The intubation difficulty scale (IDS): proposal and evaluation of a new score characterizing the complexity of endotracheal intubation

BACKGROUND

A quantitative scale of intubation difficulty would be useful for objectively comparing the complexity of endotracheal intubations. The authors have developed a quantitative score that can be used to evaluate intubating conditions and techniques with the aim of determining the relative values of predictive factors of intubation difficulty and of the techniques used to decrease such difficulties.

METHODS

An Intubation Difficulty Scale (IDS) was developed, based on parameters known to be associated with difficult intubation. It was then evaluated prospectively in a group of 311 consecutive prehospital intubations and 315 intubations in an operating room. In the operating room, the IDS was compared with two other parameters: the time to completion of intubation and the visual analog scale (VAS). Time was measured by an independent observer. Operators in both groups completed a checklist regarding the conditions of intubation.

RESULTS

There is a good correlation between the IDS scale and the VAS assessment of difficulty and time to completion of intubation. VAS and time to completion have a significant but lesser correlation to each other. Comparison of IDS with operator-assessed subjective categorical impression of difficulty by Kruskall-Wallis was statistically significant.

CONCLUSIONS

The IDS correlates with but is less subjective than the VAS and categorical classification. IDS correlates with time to intubation, but it offers details regarding the difficulty encountered that time alone does not. This score may not only aid in evaluation of factors linked to difficult intubations, but it may provide a uniform approach to comparing studies related to this subject.

The incidence and risk factors of difficult mask ventilation

PURPOSE

The ability to ventilate and oxygenate a patient using a bag-mask breathing system may be lifesaving in the case of failure of the initial intubation attempt. In this study, we aimed to determine the incidence of difficult mask ventilation (DMV) and to find preoperative risk factors for this procedure.

METHODS

Based on methods used for overcoming some difficulties with bag-mask ventilation (MV), classification has been made into four categories: easy MV, awkward MV, difficult MV, and impossible MV. A univariate analysis was performed to identify potential risk factors predicting DMV, followed by a stepwise forward binary logistic regression, and the odds ratio and 95% confidence interval were calculated.

RESULTS

A total of 576 patients were studied. Incidence of easy MV, awkward MV, and difficult MV were found to be 75.5% (n = 435), 16.7% (n = 96), and 7.8% (n = 45), respectively. Height, weight, age, male gender, increased Mallampati class, history of snoring, lack of teeth, and beard were found to be DMV risk factors (P < 0.05). Using a multivariate analysis, Mallampati class 4, male, history of snoring, age, and weight were found to be significantly associated with DMV. Although the incidence of DMV in general was 7.8% (n = 45), the incidence of DMV among patients with difficult intubation (n = 123) was found to be 15.5% (n = 19).

CONCLUSIONS

Mallampati class 4, male patients, history of snoring, increasing age, and increasing weight were found to be risk factors for DMV in our study.

The Reliability and Validity of the Upper Lip Bite Test Compared with the Mallampati Classification to Predict Difficult Laryngoscopy: An External Prospective Evaluation

Recently, a new bedside screening test to predict the occurrence of a difficult laryngoscopy has been developed as a substitute for the Mallampati classification. The Upper-Lip-Bite test (ULBT) evaluated the patient's ability to reach or completely cover the upper lip with the lower incisors. It is often accepted that new predictive tools should undergo an external evaluation before the tool is used in clinical practice. Thus, we evaluated this test with respect to applicability, interobserver reliability, and discriminating power and compared it with the Mallampati-score (using Samsoon and Young's modification). The ULBT could not be applied in 12% of all patients (Mallampati score, <1%). However, the interobserver reliability was better for the ULBT (kappa = 0.79 versus kappa = 0.59). The discriminating power to predict a patient with difficult laryngoscopy was evaluated in 1425 consecutive patients. Both tests were assessed simultaneously in these patients by two specially trained independent observers. After the induction of anesthesia, the laryngoscopic view was assessed by the attending anesthesiologist using the classification of Cormack and Lehane. A grade I or II was called easy laryngoscopy and grade III and IV difficult laryngoscopy. The discriminating power for both tests was low (0.60 for the ULBT [95% confidence interval, 0.57-0.63] and 0.66 [0.63-0.69]) for the Mallampati score), indicating that both tests are poor predictors as single screening tests.

A Proposed Classification and Scoring System for Supraglottic Sealing Airways: A Brief Review

We provide an approach to evaluating sealing supraglottic airways by using a classification based on a sealing mechanism. Three main sealing mechanisms are identified, thus defining three groups: cuffed perilaryngeal sealers, cuffed pharyngeal sealers, and uncuffed anatomically preshaped sealers. We provide a brief overview of supraglottic airways and present a scoring system that is relevant to particular requirements. Scoring airways for routine applications is the example provided.

