Digital Filter Design II: Applications - Digital Signal Processing Laboratory - page 96

NORMAL, HYPERKALEMIA AND HYPOKALEMIA EKG PATTERNS

1.2

1

0.8

Normal
Hyperkalemia
Hypokalemia

0.6

0.4

0.2

0

-0.2

-0.4

0 0.08 0.16 0.24 0.32 0.4 0.48 0.56 0.64 0.72 0.8 0.88 0.96

Time (sec.)

FIGURE 6.8
EKG patterns for normal, hypokalemia, and hyperkalemia cases.

Hypokalemia : The normal potassium level in the human body is in the
range of 4 to 5.5 meq./liter. However, when the potassium level is
lower than normal, the condition is called hypokalemia, and the
EKG recording of a patient with this condition is also shown in
Figure 6.8.
Hyperkalemia : When the potassium level is higher than normal, the
condition is called hyperkalemia, and the EKG recording of a patient
with this condition is shown in Figure 6.8.

a. Sample each of the signals, shown in Figure 6.8, over a time period

of 1 sec. The numerical values of the EKG patterns, shown in Figure

6.8, are given in Table 6.2 . Use a value of N (number of sampling

points) as 16 or higher to obtain good resolution. Use zero-padding
if necessary, in order to use a radix-2 FFT.

b. Determine the FFT spectrum of each of the sampled signals, using

the procedure detailed in Section 3.1.3. Plot the FFT magnitude and
phase spectra of each of the signals.

c. Compare the magnitude spectrum of the FFTs obtained in the pre-

vious step and comment on the differences in the spectrum that will
enable the user to distinguish between normal, hypokalemia, and
hyperkalemia conditions.