult airway. This update includes the technical advances and changes observed in clinical practice since publication of the first edition of the guidelines in 2008. The recommendations were defined by a consensus of experts from the 19 participating hospitals, and were adapted from 5 recently published international guidelines following an in-depth analysis and systematic comparison of their recommendations. The final document was sent to the members of SCARTD for evaluation, and was reviewed by 11 independent experts. The recommendations, therefore, are supported by the latest scientific evidence and endorsed by professionals in the field. This edition develops the definition of the difficult airway, including all airway management techniques, and places emphasis on evaluating and classifying the airway into 3 categories according to the anticipated degree of difficulty and additional safety considerations in order to plan the management strategy. Pre-management planning, in terms of preparing patients and resources and optimising communication and interaction between all professionals involved, plays a pivotal role in all the scenarios addressed. The guidelines reflect the increased presence of video laryngoscopes and second-generation devices in our setting, and promotes their routine use in intubation and their prompt use in cases of unanticipated difficult airway. They also address the increased use of ultrasound imaging as an aid to evaluation and decision-making. New scenarios have also been included, such as the risk of bronchoaspiration and difficult extubation Finally, the document outlines the training and continuing professional development programmes required to guarantee effective and safe implementation of the guidelines.

Analysis of Production, Impact, and Scientific Collaboration on Difficult Airway Through the Web of Science and Scopus (1981-2013)

BACKGROUND

Bibliometrics, the statistical analysis of written publications, is an increasingly popular approach to the assessment of scientific activity. Bibliometrics allows researchers to assess the impact of a field, or research area, and has been used to make decisions regarding research funding. Through bibliometric analysis, we hypothesized that a bibliometric analysis of difficult airway research would demonstrate a growth in authors and articles over time.

METHODS

Using the Web of Science (WoS) and Scopus databases, we conducted a search of published manuscripts on the difficult airway from January 1981 to December 2013. After removal of duplicates, we identified 2412 articles. We then analyzed the articles as a group to assess indicators of productivity, collaboration, and impact over this time period.

RESULTS

We found an increase in productivity over the study period, with 37 manuscripts published between 1981 and 1990, and 1268 between 2001 and 2010 (P < .001). The difficult airway papers growth rate was bigger than that of anesthesiology research in general, with CAGR (cumulative average growth rate) since 1999 for difficult airway >9% for both WoS and Scopus, and CAGR for anesthesiology as a whole =0.64% in WoS, and =3.30% in Scopus. Furthermore, we found a positive correlation between the number of papers published per author and the number of coauthored manuscripts (P < .001). We also found an increase in the number of coauthored manuscripts, in international cooperation between institutions, and in the number of citations for each manuscript. For any author, we also identified a positive relationship between the number of citations per manuscript and the number of papers published (P < .001).

CONCLUSIONS

We found a greater increase over time in the number of difficult airway manuscripts than for anesthesiology research overall. We found that collaboration between authors increases their impact, and that an increase in collaboration increases citation rates. Publishing in English and in certain journals, and collaborating with certain authors and institutions, increases the visibility of manuscripts published on this subject.

Influence of pharyngolaryngeal anomalies diagnosed through indirect laryngoscopy in the prediction of difficult intubation

OBJECTIVE

To determine the pharyngolaryngeal anomalies not usually included in the evaluation of difficult airway, in order to investigate the influence of these anomalies in the prediction of difficult intubation. To do this, indirect laryngoscopy with a 70° rigid laryngoscope was performed on all patients during the preoperative period.

METHODS

This is an observational, prospective study on 300 consecutive patients who were scheduled for endotracheal intubation under general anesthesia. In addition to assessing the airway in the preoperative period by demographic and clinical predictors of difficult airway, rigid indirect laryngoscopy was performed to diagnose pharyngolaryngeal anomalies. Later, under general anesthesia and direct laryngoscopy it was checked to see if there was difficulty in intubating the larynx, and its association with all previous variables was investigated. A logistic regression model for prediction purposes was developed, and its power of discrimination was achieved by assessing the area under the curve.

