Abnormal stenosis of a drainage cannula due to excessive negative pressure during venovenous extracorporeal membrane oxygenation management: a case report.

We report a case in which excessive negative pressure may have been applied to the proximal side hole of a drainage cannula during venovenous extracorporeal membrane oxygenation (V-V ECMO), resulting in abnormal stenosis of the drainage cannula. V-V ECMO was introduced in a 71-year-old male patient who was transferred from another hospital for severe respiratory failure associated with varicella pneumonia and acute respiratory distress syndrome. Drainage was performed using a PCKC-V™ 24Fr (MERA, Japan) cannula via the right femoral vein with the tip of the cannula near the level of the diaphragm under fluoroscopy. Reinfusion was performed via the right internal jugular vein. Due to poor systemic oxygenation, the drainage cannula was withdrawn caudally and refixed to reduce the effect of recirculation. Two days later, drainage pressure dropped rapidly, and frequent ECMO flow interruption occurred due to poor drainage. An abdominal X-ray revealed abnormal stenosis of the proximal side hole site of the drainage cannula. We diagnosed that the drainage cannula was damaged, and it was replaced with another, namely a Medtronic Bio-Medicus™ 25 Fr (GETINGE, Sweden) cannula. However, the removed drainage cannula was not damaged, suggesting that the cannula was temporarily stenosed by momentary excessive negative pressure. In a multi-stage drainage cannula, the main drainage site is the proximal side hole, with little negative pressure applied at the apical foramen in a mock experimental ex vivo drainage test in a water tank. Hence, improvement of a multi-stage drainage cannula is recommended, such as adequate reinforcement of the side hole site with a wire.