Parks 915-BL Instruction and safety manual

1
915-BL Dual Frequency Doppler
PARKS
915-BL Dual-Frequency Doppler
Operating/Service Manual
Read this manual prior to use.
Follow manufacturer’s guidelines for safety and maintenance of equipment.
This instrument was manufactured to comply with all relevant national or international regulations and
left the factory in safe condition. In order to keep this instrument in a perfect and safe condition, it is up
to the user to observe all instructions and warnings included in this manual.
The 915-BL Dual-Frequency Doppler is two Dopplers in one case. The low-frequency nominal 2 MHz
precordial probe may be used to detect the passage of air emboli in the heart. The high-frequency nominal
8-9 MHz 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 flow 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.
915-BL, UNM 5.5 6/2012

2Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.

3
915-BL Dual Frequency Doppler
Table Of Contents
Introduction
Installation and Setup............................................ 4
Safety .................................................................... 4
Instrument Identification Information ..................... 4
Equipment Description
Probes .................................................................. 6
Battery Charger..................................................... 7
Cautery Suppressor .............................................. 7
Optional Headphones............................................ 7
Operating Instructions
Setting Up the Instrument...................................... 8
Using the Coupling Gel ......................................... 8
Using the Probe..................................................... 8
Using the Cautery Suppressor .............................. 9
Shutting Down the Instrument............................... 9
Charging the Battery ............................................. 9
Diagnostic Procedures
Performing Diagnostic Procedures...................... 10
Detecting the Passage of Air Emboli in the Heart..... 10
Positioning the Precordial Probe......................... 10
Taking Blood Pressure (BP) Measurements ....... 10
Measuring Systolic Pressure................................11
Lower Extremity Arterial Evaluation......................11
Preoperative and Postoperative Blood Pressure
(BP) Measurements ............................................ 13
Upper Extremity Arterial Evaluation..................... 13
Venous Evaluation............................................... 13
References.......................................................... 14
Maintenance and Service
Cleaning the Instrument ...................................... 15
Cleaning the Probes............................................ 15
Tuning ................................................................. 15
Routine Maintenance .......................................... 15
Replacing the Battery.......................................... 16
Replacing the Fuse ............................................. 16
Technical Support and Service............................ 16
Troubleshooting Guide ........................................ 17
Technical Information and Notes
Specifications .................................................... 20
Warranty.............................................................. 21
Physiological Effects of Ultrasound..................... 21
Environmental Hazards....................................... 21
Electrical Safety................................................... 22
Ordering Information and Replacement Parts..... 23
Contact Information............................................. 23
Appendix
Acoustic Output Power ....................................... 25
Practical Office Technics for
Physiologic Vascular Testing ............................... 32

4Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Introduction
Installation and Setup
Unpack the instrument and accessory equipment from the packing box.
The 915-BL kit includes:
915-BL Dual-Frequency Doppler
2.1-2.25 MHz (Specified) Precordial Probe
8.0-9.9 MHz (Specified) Pencil Probe or Adult Flat Probe
24VDC
0.63 A Battery Charger
Ultrasound Transmission Gel, 0.25 L
Operating/Service Manual
Place this instrument on a clean, nonconductive, level surface.
The instrument should not be placed near devices which may cause radio interference or grounding.
The Doppler unit is shipped fully charged and ready to use.
Read the Operating Manual prior to using instrument.
Safety
This instrument is intended for use by health care professionals only.
The following symbols are used throughout this manual:
CAUTION: Indicates a potentially hazardous situation that, if not avoided, could result in personal
injury or damage to the instrument.
DANGEROUS VOLTAGE: Indicates a potential electrical hazard that, if not avoided, could result in
personal injury or damage to the instrument.
TYPE B APPLIED PART
MEDICAL EQUIPMENT
Type B Applied Part:complies with degree of protection against electric shock required by IEC 60601-1.
Class IIa Equipment:
This noninvasive ultrasound Doppler meets the safety requirements specified for a Class IIa active
medical device.
Acoustic Output Power is within limits set by the FDA and the European Union.
This device is intended for vascular studies. It is not intended for obstetrical use.
Parks Medical Electronics, Inc. manufactures a complete line of obstetrical Dopplers.
Instrument Identification Information
Write the information from your instrument bar code label here or on the parts page for reference when
reordering parts or requesting technical support:
Serial Number Part Number
Model Date of Manufacture
Date instrument purchased Customer Number

