Topics in Airway Management: Intelligent Airway Evaluation Donald M. Voltz, MD Assistant Professor of Anesthesiology Case Western Reserve University

Topics in Airway Management:Intelligent Airway Evaluation

Donald M. Voltz, MDAssistant Professor of Anesthesiology

Case Western Reserve University / University Hospitals of Cleveland

3 November 2004

What we focus on and our mental models determine what

we see.

What is Intelligence?

Intelligence = Behavior

Turing Test

Intelligence = Prediction

Is There Such a Thing as an Unexpected Difficult Intubation?

What is the Problem?

“More than 85% of respiratory-related closed claims involve a

brain-damaged or dead patient.”

Jonathan Benumof, MD

Incidence of Difficult Intubation

• Successful with multiple attempts

• Successful, many attempts, many people

• Unsuccessful• Can not ventilate or

intubate

• 100-1800/10,000

(1-18%)• 100-400/10,000

(1-4%)• 5-35/10,000

(0.05-.35%)• 0.01-2/10,000

(0.0001-0.02%)

What do we want to Predict?

Cormack-Lehane Classifications

Airway Prediction Models

Airway Prediction Models

• Mallenpatti Classification

• Neck Range of Motion

• Thyromental/Thyrosternal Distance

• Upper Lip Bite Test

• Multivariate Analysis

Mallinpatti Classification

Mallinpatti Classification

Upper Lip Bite Test

Upper Lip Bite TestTable 1. Relationship Between the Results of Two Predicting Tests and Laryngoscopy Grades in 300 Patients

I and II III and IV Predicting test

Modified Mallampati

    Classes I and II 189 3

    Classes III and IV 94 14

Upper lip bite

    Classes I and II 251 4

    Class III 32 13

Laryngoscopic view

ASA Difficult Airway ASA Difficult Airway AlgorithmAlgorithm

Updated 2003Updated 2003

Airway Evaluation

Mouth (4)

Oral Cavity (3)

Neck (4)

Airway Evaluation - Mouth

• Length of Upper Incisors

• Relationship of Maxillary Incisors to Mandibular Incisors

• Ability to Prognath the Mandible

• Interincisor Distance

Airway Evaluation – Oral Cavity

• Visibility of the Uvula

• Shape of the Palate

• Compliance of the Mandibular Space

Airway Evaluation - Neck

• Thyromental/Thyrosternal Distance

• Length of the Neck

• Thickness of the Neck

• Range of Motion of the Head and Neck

Approaching the Difficult Airway Algorithm

William H. Rosenblatt, M.D.

Yale University School of Medicine

Is Airway Management Required?

Do you predict difficult direct laryngoscopy?

Will superlarngeal ventilation be possible?

Predictors of Difficult Mask Ventilation

• Age greater than 55 years

• Body mass index greater than 26 kg/m2

• History of snoring

• Edentulous

• Presence of facial hair

Is the patient at an increased risk of aspiration?

Will the patient tolerate a judgment error?

Problems with Prediction Methods

Future of Airway Prediction

References

• Rosenblatt, W.H. Decision making in airway evaluation. ASA Refresher Course in Anesthesiology, V. 32, 2004.

• Benumof, J.L. Airway Management, pp. 121-158, 1996.

• ASA Task Force on Airway Management. 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, Anesthesiology, 98(5), 1269-1277.