title: Design and evaluation of a new bladder volume monitor.
abstract: OBJECTIVE
  To introduce and evaluate a new implantable bladder volume monitor.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Animal laboratory.
  
  
  METHODS
  Eight dogs.
  
  
  METHODS
  A coin-shaped permanent magnet was stitched onto the anterior bladder wall and a magnetic field sensor was fixed onto the lower abdominal external wall in 8 male dogs. The bladder was filled with sterile normal saline in consecutive steps of 25 mL each from 0 to 200 mL by a transurethral catheter.
  
  
  METHODS
  Sensor readings were recorded after each step of bladder filling.
  
  
  RESULTS
  The sensor baseline was set at 70 degrees when the bladder was empty. After filling the bladders with 25, 50, 75, 100, 125, 150, 175, and 200 mL saline water, the sensor readings were 74.6+/-0.9 degrees , 79.6+/-1.2 degrees , 84.5+/-0.9 degrees , 90.1+/-0.8 degrees , 95.5+/-1.1 degrees , 101.8+/-2.1 degrees , 110.5+/-2.9 degrees , and 121.9+/-3.5 degrees , respectively. Sensor readings were positively correlated with bladder volume (r=1; P<.01).
  
  
  CONCLUSIONS
  The design of a new bladder volume monitor that is made up of an external magnetic field sensor and an internal permanent magnet is reasonable and feasible. The new bladder volume monitor is simple in structure.
authors.affiliation: Department of Orthopedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, P. R. China.
authors.forename: Jianhuo
authors.initials: J
authors.lastname: Wang
authors.forename: Chunlin
authors.initials: C
authors.lastname: Hou
authors.forename: Xianyou
authors.initials: X
authors.lastname: Zheng
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Aimin
authors.initials: A
authors.lastname: Chen
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xu
mesh_terms: D000818:Animals; D004285:Dogs; D004574:Electromagnetic Fields; D004867:Equipment Design; D005240:Feasibility Studies; D023421:Models, Animal; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D001743:Urinary Bladder / Q000502:physiology*; D001750:Urinary Bladder, Neurogenic / Q000503:physiopathology; D014563:Urodynamics