5
915-BL Dual Frequency Doppler
Equipment Description
Battery Charger Jack7.
The battery charger plugs into this jack.
8. Headphone Jack
Optional headphones plug into this jack.
9. Cautery Suppressor Control Knob
This knob controls the amount of cautery
noise that is cut out.
The full counterclockwise position turns the
cautery suppressor off (SUP OFF).
Turning the knob clockwise cuts out more
noise.
10. Cautery Suppressor Indicator Lamp
This indicator lamp is lit only when the
cautery suppressor is on (SUP ON).
11. Volume Control Knob
This knob controls the Doppler sound level.
Turning the knob clockwise increases the
volume.
DUAL-FREQUENCY DOPPLER
MODEL 915-BL
ALOHA, OREGON U.S.A.
PARKS MEDICAL ELECTRONICS, INC.
24 V
0.63 A
FLASHING LIGHT
INDICATES LOW
BATTERY
ON OFF ON
PROBES
CHARGER HEADPHONES
VOLUME
KEEP ON CHARGE WHEN NOT IN USE
TYPE B
APPLIED PART
MEDICAL EQUIPMENT
SUP. ON
CAUTERY SUPPRESSOR
SUP. OFF
LOW HIGH
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Front Panel
1
24 V
0.63 A
1. Manufacturer’s Label
Lists serial number (SN), part number,
model, and date of manufacture.
Battery2. Indicator Lamp
This lamp lights when the unit is turned on.
Blinking lamp warns battery needs charging.
3. Power Control Knob
The center position turns instrument off.
Turn switch to the left for 2 MHz probes.
Turn switch to the right for 8 MHz probes.
4. 2.1-2.25 MHz (Specified) Probe Jacks
The low-frequency precordial probe
plugs into these jacks.
5. 8.0-9.9 (Specified) MHz Probe Jacks
The high-frequency pencil probes and flat
probes plug into these jacks.
6. Battery Charger Indicator Lamp
This lamp lights when the unit is charging.

6Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Equipment Description
Probes
Each probe consists of two crystals; one transmits ultrasound waves and one receives the reflected
waves. The initial energy beam is as wide as the crystal. The probe’s two connectors can be plugged into
either of the two jacks on the Doppler that match the probe frequency. The Doppler is tuned to the probe
frequency. The frequency is identified on the panel next to the jacks and on the label attached to each
probe cable.
Damage to either crystal will impair or prevent probe function. The material covering the crystals can be
damaged by abrasion, soaking in alcohol or cleansers, and excessive heat.
The 915-BL comes with a 2.1-2.25 MHz (frequency specified) precordial probe and either a 8.0-9.9
MHz (frequency specified) standard pencil probe or flat probe. The precordial probe is used to detect air
emboli in the heart. The pencil probe is used to detect blood flow and monitor systolic blood pressure in
the legs. The flat probe is designed to be taped on the wrist for repeated blood pressure measurements.
Infant Adult
Skinny Pencil Probe
(optional at additional cost)
Frequency: 8.0-9.9 MHz (Specified)
Diameter: 1/4 in
Cable length*: 5 ft standard
The smaller probe crystal concentrates power to produce a beam with higher
intensity than the standard probe, providing better resolution for small vessels.
Flat Probes
(an option with kit)
Frequency: 8.0-9.9 MHz (Specified)
Size: Adult 5/8 in X 3/4 in; Infant 1/2 in X 5/8 in
Cable length*: 5 ft standard
Crystals are set into the plastic so that the ultrasound beam goes into the vessel at about 15 degrees
from perpendicular. Flat probes are easily taped into place for taking repeated measurements.
*7 and 10 ft cable lengths are available by special order. Doppler must be tuned to probes with longer cables.
Standard Pencil Probe
(an option with kit)
Frequency: high: 8.0-9.9 MHz (Specified)
Diameter: high: 3/8 in
Cable length*: 5 ft standard
Standard diagnostic probe.
Precordial Probe
(included with kit)
Frequency: 2.1-2.25 MHz (Specified)
Diameter: 3/4 in
Cable length*: 5 ft standard (Double Shielded)
May be used for detecting air emboli in
the heart.
Probes with double-shielded
cables can be ordered for use
in locations with high levels of
electrical interference.

