MMED High Performance ​Blood Warmer

Mechanical and Medical Engineered Designs, LLC
  • BEST WARMING CAPACITY
    Similar to Level 1® H1200, Belmont® FMS 2000, and
    ThermaCor® 1200 Blood Warmers

  • DRY HEAT WARMER
 
  • PATENTED HEATED / ​INSULATED
    PATIENT LINE
    Delivers warm fluid down to KVO
 
  • COMPLETE AIR EMBOLISM ​PROTECTION
    Ultrasonic Air Detector with solenoid Pinch Valve
    and Optional In-Line Air Eliminator
 
  • WARMER MUCH LOWER COST
    ​    Compared to Level 1® H1200, Belmont® FMS 2000,
    ​and ThermaCor® 1200 Blood Warmers
 
  • LOW COST, SIMPLE DISPOSABLE
DEVELOPED BY a retired anesthesiologist and former United States Marine who holds a Stanford master’s degree in mechanical engineering (with heat transfer emphasis) and previously worked as a Research Engineer for NASA.
​​The purpose of this website is to describe the capabilities and benefits of the MMED High Performance Blood/Fluid Warmer, and is directed toward medical device companies or motivated individuals with interest in medical fluid warming. 

MMED seeks a partner company to license or purchase this technology. If you have questions, please contact MMED. Inquiries or proposals from entrepreneurial individuals who may be interested in entering medical device business are also welcome.
​MMED High Performance Blood Warmer 
​Advanced Prototype
  • Fully functional,  including​
    ​​developed heat exchanger disposable.
  • Approximate dimensions:  
    9 inches x 14     inches  x 5 inches ​
  • Weight:   18 lb.  (reducible to 14 lb.)
The exceptional performance of the MMED ​High Performance Blood Warmer (compared to other flat plate, dry heat warmers) relies on physics.

The heating plates are "flat heat pipes." They have the characteristic of constant temperature—they attempt to be isothermal. Thus they provide much higher heat transfer where the incoming fluid is colder.

​We have sourced these heat pipes, having our specific design needs and prototypes produced (by a leading heat pipe producer).

The disposable heat exchanger (bag or envelope) is simple (see photo below). Its hydraulic resistance is low. Its thermal resistance is low. Its "paper needle" insertion method is patented and allows the heating plates to be closely spaced for best heat transfer.

​These disposable heat exchangers have been detail designed and produced by an expert plastics welding company.  Test results shown below were achieved with gravity only (42 inch elevation, about 80 mm Hg).

​The disposable heat exchanger should be very low cost compared to Level 1® Fast Flow 1200, Belmont® FMS 2000 or ThermaCor® 1200 disposables.  

Safety Features

Safety features, necessary for pressurized high flow and high "anxiety" fluid resuscitation are included in the MMED prototype.

  1. Air Eliminator (optional)—dual hydrophobic membranes capable of venting more than 200 ml air (residual in pressurized bag). In rapid administration of fluids, "de-airing" of fluid bags may not always be accomplished. ​
    ​
  2. Air in Line detection—if air removal device not used, or if overwhelmed by gas, an ultrasonic detector senses air in line. The "drip chamber" is normally completely full of fluid. If air enters, the ultrasonic detector will detect air when the fluid level reaches the detector level (about 1/2 full).
    ​
  3. Pinch Valve flow interruption—if air is detected in the drip chamber, the solenoid pinch valve closes and flow is immediately interrupted. An audio alarm sounds. The alarm may be switched off while air is removed from system (by injection site on top of drip chamber). The pinch valve is "Fail Safe;" valve closes upon power failure.

Performance

The graphed data below show results of tests with the prototype performed January and February, 2013 and by Mayo Clinic in January, 2017. All tests were done with cold water, and all were done with inlet water temperatures 6-10°C and some about 22°C. Flow pressure was supplied by gravity only for flow rates to 550 ml/min, with the source water about 42 inches above the bag inlet (about 80 mm Hg). Higher flow rates were obtained with a 300 mm Hg pressurizer. Outlet temperatures were measured about 4 ft. from warmer outlet, except that for Mayo Clinic tests temperatures were measured 1 ft. from warmer outlet.  Also, Mayo Clinic tests were done with 300 mm Hg pressurizer.  For moderate to high flows, as in these tests, little cooling toward ambient temperature occurs in the outlet line.
​
At about 500 ml/min, roughly 1000watts are required to achieve the warming of 10°C fluid. The MMED Prototype uses heater power of about 1500 watts, similar to the three currently marketed high performance warmers (ThermaCor® 1200 heater power is not published but is likely similar).
​MMED Prototype Blood/Fluid Warmer performance tests of January and February 2013 and January 2017 (by Mayo Clinic).

​MMED In-Line Air Eliminator


​The photo above shows (enlarged) the MMED in-line Air Eliminator. It employs two hydrophobic disks, spaced apart, between which flows the blood or fluid that has been warmed in the MMED blood warmer. Its operation is independent of orientation, as one disk is always "up" and air in the flow stream is passed out of the stream, while liquid is allowed to continue through. The MMED Air Eliminator successfully vents more than 200 ml residual air from an i.v. bag pressurized to 300 mm Hg.

This Air Eliminator is an optional part of the disposable. It makes flow interruptions (by the ultrasonic air detection function) much less likely, and would be beneficial in high-flow, (high stress/anxiety) fluid resuscitation cases.

MMED Disposable Heat Exchanger Bag / Envelope


​The MMED disposable heat exchanger bag is deployed by inserting the "paper needle" between the closely spaced apart flat heat pipe heating plates and pulling the bag into place. This bag is a 4-pass bag. Fluid enters in the passage second from the foreground, and exits the passage nearest the foreground. This disposable passed over 500 ml/min at 38°C outlet temperature with gravity pressure alone (about 42" water pressure head or 80 mm Hg). Higher flow rates, up to 1100 ml/min were achieved with 300 mm Hg pressurization. Acceptable outlet temperatures (>35°C) were attained for flow rates of 600 and 1100 ml/min for 10°C and 22°C inlet temperatures respectively.