Explore This IssueJuly 2019
What are the risk factors and physical findings that predict difficult intubation?
Bottom Line: Although several simple clinical findings are useful for predicting a higher likelihood of difficult endotracheal intubation, no clinical finding reliably excludes a difficult intubation.
Background: Endotracheal intubation is often required for major surgical procedures and for respiratory support in critically ill patients. Recognizing a potentially difficult intubation can help clinicians prepare for complications, which, although extremely rare, can result in major complications associated with long-term morbidity and account for 25% of anesthesia-related deaths.
Study design: Case review of 62 studies.
Setting: MEDLINE (from 1946 to June 2018) and EMBASE (from 1947 to June 2018) databases.
Synopsis: The overall proportion of patients having a difficult intubation was 10%. A history of difficult intubation was the risk factor most predictive for a difficult intubation. The upper lip bite test strongly predicted a difficult intubation. A Wilson score (≥2 in seven studies and ≥3 in one study) was strongly predictive of a difficult intubation, but a lower score did not exclude difficulty. Retrognathia and impaired mandibular protrusion were good predictors of difficult intubation. A high ratio of height to thyromental distance, as well as shorter thyromental and hyomental distances, were predictive of a difficult intubation. Impaired neck mobility, and a positive palm print test result and prayer sign result had modest predictive accuracy. A short interincisor gap had moderate accuracy for predictive accuracy. A modified Mallampati score of 3 or 4 had moderate accuracy for predicting a difficult intubation, but a lower Mallampati score (1 or 2) did not rule it out. Limitations included significant variability in reference standards, the requirement of subjective assessments in some cases, studies conducted only in the operating room, and independent analysis of predictors.
Citation: Detsky ME, Jivraj N, Adhikari NK, et al. Will this patient be difficult to intubate? The rational clinical examination systematic review. JAMA; 2019;321:493-503.