7
915-BL Dual Frequency Doppler
Equipment Description
Battery Charger
The Doppler comes with a 24VDC 0.63 A battery charger; the charger plugs into the front of the
Doppler and must be connected to an AC power supply (appropriate wall plug adapter must be used for
outlets other than 120 V). The Doppler battery cannot be overcharged. The Doppler cannot be operated
while it is connected to the battery charger.
Battery Life
Battery life between charges for a new battery will be more than 16 hours on a full charge. The battery
life will decrease as the battery ages or if it is not kept fully charged.
With normal service and care, a battery can be expected to last two to three years. Leaving the battery
discharged for days will shorten the life of the battery.
Cautery Suppressor
Under normal operating conditions, the cautery suppressor is off.
Use of the Doppler in the presence of a cautery can cause interference. A cautery generates sound over
a wide band of frequencies that cannot be filtered by the Doppler. The frequencies close to the probe
frequency will be picked up by the probe wires and transmitted to the Doppler speaker. Experimenting
with placement of the probe cable and the Doppler can minimize cautery interference, but not eliminate
it. The cautery suppressor is designed to shut off sound to the Doppler speaker or headphones when the
volume of the cautery interference exceeds that of the blood flow or air emboli detected by the probe.
The control knob for the cautery suppressor is on the front panel of the Doppler. The cautery suppressor
is off when the cautery suppressor control knob is turned all the way counterclockwise. Turning the knob
clockwise increases the level of suppression.
Headphones
The speaker is disconnected when the optional low impedance stereo headphones are plugged in. You will
always hear more through the headphones, especially when checking weak flow or veins.

8Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Operating Instructions
Setting Up the Instrument
Place the instrument near the patient to be tested.1.
▪The instrument should not be placed near devices which may cause radio interference.
The instrument should not come into contact with metal surfaces or other electronic devices.▪
Plug the desired probe into the correct MHz jacks; the probe cable connectors can plug into either2.
jack of the same frequency. The probe frequency is identified on the panel and on the probe label.
Remove the3. red protective cover from the probe tip prior to use.
Using the Coupling Gel
The probes require a conductive medium to maintain an interface between the skin and the probe for
signal transmission. Use only a coupling gel made for ultrasonic applications.
Using the Probe
Parks’ pencil probes are positioned differently than other Doppler probes because they are designed to
detect blood flow in vessels that are too deep to feel. The main energy of the beam is only as wide as the
crystals in the probe, so you must always search the area of the vessel and tilt the probe to obtain best
Doppler sounds. Parks recommends that you practice searching for arteries at the ankle
1. Inspect the probe for cleanliness and damage prior to each use (See Electrical Safety).
Invert the2. gel squeeze bottle and shake it downward to get the gel near the bottle opening.
Squeeze about ¼ inch of gel onto the tip of the probe or skin surface, making sure there are no3. air
bubbles.
Turn the volume control all the way down (counterclockwise).4.
Turn the instrument on, setting the control knob to the frequency of the probe.5.
For normal operation, turn the cautery suppressor off.6.
7. Gradually turn up the volume (clockwise).
A rumbling sound can be caused by the vibration of the gel from operator movement.
Positioning the Pencil Probe*
Place the pencil probe over the approximate position of the target vessel.1.
Align the probe’s crystals parallel to the vessel for best artery-vein▪
separation.
Tilt the back of the pencil probe to an angle about 15 degrees from2.
perpendicular, making certain there is gel in the pathway between the
probe and the skin.
Move the probe and the skin to try to find the center3.
of the vessel.
Search for the most “pulsating” sound by adjusting▪
the angle and direction of the probe on the skin.
The Doppler sound for an artery is a hissing noise▪
at systole.
Background sounds are more or less continuous.▪
If you do not hear any sounds, move probe to a▪
different location.
Note that too much pressure on the skin can▪
occlude a vein, less likely an artery.
Probe crystals
Blood vessel gel
*See Diagnostic Procedures section for placement of precordial probe and flat probe.
Probe
Gel
Skin Line Listen for best signal
Flow Direction Blood Vessel

