Model 842 Operating Manual Ver1.0

MODEL 842 POCKET DOPPLER

Before You Begin, Please Read This!

Information contained in this operating manual is provided to help the user operate the instrument controls. In no way must a diagnosis be made on the basis of information provided in the manual. We provide generalized examples of procedures which we believe to be in current usage. However, the procedure to be used and the diagnosis of an individual patient must be determined by the attending physician from information in scientific literature and from other medical sources.

MODEL 842 POCKET DOPPLER SPECIAL INSTRUCTIONS This instrument is similar to our Model 841/841-A Doppler but has the additional feature of providing an output signal for a graphic recorder. Flow-velocity curves can be recorded. CONNECTING TO THE ELECTROCARDIOGRAPH: The dc inputs of most single-channel and some multi-channel ECG machines are compatible with this Doppler and all others we make. The input characteristics of the recorder should be dc, high impedance (100K or more), and provide a stylus deflection of 1 cm. with 50 mv. of signal. This requirement is met by almost all single-channel electrocardiographs of American manufacture. The connector used to plug into the Doppler is a miniature type (1/8 inch diameter Switchcraft 780). MAKING A RECORDING: There is one factory preset control in the Doppler which is a threshold control. If it is set too low or if your battery is weak, the recording will have flat spots on the bottom as shown below. We advise you to keep the speaker volume low to conserve battery power and maintain the proper setting of the input-level (threshold) control. Recorded wave height is set by means of a screwdriver adjustment on the front panel. It need not be adjusted for each recording because the useful information is in the shape of the wave, and not its height. Find a setting which provides a suitable recording size for the majority of your work.

TOO LOW (too far clockwise)

CORRECT

BATTERY LIFE: The life of the battery is determined by the quality of battery you use and how loudly you drive the speaker. For maximum battery life never use a mercury battery, only use an alkaline battery and keep volume low. When the sound gets weak or distorted, the battery should be replaced. TURN OFF WHEN NOT IN USE! BATTERY REPLACEMENT: Refer to the battery sheet in the back of this manual for instructions on how to replace the battery. SERVICE: Most failures of the Doppler are related to the probe in some way. Should you suspect the probe, a replacement is available from the factory. It should be replaced with the same frequency that is engraved on the body of the original probe. Should you not have access to a biomed department to replace the probe, it is best to return the instrument to the factory if there is a sensitivity problem. But don’t do so without first calling us. We can handle many service problems over the phone and we are glad to do so. Parks Medical Electronics, Inc.

Model 842

Ver 1.1

MODEL 842 POCKET DOPPLER

THE COUPLING GEL ____________________________________________________________ YOU MUST USE GEL IN FRONT OF THE PROBE. We recommend you use a coupling gel made especially for ultrasound. Don’t use a gel that is too runny. You can use sterile jellies internally. Ultrasound coupling gels are available from us, or will usually be available from one of your surgical supply dealers. These gels are available in bulk, sterile packets and bottles. Gel in a semi-rigid tube with a small extended tip is easier to use than that which is in collapsible tubes. Refilling from bulk is much less expensive than buying more bottles or packets. Some tubes can be autoclaved. PLEASE DO NOT USE ECG PASTE OR CREAM. THE RED PROTECTIVE COVER MUST BE REMOVED FROM THE PROBE BEFORE USE.

WA R N I N G : T H I S D O P P L E R I S I N T E N D E D F O R U S E B Y H E A LT H C A R E PROFESSIONALS ONLY. This Doppler may cause radio interference or may disrupt the operation of nearby equipment. It may be necessary to take mitigation measures, such as reorienting or relocating the Doppler, or shielding the location. PHYSIOLOGICAL EFFECTS OF ULTRASOUND _______________________________ IMPLANTED DEVICES Implanted devices such as cardiac pacemakers should be avoided due to the possibility of affecting their operation. Also some plastics used in replacement surgery may be affected by absorption of ultrasound energy. Metal implants may lead to reflections and as a precaution, avoid using ultrasound close to these. STUDIES NEAR SENSITIVE TISSUES Extreme care should be taken when treating areas near the eye because of the danger of damage to the retina. Similarly, extreme care should be taken near other sensitive nervous tissue. Based on experimental and epidemiological data, there is presently no identified risk associated with diagnostic ultrasound. However, a prudent and conservative approach is recommended in which diagnostic ultrasound should be used only for medical benefit and with minimal exposure.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

OPERATING INSTRUCTIONS MODEL 842 USE OF THE PENCIL PROBE IN THE DIAGNOSIS OF ARTERIAL DISEASE IN THE LIMBS

1. THE PROBE. The probe consists of two crystals; one for transmitting the ultrasound waves and the other for receiving the reflected waves. If either crystal is damaged, the probe will not work properly or will not work at all. The crystals are covered by a material that is vulnerable to attack by heat, alcohol and ECG paste or cream. Therefore, DO NOT use ECG paste as the contact medium between the skin and the probe. Use AQUASONIC or any gel made for ultrasonic physical therapy equipment. In an emergency use any surgical jelly or lubricant, even petroleum jelly or mineral oil. Remove the gel after use with a soft tissue. If you should find the probe with dried gel on it, wash it off under running water. Do NOT scrape off the gel because you may damage the coating over the crystals. 2. POSITION OF THE PROBE: Invariably, people not accustomed to our probe use it incorrectly. The probe we furnish is different from that of the other manufacturers and is used differently. If you hand someone the probe and say “Here, try it for yourself”, they will almost always put it over their radial artery and place the probe perpendicular to the artery-and perhaps with no coupling gel. Many people have tried to compare our Doppler with other makes by this method. Keep in mind that you are not buying a Doppler for use on the radial artery, but for use on vessels you cannot feel. The best testing ground is therefore in your particular area of interest. We believe our instruments will permit you to find the vessels easier, let you hear the venous sounds easier and follow the vessels better than any other device on the market, regardless of price. But it takes some practice in order to be able to do this. We believe the arm is a good and most convenient limb for you to learn on-to learn how to hold the probe depending on the depth of the artery and vein. The area about 6 inches each side of the elbow is a good place to start. First, put some gel on the tip of the probe. The gel squeeze-bottle must be shaken downward and then gently squeezed to get the gel to come out. Pile up about a quarter of an inch of gel on the probe, making certain there are no large air bubbles in the pile because ultrasound does not go readily through air. It needs a continuous conducting medium, and the gel is ideal. Turn the VOLUME control fully down (counter clockwise) and turn the instrument on. Gradually turn up the volume. You should hear a rumbling sound if you are holding the probe. This is caused by the vibration of the gel due to tremor in your arm. Now place the probe over an artery in the arm about half way between the elbow and the wrist. Tilt the back of the probe toward the hand at an angle of about 45 degrees, making certain there is gel in the pathway between the probe and the skin. Move the probe and the skin sideways to try to find the center of the artery and the hissing noise at heart rate, which is the Doppler sound for an artery. If the sounds you hear are more or less continuous, that is simply the background noise of the instrument and it means that you are not over the artery. The main energy of the beam is only about as wide as the crystals in the probe, so there isn’t much room for error in aiming the probe. For this reason you must always search the area of the artery and tilt the probe for best Doppler sounds.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

