Journal: Anesth Analg 106(4):1132-1136, 2008
Reprint: Dept of Anesthesiology and Intensive Care, University Hospital of Toulouse, Toulouse, France (V Minville, MD, MSc)
Faculty Disclosure: Abstracted by S. Ouellette, who has nothing to disclose.
Difficulties with tracheal intubation significantly contribute to the morbidity and mortality associated with anesthesia. Identifying situations and patients at risk for airway management problems is a key to optimal care and has been a focus for numerous publications.
Several reviews have reported that endotracheal intubation is more difficult in obese than in lean patients. This assertion is controversial, however, because other studies have found no evidence that tracheal intubation is more difficult in obese patients. One reason for the discrepancies is the lack of consensus on the definition of the term "difficult intubation." A strong scoring system has been pro¬posed to assess intubation difficulty: the intubation difficulty scale (IDS) score, which has been validated by Adnet et al. This score uses several variables associated with difficult intubation and has already been used to compare obese with lean patients.
Although obesity is thought to increase the risk of difficult intubation, increased body mass index (BMI) poorly predicts difficult laryngoscopy. Prediction of difficult laryngoscopy in obese patients is challeng¬ing. Suggested predictors include history of obstruct¬tive sleep apnea, high Mallampati score, increased age, male sex, short neck, and abnormal upper teeth. The aim of this study was to compare the incidence of difficult tracheal intubation, by means of the IDS score, between lean and obese patients assessed with classical bedside tests and neck circumference.
Seventy obese (BMI ≥ 30 kg/m2) and 61 lean patients (BMI ≤ 30 kg/m2) were studied. The IDS scores, categorized as difficult intubation (IDS > 5) or not (IDS ≤ 5), and patient data, were compared between lean and obese patients. Preoperative measurements (BMI, neck circumference, width of mouth-opening, sternomental distance, and thyromental distance), medical history of obstructive sleep apnea, and several scores (Mallampati, Wilson, El Ganzouri) were recorded. The view during direct laryngoscopy was graded, and the IDS was recorded. Investigators then compared patients with IDS ≤ 5 and > 5, con¬cerning each item.
The results indicate that difficult tracheal intubation is more frequent in obese than in lean patients (14.3% vs. 3%, respectively). In patients with IDS > 5, thyro¬mental distance, BMI, large neck circumference, and higher Mallampati score were the only predictors of potential intubation difficulty. Problematic intubation was associated with thyromental distance, increased neck circumference, BMI, and a Mallampati score ≥ 3. Neck circumference should be assessed pre¬operatively to predict difficult intubation. |
