Which French size is used for the Swan-Ganz catheter?

• A. 7F
• B. 6F
• C. 8F
• D. 9F

Answer: (A)

Sizing a Swan-Ganz catheter in French units reflects the need to balance trackability through the venous access with enough lumen area for all measurement and inflation functions. In adults, the commonly used size is 7F, about 2.3 mm in outer diameter (7 × 0.33 mm). This size provides sufficient space for the distal port to sample pulmonary artery pressures, the proximal lumen for central venous pressure, the balloon lumen for occlusion, and the sensor/thermistor, while minimizing the risk of vascular injury compared with larger sizes. Smaller catheters (like 5F or 6F) may lack adequate lumen for all channels and accurate measurements, whereas larger catheters (8F or 9F) increase the risk of trauma during placement.