9
915-BL Dual Frequency Doppler
Operating Instructions
Turn the volume up to near maximum to search for deep arteries, small or obstructed arteries, and4.
veins.
The▪Doppler sounds associated with low-velocity blood flow have a very low pitch.
The higher volume setting will also increase the transient background noise.▪
Avoid unnecessary movement of the probe on the skin to minimize transient background noise.5.
Using the Cautery Suppressor
To Minimize Cautery Interference:
1. Keep probe wires as far away from the cautery wires as possible.
2. Make sure that the patient is well grounded with the cautery machine’s grounding plate.
3. Do not hang the Doppler by its handle on an IV pole; hang it with nonconductive material.
Setting the Cautery Suppressor Level
Position the probe to obtain the best flow sound from the patient.1.
After the patient is anesthetized and before the cautery is used, gradually turn up the cautery2.
suppressor level until the patient’s blood flow sounds start cutting out on peak sounds.
Turn the control down (counterclockwise) until the sounds are again normal.3.
If the patient’s flow varies, you may need to make this adjustment again.4.
Shutting Down the Instrument
Turn the instrument off.1.
Wipe the gel off of the probe with a soft tissue.2.
Disconnect the probe from the Doppler only if necessary for cleaning; probe jacks wear out with▪
repeated connecting/disconnecting of the probes.
Connect the instrument to the3. battery charger.
Charging the Battery
The 915-BL comes with a 24VDC 0.63 A battery charger. The instrument should be connected to the
battery charger after the last usage of each day.
Plug the connector of the battery charger into the battery charger jack on the front of the instrument.1.
Plug the charger into an AC outlet (use appropriate plug adapter for outlets other than 120 V).2.
The charger indicator lamp will light up to show that the Doppler battery is being charged.
The 915-BL has two battery-charging safety features:
The Doppler cannot be operated while the battery is being charged. The battery is disconnected1.
from the unit while it is being charged; only the charging circuit is active.
The battery cannot be overcharged.2.
A blinking battery indicator lamp warns that the battery needs to be charged. The unit will continue to
operate for a few hours if necessary after the light begins to flash, but should be recharged as soon as
possible. Allow 12 hours to completely recharge the battery. Letting the battery completely discharge
shortens the life of the battery.
Charging Doppler in the Optional Carrying Case
If your Doppler came in a carrying case, Parks recommends that you keep the unit on charge with the
carrying case lid off. The carrying case has slip hinges that allow for easy removal of the lid.
If you do not remove the lid during charging, be sure the charger cord is in the small rubber grommeted
half-moon cutout before closing the lid of the carrying case. This will prevent damage to the charger cord
which might lead to electrical shock.

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 flow 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 reflected. 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 fifth 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 first few inches of the probe cable in the intercostal space and
taping it in place improves alignment.
Verify probe placement by listening for venous flow or passage of air embolus.3.
Affix 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 flow and valve leaflet 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,
fingers, 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 flat 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.

11
915-BL Dual Frequency Doppler
Diagnostic Procedures
Measuring Systolic Pressure
Because the sound quality is not as critical, it is possible to align the pencil probe’s crystals perpendicular
to the vessels to take blood pressures. Follow the operating instructions for positioning the pencil probe
to optimize Doppler sounds.
Accurate systolic measurements require a BP cuff width suitable to the limb
being tested. The cuff is inflated 20-30 mm Hg above estimated systolic
pressure and then released, just as with BP measurements using a stetho-
scope. The systolic pressure is the sphygmomanometer reading when the
Doppler detects the first flow sound as the cuff is deflated.
Patients with calcified vessels resulting from diabetic or renal disease processes can have falsely
elevated blood pressures.
Lower Extremity Arterial Evaluation
Peripheral arterial Doppler studies can give an indication of the severity and location of arterial disease and
monitor its course. Generalized Doppler studies may not differentiate between a stenosis and an occlusion.
Ankle/Brachial Index (ABI)
When a full lower extremity study is not needed, bilateral brachial and ankle blood pressures (BP) can
be taken. The values are used to calculate the ankle/brachial index (ABI), also known as the ankle/arm
pressure index (API). The interpretation of the indices varies, but the normal ratio is ≈1.
To Obtain Ankle/Brachial Indices:
Obtain bilateral arm blood pressures of brachial or radial artery with the Doppler, using the standard1.
pencil probe.
Place a BP cuff on the right ankle; using a Doppler, listen for a signal on the2. posterior tibial and
dorsalis pedis arteries (see drawing).
Inflate the BP cuff 20-30 mm Hg beyond the last detectable Doppler signal (target 20-30 mm Hg3.
above higher brachial pressure), and then gradually decrease the pressure in the cuff until you hear
a Doppler signal. This is the ankle pressure. Use result from artery which gives the higher reading.
Repeat this procedure for the left ankle.4.
If pressure measurements must be repeated, allow a rest time of about a minute between inflations5.
of the BP cuff.
Divide the ankle pressures by the highest brachial pressure; this is the ankle/brachial index.6.
Example: R L7.
Brachial systolic pressure 125 140 Higher brachial pressure
Ankle systolic pressure 90 85 is used for calculations.
Ankle/brachial indices (ABI) 0.64 0.61
If the ABI is unquestionably normal bilaterally, there is no need to perform segmental studies.
Probe crystals
Blood vessel gel