OPERATING INSTRUCTIONS MODEL 842 When you are looking for deep arteries, or for small or obstructed arteries, you will have to turn the VOLUME control near maximum. This also means that every time you move the head of the probe you are going to get some pretty big thumping noises in the earphones. Therefore you want to avoid moving the head of the probe with respect to the skin as much as possible. That is why you place the probe over the area where you think the artery is and then you search for the exact point by moving the skin with the probe and changing the angle of the probe with respect to the skin. You might wonder why these big transient noises can’t be filtered. We do limit their intensity, but we do not filter. The reason is that in the search for low-velocity blood flow, such as in occluded arteries and in the veins, the pitch of the Doppler sounds associated with the blood flow are very low. Any filtering to eliminate or minimize the sounds accompanying movement of the probe would also reduce the response to low-velocity blood flow sounds, and of course this is undesirable. 3. DIAGNOSIS OF ARTERIAL DISEASE: The Doppler method of diagnosing arterial disease of the limbs is only one of several good methods. It is probably the most convenient and least expensive of the better methods. It is only qualitative but can be made semi-quantitative by permitting you to make systolic blood pressure measurements along the leg with the aid of a proper cuff and manometer. The great sensitivity of the transcutaneous Doppler can cause a doctor or technician to conclude improperly that an arterial pathway is open when it isn’t. Collateral flow around an obstruction can be well-developed, especially in the thigh, and cause pulsatile blood to flow in the distal arteries. Or a major artery may be narrowed, causing pulsatile flow distally. These mistakes in diagnosis can be avoided almost entirely by simple means and a little bit of experience. An experienced user of the Doppler can recognize the characteristic sounds of open and obstructed arteries. Remember that Doppler sounds vary in pitch (frequency) with the velocity of blood flow. When you hear the Doppler sound on a normal artery and compare it with a normal arterial pulsepressure wave, you will recognize the sound of the dicrotic notch, the very fast rise time of the wave and perhaps a third sound just before the onset of a new pulse wave. While the origin of these second and third waves in the descending branch of a pulse wave may be in dispute, their absence in vessels distal to an obstruction is not disputed. So a diagnostic rule is that whenever you hear the second and perhaps third sounds of a pulse wave of a major artery, you can be sure the artery is open proximal to the probe. Plethysmographic studies also show a delayed crest to the wave, associated with a slower rise time to the wave when there is an obstruction proximally. Though the Doppler is permitting you to hear velocity changes rather than true volume changes, the correlation is good enough to be quite valuable diagnostically. Now the opposite is not necessarily true-that when you can’t hear second and perhaps third sounds the artery is obstructed proximally to the probe. In the digits and smaller vessels the pulse wave is smoothed out more, especially when there is some vasoconstriction. Now of course there are cases that are in doubt. If you cannot clearly hear the second and third sounds (the third sound is frequently missing), compare with the same artery on the other limb. If you find a radical difference in the sound of the Doppler, both in pitch and in amplitude, you are justified in being quite suspicious of the patency of the artery of the first limb you studied provided you are now fairly skilled at optimizing the sounds. Parks Medical Electronics, Inc.

Model 842

Ver 1.1

OPERATING INSTRUCTIONS MODEL 842 Another thing you listen for is the relative clarity of the arterial wave. How well it stands out from the background noise of the instrument and perhaps the venous flow adjacent to the artery. Move the probe a little to each side of the artery to make this estimation. In a normal person you will find that you can make the arterial pulse wave almost completely separate from the venous sounds by positioning of the probe. The way you really come to a final conclusion that the artery is obstructed proximal to the probe is by measuring the systolic pressure at the ankle with an ordinary arm cuff. If you want to measure pressure at other places on the leg you will need a special cuff, the bladder of which encircles the limb. We sell such cuffs. The method is as follows: Wrap the cuff around the ankle or slightly above it so you can get the probe on the posterior tibial and hear the arterial sounds adequately. Inflate the cuff to a pressure well above the patient’s arm pressure or at least 30 points above the pressure at which the Doppler sounds disappear. Gradually reduce cuff pressure until you hear blood flow, though the sound won’t be normal. At that point read the pressure to obtain systolic pressure at the ankle. If you have doubts, center the probe on the artery and inflate the cuff again. You can observe at what cuff pressure the blood flow stops and again where it starts. Where it starts is normally used. This procedure is very similar to taking pressure on the arm using a stethoscope. There you are using sounds of turbulence or wall motion. Here we are sensing the flow of blood under the cuff with a much more sensitive device. You can get a clear indication of systolic pressures as low as 30 mm. of Hg. The only problem is keeping the probe right on the center of the artery while you are inflating and deflating the cuff. An aneroid manometer mounted on the inflation bulb of the cuff is preferable. Tycos makes such a device and perhaps others do too. The possibility of misdiagnosing is greatly reduced by this method provided you make two or more measurements and you are skilled at holding the probe in the right place and at the right angle. A low pressure reading is quite reliable. On diabetics you may get readings of 300 mm. Hg. or more, even though they have ulcers on their toes. These people with end-artery disease studied plethysmographically with the mercuryin-silastic strain gage, which we also make, will have quite large and normal looking pulsations in the toes. Their arterial walls are sclerosed so badly sometimes that they will not compress with cuff pressure. The normal pressure in the ankles should be about the same as the systolic pressure in the arm, or a little higher. If the ankle pressure is 30 mm or more lower than the arm pressure, an obstruction is almost certainly present. Normally one finds that people with arterial obstructions have pressures of 100 or less. If you have a proper cuff you can take pressures in the same manner (with the probe at the posterior tibial) just below the knee, just above it and at the top of the thigh. By measuring systolic pressure (the pressure measurement is always where the cuff is, not where the probe is) you will find radical differences between measuring sites if the obstruction is between them or you will find that pressures at corresponding points on the two legs are quite different. An exception is bilateral obstruction of the bifurcation of the abdominal aorta which may give you fairly symmetrical pressures on both legs. Unfortunately you cannot use the Doppler above the top of the thigh. The pressure measurements made on the thigh with a narrow cuff will be clinically useful, though not accurate. Parks Medical Electronics, Inc.