RESULTS

During the examination by indirect laryngoscopy 46 anomalies were found, which were as follows: 31 abnormalities of the epiglottis (22 omega epiglottis, 9 flaccid or hypertrophic epiglottis); 6 findings of hypertrophic lingual tonsils, 3 cases of upper airway tumors, and 6 patients with tongue disorders. Intubation difficulty was found in 14 cases (4.66%). The regression model found, and its coefficients to develop it were: f(x)=1.322+(2.173 thyromental distance <6.5 cm)+(1.813 omega epiglottis)-(1.310*cm opening mouth). Global power of discrimination was 0.83, with a 95% confidence interval from 0.709 to 0.952).

CONCLUSION

Indirect laryngoscopy allowed pharyngolaryngeal anomalies to be diagnosed, including omega epiglottis, which was one of the variables included in the logistic regression model.

[Prophylactic use of icatibant before tracheal intubation of a patient with hereditary angioedema type III. (A literature review of perioperative management of patients with hereditary angioedema type III)]

Type III hereditary angioedema is a rare familial disorder that has recently been described as a separate condition. Triggers for episodes of angioedema include surgery, dental procedures, and tracheal intubation maneuvers. Since episodes affecting the upper airway are potentially life-threatening, prophylactic treatment is recommended in these situations. The use of icatibant (Firazyr(®)), for prevention of angioedema prior to tracheal intubation, is reported in a patient with type iii hereditary angioedema. A literature review on the anesthetic management of this condition was conducted.

[Fibreoptic clinical training in anaesthesia. Course design and results based on a self-assessment survey]

BACKGROUND AND OBJECTIVE

Fibreoptic intubation is the technique of choice for resolving complications related to a difficult airway. Our aim was to determine whether a clinical-practice-based, individualized course provides sufficient training and confidence to allow anaesthetists to routinely practice fibreoptic intubation.

METHODS

Our hospital developed a clinical-practice-based, individualized course on fibreoptic intubation in general anaesthesia that provided practice in sedated spontaneously breathing patients and insertion through supraglottic devices. From 2005 to 2009, we e-mailed participants for response to an anonymous online self-assessment survey. We asked participants about the training outcomes and their overall degree of satisfaction.

RESULTS

Seventy-seven participants were sent the questionnaire six months after the course and 61% responded. All respondents considered themselves skilled in handling the bronchoscope at the end of the course and 97% used it in their routine practice in patients with difficult airways.

CONCLUSIONS

These results suggest a high success rate can be expected from individually tailored fibreoptic intubation courses that supplement theory and mannequin experience with clinical practice.

[An awake fiberoptic intubation protocol: descriptive retrospective assessment of safety and efficacy]

BACKGROUND AND OBJECTIVE

Flexible fiberoptic intubation of the trachea is emphasized in guidelines on the management of difficult airway. The aim of this study was to analyze the efficacy and safety of our tertiary hospital's awake fiberoptic intubation protocol.

MATERIAL AND METHODS

For retrospective descriptive study we collected information on all fiberoptic intubations performed on awake patients in the 3 years after a specific protocol was implemented. The protocol's key points focus on operating room arrangement, required staff, and sedation before the procedure. Data gathered included demographic variables, patients' diseases, preanesthetic assessment of potential difficult airway, adherence to the protocol, medication administered, and complications recorded.

RESULTS

In the course of the study, 634 fiberoptic intubations were performed; 473 patients (74.6%) had at least 1 risk factor for aspiration and 232 patients (36.5%) had at least 1 type of cardiovascular comorbidity. Difficult intubation was expected in 67%. In 99%, remifentanil was administered via target controlled infusion with a mean effect concentration of 2.9 ng/mL. The operating room arrangement and staffing protocol was followed in all cases. No pulmonary or hemodynamic complications occurred during fiberoptic intubation or immediately after surgery.

CONCLUSION

Our hospital's protocol was followed in all cases and no post-implementation complications were detected.

