REAL-TIME ULTRASOUND GUIDED ENDOTRACHEAL INTUBATION

Background
End tidal carbon dioxide (EtCO2) waveform (capnography) is considered to be the gold standard in confirming the position of the endotracheal tube. Real-time Ultrasonography is a new method to confirm endotracheal intubation in situations where capnography is not available.

Methods
During intubation the linear probe of ultrasound was placed over the cricothyroid membrane. Ultrasonographic images of endotracheal intubation shows ‘empty esophagus sign’ while esophageal intubation shows a ‘double trachea sign’. Simultaneously, another operator will connect the capnography and will observe the EtCO2 wave. Endotracheal intubation will be confirmed when square waveform is maintained with end-tidal carbondioxide greater than 4mm Hg. The accuracy, sensitivity, specificity and time taken to identify is noted using both the methods.
Results
Real-time Ultrasound was 98.46% ( 95% CI : 91.72% - 99.96%) accurate in confirming endotracheal intubation. The empty esophagus sign was 98.36% sensitive and 100% specific. Endotracheal intubation was confirmed earlier with real-time ultrasound (12.43±5.4sec) than capnography (16.68±5.50sec) and difference in time taken to confirm the position of the endotracheal tube was statistically significant with p<0.05.
Conclusion
Real-time tracheal ultrasound is an effective alternate method which is as sensitive and accurate as gold standard capnography to confirm endotracheal intubation. It can be used in clinical settings where capnography cannot be used as in massive pulmonary embolus and cardiac arrest or in settings where it is not available.