12 Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Diagnostic Procedures
Lower Extremity Segmental Systolic Pressures
Doppler segmental pressures can locate the general area of an occlusion or stenosis, and indicate the
severity of the disease. Radically different pressures between sites can isolate the region of an obstruc-
tion. Significantly different pressures at the same site on opposite legs can signal an obstruction proximal
to the site in the leg with the lower pressure.
Segmental pressures require the use of blood pressure cuffs sized for the area of the limb to be tested.
This test should be performed on a supine patient after at least 20 minutes rest. Bilateral systolic
pressures are obtained at these sites:
Arm, using highest1. brachial (or radial) artery reading, if ankle/brachial indices are indicated.
Ankle, using the2. doralis pedis or posterior tibial artery, whichever gives the higher reading.
Below knee (BK) or calf, using the doralis pedis or3. posterior tibial artery, whichever gives the higher
reading.
Above knee (AK), using popliteal artery if readings are difficult to obtain with dorsalis pedis or4.
posterior tibial artery.
High thigh (HT), using5. popliteal artery if readings are difficult to obtain with dorsalis pedis or
posterior tibial artery.
Lower Extremity Segmental Pressures After Exercise
Doppler segmental pressures are measured after standardized exercise reproduces a patient’s ischemic
symptoms. The post-exercise (stress) drop in pressures can be diagnostic. Immediately after exercise,
the systolic pressure is taken in both ankles and then in the arm that had the greatest brachial systolic
pressure. If one leg is more symptomatic, the pressure should first be measured in that ankle before
measuring the contralateral ankle. The length of time required to recover resting pressures is also noted.
Lower Extremity Segmental Pressures After Reactive Hyperemia
If exercise is not an option for the patient, reactive hyperemia can be induced. Thigh cuffs are inflated
20-30 mm Hg above the highest brachial pressure for 3-5 minutes and then released. Systolic pressures
are measured as with the exercise regimen. This procedure may be contraindicated because of the level
of discomfort associated with it.
Popliteal Artery

13
915-BL Dual Frequency Doppler
Diagnostic Procedures
Preoperative and Postoperative Blood Pressure (BP) Measurements
The Doppler is used to monitor blood pressures before and after lower extremity vascular surgery.
Measure and record1. systolic pressure at both ankles immediately prior to surgery.
When the2. blood flow is restored in the treated leg, measure both blood pressures again.
The pressure of the treated▪leg should be higher than that of the non-treated leg.
Reactive hyperemia following surgery may result in equal or lower pressure of the affected leg on▪
rare occasions, but the leg will be warm to the touch.
Blood pressure measurements provide an objective evaluation of the surgery. Some surgeons▪
use the pencil probe (or optional microtip probe) directly on the artery (with sterile jelly for
coupling) just distal to the repair. Critical evaluation of the flow sound detects problems which can
be corrected during surgery.
Follow up after surgery by measuring pressures and obtaining3. ankle/brachial indices.
Upper Extremity Arterial Evaluation
The optional flat probe can be used to make repeated systolic pressure measurements in the radial artery.
Positioning the Flat Probe
1. Position the flat probe over the radial artery with the cord lying across the hand; this will orient the
crystals to point cephalad (antegrade).
Use a Velcro strap or tape to hold the probe in place, and anchor the cord at least one place distal2.
to the probe.
Upper Extremity Segmental Systolic Pressures
Doppler segmental pressures are taken with an appropriately-sized cuff aligned so the bladder is directly
over the artery being measured. Bilateral systolic pressures are obtained at these sites:
Upper arm, using the1. brachial artery.
Forearm, using the radial or2. ulnar arteries.
The differences in pressure readings between extremities and between the sites on each arm can be
diagnostic for a stenosis or an occlusion.
Venous Evaluation
Venous Doppler testing is the most subjective test done in the vascular laboratory. To provide consistent,
reproducible results, the technologist must be thoroughly familiar with venous anatomy (including
deviations from normal) and the subtleties of venous Doppler signals.
Veins are located by first finding the artery, and then moving the probe slightly to either side of the arterial
signal until the characteristic windstorm-like sound of venous flow is heard.
Doppler studies can be used to assess patients for the presence of occlusions, deep vein thrombosis
(DVT), and valvular incompetence associated with varicose veins. Doppler studies can detect
spontaneous venous flow, which is phasic with respiration, and augmentation with distal compression.
See standard textbooks for more information.