[Evaluation of a protocol for predicting difficult airway in routine practice: interobserver agreement]

OBJECTIVES

To evaluate a protocol for routine assessment of potential risk factors for difficult airway intubation in an anesthesia department, by measuring interobserver agreement and the behavior of the factors in a predictive model.

MATERIAL AND METHODS

A cross-sectional study group of 320 consecutive patients undergoing major surgery requiring orotracheal intubation was assessed for possible difficult airway. We calculated interrater agreement for recording of the Mallampati score, thyromental distance less than 6 cm, thick neck, kyphosis, small mouth, macroglossia, and dental prosthesis during the preanesthesia examination (by an anesthetist) and on the day of the operation (by an anesthetist and a resident). We constructed a model to predict difficult intubation (requiring 3 or more attempts).

RESULTS

The kappa indices of agreement between the anesthetists at the preoperative examination and in the operating room or the resident were all less than 0.6. Factors like thyromental distance, small mouth, and kyphosis had kappa indices less than 0.21. The kappa index between the resident and the anesthetist in the operating room was over 0.55. The only factor that had a different level of agreement was the presence or not of a dental prosthesis. None of the studied individual factors, nor these factors in association with the Mallampati score, achieved significance in a bivariate regression model to predict difficult intubation.

CONCLUSIONS

There is poor interobserver agreement on factors for predicting difficult airway in comparisons between preoperative and operating room assessment by an anesthetist or a resident. The individual predictive factors and their association with the Mallampati score did not prove useful for predicting difficult intubation.

[Tracheal laceration during intubation with a Frova introducer]

Chest trauma is the most frequent cause of tracheobronchial injury. Less common but potentially serious are lesions caused during intubation maneuvers in a difficult airway, during repeated attempts, or with stylets or other introducers. Though rare, airway lesions are life-threatening complications. We describe the case of a 46-year-old woman undergoing laparoscopic cholecystectomy whose trachea was injured during intubation with a Frova introducer. The lesion manifested with hemoptysis and subcutaneous and mediastinal emphysema early during recovery. The lesion resolved with conservative treatment and there were no sequelae.

[Management of the easy or complicated airway by nonexperts using the AirTraq optical laryngoscope]

OBJECTIVES

To evaluate the utility of the AirTraq optical laryngoscope in a retrospective case series, assessing indications for use and benefits as well as possible limitations.

PATIENTS AND METHODS

Retrospective study of the first 124 patients in whom we used the AirTraq for tracheal intubation. Anatomical and demographic variables were recorded in addition to preoperative findings on examination of the airway. Ease in accomplishing the maneuver and quality of the procedure were assessed after intubation with the AirTraq.

RESULTS

The trachea was correctly intubated in 97.6% of the patients. Intubation failed in only 3 (2.4%) patients. Laryngoscopic quality was optimal in over 95% of the cases. There were few complications or other events.

CONCLUSIONS

The AirTraq laryngoscope has been shown to facilitate intubation even when nonexpert staff perform the maneuver in cases in which previous attempts at laryngoscopy have failed and in which a difficult airway is anticipated. Ease of use and relative safety make the AirTraq a practical device for a variety of patient types and clinical settings.

[Use of a rigid laryngoscope and a flexible nasal fiberoptic scope to assess the difficult airway: description of 3 cases]

Indirect inspection of the airway using a 70 degrees rigid laryngoscope plus a flexible nasal fiberoptic scope can provide additional information when the anesthesiologist foresees that airway management will be difficult. These devices are useful for detecting structural abnormalities, they can be attached to the same visualization system, and they do not require topical anesthesia or sedation of the patient. We report on 3 patients diagnosed with difficult airway. Inspection with a rigid laryngoscope during the preanesthetic assessment visit revealed abnormalities that prevented visualization of the glottis. In the first case, the epiglottis was absent, as it had been removed with a surrounding tumor; in the second and third cases, an epiglottic deformity and hypertrophy of the base of the tongue were found. A flexible nasal fiberoptic scope gave an unobstructed view of the glottis in these cases, making it easier to choose an intubation method.