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.
examination should be performed to screen for
difficulties with airway management and conducted in an orderly sequence (2,
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.
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.
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
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).
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.
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).
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.
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
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
Documentation and Dissemination of Preoperative Findings and Test Results