ett_depth_tidal_volume: Endotracheal Tube (ETT) Depth and Tidal Volume Calculator

In cliot: Clinical Indices and Outcomes Tools

Endotracheal Tube (ETT) Depth and Tidal Volume Calculator

Description

Calculates the appropriate depth for endotracheal tube placement and target tidal volumes based on patient height and sex. It provides depth estimates using two methods: the Chula formula (Height/10 + 4) and the 3x Tube Size rule. It also calculates Predicted Body Weight (PBW) to determine lung-protective tidal volume ranges (6-8 mL/kg).

Usage

ett_depth_tidal_volume(height_cm, sex, tube_size_mm)

Arguments

height_cm	Numeric. Patient height in centimeters.
sex	String. Patient sex ("Male" or "Female"). Used for PBW calculation.
tube_size_mm	Numeric. Internal diameter of the endotracheal tube in millimeters (e.g., 7.5).

Value

A list containing:

Predicted_Body_Weight_kg	Calculated PBW used for tidal volume dosing.
Tidal_Volume_Target_6_8_ml_kg	Recommended tidal volume range (6-8 mL/kg PBW) for lung-protective ventilation.
ETT_Depth_Chula_cm	Estimated depth of insertion from the Chula formula.
ETT_Depth_3x_Size_cm	Estimated depth of insertion using the 3x tube size rule.

References

Techanivate A, Kumwilaisak K, Samranrean S. Estimation of the proper length of orotracheal intubation by Chula formula. J Med Assoc Thai. 2005;88(12):1838-1846. Acute Respiratory Distress Syndrome Network. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342(18):1301-1308. doi:10.1056/NEJM200005043421801

Examples

# Example 1: Adult Male
# 180 cm, Male, 7.5 mm tube
# PBW = 50 + 0.91*(180-152.4) = ~75 kg
# TV = 450-600 mL
# Depth (Chula) = 18 + 4 = 22 cm
# Depth (3x) = 22.5 cm
ett_depth_tidal_volume(180, "male", 7.5)

# Example 2: Adult Female
# 160 cm, Female, 7.0 mm tube
# PBW = 45.5 + 0.91*(160-152.4) = ~52 kg
# TV = 312-416 mL
# Depth (Chula) = 16 + 4 = 20 cm
# Depth (3x) = 21 cm
ett_depth_tidal_volume(160, "female", 7.0)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.