Internet Journal of Airway Management

 

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Volume 5 (January 2008 to December 2009)

 

Zadrobilek E, Missaghi SM, Krasser K, Puchner W, Marian F (for the Austrian Working Group for Airway Management). Recommendations of the Austrian Working Group for Airway Management: Preoperative Airway Evaluation and Documentation, Dissemination, and Communication of Difficult Airway Information


 

Preoperative Airway Evaluation

 

 

Focused interview of the patient and review of available medical records may substantially contribute to the detection of the presence of a difficult airway (DA) and should be performed on a regular basis (1, 2). Some features of the medical history and medical records may be related to the likelihood of encountering a DA; this presumption is based on recognized associations between a DA and a variety of congenital and acquired diseases.

 

Furthermore, physical airway examination should be performed to screen for difficulties with airway management and conducted in an orderly sequence (2, 16, 17). Based on a large clinical evaluation, El-Ganzouri and co-workers (7) recommended to assess multiple features predictive for difficult conventional laryngoscopy (CL) and tracheal intubation: mouth opening, thyromental distance, Mallampati classification, neck movement, mandibular protusion, body weight, and history of difficult tracheal intubation; in their study, the information of a previously experienced DA was the most reliable predictor of a DA during subsequent general anesthesia. In a recently published meta-analysis, Shiga and co-workers (18) evaluated frequently used screening tests: Mallampati classification, thyromental distance, sternomental distance, and mouth opening. When used alone, these tests have only poor to moderate discriminative power. The combinations of tests add some incremental diagnostic value in comparison to the value of each test alone; the most useful tests for prediction were the Mallampati classification and the thyromental distance.

 

Difficult CL and tracheal intubation are considered to occur more often in obese than in normal patients. Juvin and co-workers (11) have shown that difficult conventional tracheal intubation is more common in obese than in standard-weight patients; however, this issue is debatable and controversial. When obesity was estimated with respect to the Mallampati classification, the predictive value for difficult CL was greatly increased (19). Ezri and co-workers (9) demonstrated in patients with morbid obesity that associated risk factors, increased age, male gender, temporomandibular joint pathology, and high Mallampati classification scores, rather than increase in body mass index (BMI) may be responsible for difficult CL. Furthermore, an increased amount of anterior neck fat at the level of the thyroid cartilage rather than the magnitude of BMI itself may be a predictor of difficult CL (8). Brodsky and co-workers (4) studied morbidly obese patients to identify factors that complicate CL and tracheal intubation; large neck circumference measured at the level of the thyroid cartilage and high Mallampati classification scores were the only predictors of potential tracheal intubation problems.

 

In their updated guidelines (2), the American Society of Anesthesiologists task force focuses special attention to the evaluation of signs predictive for difficult face-mask ventilation (MV). Langeron and co-workers (12) found that a high BMI and the history of snoring were independent risk factors of difficult MV; additional risk factors of difficult MV included increased age, full beard, and edontulesness. The presence of two of these risk factors indicated a high likelihood of difficult MV. The study performed by Yildiz and co-workers (20) provided similar results: high Mallampati classification scores, male gender, history of snoring, increased age, and increased weight were found to be risk factors of difficult MV. Gautam and co-workers (10) reported that BMI and the mandibular protusion test provided the best overall prediction of difficult MV.

 

Because of the high prevalence of obstructive sleep apnea (OSA) and its association with potential problems and difficulties maintaining a patent airway during induction of general anesthesia and an unobstructed upper airway during sedation and pain therapy, screening of surgical patients for OSA is required (3). Chung and co-workers (5) evaluated three practical screening tests for OSA, the American Society of Anesthesiologists checklist and the Berlin and a self-developed questionnaire; all had a moderately high sensitivity especially for patients with moderate to severe OSA. Patients in whom OSA is suspected should be referred to a sleep clinic in advance of surgery to allow preoperative verification of OSA and appropriate preparation or should be managed perioperatively based on clinical criteria and conduction of a more extensive airway examination alone (3).            

 

Recommendatons of the Austrian Working Group for Airway Management

 

We recommend a focused interview of the patient and the review of available medical records for the detection of the presence of a DA in all patients requiring anesthetic care. Furthermore, we emphasize routine physical airway examinations to screen for difficult CL and tracheal intubation with special attention to difficult MV and the presence of OSA to be prepared for an appropriate perioperative airway management plan.

 

 

Documentation and Dissemination of Preoperative Findings and Test Results


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