Model 842

Ver 1.1

OPERATING INSTRUCTIONS MODEL 842 Once you have determined that there is an obstruction it is often desirable to determine just where it is. It is permissible to check at certain points provided you are quite familiar with normal sounds-second and perhaps third sounds. Start at the top of the thigh and listen for the normal arterial sounds. A little to one side you should hear venous flow varying with respiration. The adjacent venous flow assures you that you are indeed listening to a major artery. This is important because you can get beautiful sounds from a collateral that is aimed toward your probe and giving a tremendous Doppler effect. But a collateral follows a tortuous path and the venous sounds will not be found adjacent to it. If you have a little problem hearing the vein (and you shouldn’t over big veins) give the leg a slight squeeze distal to the probe to increase the velocity of the venous blood and make its pitch higher. As you follow the superficial femoral artery down toward the knee you will lose the sound, even on normals, in some parts of the path because of tendons or other anatomical obstructions between the probe and the artery. You should be able to pick it up again easily in the popliteal region. Your ear and concentration make a filter to extract wanted information from background noise that exceeds anything that can be done electronically. You can follow these small arteries distal to the knee and in some cases they can be followed all the way to the ankle and beyond. Keep in mind that some people don’t have a dorsalis pedis artery. If you are working on arteries in the foot, make sure they are dilated by immersing the foot in a bucket of warm water for a few minutes. Some people are vasoconstricted most of the time. They usually will dilate for a while after the immersion and in a few minutes be constricted again. Also they usually do not have arterial disease. If you want to quickly determine the efficiency of flow in the arterial system of the leg, pick up the posterior tibial and listen for 2nd and perhaps 3rd sounds. If you hear them, and you are sure you know the difference between normal and abnormal, go no further. If they do not sound normal or there is doubt, make a blood pressure measurement and compare it with systolic pressure on the other ankle and on the arm. To find the location of the obstruction you can listen with the Doppler, or using a special cuff you can make blood pressure readings farther up the leg. If the obstruction is in the iliacs you can note it by the Doppler sound distal to the obstruction or by a much lower than normal blood pressure at the top of the thigh as measured with the cuff and the Doppler. PRE-OPERATIVE AND POSTOPERATIVE use of the Doppler is very important. When the patient is on the table, measure systolic pressure at both ankles and record it. After blood is again permitted to flow measure both pressures again. The pressure on the operated leg should be UP compared to the pressure in the other leg, the control. If it isn’t, then it is pretty safe to assume something is wrong. On rare occasions a limb will have such a high degree of reactive hyperemia that pressure will not be up and may even be lower, but the leg will be hot. A large percentage of patients are blocked to some degree before they get off the table. Blood-pressure measurements will give you an objective evaluation of the surgery. Some surgeons use the pencil probe directly on the artery (using sterile jelly for coupling) just distal to the repair. The characteristic of the flow sound is important. If the runoff is inadequate an experienced ear can detect it and often correct the cause on the table. You can also use Doppler and pressure measurements for follow up, comparing pressures at both ankles with systolic pressure at the arm, measured either with a Doppler or stethoscope.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

USING THE DOPPLER ON DIGITS MODEL 842 Line up the long way of the crystals and the pencil probe body with the length of the artery for best separation of arteries and veins at the ankle and best efficiency on the digital arteries. Whenever you try to pick up arterial flow from the digits you must consider digit temperature. It is often difficult to get a digital pulse when feet are cold or cool. The digits can be so vasoconstricted that blood only oozes through, which is sufficient to nourish but does not give a good recording or sound on any device. This occurs in perfectly healthy digits under normal conditions. It also occurs after surgery when severe vasospasm may occur. In order to get a good sound, blood pressure measurement or recording under these conditions you must cause vasodilatation to take place. One method is to warm the extremity by immersing it in warm water, not hot water. Within a few minutes you will be able to evaluate the condition of the flow when the limb is at heart level or slightly above. Another method used to dilate peripheral vessels is to occlude all flow at the ankle or forearm with an ordinary arm cuff infrated to well above systolic pressure. This is not normally painful, especially when vascular disease is present in the arterial system. If too much discomfort is apparent, a different procedure could be tried. Five minutes is usually enough time. On release of cuff pressure a reactive hyperemia will take place and last for a short time at least. There should be enough time to make an evaluation of arterial patency. Diabetics may have incompressible arteries so this technique may not work with them. When there are two sounds to the arterial pulse wave, the first caused by the filling of the vessel with systole and the second being either forward or reverse flow in the diastolic phase, vessels are usually patent. However, blockage of major proximal arteries may be present with good collateral flow around them. When there is only one sound with each cardiac cycle and the sound is not brisk, a proximal stenosis or occlusion may be present. PROPER PROBE PLACEMENT AND PROPER USE OF GEL ARE VERY IMPORTANT! The pencil probe body should be in line with the artery, not crosswise to it, and should be at about a 45 degree angle. You must be very careful about probe pressure, because a slight amount of pressure against the skin will occlude the artery. You must use a dab of gel in front of the probe. You may find it impossible to make blood pressure measurements on the digits with a Doppler, especially the toes. It is better to use our photoplethysmograph for that purpose. Doppler sounds from digital arteries will be very helpful once you become familiar with normal and pathological sounds. Making digital pressure measurements on the toes is not a very popular procedure. Refer to your medical literature for diagnostic procedures. This information is primarily meant to be a simplified guide to the use of the instruments and the probe.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