14 Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Diagnostic Procedures
References
The following is a partial listing of standard textbooks which provide more detailed information about the
use of Doppler technology to diagnose vascular disease:
Ali F. Aburahma, John J. Bergan, Editors. Noninvasive Vascular Diagnosis: A Practical Guide to Therapy.
Springer; 2006
C. Rumwell, M. McPharlin. Vascular Technology: An Illustrated Review. Davies Publishing; 2003
Noninvasive Diagnosis of Vascular Disease. Davies, Inc; 1999

15
915-BL Dual Frequency Doppler
Maintenance and Service
Cleaning the Instrument
Clean the outside of the instrument as needed. First turn off the power and unplug the battery charger.
Remove dust with a soft cloth or small paint brush. Wash with a soft cloth dampened in a mild solution
of detergent and water. Never use abrasive cleaners. To disinfect surface, use a soft cloth dampened
with liquid disinfectant or use a surface germicidal cloth. After cleaning/germicidal agent dries, remove
any residue with a soft cloth dampened with water. Never let the inside of the instrument get wet.
Cleaning the Probes
1. Remove the gel with a soft tissue after each probe use.
2. Wash any dried gel off the probe with running water. DO NOT scrape off dried gel to avoid
damaging the coating over the crystals.
3. User may opt to wipe probe with alcohol, surface germicidal cloth, or liquid disinfectant; rinse probe
with warm water to remove any residue after cleaning/germicidal agent dries. Do not use bleach.
Do Not Autoclave the Probes
Temperatures above 57.2 degrees Celsius (135 degrees Fahrenheit) destroy the crystal activity and
cause the covering over the individual cables and the outer sheath to shrink and crack. With a raised
temperature, a severe loss of sensitivity will occur. Autoclaving will void the probe warranty.
Tuning
The Doppler unit is tuned by the manufacturer to match the frequency of the probe, and the tuning of
the circuit is very stable. If sensitivity problems are suspected, do not attempt to adjust the instrument;
contact your sales representative or Parks Medical Electronics, Inc.
Routine Maintenance
The Doppler unit does not require regularly scheduled maintenance. The battery may need to be
replaced every two or three years. The probe jacks can wear out with extended use.
To Check the Battery:
1. Determine how long, at most, the Doppler is kept on continuously.
2. Recharge the battery for at least 8 hours.
3. Connect a dry probe to the unit, turn the unit on, and turn the volume 2/3 of the way up.
4. After one hour or twice the longest period of continuous use, whichever is greater, check the
battery indicator lamp. If the lamp is blinking, replace the battery.
To Check the Probe Jacks:
1. Bend back the four sections of the ground flange of the plug of a defunct probe .
2. Insert the center pin of the plug into each probe jack.
3. If there is no friction or resistance, replace the probe jack.
4. If you do not have a defunct probe, contact technical support.

16 Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Maintenance and Service
Replacing the Fuse
If the Doppler will not turn on (see Trouble Shooting Guide 1.1), and replacing the battery does not solve
the problem, the fuse may need to be replaced.
To Replace the Fuse:
Be sure the instrument is turned off.1.
Open the case by removing the four corner screws.2.
Carefully remove the circuit board assembly.3.
Refer to F1 on the4. Parts Location Diagram to find
the location of the fuse, or see accompanying
photo.
Replace with a 1 A FAST fuse, Parks part #865-5.
6001-00.
Carefully replace the circuit board assembly in the6.
case.
Replace the four corner screws.7.
Technical Support and Service
If following the troubleshooting guide does not correct the problems you are experiencing with the
Doppler, call technical support at Parks Medical Electronics, Inc.
Should this Doppler require technical service, Parks recommends that the instrument be returned to the
factory. Parks will ensure that electrical components meet the company’s standard of performance.
Follow the instructions in the accompanying illustration to7.
position and secure the new battery.
Gently reconnect the red wire first and then the black8. wire.
Caution: Failure to match wire and terminal colors will
do permanent damage to the instrument.
Carefully replace the circuit board assembly in the case.9.
Replace the four corner screws.10.
Replacing the Battery
This device uses a 12V, 1.2 Ah sealed lead acid rechargeable battery for its power source. Replace with
Parks Part # 854-0017-01.
Caution: Replace only with the same size sealed lead-acid rechargeable battery. The use of a larger
battery could cause the terminals to come in contact with the circuit board or metal case. Never allow
battery terminals to come into contact with any metal part of the instrument. This could result in fire or
internal damage to the instrument.
To Replace the Battery:
1. Be sure the instrument is turned off
and the charger is disconnected.
Open the case by removing the four2.
corner screws.
Carefully remove circuit board3.
assembly from the case.
Locate the battery and note how the4.
battery wires are connected.
5. For safety reasons, disconnect the
black battery wire first and then the
red wire. Wiggle and gently pull the
connectors, being careful not to break
the insulation or short to ground.
The battery is mounted to the panel6.
with adhesive. Gently pry or cut the
battery loose.
1. Position battery with
positive terminal next
to front panel, so both
wire leads reach
battery terminals.
2. Center and attach
battery 1/8” from
edge of circuit
board with two
strips of two
layered double
sided tape.
3. Use single
strip of tape
for padding.
Attach tape to
battery, but do
not remove top
plaid covering.
1/8”

