Hadeco Smartdop 30EX - Operating Principles

Smartdop
®
30EX Basic Operation
11. OPERATING PRINCIPLES
The Smartdop
®
30EX bidirectional Doppler is designed to obtain blood ow velocities through
the use of ultrasound, which is transmitted from the probe to the patient’s body and reected by
the blood (hemocyte, etc.).
The unit amplies the high frequency oscillation output and then supplies it to the transmitter
transducer. It is then converted to ultrasound by the transducer and the ultrasound is
transmitted to external objects. The ultrasound moves straight through a biophysical object, and
is reected by a moving object (blood ow, etc.). The reected ultrasound is received by the
receiving transducer and is converted into an electric signal.
The converted signals are amplied and then detected. After removing unnecessary noise from
the signals and improving S/N ratio at the lter circuit, the Doppler shift signals are amplied and
converted to audible sounds through a speaker or headset.
Simultaneously the Doppler shift signals are applied to the CPU and converted to blood ow
velocity waveform signals which can be displayed and printed.
While in the Arm/Leg and Toe Pressure modes, a blood pressure cu󰀨 is placed on the patient at
the appropriate position and the probe is placed on the appropriate artery. Before ination, the
peak amplitudes of the blood ow signals should be stable. The ination pump is activated and
the cu󰀨 pressure increases causing the blood vessel to be constricted and the peak amplitudes
decrease. The CPU nds the point at which peak amplitudes are below the threshold and waits
until the cu󰀨 pressure has been inated approximately 20 mmHg above the point of sound
cessation. Then, the CPU deactivates the ination pump and the cu󰀨 pressure is decreased at
a moderate rate until the rst blood ow signal that exceeds the threshold is detected.
The cu󰀨 pressure present at the rst signal is the systolic pressure. After conrming a return
of the rhythmic blood ow signals, the CPU opens the air valve to dump the cu󰀨 pressure and
displays the systolic blood pressure on the LCD.
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