Endotracheal Tube (ETT) Depth and Tidal Volume Calculator

Why Use

Placing the ETT too deeply may cause right mainstem intubation, hypoxemia, and pneumothorax. However, placing the ETT too shallowly may risk injury to the vocal cords and accidental extubation. Standard approaches to verify ETT depth (e.g. bilateral auscultation) are insensitive. Use of lower tidal volumes appears to prevent the development of acute respiratory distress syndrome, even in patients who do not have lung injury.

When to Use

Adult patients requiring orotracheal intubation.

Formula

Pearls / Pitfalls

ETT depth is measured based on the patient’s front teeth (not the molars). Larger tidal volumes may be temporarily required for patients with severe metabolic acidosis. This tool uses the Devine formula to approximate ideal body weight (IBW), which is most accurate in patients who are at least 60 inches tall. Currently, there is no universally accepted alternative formula for shorter adults.

Management

Endotracheal intubation and mechanical ventilation.

Critical Actions

Chest radiograph and measurement of CO₂ level (e.g. end-tidal CO₂ or blood gas analysis) to confirm ETT position and adequacy of ventilation.

Advice

ETT position should still be verified with a chest radiograph among patients who will remain intubated for an extended period of time. Tidal volume: (6-8 mL/kg)* ideal body weight (IBW) is generally a safe initial setting, but further ventilator adjustment may be required depending on the adequacy of ventilation and airway pressures.