RESUMEN
BACKGROUND: Tube thoracostomy is a commonly performed procedure in trauma patients. The optimal chest tube size is unknown. This study measures chest tube drainage in a controlled laboratory setting and compares measured flowrates to those predicted by the Hagen-Poiseuille equation. MATERIALS AND METHODS: A model of massive hemothorax was created, consisting of a basin containing synthetic blood substitute (aqueous Glycerin and Xanthan gum) and a standard pleur-evac setup at -20 cm H2O suction. Flow measurements were calculated by measuring the time to drain 2L of blood substitute from the basin. Chest tube sizes tested were 20F, 24F, 28F, 32F, and 36F. Thoracostomy opening was modeled using custom built device that represents two ribs, with the distance between varied 2 to 12 mm. Flowrate increases were compared against predicted increases according to the Hagen-Poiseuille equation. Percent of predicted increase was calculated, both incremental increase and using 20F tube benchmark. RESULTS: All tubes were occluded at a 2 mm thoracostomy opening. At 3 mm, 32F and 36F were occluded while smaller tubes were patent. Tubes 28F and larger exhibited high speed and consistent flowrates, even after decreasing thoracostomy opening down to 7 mm, while flowrates rapidly decreased at opening smaller than 7 mm. Smaller 24F and 20F tubes exhibited highly variable flowrates through the system. Maximum flowrates were 21.7, 36.8, 49.6, 55.6, and 61.0 mL/s for 20F-36F tubes, respectively. The incremental increase in flow ratio for increasing chest tube size was 1.69 (20F to 24F), 1.35 (24F to 28F), 1.12 (28F to 32F), and 1.10 (32F to 36F). CONCLUSIONS: The 28F chest tube exhibited high and consistent velocity, while smaller tubes were slower and more variable. Larger tubes offered only slightly higher flowrates. The 28F is a good balance of reasonable size and high flowrate and is likely the optimal size for most clinical applications.