Artificial Airway Catheter Size Calculator

Calculator for estimating recommended suction catheter size from the internal diameter of an artificial airway. Output is shown in French units and rounded down to the nearest catheter size.

Airway Inputs

Enter the internal diameter of the endotracheal tube or tracheostomy tube.

Recommended Catheter Size

French Output
Formula (display):
Given:
ID mm
Compute:
Exact estimate
0.0
Fr
Rounded down recommendation
0
Fr
Selection note:

Airway Occupancy View

Approximate catheter-to-airway occupancy indicator
Pediatric caution threshold: 70%
More airway patency Greater airway occlusion
0%25%50%70%100%
Approximate catheter diameter
0.0
mm
Approximate occupancy
0
% of airway diameter
Pediatric caution
Not selected
Applied when infant / pediatric mode is selected

Clinical Significance

The artificial airway catheter size equation estimates the recommended catheter size for suctioning an artificial airway based upon the internal diameter of the airway. The output is expressed in French units.

This equation allows practitioners to quickly determine an appropriate recommended size for suctioning an artificial airway. Catheters that are too large can occupy too much of the airway and evacuate an excess of gas during the suction procedure, while catheters that are too small may have inadequate capacity to remove secretions effectively.

In the infant and pediatric population, selected suction catheters should not exceed approximately 70% of the internal diameter of the artificial airway. This page highlights that threshold when pediatric mode is selected so the recommendation can be interpreted with that caution in mind.

This calculator rounds down to the nearest French catheter size to stay conservative when converting from the estimated value to a practical catheter selection. Clinical judgment and available catheter sizes should still guide final choice.

References (APA 7th Edition)

  1. Kacmarek, R. M., Stoller, J. K., & Heuer, A. J. (2022). Egan’s fundamentals of respiratory care (12th ed.). Elsevier.
  2. American Association for Respiratory Care. (2010). AARC clinical practice guideline: Endotracheal suctioning of mechanically ventilated patients with artificial airways 2010. Respiratory Care, 55(6), 758–764.
  3. Cairo, J. M. (2020). Pilbeam’s mechanical ventilation: Physiological and clinical applications (7th ed.). Elsevier.
  4. Hess, D. R. (2014). Tracheal suctioning: A review of the evidence. Respiratory Care, 59(6), 930–946.