|BlueDop Vascular Expert|
Detecting vascular disease just got easier ....... much easier!!!
"Cuffless ABI" Screening for PAD by Healthcare Professionals
Calling Physicians, Surgeons, Podiatrists, Vascular and Diabetic Nurses and Tissue Viability Nurses everywhere. We know your World!
Vascular Expert from BlueDop Medical has been developed by Vascular Scientists with decades of experience in the field. We are aware that some 30% of PAD referrals from physicians are Diabetics who are poorly diagnosed by current ABI technology.
Time for change!
Every day in the Vascular Laboratory we are asked to assess the contribution of PAD to the patient symptoms where conventional ABI tests have failed. The solution is here, the solution is now.
Using a patented "pressure from flow" algorithm, Doppler spectra obtained from any convenient pedal artery can generate accurate diagnostic ABI, and perfusion pressure data, unaffected by medial artery calcification, ulceration and calf swelling. Every component of the system is designed to make life easier for hard pressed health professionals. If you already use Doppler based ABI assessments you will have gained all the skills you require to get started.
Training can be as simple as navigating to the "getting started" page on the website. The Doppler probe ("The Egg") communicates with the tablet computer (The "Brain") using Bluetooth technology so no annoying cables to get tangled up.
The egg is hermetically sealed in a smooth biocompatible silicone rubber casing which can be washed under a tap and wiped clean with your preferred sterilising wipes so there is nowhere for bugs to hide. The tablet ("Brain") is housed in a rugged shock proof case and has battery power to run continuously through a complete clinic session.
It displays the Doppler Spectra in real time, ignores any non-physiological (artefactual) input and freezes the display screen when repeatable blood flow waveforms are identified. It then shows on screen "Cuff free ABI" and a whole lot more!
At the end of a clinic session just place the "Egg" onto the "Basecharger" unit. This will inductively charge its batteries. Plug the charger "umbilical" into the "Brain" and Vascular Expert will be "topped up" ready for use in the next session.
No calf cuff required!
Mean arm pressure is obtained by conventional brachial BP cuff measurement. The "pressure from flow" algorithm yields mean blood pressure data so "cuff free" ABI differs from conventional ABI as it is the ratio between mean ankle and arm blood pressure. Its maximum value is 1.0. Values between 1.0 and 0.8 are consistent with PAD free limbs, between 0.79 and 0.50 is consistent with claudication and values between 0.49 and 0.0 are consistent with Critical Limb Ischaemia (CLI). More precisely with loss of autoregulation, the vascular system is failing to maintain optimum pressure and flow to the limb.
We need perfusion pressure!
Perfusion pressure in the foot is directly correlated with ABI, however because mean arm BP (MAP) can vary between individuals (70mmHg to 140mmHg) the same value of ABI could be associated with perfusion pressure of 30mmHg in one patient and 60mmHg in another. At 30mmHg there is a high probality of necrosis. At 60mmHg the tissue will probably remain viable despite the loss of autoregulation.
Vascular Reserve 'tank is empty'
Regard this useful little gadget as the fuel tank. It will go negative as the autoregulatory system reaches its limits and passes into CLI territory.
Clinical Information in the Report page!
‘Cuff Free’ ABIm is vital. The threshold value for PAD is < 0.8. Expect sensitivity and specificity in the 90 – 95% range for even the most challenging cases, well above the documented diagnostic accuracy for conventional ABI testing.
Perfusion pressure is also important, assisting the decision to compress or not to compress a swollen calf. The “perfusion pressure” is defined as the blood pressure measured at an insonation point that is feeding a distal vascular bed.
Vascular Reserve signals loss of autoregulation when it drops into negative territory. The color bar is an innovative independent indicator of disease, switching from Blue to Red in the presence of significant arterial disease. The additional available cardiac pump pressure when the exercised periphery is maximally dilated is zero (Vascular Reserve = 0%) in normal subjects and in PAD patients. Peripheral perfusion pressure is then exactly one half of the central BP (Perfusion Pressure = MAP/2). The autoregulatory system controls flow rate to the periphery to ensure that peripheral perfusion pressure does not fall below MAP/2. In the normal resting subject all of that additional pressure is available (MAP/2) and so Vascular Reserve approaches +100%. Beyond maximal vasodilation which is by definition beyond the limits of autoregulation a driving pressure debt exists. This is Critical Limb Ischaemia (CLI). Worst case would be an absolute pressure of 0mmHg where the Vascular Reserve = -100%. Typically symptoms of rest pain and or tissue loss will occur at negative Vascular Reserve values between -10 and -30%. It should be kept in mind that absolute perfusion pressure determines tissue viability and an abnormally low central BP will determine that value.
Pressure from flow
Our patented ‘pressure from flow’ algorithm just needs an arm BP reference to estimate MAP and a Doppler signal from an ankle artery to estimate mean perfusion pressure at the ankle site. This graph shows the relationship between measured and estimated perfusion pressure compiled from in-vivo experiments.
Cuff free ABI (ABIm)
By dividing mean perfusion pressure by MAP we obtain ‘cuff free ABI’. When correlated with PAD identified on Duplex assessment, two distinct curves emerges. The distribution of PAD and normal limbs taken from a cohort of vascular patients shows a clear crossover, indicating a PAD diagnosis at ABIm < 0.8.
Belt & Braces
We don’t just rely on perfusion pressure and ABIm to diagnose PAD, we have ‘the notch’ algorithm to back up our results, even when an accurate arm BP is not obtainable. The diagnosis is shown as a simple colour bar, Blue=Normal. Vascular Expert detects subtle timing changes in the Doppler Spectrum that human experts just can’t do, so adding an extra confidence factor into our diagnosis.
To see a demonstartion of the Vascular Expert please visit:
Lease BlueDop Vascular Expert from only £237.75 per month plus VAT for 36 months.
Includes complete system and 3 years product warranty.
For more information please contact Medimax Global UK Ltd on +44 (0) 1420 88688