HCloud, a Healthcare-Oriented Cloud System with Improved Efficiency in Biomedical Data Processing - Cloud Computing with e-Science Applications - page 182

8.3.2.1 Calculation of PPG Data
A PPG is an optically obtained plethysmogram, which represents a volu-
metric measurement of an organ. It is often obtained using a pulse oximeter
that illuminates the skin and measures changes in light absorption [21-23] . It is
used to monitor conditions related to breathing, hypovolemia, and other cir-
culatory situations. The HCloud system provides the heart function indices,
which evaluate the heart's blood pumping capability, and peripheral vascu-
lar function, which assesses for HBP and arteriosclerosis. Two assessments of
PPG are delivered to users: heart function and peripheral vascular function.
Meanwhile, the system provides a detailed PPG index on heart function for
the physician, including average pulse rate (PR), cardiac output (CO), stroke
volume (SV), blood oxygen saturation, and cardiac index (CI). To make users
and the physician understand the heart function parameters intuitively, this
system provides each index specification as well as the index of heart function
histogram, as shown in Figure 8.13a. It is known that the index of peripheral
vascular function can reflect the health status of the peripheral vascular system,
which can help a physician assess serious degrees of HBP and arteriosclerosis.
On the other hand, this health care cloud platform provides users the wave-
form characteristic (K), blood viscosity (V), peripheral resistance (TPR), sclero-
sis index (SI), degree of vascular conformity (AC), and pulse wave transit time
(PWTT). At the same time, it plots the peripheral vascular histogram and gives
specifications, as shown in Figure 8.13b. From those indices, a PPG diagnostic
report can be generated by the system for the end user.
8.3.2.2 Presentation of HBP Signals
High blood pressure or hypertension is a chronic medical condition in
which the blood pressure in the arteries is elevated, which causes the heart
to work harder than normal to circulate blood through the blood vessels.
Blood pressure involves two measurements: systolic and diastolic. These
measurements depend on whether the heart muscle is contracting (systole)
or relaxing in the interval between beats (diastole). Normal blood pressure
at rest is within the range of 100-140 mm Hg systolic (top reading) and
60-90 mm Hg diastolic (bottom reading) [24] . HBP is said to be present if the
blood pressure reading is persistently at or above 140/90 mm Hg, which can
cause problems with the metabolism of fat and sugar, as well as changes of
the heart, brain, kidneys, and retina. An HBP report is provided in HCloud
to provide detailed data on the systolic and diastolic blood pressure and
inform users whether they suffer from HBP. Over the long term, it can
reflect that the degree of control of HBP may be associated with the health
status of the user and prompt the user to change his or her lifestyle. Due to
the absence of obvious clinical symptoms in some patients with HBP, it is
known as the “invisible killer” [ 25 ]. Fortunately, HCloud can draw a curve of
HBP for a long-term trend of threatening status.