ActiveCare®+DTx adds innovative capabilities to the products using S.F.T. technology (see ActiveCare® S.F.T.) as it has the ability to detect real time potential venous flow.
This combination of measuring technologies and algorithms has created a truly unique and revolutionary system that was proven to have the best outcomes in terms of efficacy and safety in DVT prevention.
- Continuous monitoring of each patient’s venous phasic flow on a real-time basis to identify the timing of patient’s natural venous return.
- External compression so that it is timed so that it is in sync with each patient’s natural venous return to achieve a higher pulsatile venous flow. This can be demonstrated by the high peak venous velocity created at each compression cycle at the common femoral vein (c.f.v.), the main venous vessel clearing blood from the legs towards the trunk of the body.
- And now, detection of possible conditions that may be indicative of the development of venous flow obstruction.
Learn more on the ability to detect venous flow obstruction:
What is the Venous Phasic Flow (VPF) signal?
When at rest the venous flow from the legs towards the trunk of the body is controlled by the respiratory cycle. The respiratory cycle, at inhale, increases the abdominal pressure on the common femoral vein which is the main vessel clearing blood from the legs. Since the vein is very flexible, this pressure actually shuts it down just below the pelvic level making it work as a “gate”. At times when the “gate” is closed, a higher pressure builds at the venous system below and when the increased abdominal pressure created by the respiratory cycle is cleared, at exhale, a surge of venous blood then moves towards the trunk of the body.
Thus, the respiratory cycle (inhale and exhale) is creating a cyclic wave pattern of venous flow from the legs towards the truck of the body. This cyclic wave of venous flow is called The Venous Phasic Flow.
The following image shows a Doppler image of the Venous Phasic Flow:
How does the ActiveCare® system create a high pulsatile flow with a very gentle compression?
The S.F.T. technology continuously monitors the Venous Phasic Flow and synchronizes the external compression it creates so that it is in sync with these naturally occurring waves.
By doing this, the system is adding its externally induced surge of venous blood to the natural one. The combined wave allows for a higher volume and higher speed surge of blood to move upwards from the lower part of the legs upwards.
In the following Doppler image you can see an example of the venous wave that is moving through the common femoral vein when the external compression is timed to sync with the natural VPF -vs. the wave observed when it is not.
How does the ActiveCare® reproduce the high pulsatile flow with each compression cycle?
Natural venous phasic flow occurs only when the femoral “gate” is open. By synchronizing its compressions with this natural venous phasic flow pattern, the system capitalizes on the open “gate” to achieve a reproducibly high pulsatile flow.
Without the synchronization, compression can happen at such times that the “gate” is closed and therefore there will be no increase of venous blood flow towards the truck of the body.
In the following Doppler image you can see an example of the venous wave that is moving through the common femoral vein when the external compression is timed to match when the “gate” is opened vs. the wave observed when the “gate” is closed.
How does the ActiveCare®– system detect conditions that may indicate the development of venous flow obstruction?
Since the S.F.T. technology monitors the Venous Phasic Flow on a real time 24/7 basis in order to time its compression by the ActiveCare®, any obstruction at the common femoral vein at the pelvic level will have a severe dampening effect on the Venous Phasic Flow.
The ActiveCare® -system uses a sophisticated algorithm that allows it to store and analyze the Venous Phasic Flow signals. When the system is in DTX mode the algorithm combines the data from this continuous monitoring with the data from a 7 min dedicated test to detect possible flow obstructions and prompt the attending staff to take further action.
In the following images you can see an example of a Doppler image and the ActiveCare® recordings of a non-obstructed flow vs. an obstructed flow caused by proximal DVT.