Variation in the accuracy of ultrasound for the detection of intubation by endotracheal tube size



      Rapid and accurate confirmation of endotracheal tube (ETT) placement is a fundamental step in definitive airway management. Multiple techniques with different limitations have been reported. Recent studies have evaluated the accuracy, time to performance, and physician confidence for ultrasound in both cadaveric models and live patients. However, no study to date has measured the effect of ETT size. Our study is the first to measure the accuracy of ultrasound for ETT confirmation based on ETT size.


      This study was performed in a cadaver lab using three different cadavers chosen to represent varying neck circumferences. Cadavers were intubated in a random sequence with respect to both the location of intubation (i.e., tracheal vs esophageal) and sizes of ETT. Three ETT sizes were utilized: 6.0-, 7.0-, and 8.0-mm. Blinded sonographers assessed the location of the ETT using the static technique. Accuracy of sonographer identification, time to identification, and operator confidence were assessed.


      453 assessments were performed. Overall, ultrasound was 99.1% (95% CI 97.8% to 99.7%) accurate in identification of correct location of intubation. The mean time to placement was 6.45 s (95% CI 5.62 to 7.28). The mean operator confidence level was 4.72/5.0 (95% CI 4.65 to 4.78). There was no significant difference between ETT sizes with respect to any of the outcomes.


      The diagnostic accuracy of ultrasound for ETT confirmation did not vary with the use of different ETT sizes. Further studies are needed to determine if the accuracy would change with more novice providers or in specific patient populations.


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