TECHNIQUES FOR BETTER DOPPLER RECORDINGS MODEL 842 A few hints on use of the probe will probably help you to get better recordings than you otherwise would. Basically, they involve the angle of the probe, how much gel to use, how much pressure to use, and how to orient the crystals in the end of the probe. The angle of the probe to the vessel is important and there are two opposing factors which you must balance. If you are studying a vessel near the surface, holding the probe almost tangent to the vessel, or at least 30 degrees off tangency, will give you a good recording with minimum filtering. You want to use minimum filtering because it gives you a truer picture of velocity changes occurring during the cardiac cycle which is an important part of diagnosis. So whenever you are studying digital vessels, supraorbitals dorsalis pedis, etc., try to make your angle to the skin less than 45 degrees. Use no more filtering than is necessary to get an acceptable recording, if you can tolerate the raggedness. The reason this works better is that the shift in frequency by the Doppler effect is a function of the angle of the incident ultrasound to the blood flow. The pitch of the sound is higher, and with higher pitched sounds you need less smoothing. Smoothing introduces distortion into the true velocity picture, so minimal smoothing gives you more realistic picture of flow velocity changes. Of course you may choose to use more smoothing to have a better looking graph. A problem with small vessels is that it is difficult or impossible to separate the artery from an adjacent vein. Venous flow is low velocity, and when the beam of ultrasound hits the vein, low-pitched sounds will be mixed in with the higher-pitched arterial sounds. They will contaminate the recording. About the only thing you can do to minimize venous contamination is to orient the crystals in the end of the probe so they are vertical with respect to the skin. The size of the ultrasound beam sent into the skin, near the crystal at least, is approximately the size of the crystal. This means that if artery and vein are lying side by side, vertical crystals will give you a narrow beam and a better chance of insonating the desired vessel. In the case of making blood pressure measurements at the ankle, you are really not that interested in getting a pure arterial signal. You would prefer a wider beam so that slight movements of the foot during inflation or deflation of the cuff don’t cause you to move the beam off the vessel. Therefore you would want the crystals on the probe to be parallel to the skin, utilizing the full width of the crystal. Furthermore, in order to get a good signal, you may have to tolerate a wider angle between the probe and the skin. In fact, the deeper the vessel the more the probe has to be aligned toward perpendicular, which is the worst possible position from a Doppler shift standpoint. The reason you have to go more vertical is because of the power loss of the ultrasound energy as it passes through the tissue. When vessels are deep and you want a good recording, align the crystals in the probe along the length of the artery so that as much ultrasound as possible is hitting the target artery. This means you will possibly have to use more filtering to get an acceptable recording, but that is the trade off. If your sound is weak and there is considerable background noise, the recording is not going to be good anyway. You must get the best signal-to-noise ratio you can, and you do that by a combination of crystal alignment, angle, and how close you can get to the artery. Don’t hesitate to use pressure on deep vessels. If you use pressure on shallow ones such as the digits and dorsalis pedis, the edge of the probe will shut off the flow.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

TECHNIQUES FOR BETTER DOPPLER RECORDINGS MODEL 842 For vessels near the surface, higher frequency probes work best. This is because, in theory at least, the efficiency of reflection of ultrasound varies as the fourth power of the frequency. This means, in theory, that for near-surface vessels 10 MHz. is 16 times better than 5 MHz. In practice there is a noticeable difference but it is nowhere near that great. When it comes to depth, the inverse applies. Many people have the impression that you need 4 or 5 MHz for veins. You need lower frequencies for an advantage in depth. It has nothing to do with arteries or veins. In fact, the Doppler shift is twice as much at 10 as it is at 5 so the sounds are easier to hear. Use whatever works best for you and don’t try to stick to anybody’s rules. If lower frequencies were better, why don’t we use 2 MHz. The reason is that the efficiency of reflection off red cells in the smaller vessels is very poor. The radial artery does not give a good signal, but the highly vascular placenta does and so does the abdominal aorta. 2 MHz. is used mostly for obstetrics and for the detection of air emboli in neurosurgery done in the sitting position. In the first case there is much more blood involved plus the beating fetal heart, and in the second case the air embolus is much larger than a red cell. So in both cases the targets are bigger. 10 MHz. makes a very poor obstetrical Doppler and 5 isn’t much better. We make a smaller probe we call a skinny pencil. Its outside diameter is 1/4" as opposed to the 3/8" diameter of our standard probe. It is a bit easier to manipulate around digits and its smaller beam separates small arteries and veins better. Some people like it especially for the supraorbial arteries. We also make two sizes of flat probes which can be attached to the skin. They are mostly used for blood pressure measurements in the O.R. and in nurseries, but sometimes they are affixed over the dorsalis pedis or posterior tibial during vascular surgery. There can be a problem of the gel running out and compression of the artery inadvertently, especially the dorsalis pedis. The posterior tibial at the level of the external malleolus may be under quite a bit of tissue and not give a good signal to noise ratio except on skinny people. A further complication is that after vascular surgery you may get vasospasm and need a pencil probe to pick up the signal. If you have spasm or suspect it, you have to make repeated ankle pressure measurements over a period of time and see if pressure continues to rise. Knees should be bent to pick up popliteals. The groin crease is an easy place to pick up deep venous flow. With the patient lying down, you should hear considerable variation in venous velocity with respiration. With a special cuff you can measure finger and penile pressures. You can monitor the effects of warming or drugs on the fingers of people with vasospastic disease with an infant probe attached with Velcro or tape. You can monitor or record supraorbital flow with a flat probe above the supraorbital notch. When you try to get a supraorbital recording, which can be difficult, it is easy to get a nearby artery that feeds the eyelid and flows in the wrong direction. This can be avoided to a large extent by laying the probe flat against the cheek, pointed upward. With older people you may have to stretch the skin above the notch to straighten out a twisted artery. You’ll probably get the best recordings by using the probe from above the notch, but be aware of the hazard of getting the wrong artery. Internal carotids can be picked up just below the angle of the jaw and on the anterior pillar of the tonsillar fossa. Internal flow tends to be more continuous and is fairly easily distinguished from external carotid or common carotid flow. Always know your own flow sounds well so you know what is normal. It takes some time to get familiar with normal sounds, but after a while you will know what the recording would look like just by listening. Parks Medical Electronics, Inc.

