The PVL compliance map is the fundamental vascular control system which regulates blood flow in the body. Current blood pressure monitoring capabilities are limited to arterial blood pressure (ABP) and central venous pressure (CVP). These two blood pressure parameters frame the PVL pressure gradient from the left heart back to the right heart but tell physicians little or nothing about the internal structure of the PVL at the microvascular level. Furthermore, accurate measurement of these two blood pressure parameters by current monitoring systems requires risky catheterization on both the arterial side and the venous side of the PVL. The VasoMapTM measures these conventional cardiovascular framing pressures noninvasively but also measures the microvascular pressures (Capillary Filling Pressure and Venule Filling Pressure) that frame the capillary bed.
The ‘secret sauce’ of the VasoMap is its ability to concurrently measure the vascular volume changes while the blood pressure cuff is inflating and deflating. From this combined Volume and Pressure data the VasoMap produces a Volume vs Pressure (Vessel Compliance) loop graph as shown in Figure A3.
What may not be visually apparent from Figure A3 is that it is not a smooth curve but a series of line segments which characterize regions of pressure along the pathway of flow. There exist “Compliance Inflection Pressures” (CIPs) along the pathway of flow that identify segments in this volume vs pressure data along the pathway. The cardiovascular system exists in the pressure domain and the CIPs segment the pressure domain between the MAP in the Arteries and the CVP in the Veins.
Figure A5: Vascular Segmentation by Compliance Inflection Pressures (CIPs)
The VasoMapTM requires an understanding of the Peripheral Vascular Loop (PVL) and how the organizational structure of the PVL regulates blood flow in the body. Unfortunately, physicians can view only a small part of the CV system (arteries) with existing healthcare instrumentation and they have no way to relate the relative status of those arteries to the status of the capillaries and the veins. Consequently, the relationship of the venous vascular status to overall vascular performance is poorly understood in current healthcare delivery. If you cannot measure it, you cannot properly integrate it with medical protocols. This lack of observation and understanding of the venous structure is responsible for the relatively poor outcomes currently associated with the treatments of Sepsis, Shock, and Heart Failure in current healthcare delivery.
VasoMap Vascular Segmentation offers substantial new insight into cardiovascular disease diagnosis and management. Venous Compliance, Volumes, and Pressures are new indicators which are important in Heart Failure, Shock (Sepsis), Hypertension, and Renal Dialysis management. Previously, the microvasculature and veins were a Blind Spot in cardiovascular monitoring as shown in Figure 4. Being able to characterize the venous vascular structures, noninvasively, is a huge advancement in hemodynamic monitoring, cardiovascular disease diagnosis, and treatment. The VasoMap is the first medical instrument that produces an integrated view of all three main operating parts of the peripheral vascular loop, arteries, capillaries, and veins. In particular Venous Compliance, Venous Volume, and Venous Pressures are new parameters that will greatly improve healthcare quality, outcomes, and reduced costs of care. The Vascular Blind Spot is now exposed for business.
The Science Behind the Breakthroughs
VasoMap Technology and the Peripheral Vascular Loop (PVL)
The VasoMapTM monitor non invasively characterizes peripheral vascular behavior by measuring the Residual Volume vs Pressure profile of the Peripheral Vascular Loop (PVL), including filling pressures and residual fluid volumes of each vascular compartment along the pathway of flow, Figure A1. We know from fluid mechanics that for flow to exist in the vascular system, the pressure must drop along the pathway of flow. It has been shown that key Compliance Inflection Pressures (CIP’s) exist along the pathway of blood flow in the body. The VasoMapTM identifies these CIP’s in the Veins, Capillaries, and Arteries thereby creating a Compliance Map of the Peripheral Vascular Loop (PVL). The initial key physiologic parameters derived by the VasoMapTM are Central Venous Pressure (NICVP) as well as continuous Arterial Blood Pressure (CNIBP) with a device that is as easy to use as a conventional blood pressure cuff.
Arterial vs. Venous Segmentation of the Peripheral Vascular Loop (PVL)
The Volume vs Pressure Loop in Figure A3 illustrates the serial organization of the PVL by vessel types as the blood flows from the left ventricle of the heart through the systemic circuit and back to the right atrium of the heart. It is important to understand that the VasoMapTM is not just measuring fluid mechanical properties of the blood (i.e. pressure and volume) but biomechanical properties of the vessel walls (i.e. compliance and elastance). Figure A1 illustrates the PVL path of blood flow from the left side of the heart back to the right side of the heart. It is this structure that is mapped by the VasoMapTM.
Noninvasive fluid volume status information is not currently available to physicians for determination of hydration status of the patient (of prime interest in pediatrics, obstetrics, nephrology, emergency care and critical care). Fluid volume status of a patient could be viewed on the basis of “whole body” or as a “body region.” The VasoMapTM evaluates the comprehensive distribution of fluids within a “body region” by segmenting and compartmentalizing the fluid volume contributions within the body region. The relationship of fluid volume distribution in a body region of a limb to the overall fluid volume distribution of the whole body remains to be demonstrated in clinical trials, however, the capability of comprehensively and quantitatively measuring the relative fluid volume distribution in a body region by compartment is a huge advancement over currently available clinical information. NIVasc has demonstrated the VasoMapTM monitor’s ability to observe known fluid volume shifts in a body region over time.
How the VasoMapTM Works
The patented VasoMapTM is NOT a conventional blood pressure monitor. The VasoMapTM introduces to healthcare a new comprehensive view of the cardiovascular system based upon a compliance map of the Peripheral Vascular Loop (PVL) shown below.
Figure A2 – Three patients with different Compliance Stacks
The PVL exists in a Pressure/Volume structure. The PVL spans vessels from the left side of the heart through the Capillary bed to the right side of the heart following the natural flow of blood. Like any path of travel, it is much easier to understand the route and ease of travel if we have mileposts or road signs along the way to guide us. In terms of the peripheral vascular bed the only mileposts or road signs presently available to guide physicians and researchers are Arterial Blood Pressure (ABP) and Central Venous Pressure (CVP). These pressure values reveal the state of the blood’s trip at the start (left ventricle of the heart) and again at the end of its trip (right atrium of the heart) around the PVL. It tells us little about the state of the vascular structure in the core microvasculature where the real work of the vascular system is being performed. The VasoMapTM identifies mileposts and road signs along the entire PVL on the basis of changes in vessel compliances along that pathway. We anticipate that these mileposts and road signs of the PVL will have dramatic influence on vascular research and cardiovascular clinical practice as they become known and understood regarding their role in cardiovascular (CV) function. ABP and CVP are important values in describing the organization and function of the CV system at the top and the bottom of the PVL but we will see that they fall well short of being reliable and effective clinical indicators of CV performance.
The VasoMapTM measures how blood flows around the PVL according to the Compliance and Resistance organization of the Peripheral Vascular Bed (the Davis Vascular Compliance Stack, Figure A2).
NIVasc IP Portfolio and Strategy
Coextensive Volume and Pressure