Method and system for programmed in situ tissue expansion

Abstract

A tissue expansion system includes driver assembly having a syringe pump and a controller held in a common enclosure. The driver assembly is connected to both an inflatable bladder and an inflation medium source. Fluid is delivered from the driver assembly to the inflatable bladder through a pressure sensor. The pump is actuated to deliver predetermined incremental volumes of the inflation medium to the inflatable bladder at spaced apart time intervals. Pressure is monitored and the pumping is interrupted if the pressure exceeds a predetermined high threshold value. Pumping is recommenced when the pressure falls below a lower threshold value until the total incremental delivery volume has been reached.

What is claimed is: 
     
         1 . A method for expanding tissue, said method comprising:
 (a) locating an expandable bladder underneath a region of skin, fascia, or muscle to be expanded by introducing an incompressible inflation medium;   (b) pumping a preselected incremental volume of the incompressible inflation medium into the bladder;   (c) monitoring pressure of the inflation medium while the preselected incremental volume of inflation medium is being pumped into the bladder;   (d) terminating pumping of the incremental volume when said the preselected incremental volume has been delivered to the bladder or when said the monitored pressure exceeds an upper threshold level,   (e) if the pumping was stopped because the monitored pressure exceeded the upper threshold level, recommencing pumping of the incremental volume when the monitored pressure falls back below a lower threshold level and continuing pumping until the preselected incremental volume has been reached or the monitored pressure once again exceeds the upper threshold level;   (f) repeating step (d) if the monitored pressure once again exceeds the upper threshold level before the preselected incremental volume has been delivered; and   (g) repeating steps (b) through (f) at preselected time intervals until a preselected cumulative volume of the inflation medium has been delivered to the expandable bladder.   
     
     
         2 . A method as in  claim 1 , wherein locating comprises placing the expandable bladder beneath skin located adjacent to a defect. 
     
     
         3 . A method as in  claim 1 , wherein locating comprises placing the expandable bladder in a subpectoral pocket following a mastectomy. 
     
     
         4 . A method as in  claim 3 , wherein the expandable bladder is initially inflated with a volume of saline in the range from 50 cc to 100 cc. 
     
     
         5 . A method as in  claim 1 , wherein the preselected incremental volume is in the range from 1 cc to 10 cc and the preselected time interval is in the range from 10 minutes to 3 hours. 
     
     
         6 . A method as in  claim 5 , wherein the upper threshold level is in the range from 40 mmHg to 50 mmHg and the lower threshold level is in the range from 25 mmHg to 35 mmHg. 
     
     
         7 . A method as in  claim 5 , wherein pumping is performed with a constant speed positive displacement pump so that the predetermined incremental volume is provided by a predetermined incremental run time for the pump and the preselected cumulative volume of the inflation medium is provided by a preselected cumulative run time of the pump. 
     
     
         8 . A method as in  claim 2 , wherein the bladder is removed after the skin has been expanded to create a flap and the flap is used to cover the defect.