Model 842

Ver 1.1

TECHNIQUE OF EVALUATING CALF VENOUS DISEASE MODEL 842 The assessment of calf venous disease by Doppler ultrasound may be achieved with an accuracy of up to 85% compared to venography when one is experienced with the technique. The status of the calf veins can be assessed by listening with the Doppler at the posterior tibial vein at the ankle, the popliteal vein, the superficial femoral vein, and the common femoral vein. The status of the calf veins is determined by a combination of augmentation maneuvers when listening at these various points. Normal Respiration Flow Sounds: The Doppler is initially placed over the posterior tibial vein at the ankle behind the medial malleolus. Generous amounts of acoustic gel must be used, and one must be careful to avoid undue pressure with the probe which might result in obstruction of venous flow. Initially the posterior tibial artery signal is elicited. The probe is then moved slightly to either side of the arterial signal until the windstorm like venous signal is heard. Normally this signal should wax and wane with respiration. In the presence of calf vein thrombosis, the signal may be more continuous or there may be no audible signal present. If the feet are vasoconstricted, a venous flow signal may not be heard until the venous velocity is increased by gentle compression of the foot. Checking Competency of the Valves: Once the optimal venous signal is elicited, the calf is then compressed with the hand which is not holding the probe. The fingers should be spread so that much of the calf muscle is compressed. During this procedure, no venous flow should be heard. If venous flow signals are elicited, this is a sign of deep venous valvular incompetence, usually secondary to old deep vein thrombosis. Augmenting Venous Velocity by Compression: Next the calf is released and one should normally hear an augmentation of venous flow as blood enters the previously decompressed calf veins. The magnitude and duration of the augmented signal can be influenced by several factors including the temperature of the foot, the general vasomotor tone of the patient and the presence or absence of venous thrombosis in the calf. It is important to compare the augmentation signals in each foot. In vasoconstricted individuals with cold feet, the posterior tibial venous augmentation may be very minimal but it should be symmetrical. If there is good augmentation in one leg and poor augmentation in the other, the latter leg is usually the site of venous thrombosis. Next, the common femoral and then the superficial femoral veins are examined and the signals assessed for augmentation upon calf compression. Calf-vein thrombosis will result in a decreased augmentation of the venous signals at these sites. Similarly the popliteal vein should be examined. In general, the most sensitive indicator of calf-vein thrombosis is a relative decrease in augmentation upon release of calf compression with the probe positioned over the posterior tibial vein at the ankle. There are certain conditions which will imitate calf-vein thrombosis. Such problems as subfascial hematoma, a ruptured Baker’s cyst, extensive edema, or other conditions which cause increased pressure on the calf veins may result in a decreased augmentation of flow during the aforementioned maneuvers. Such conditions can be best diagnosed by a venogram if the diagnosis is in question.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

STRANGE NOISES FROM THE DOPPLER MODEL 842 On occasion there are noises you might not expect from the Doppler when in fact the Doppler is working fine. The following are some common concerns and their causes.

Concern:

Remedy:

Cause:

Popping scratchy noises sounds when the probe is first placed on the skin.

Air bubbles in the gel are moving and/or popping. Hair movement can also cause these noises.

Use a new dab of gel that looks clear, push the probe down enough so hair is immobilized, and wait a few seconds for everything to settle. If the noise is not there when the probe is clean (no gel) and suspended in the air, the Doppler and/or probe are probably working fine.

Static when the dry probe is moved through the air.

Possibly loose connectors internally, where the probe connects to the instrument.

There is normally some static generated when the instrument is moved through the air without gel on the probe, but it isn’t severe. Have the probe replaced or contact the factory if the problem persists.

High pitched tone.

Radio interference from a mobile service, police station nearby, even another Doppler working close by. Usually occurs near large open windows, rarely in the center of the building.

Move the Doppler to another location away from windows and toward the center of the building. If the problem persists contact the factory.

Buzzing noise that almost obliterates the Doppler signal.

Electrocautery or other sparking device, bad fluorescent light fixture or neon signs nearby.

Move the Doppler to another location away from the interference. If the problem persists contact the factory.

Howling noise when probe is held or laid on a table with gel on it.

Probe is acting as a microphone and you are getting acoustic feedback.

Wipe gel from probe, If the noise does not occur without gel on the probe, it is probably working fine.

ADDITIONAL TESTS: 1. 2.

Try using earphones if you have a howling noise. If there is no howl using earphones but there is with a speaker, it is acoustic feedback. Should you have access to a biomed department, try a different probe, even if it is the wrong frequency it will let you know if the problem is noisy connectors inside the instrument or frayed shielding near the probe body.

SUMMARY: The problem may simply be a probe or it may be peculiar to the environment in which it is used. If you have tried the tests and remedies mentioned and you still suspect a problem contact the factory toll-free at 1-800-547-6427. Parks Medical Electronics, Inc.

