NONDIMENSIONAL PHYSIOLOGICAL INDICES FOR MEDICAL ASSESSMENT
Authors: GHISTA DHANJOO N. 
Published: January 2010

In medicine, for making a diagnosis, many tests are needed. It may so happen that some test results may be in the normal range, while some test results may be abnormal. So how is the doctor going to precisely decide how "sick" is the patient: is s/he at risk, or marginal, or very sick?

Hence, we have developed the new concept of a Nondimensional Physiological Index (NDPI). This NDPI is made up of a number of parameters characterizing organ function and dysfunction or a physiological system function and disorder or an anatomical structure's property and pathology, in the format of a medical assessment test; the NDPI combines these parameters into one nondimensional number. Thus, the NDPI enables the doctor to integrate all the parameters' values from the medical test into one nondimensional index value or number. Then, by examining a large number of patients, we can determine the statistical distribution of that particular NDPI into normal and abnormal categories. This makes it convenient for the doctor to make the medical assessment or diagnosis.

Now for an organ or physiological system assessment test (such as a Treadmill test or Glucose tolerance test) or for an anatomical structure's property and pathology determination (such as for determining mitral valve calcification and pathology), the method of formulating and evaluating the NDPI (from the medical test) entails developing its bioengineering model equation incorporating the parameters characterizing the organ state or physiological system function or the anatomical structural constitutive property. These parameters are adroitly combined into a NDPI, so that the NDPI unambiguously conveys the normal and abnormal state of the organ or physiological system or anatomical structure. This bioengineering model's governing equation or solution (involving the model parameters) is then applied to fit or simulate the monitored test data of the physiological system or the anatomical structure. The model parameters are then evaluated (from the simulated solution to the test data), and their ranges are determined for normal and abnormal states of the organ or physiological system or anatomical structure. Then, the NDPI (composed of the parameters of the organ function or physiological system function or the anatomical structural constitutive property) is also evaluated for normal and abnormal states of the patient's organ or physiological system or anatomical structure.

In this way, we can apply these NDPIs to reliably diagnose the patient's state of health, from preferably noninvasive medical assessment tests. In this paper, we have developed a number of noninvasive medical tests involving NDPIs, based on biomedical engineering formulations of organ function, physiological system functional performance and anatomical structural constitutive property, to provide the means for reliable medical assessment and diagnosis. These tests include (i) some conventional tests, such as Treadmill and Glucose tolerance tests, (ii) determination of cardiac contractility (and myocardial infarcted segments) and lung ventilation performance characteristics (and lung diseases) as well as (iii) some of our newly formulated tests, to detect arteriosclerosis, aortic pathology, mitral valve calcification, and osteoporosis.