Interosmolar fluid removal

Abstract

Inventions are disclosed that generate osmotic pressure that can be used to remove fluids from a patient. One embodiment involves implanting a reservoir that has a semipermeable membrane sidewall. The reservoir contains trapped osmotic solutes that can not pass out through the membrane. But fluid from the patient can flow in. The osmotic pressure from the trapped solutes in the reservoir draws fluid from the patient across the semipermeable membrane and into the device. The reservoir may optionally be recharged from time to time and/or replaced by a new reservoir.

1 . A method of collecting fluids from a patient comprising
 placing, in a patient, a fluid collection device that comprises a semipermeable membrane that at least partially bounds a lumen containing trapped osmotic solutes in aqueous solution, with the lumen being in fluid communication with a reservoir that is removable or reloadable while the device is in use,   wherein the trapped osmotic solutes
 have a molecular weight greater than a molecular weight cutoff of the semipermeable membrane and create an osmotic pressure that draws physiological fluid from the patient across the membrane and into the lumen. 
   
     
     
         2 . The method of  claim 1  wherein the reservoir is removable while the device is in use, and further comprising
 removing the reservoir and
 reloading the reservoir with fresh solution, and replacing the reservoir to thereby re-use the reservoir, or 
 replacing the reservoir with a fresh reservoir unit. 
 
 
     
     
         3 . The method of  claim 2  wherein the removal of the reservoir and the reservoir reloading or replacement is performed a plurality of times. 
     
     
         4 . The method of  claim 2  wherein the reservoir that is removed is disposable and is replaced with a fresh reservoir unit. 
     
     
         5 . The method of  claim 1  comprising removing fluid from the reservoir without replacement of the reservoir. 
     
     
         6 . The method of  claim 1  wherein the lumen is connected to a percutaneous port or a transcutaneous port and the reservoir fastens to the percutaneous port or transcutaneous port. 
     
     
         7 . The method of  claim 6  wherein the reservoir is connected to the port with a fastener. 
     
     
         8 . The method of  claim 1  wherein the osmotic solutes are present at a concentration to produce the osmotic pressure of between 50 and 100,000 Torr. 
     
     
         9 . The method of  claim 1  wherein the trapped osmotic solutes have an average molecular weight in a range from about 500 to about 50,000. 
     
     
         10 . The method of  claim 1  wherein the trapped osmotic solutes comprise polymers. 
     
     
         11 . The method of  claim 1  comprising placing the semipermeable membrane of the fluid collection device in: a peritoneal space; in an arm; in a leg; or in the patient at or near a lymph node that collects lung fluids. 
     
     
         12 . The method of  claim 1  wherein the physiological fluid is withdrawn to treat edema. 
     
     
         13 . The method of  claim 1  wherein the physiological fluid is withdrawn to treat congestive heart failure. 
     
     
         14 . A medical system for collecting physiological fluid from a patient that comprises:
 a fluid collection device that comprises a semipermeable membrane that at least partially bounds a lumen containing trapped osmotic solutes in aqueous solution, with the lumen being in fluid communication with a reversibly attachable or reloadable reservoir,   wherein the trapped osmotic solutes
 have a molecular weight greater than a molecular weight cutoff of the semipermeable membrane and create an osmotic pressure that draws physiological fluid from the patient across the membrane and into the lumen. 
   
     
     
         15 . The system of  claim 14  wherein the reservoir is reversibly attachable. 
     
     
         16 . The system of  claim 15  wherein the reservoir is disposable. 
     
     
         17 . The system of  claim 14  wherein the reservoir is reloadable and fluid is removable from the reservoir while the device is in use. 
     
     
         18 . The system of  claim 14  wherein the lumen is joined to the reservoir with a fastener. 
     
     
         19 . The system of  claim 14  wherein the osmotic solutes are present at a concentration to produce the osmotic pressure of between 50 and 100,000 Torr. 
     
     
         20 . The system of  claim 14  wherein the trapped osmotic solutes have an average molecular weight in a range from about 500 to about 50,000. 
     
     
         21 . The system of  claim 14  wherein the trapped osmotic solutes comprise polymers.