17
915-BL Dual Frequency Doppler
Maintenance and Service
Troubleshooting Guide
This table lists common problems and suggestions for troubleshooting them. If a problem persists after
these actions have been taken, contact Parks Medical Electronics, Inc.
Problem Situation Suggested Actions
1.0 Doppler unit
doesn’t turn on
1.1 The power control
knob is on but the battery
indicator lamp does not light
up
Disconnect the• battery charger
Replace• fuse (See Maintenance)
Replace• battery if > 3 years old
(See Maintenance)
1.2 The power control
knob is on and the battery
indicator lamp lights up
Listen with headphones
If there is sound with the headphones but not the
speakers, go to 3.2.1
2.0 Battery is not
charging
2.1 Battery CHARGER
lamp does not light up when
Doppler is turned off and
charger is connected
Replace the battery charger
See Specifications and Replacement Parts
2.2 Battery CHARGER lamp
lights up when connected to
charger with Doppler off.
Battery INDICATOR lamp
blinks with Doppler on
and charger disconnected
after charging for at least 8
hours.
See Routine Maintenance
Replace the battery
See Specifications and Replacement Parts
3.0 Hard to hear
blood sounds (poor
signal : noise ratio)
3.1 Too much noise 3.1.1 Prevent feedback (screeching sound):
Keep the• probe against the skin once gel is
applied.
Keep the• probe out of line with the sound
waves from the speaker.
Keep probe• cable from looping around and
touching itself.
3.1.2 Check for a noisy circuit:
Disconnect the probe and turn the Doppler unit1.
on.
Turn the volume all the way up.2.
You should hear smooth white noise or hissing3.
like the noise of wind or surf.
It may be loud, but it must be smooth.
If you hear crackling or sputtering, the circuit is4.
noisy. Call technical support.
3.1.3 Check for a microphonic circuit:
Tap or drum on panel and case with your1.
fingers. You should hear a dull thud.
If you hear a ringing noise, the circuit may be2.
microphonic. This makes it prone to scream
whenever there is gel on the probe. Call
technical support.

18 Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Maintenance and Service
Troubleshooting Guide
This table lists common problems and suggestions for troubleshooting them. If a problem persists after
these actions have been taken, contact Parks Medical Electronics, Inc.
Problem Situation Suggested Actions
(continued)
3.0 Hard to hear
blood sounds (poor
signal: noise ratio)
(continued)
3.1 Too much noise 3.1.4 Check for noisy probe:
Clean and dry the crystal end of the probe.1.
Connect the dry probe to the Doppler unit, turn2.
the Doppler unit on, and turn the volume up.
Wiggle the probe plugs.3.
If you hear a crackling sound, the connection
is noisy.
Clean and tighten the probe plugs:4.
Wipe the pin in the center of the plug and•
the flange around it with contact cleaner or
isopropyl alcohol.
Squeeze the flange with your fingers (or•
gently with pliers). Make the flange form
a smaller circle so that it grips the jacks on
the Doppler panel more tightly.
Check for noise again.5.
If there is still noise, bend the cable here:6.
Send the cable back to the factory for new
plugs if the noise originates here.
Flex the cable near the crystals. If the cable7.
is noisy near the transducer, it cannot be
repaired. Replace probe.
Press gently on each8. crystal with your fingernail.
If a crackling or popping sound occurs, the
probe cannot be repaired. Replace probe.
3.1.5 Check for electromagnetic interference:
Noise that is probably caused by an
electromagnetic field:
a tone or whistle that does not change pitch•
a buzz or a hum•
a noise like a radio station•
a ticking sound that seems periodic•
Confirmation criteria:
The noise worsens when the probe is held or•
applied to the patient.
The noise disappears when the Doppler unit is•
used at another site
Possibly if the noise lessens when the probe is•
disconnected

