Trans-tracheal ultrasound: A feasible method for endotracheal tube position reconfirmation during COVID-19 pandemic

Dear sir,

Reconfirmation of endotracheal tube (ETT) position in intubated patients is mandated especially after transportation. To date, end-tidal CO₂ (ETCO₂) is recommended for ETT position confirmation. Nevertheless, using a portable or continuous ETCO₂ monitor, frequent connect and disconnect of the ETT expose medical staffs to potential aerosol transmissible disease. This idea raises our concern during COVID-19 pandemic.

In our practice, during emergent endotracheal intubation, we performed trans-tracheal ultrasound (TTU) to confirm ETT position (Figure 1(a)). We performed TTU again to confirm the ETT position after patient’s transportation. We found that there is accumulation of subglottic secretion just above the cuff of the ETT, especially 30 min after the patient was intubated (Figure 1(b) and (c), video). A routine oral suction performed by nurse staff failed to cleanse the accumulated secretion. Similar findings repeated in many cases, indicating (1) the accumulation of subglottic secretion facilitates direct ultrasound visualization of ETT and (2) routine oral suction could not effectively reduce the accumulated secretion.

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Figure 1.

(a) Transverse view of trans-tracheal ultrasound, right after endotracheal intubation (using a linear probe, scanning over upper trachea). (b) Transverse view of trans-tracheal ultrasound, 30 min after endotracheal intubation (using a linear probe, scanning over upper trachea), there was fluid accumulation (arrow) around endotracheal tube. (c) Longitudinal view of trans-tracheal ultrasound, 30 min after endotracheal intubation (using a linear probe, scanning over midline of neck, superior to suprasternal notch), there was fluid accumulation (F) around endotracheal tube (blue dot).

As the accumulation of subglottic secretion facilitates direct ultrasound visualization of ETT, we propose the usage of bedside TTU in timely reconfirmation of ETT position after transportation, in order to prevent frequent connection of ETT with ETCO₂ monitor, especially during the COVID-19 pandemic. Our previous study proposed the usage of tracheal ultrasound exam for real-time confirming tube placement during emergent intubation. ¹ Currently, there is no study in validating the usage of ultrasonography for reconfirming ETT position. We strongly encourage further study to validate the usage of TTU in reconfirming ETT position after transportation.

Micro-aspiration of subglottic secretions through the ETT cuff is considered a significant cause of ventilator-associated pneumonia (VAP). ² Our another finding showed that routine oral suction could not clear up subglottic secretion in intubated patients. In the aspect of micro-aspiration, maintaining strict oral hygiene may have a little help in preventing VAP.