Model 842

Ver 1.1

CARE OF THE PROBE MODEL 842 The Doppler probes are easily ruined through misunderstanding and neglect. Over 90% of the failures of the Doppler are due to failure of the probe in some way. It will pay you to read what follows and transmit this information to any person using the Doppler. ABOUT THE PROBE: The active part of the probe consists of two crystals. One transmits the ultrasonic waves and the other receives them. Each crystal can serve either function. The crystals are held in place by a material that protects the crystals and the tiny wires soldered to them. This material is vulnerable to attack by heat, alcohol and ECG paste. We recommend an ultrasonic gel but in an emergency, use any surgical jelly. DO NOT use ECG paste or cream as a contact medium between the skin and probe. After use, the probe should be gently wiped clean of the Aquasonic or other acoustical coupling gel with a soft tissue. If the gel has dried on the probe, put it under warm tap water to soften the gel and permit you to wipe it off. Should someone use a sharp instrument to scrape off dried gel, they may also succeed in scraping off the material covering the tiny wires and crystals as well. We speak from long experience. Damage such as this will make your probe inoperable. A replacement probe is available from the factory. When calling, please specify the frequency that is engraved on the body of the original probe or specified on a label attached to the cable. DO NOT remove the label attached to the cable, it contains important reordering and warranty information. Warranty void if removed. Should you not have access to a biomed department to replace the probe, it is best to return the instrument to the factory if there is a sensitivity problem. THE COUPLING GEL which we furnish is called Aquasonic, made by Parker Laboratories. This gel is available from us or a similar ultrasonic gel (not runny) will usually be available from one of your surgical supply dealers. The .25 liter bottles may be autoclaved. Other makes of gel may work as well, though the dispenser may not be as convenient. Coupling gel in sterile packets is also available from us. You can also use sterile jellies internally such as K-Y or ABCO. Any sterile liquid or gel without excessive bubbles may be used. Placing the pencil probe directly on wet tissue will also work.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

GENERAL MAINTENANCE OF THE DOPPLER MODEL 842 NOTES FOR THE SERVICE TECHNICIAN In addition to true service problems you will frequently encounter “operator trouble” . Things to watch out for are: 1. The Doppler is tuned to a frequency which is different from that marked on the probe. This occurs in hospitals that have Dopplers and probes of more than one frequency. The probes and instruments get mixed up. We try to circumvent this by sending a particular hospital Dopplers and probes of the same frequency. The frequency of the Doppler is marked on the inside of the instrument and the frequency of the probe is marked on its connector. These frequencies should match. A variation of .1 MHz is not significant at around 5 or 10 MHz, but it is around 2 MHz. 2. The Battery is either the wrong type or was shorted while being installed. The result is diminished battery life. 3. If you have a problem with the recording being too small it may be caused by incompatibility of the recorder. The Doppler output is designed to work with the dc input of an electrocardiograph which has a high input impedance (usually 100k or more) and deflects the stylus 1 cm for a 50 mV input. Most research recorders are compatible with the high-impedance single-ended output of our Doppler, but some require a low impedance signal of around .1 volt for a cm of deflection and they will not function properly with the Doppler without a pre-amplifier. 4. An attempt is made to feed the signal from the earphone jack on the Doppler to another device for either amplification or processing and it does not work. The most likely reason for this is that a tip-ring-sleeve-type (stereo) plug has been used. You must use a single ended plug to take off the audio signal. True service problems can be broken down into the following general categories which are listed in the approximate order of their occurrence. 1. Failure of the probe. This accounts for about 90% of all the service problems . The user should keep a spare probe of the proper frequency on hand if they depend on the Doppler. Should you not have access to a biomed department to replace the probe, it is best to return the instrument to the factory if there is a sensitivity problem. 2. Failure of the battery or plastic case because the instrument was dropped. Battery connector is sprung so that good contact is not made. 3. A leaking battery has corroded battery connector so that good end contact is not made or corrosive fluid has penetrated end insulator causing electrical leakage to ground. 4. Component failure, unsoldered joint or poorly soldered joint, wire to battery or connector broken (perhaps only internally). Look for broken resistors around the edge of the circuit board. They may be broken inadvertently during the process of changing the battery. In general we suggest you return the unit to us for service that might be complicated or that may require transistors. The reason is that transistors are often selected for low noise or their dc operating characteristic. Customers in the U.S. can call us toll-free at 1-800-547-6427. Our regular business phone is 503-649-7007. Business hours are 7:00 am to 3:30 pm, Pacific Time, Monday through Friday.

Parks Medical Electronics, Inc.

Model 842

Ver 1.1

BATTERY REPLACEMENT MODEL 842 THIS DEVICE USES A 9 VOLT BATTERY FOR ITS POWER SOURCE.

FOR BETTER PERFORMANCE ALWAYS USE A 9 VOLT ALKALINE BATTERY.

When the sound gets weak or distorted, the battery should be replaced. CAUTION: Never use mercury batteries! TO REMOVE BATTERY: Remove three screws on the back of instrument; lift off back; unsnap the battery by pulling off the snap-on cover. When replacing the battery, be sure the snap-on cover is properly mated to the battery terminals before applying pressure to snap it into place.

Battery must be recycled or disposed of properly. Parks Medical Electronics, Inc.

Model 842

Ver 1.1

Diagnosis and Treatment of Chronic Arterial Insufficiency of the Lower Extremities HOWARD C. BARON, M.D., F.A.C.S.*

Leg distress -- cramps, fatigue, or just vague pain -- often signal the presence of a peripheral vascular disease. It could be arterial -- the first sign of arteriosclerosis obliterans. Simple office evaluation, including the patient’s description of leg pain, and an examination of the affected limbs, will often give a clear picture of the underlying vascular problem -- where it is, how extensive it is, which vessels are involved, and how adequate is the collateral circulation. A typical patient with arteriosclerosis obliterans, the most common of the arterial occlusive diseases, develops pain in one or both legs that requires him to stop and rest after walking a short distance. He may call it a cramp, a charley horse, or it may be just a feeling of tiredness in the limb after walking a certain distance. An elderly patient often admits to having calf pain for months or sometimes years with “no reason to mention it since aches and pains are bound to occur as you grow older.” However, where he previously could walk 4-5 blocks before the calf pain occurred and made him stop, he’s concerned because the pain now occurs after walking only a block or so. Arterial occlusive disease due to arteriosclerosis obliterans, is insidious in onset and often present in a patient for many years before any ischernic symptoms occur. Rarely will anyone complain of intermittent claudication, the most commonest symptom of arterial occlusive disease, while indoors. However, walking outdoors causes the pain to occur. There is a typical pattern to this symptom of limb ischemia; exercise -- pain -- rest -- relief. Patients characterize the pain of intermittent claudication in various ways. One will describe it as a sensation of cramping or tightness, “as if the leg is in a vise”. Another will describe increasing fatigue eventually forcing the patient to stop walking and rest. However, in all of these patients, resting for a few minutes is sufficient to relieve the pain If the need to sit down or elevate the extremity is a feature of a patient’s complaint, or if it takes more than a few minutes for the pain to abate, suspect a disease process other than arterial insufficiency as the cause of the pain.

