Is an endotracheal tube (ETT) size 7.5 at a depth of 26 cm indicative of gastric insertion in an adult patient?

ETT 7.5 at 26 cm Depth: Assessment of Gastric vs. Tracheal Placement

An endotracheal tube size 7.5 at a depth of 26 cm is NOT indicative of gastric insertion in an adult patient and represents an excessively deep tracheal placement that likely positions the tube at or beyond the carina, risking endobronchial intubation.

Understanding Normal ETT Depth in Adults

The typical depth for proper endotracheal tube placement in adults is significantly shallower than 26 cm:

• Optimal tracheal positioning places the ETT tip 3-5 cm above the carina in the mid-tracheal region 1
• For adult patients, proper ETT depth at the teeth/lips typically ranges from 21-23 cm for most adults, with variation based on patient height and anatomy 1
• Airway exchange catheters should never be advanced beyond 25 cm in adults because the distal tip must remain above the carina 2, 1

Why 26 cm Suggests Deep Tracheal (Not Gastric) Placement

A tube at 26 cm depth is concerning for endobronchial intubation rather than esophageal/gastric misplacement:

• At 26 cm, the tube has likely advanced past the optimal mid-tracheal position and may be at or in a mainstem bronchus (typically the right) 1
• Gastric/esophageal placement would be identified by absence of CO2 on capnography, not by depth measurement alone 2
• The depth measurement of 26 cm falls within the range where tracheal tubes can still be positioned, albeit too deeply 2

Immediate Verification Steps Required

You must immediately verify tube position using multiple methods 1:

• Continuous waveform capnography is the most reliable method for confirming tracheal (not esophageal/gastric) placement (Class I, LOE C-LD) 2
• Auscultate for bilateral breath sounds - unilateral breath sounds at 26 cm depth would suggest right mainstem intubation 1
• Obtain a chest X-ray to confirm the tube tip position relative to the carina 1, 3
• If capnography shows CO2 waveform, the tube is in the airway (trachea or bronchus), not the stomach 2

Critical Management Decision

If capnography confirms tracheal placement at 26 cm:

• Withdraw the tube to 21-23 cm depth (depending on patient size) to achieve proper mid-tracheal positioning 3-5 cm above the carina 1
• Reconfirm bilateral breath sounds and capnography waveform after repositioning 1, 3
• Secure the tube and document the new depth at the teeth/gums 3
• Obtain post-repositioning chest X-ray to verify proper placement 1, 3

Common Pitfall to Avoid

Do not assume depth alone determines gastric vs. tracheal placement - a tube can be in the trachea at various depths (though 26 cm is too deep). The presence or absence of CO2 on capnography is the definitive indicator of tracheal vs. esophageal/gastric placement 2. A tube at 26 cm with a normal capnography waveform is in the airway but positioned too deeply, while absence of CO2 would indicate esophageal/gastric misplacement regardless of depth 2.