Performance of the Airtraq laryngoscope after failed conventional tracheal intubation: a case series

BACKGROUND

The Airtraq, a new disposable indirect laryngoscope, was evaluated in patients with difficult intubation.

METHODS

The Airtraq was used in 47 patients with predicted or unpredicted difficult intubation after failed orotracheal intubation performed by two senior anaesthesiologists with the Macintosh laryngoscope.

RESULTS

Tracheal intubation with Airtraq was successful in 36 patients (80%). The Cormack and Lehane score was IIb-III in 35 patients, and IV in 12 patients, with the Macintosh laryngoscope, while Cormack and Lehane score was I-IIa in 40 patients, IIb-III in three and IV in four with Airtraq. A gum elastic bougie was used to facilitate tracheal access in one-third (11/36) of the cases. Orotracheal intubation was not possible with Airtraq in nine cases, five of whom had a pharyngeal, laryngeal or basal lingual tumour.

CONCLUSION

In patients with difficult airway, following failed conventional orotracheal intubation, Airtraq allows securing the airway in 80% of cases mainly by improving glottis view. However, the Airtraq does not guarantee successful intubation in all instances, especially in case of laryngeal and/or pharyngeal obstruction.

[Difficult tracheal intubation in paediatric: myth or reality?]

Difficult tracheal intubation is a rare event according to the airway feature in child. This situation is mostly predictable, occurring in identified malformations and in specific diseases. Pre-operative clinical evaluation must detect facial abnormalities (lip or palate cleft, microtia, facial asymmetry.), micro or retrognathia, limited mouth opening, reduced distance between thyroid cartilage and chin, macroglossia and external ear malformations. According to this clinical evaluation, a strategy for managing difficult tracheal intubation is planned.

Tiefe Halsinfektionen und Mediastinitis

Deep neck infections and subsequent mediastinitis can occur as lethal complications after endotracheal intubation. A 53 year old female patient developed a neck abscess and mediastinitis due to esophageal perforation after endotracheal intubation. Neck and mediastinal exploration were performed as primary surgical treatment in cooperation with thoracic surgeons. Drainage tubes for neck and mediastinum were inserted and irrigated frequently. The abscess cavity was re-examined twice after primary surgery. Microbiological tests were performed at regular intervals to guarantee appropriate antibiotic therapy. This case demonstrates the importance of early and extensive surgical intervention and the necessity of interdisciplinary cooperation in treating such infections.

Difficult tracheal intubation--analysis and management in 37 cases

AIM

To analyse the anatomical features of difficult airways encountered during general anaesthesia and study how difficult intubation was circumvented during anaesthesia in our local population.

METHOD

Difficult intubation was defined as failure to visualise the larynx during laryngoscopy after neck flexion and external cricoid pressure was applied. All cases of difficult intubation collected over 1 1/2 years during general anaesthesia were recorded prospectively and analysed.

RESULTS

Thirty-seven cases of difficult intubation were identified among 5,379 cases of general anaesthesia requiring endotracheal intubation. 40.5% of the cases were not expected to be difficult pre-operatively. 5.4% of the cases were Lehane II, 91.9% Lehane III and 2.7% Lehane IV. The anatomical features encountered included receding chin, limited mouth opening, limited neck extension, abnormal dentition, short thyromental distance, large tongue, supraglottic mass and floppy epiglottis. Gum elastic bougie was commonly used to overcome the intubation difficulties. Laryngeal mask, blind nasal tracheal intubation, fiberoptic bronchoscopic intubation and sometimes an alternative anaesthetic technique, such as regional anaesthesia, were resorted to.

CONCLUSION

Assessment of multiple anatomical features would improve prediction of difficult intubation. Assessment of receding chin, neck extension, mouth opening, teeth, tongue size, thyromental distance might pick up 81% of difficult airways. Unexpected problems with epiglottis and glottic inlet are the potential sources of danger that are difficult to predict pre-operatively.

Recognition of the difficult airway in normal Nigerian adults (a prospective study)

Difficulty with laryngoscopy and intubation is known to be the most frequent cause of anaesthetic related deaths. Awareness of the possibility of difficulty would enable the anaesthetist to be adequately prepared. 57 "normal" adult patients were examined pre-operatively and at laryngoscopy using the Mallampatti (1985) and the Cormack (1984) classification respectively. The result showed that none of the patients was in the IV Mallampatti nor IV Cormack groups. Four patients with class III Mallampatti features were seen, two of which were classified Cormack III at laryngoscopy. Intubation failed in these two patients. The majority of patients were classified as Mallampatti class I (68.42%) and Cormack grade I (63.16%). This in effect demonstrates that in most "normal" patients laryngoscopy and intubation should be fairly easy.

Calculated decisions: Modified Mallampati classification

The Modified Mallampati Classification stratifies predicted difficulty of endotracheal intubation based on anatomic features.