As the disease progresses a different type of pain occurs in the toes or heel. Termed rest pain or night pain, it is an ominous symptom of advanced arterial occlusive disease due to multisegmental blocks in the major limb arteries and an inadequate collateral circulation around these blocks. This pain characteristically occurs in the distal portion of the foot, the toes, over the dorsum of the foot, in the heel area, or in the region of the metatarsophalangeal joint. The patient describes the pain as a severe ache or throbbing which often wakes him after several hours of sleep. Relief is sometimes obtained by rubbing the affected foot or placing it in a dependent position over the edge of the bed. Elevating the limb often increases the pain. In some patients, relief is afforded by sleeping in a chair with the leg in a dependent position. Leg pain and even “pseudoclaudication”, a form of leg pain that can mimic true intermittent claudication, can occur with a variety of processes other than arteriosclerosis obliterans such as degenerative disorders, for example, osteoarthritis of the hip of spondylolysis. Compression of the cauda equina also can produce claudication-like symptoms. In t h e s e patients, the typical cycle of exercise-pain-rest-relief is not present. The presence of normal pulses in the leg and a normal ankle systolic blood pressure aids in distinguishing the pain of pseudoclaudication from arteriosclerosis obliterans. Examination of the affected foot yields a great deal of information. Skin color, texture, and consistency all depend on arterial blood flow and can indicate the presence of an impaired circulation. If the patient has only mild, generally asymptornatic occlusive arterial disease, the color and nutrition of the leg and foot appears normal. As the ischemic process becomes more severe, the skin appears shiny and smooth, and hair is often absent from the toes and the dorsal region of the foot. Muscle atrophy, loss of subcuataneous fat, and pallor all indicate a severe degree of ischernia.

A fairly simple and accurate clinical test that can measure the degree of arterial insufficiency in the affected leg is the elevation-dependency maneuver performed while the patient is on the examining table. With the patient lying on his back, place his heels in the palms of your hands and elevate both legs 24-36 inches off the table. Hold the legs in this position for at least 45-60 seconds. Observe the color of the feet and legs, particularly the soles of the feet. If the arterial circulation is normal the skin coloration will decrease only slightly. Skin pallor will develop in the affected limb according to the degree of arterial insufficiency. If pallor occurs in both feet suspect either an arteriosclerotic block in the abdominal portion of the aorta or similar blocks in the major limb arteries. After the period of leg elevation, generally no more than several minutes, have the patient immediately stand up. In a patient with normal arterial circulation in the legs, color will return to the foot in 10 seconds or less, and the superficial veins in the distal portion of the foot will fill in 10-15 seconds. If arterial insufficiency is marked, the normal color may take 40-60 seconds to return; in severe cases more than 2 minutes. Reactionary rubor of the foot (a burgundy red color) may occur after the limb becomes dependent; this indicates the presence of ad-vanced limb ischemia and often portends ulceration and “ gangrene of the foot”. An absent or greatly diminished pulse is a diagnostic finding of major importance. The presence of a pulse however, does not always indicate a normal arterial flow; its absence is far more significant. In a patient who complains of intermittent claudication and has palpable resting pulses, don’t discard the diagnosis of arteriosclerosis obliterans without investigating the “disappearing pulse” phenomenon. Have the patient exercise until he experiences claudication; examination of the ankle pulses may then reveal an absent pulse associated with leg pallor. The physiologic explanation is simple: exercise causes a marked dilation of the arteriolar beds within the exercising muscles. During exercise blood is shunted to these muscle groups causing a drop in the ankle systolic blood pressure which is distal to the site of the arterial block. As the ankle systolic blood pressure falls, the distal pulses disappear. Except when life expectancy or surgical risk

contravenes due to other systemic diseases, angiography and surgical revascularization is indicated for all patients with symptomatic arteriosclerosis obliterans exhibiting cutaneous skin changes, such as ischernic ulcers or gangrene; the presence of rest pain or intermittent claudication that handicaps the patient economically or socially. Angiography is necessary to evaluate the extent of the arterial lesion. Typical arterial lesions due to arteriosclerosis obliterans are segmental, occurring in areas of branching, narrowing, or bifurcation sites of an artery. The commonest occurring at the bifurcation of the aorta, or the iliac and femoral artery divisions. Another frequent site is the distal superficial femoral artery as it emerges from the adductor canal of Hunter and the distal popliteal artery as it branches into the anterior and posterior tibial and peroneal arteries. Certain patients are not candidates for angiography; these include the elderly patient with moderate disability and associated cardiac disease, and generally any patient with the presence of another life-threatening disease. A satisfactory angiographic study provides a visual study of the anatomic lesion, indicating the extent of the lesion and to a degree its severity. The angiogram, however, does not yield information regarding the hemodynamic significance of the lesion. For this information the Doppler flow detector is a useful and accurate instrument. The importance of the ankle/arm systolic blood pressure ratio in the diagnosis and objective assessment of arterial disease underscores the value of the Doppler ultrasound blood flow detector. Although the auscultatory method with a stethoscope is one of the most common blood pressure measurements in clinical medicine, it is seldom used in the lower extremity because it is difficult to obtain the Korotkoff sounds in the distal portion of a limb, especially when arterial occlusive disease is present. The Doppler flow detector, when used with a sphygmomanometer and a pneumatic occlusion cuff, can measure the lower extremity systolic blood pressure easily and accurately. Normally, the ankle systolic blood pressure is slightly higher than the arm systolic