19
915-BL Dual Frequency Doppler
Maintenance and Service
Troubleshooting Guide
This table lists common problems and suggestions for troubleshooting them. If a problem persists after
these actions have been taken, contact Parks Medical Electronics, Inc.
Problem Situation Suggested Actions
(continued)
3.0 Hard to hear
blood sounds (poor
signal: noise ratio)
(continued)
3.1 Too much noise
(continued)
3.1.5 Check for electromagnetic interference
Identify and eliminate the source:
If the noise is a buzz or hum, the ballast1.
in fluorescent lights, motors, and battery
chargers are suspect.
Try turning off lights and unplugging nearby2.
devices. Circuitry in cell phones and laptop
computers can cause interference even
when turned off.
3.2 Weak signal 3.2.1 No sound or very little sound:
If battery indicator lamp is blinking, see 2.2•
Check headphone/speaker connection:•
Listen for sound with headphones. Then1.
unplug the headphones and listen for sound
from the speaker. If there is sound in the
headphones, but not in the speaker with the
headphones unplugged, the inside of the
headphone jack is probably bent.
Unplug the headphones.2.
Remove the four screws on the outside3.
corners of the front panel and gently remove
the Doppler unit from the case.
Turn the volume control all the way up and4.
squeeze the contacts on the inside of the
headphone jack.
If you hear bursts of sound from the speaker,5.
bend the contacts to restore the connection.
3.2.2 The speaker is loud, but flow sounds are weak:
Check the frequency shown above the jack and•
the probe frequency to be certain they are the
same. If not, obtain probe of matching frequency.
If you have another Parks Doppler unit of the•
same frequency and a probe that works with it,
try the suspect probe on the good Doppler unit
and the good probe on the suspect Doppler unit.
If the• probe is suspect, replace the probe.
If the Doppler unit is suspect, call technical•
support.
Probes fail more often than Doppler units. If you•
do not have extra equipment to check against,
order a new probe.
If replacing the probe does not solve the•
problem, contact technical support.

20 Parks Medical Electronics, Inc. Aloha, Oregon U.S.A.
Technical Information and Notes
Specifications
Bar Code Label Bar code contains information about your Doppler
When requesting service or parts, please have this information available.
Battery 12 V, 1.2 Ah sealed lead acid rechargeable battery.
Fully charged at 14.5 V, needs charging at ≈11.3 V, fails at ≈10 V.
Battery Charger Domestic Units: Output: 24VDC 0.63A.
or
International Units: Output: 24VDC 0.625A,
with international socket adaptors for ac outlets.
Carrying Case with Lid Aluminum case with handle, removable lid, and space for accessories.
(Optional)
Cautery Suppressor Controllable threshold cuts out excessive cautery noise.
Fuse 1 A FAST fuse.
Gel 0.25 Liter Ultrasound Transmission Gel.
Headphones Optional low impedance stereo headphones override internal speaker.
Internal Speaker Speaker disconnects when headphones are plugged in.
Parks 915-BL UN Manual Operating manual with maintenance and service section.
Probes
Precordial Probe: Low-frequency specified 2.1-2.25 MHz; double-shielded cable; 3/4 in
diameter circular crystal; 5 ft standard cable length.
Standard Pencil Probe: High-frequency specified 8.0-9.9 MHz; 3/8 in diameter; 5 ft standard
OR cable length.
Adult Flat Probe: High-frequency specified 8.0-9.9 MHz; crystals transmit 3/8 in
beam width at 15 degrees from perpendicular; 5 ft standard cable length.
Environmental Conditions for Transport and Storage
Ambient Temperature: -40° C to 70° C
Relative Humidity: 10% to 100%, including condensation
Atmospheric Pressure: 500 hPa to 1060 hPa
Operating Conditions
Ambient Temperature: 10° C to 40° C
Relative Humidity: 30% to 75%
Atmospheric Pressure: 700 hPa to 1060 hPa
IPXO Rating: Degree of protection against ingress of water... none provided.
Size And Weight
Length: 7.875 in
Width: 5.35 in
Depth: 3.15 in
Weight: 2.95 lb
Serial Number Part Number
Descri
p
tion Date of Manufacture