10
Parks Medical Electronics, Inc.
Aloha, Oregon U.S.A.
Diagnostic Procedures
Performing Diagnostic Procedures
Follow the attending physician’s and the institution’s protocols for diagnostic procedures.
This section of the manual is provided only as a guide, not to determine how a diagnosis is made.
The low-frequency precordial probe may be used to detect the passage of air emboli in the heart. The
high-frequency pencil probe is used for systolic pressures at sites where a stethoscope is not used, as
well as to detect blood pressures that are too low for a stethoscope to auscultate. This probe can also
be used to listen for blood
fl
ow and pulses distal to arterial repair. A built-in cautery suppressor with a
controllable threshold shuts off the sound when the interference gets too high.
Detecting the Passage of Air Emboli in the Heart
The cautery suppressor setting must be sensitive enough to detect air bubbles. It is recommended that
placement and settings be tested with an air bubble.
Positioning the Precordial Probe
The active side of the probe is the side that clearly shows the gray disc with
the stripe across the center. This side goes against the chest. You must
use ultrasonic gel over the crystal part of the probe in contact with the skin.
Placement of the probe is critical in order to provide a pathway for the beam
to be transmitted and then detected after it is re
fl
ected. Ultrasound does
not pass through bone, so the probe must be centered between the ribs.
Recommended placement is in the 4th-5th intercostal space or over the tricuspid valve.
Placement in the right intercostal space between the fourth and
fi
fth ribs:
Place the patient in a supine position.
1.
Place the probe so that the central division of the crystals is centered in the intercostal space,
2.
parallel to the ribs. Centering the
fi
rst few inches of the probe cable in the intercostal space and
taping it in place improves alignment.
Verify probe placement by listening for venous
fl
ow or passage of air embolus.
3.
Af
fi
x the probe in place with an adhesive or elastic bandage.
4.
Have the patient sit up.
5.
Retest the probe to verify probe placement.
6.
If satisfactory placement cannot be obtained using the intercostal space, place the probe over the
tricuspid valve.
Placement over the tricuspid valve:
Follow steps as above, listening for the best swishing blood
fl
ow and valve lea
fl
et movement over the
tricuspid valve to optimize placement. Do not turn the cautery suppressor control up so high that it
blocks bubble noise.
Watch for gel loss during an operation, since loss of the interface between the skin and the probe will
impair ultrasonic transmission.
Taking Blood Pressure (BP) Measurements
A Doppler can be used to make accurate systolic pressure measurements, with greater sensitivity than a
stethoscope. A stethoscope is only used to take arm blood pressure, but a Doppler can be used for both
upper and lower extremity blood pressures. The Doppler allows for the detection of low blood pressure in legs,
fi
ngers, and in animal legs and tails. Measurements as low as 10 mm Hg have been documented. Diastolic
pressure can only be estimated, not accurately measured, by Doppler use. To estimate diastolic pressure,
insert the
fl
at probe under the lower edge of the BP cuff and listen for either the loss of sound as diastolic
pressure passes or the return of the dicrotic notch, which is the beginning of the cardiac cycle.
Summary of Contents for 915-BL
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