blood pressure. Any pressure gradient or difference that exists between the arm and ankle systolic blood pressure provides a valuable, objective hemodynamic assessment of the arterial lesion. Certainly, the lower the ankle systolic blood pressure when compared to that in the arm, the greater the gradient and therefore, the more advanced the arterial occlusive lesion in the distal abdominal aorta or lower extremity arteries. Two of the most important aspects of managing patients with Arteriosclerosis obliterans are the need to avoid any form of injury to the affected foot, this includes the avoidance of any form of home surgery on the feet, and the avoidance of tobacco smoking. A recent study of ours indicates that 40 percent of major lower extremity amputations might have been avoided by taking simple precautions against infections stemming from mechanical, thermal, or chemical injuries to the feet. Meticulous, periodic, podiatric care is necessary for any foot with an impaired circulation with its known increased susceptibility to infection. Even fungal infections such as athlete’s foot can put the ischernic foot at serious risk. Certain over-the-counter pharmaceutical preparations for removing corns and calluses that contain caustic chemicals can be harmful to surrounding tissues, especially when used in the presence of an impaired circulation and should be avoided! Thromboendarterectomy of the occluded artery or the use of bypass grafts are the operative procedures most frequently used for revasculatization of the ischernic limb. Sympathectomy may be helpful in certain patients, but is rarely considered for patients who are candidates for arterial surgery and it is not recommended for treatment of intermittent claudication. However, minor ischemic ulcerations may heal and rest pain may occasionally be relieved following sympathectomy. A limited number of patients with advanced arteriosclerosis obliterans may show improvement over periods of weeks from non-surgical measures including rest, the use of vasodilators, and avoidance of tobacco smoking, permitting the development of an

additional collateral circulation. However, the long period before results can be evaluated is risky: gangrene may supervene calling for emergency surgical reconstruction of the occluded vascular bed if amputation is to be avoided.

CONCLUSION There are both humanitarian, economic and social reasons for mounting a strong effort to salvage the lower limbs in patients, who are often elderly, and debilitated, but obvious candidates for a revascularization procedure. The physical, psychological and economic burdens following amputation preclude a useful or comfortable life in the years remaining to them. Limb salvage, the desideratum of any age, is particularly important in the geriatric patient whose care then places a heavy burden on a spouse of similar age or another family member. A patient confined to a wheelchair or bed is unable to attend to even the simplest personal needs; he often becomes withdrawn from human contacts, psychologically as well as physically damaged. Partial limb revascularization, by saving the extremely valuable knee joint, is often a reasonable alternative, allowing salvage of as much as possible of a limb affected by end-stage ischernia. The goal should be treatment of the disease without loss of the lower limb or, if amputation becomes necessary, a below-knee procedure or even a transmetatarsal amputation, permitting the patient to lead a more normal life. 222 East 19th Street New York, New York 10003

*Attending Vascular Surgeon, Cabrini Medical Center, New York, N.Y.; Associate Professor of Surgery, New York, University School of Medicine, New York, N.Y.

Practical Office Technics for Physiologic Vascular Testing * COL CLYDE 0. HAGOOD, JR., MC, USAF, LTC DAVID J. MOZERSKY, MC, USAF, and SSGT RANDAL N. TUMBLIN, BS, USAF, † Lackland AFB, Tex

Abstract: The development of the Doppler ultrasonic flow velocity detector has improved diagnostic accuracy in peripheral arterial occlusive disease. Survey of the peripheral vessels with the Doppler ultrasonic flow velocity detector, measurement of systolic arterial blood pressure at the ankle and arm, and exercise testing are three easily done tests which may be readily carried out in the doctor’s office and which provide useful information. Noninvasive vascular testing should be in the armamentarium of all primary care physicians.

A therosclerosis of the peripheral vessels is extremely common in our society and is responsible for significant morbidity and mortality. It is therefore imperative that the physician who first encounters patients with vascular complaints recognizes the disease and begins proper treatment. Until recently, the diagnosis of arteriosclerosis obliterans has been dependent upon the clinical history and physical examination. As a result, the disease has only been detectable in a relatively far advanced stage. Since the introduction of the Doppler ultrasonic velocity detector in 1959, more sensitive and objective methods of evaluation have been available to the clinician.1-4 The use of these technics, however, has been restricted to a relatively small number of specialists and investigators. Although they are extremely simple to do, these examinations have not been widely used by primary care physicians. The purpose of this paper is to familiarize clinicians with three simple office technics for detecting atherosclerotic occlusive disease and to present three cases that illustrate the efficiency of these technics.

*Read before the Section on Surgery, Southern Medical Association, Sixty-seventh Annual Scientific Meeting, San Antonio, Tex. †From the Department of Surgery, Vascular Surgery Service, W i l f o r d H a l l U S A F M e d i c a l C e n t e r, L a c k l a n d A i r F o rc e B a s e , Tex . Reprint requests to CMR #8, Box 369501, L a c k l a n d A F B , Tex 78236 (Dr. Hagood).

SOUTHERN MEDICAL JOURNAL, Vol 68, No. 1

Material and Technics The Doppler ultrasonic velocity detector has become a familiar tool used by obstetricians and vascular surgeons alike.5 The instrument uses two piezoelectric crystals. One crystal, when stimulated by an electric voltage, emits a continuous wave of ultrasonic energy at a frequency of 5 to 10 MHz, which is transmitted through the skin. If this sound wave is reflected back from stationary tissue interfaces, the frequency of the returned signal received by the second crystal will be the same as the transmitted frequency. If the sound wave strikes moving red cells, the returned signal will be a different frequency from the transmitted signal. The difference is directly proportional to the velocity of the blood, according to the Doppler principle. The transmitted and received frequencies are compared electronically and the difference between the two, the Doppler shift frequency, is amplified. Since this frequency is in the audible range, it can be perceived with earphones or a loudspeaker. For most clinical purposes, the audible signal is all that is necessary. Ultrasonic energy transmitted by these instruments has been tested both in the laboratory and clinically and has been found to be non-destructive to tissue. 6 Examination can thus be carried out at frequent intervals without fear of over-exposure. After the routine history and physical examination have been completed, the peripheral vessels are surveyed with the Doppler ultrasonic velocity detector.