title: Evaluation of shunting flow differences in varied conditions in a simulated adult CPB model during normothermia.
abstract: BACKGROUND
  It is well documented that lower pump flow during clinical cardiopulmonary bypass (CPB) procedures may be significantly detrimental to tissues and organs. The major cause of hypoperfusion is due to shunting flow existing in the closed CPB circuits. The purpose of this investigation was to evaluate various shunting flow conditions in a simulated adult CPB model under normothermia.
  
  
  METHODS
  The pseudo adult patient undergoing CPB was established with an extracorporeal circuit. The pre-oxygenator flow, post-filter flow and purge line pressure were recorded. The temperature of the circuit was kept around 36°C using a heat-cooler. The pseudo patient was subjected to five pump flow rates ranging from 3000 to 5000 ml/min (500 ml/min increments), and post-filter pressure was varied from 120-220 mmHg (20 mmHg increments) using a single, static roller pump. Four different shunting states were measured with two flowmeters.
  
  
  RESULTS
  When the pump flow was constant, the percentage of shunting flow increased as the post-filter pressure increased in State 1. However, when the post-filter pressure was constant, the trend of the shunting flow was the opposite. Purge line pressure increased with the increase of the post-filter pressure at a constant pump flow rate in State 1. The shunting flow for State 2 was the largest of the four states. The shunting flow for State 3 was similar to State 4.
  
  
  CONCLUSIONS
  During different states of shunt opening, varying degrees of blood flow were diverted away from the arterial line. Shunting of blood flow may, therefore, result in hypoperfusion in the patient.
authors.affiliation: Fuwai Hospital & Cardiovascular Institute, Chinese Academy of Medical Science, Peking Union Medical College, 167 Bei li shi Road, Fuwai Da Jie, Xi Cheng, Beijing, Peoples Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Duan
authors.forename: Bingyang
authors.initials: B
authors.lastname: Ji
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Li
authors.forename: Jinping
authors.initials: J
authors.lastname: Liu
authors.forename: Kun
authors.initials: K
authors.lastname: Yu
authors.forename: Yue
authors.initials: Y
authors.lastname: Tang
authors.forename: Cun
authors.initials: C
authors.lastname: Long
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001831:Body Temperature; D002315:Cardiopulmonary Bypass; D006801:Humans; D008955:Models, Cardiovascular