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Stack #163350
ABPI and Doppler
| Question | Answer |
|---|---|
| Explain the basic science behind the Doppler | Moving objects reflect soundwaves.The Doppler probe emits soundwaves.The soundwaves are reflected off blood corpuscles within vessels and their frequency changes accordingly. |
| Name the pedal pulses and their anatomical location. | There are three pedal pulses.1) Dorsalis Pedis - a branch of the Anterior Tibial Artery, which can be palpated lateral to the Extensor Hallucis Tendon and between the bases of 1st+2nd Mets.3) Posterior Tibial Artery - palpated behind the medial malleolus |
| What is the purpose of palpating pedal pulses? | Palpating pedal pulses enables assessment of the arterial supply to the foot. |
| In addition to pedal pulses, what else would you look for when conducting a manual vascular assessment? | Temperature gradient from leg-foot and proximal-distal foot.Observations of skin colour/tone/elasticity/.Signs of venous insufficiency (oedema, haemosiderosis, varicosities).Nails (O/C, thickened)Hair growth on limb |
| How can you tell if you are listening to an artery or a vein with the Doppler? | Artery - blood is at high pressure (systolic) vs Vein - blood at low pressure so "sounds like wind blowing through trees" |
| What is the clinical relevance of ABPI readings? | Comparison of brachial and ankle systolic pressures can provide indication of the severity of Peripheral Vascular Disease (PVD). |
| Why should you always take readings from BOTH left and right sides? | Systolic pressures are sometimes different from left to right sides.If a low ABPI is missed this can place the patients life and limb at risk. |
| Why might toe systolic pressure be used instead of ankle systolic pressure? | Digital systolic pressure is sometimes used when there is medial calcification of Posterior Tibial artery suspected, because vascular calcification rarely extends to the digital arteries. |
| What impact will patient position during ABPI testing have on the results? | If a patient is sitting or standing, the ankle pressure will be higher than their arm pressure.If patient's legs are above their heart level, their ankle pressure may be lower than that at their arm. |
| What other factors may affect the accuracy of the ABPI result? | 1) sphyg cuff too large or too small2) wrong cuff wrapping technique used3) repeated inflation of cuff4) Poor Doppler signal, insufficient gel, low battery5) operator error - occluding vessel with probe pressing too hard |
| Describe the method for taking ABPI readings. | - |
| What is the ideal ABPI reading? | If there is no Peripheral Vascular Disease, systolic pressure at the Posterior Tibial artery should be the same as that within the brachial artery. |
| What does an ABPI reading <0.8 indicate? | ABPI <0.8 suggests possible arterial obstruction. |
| What ABPI value would you expect to see in significant PVD? | ABPI of <0.75 indicates significant PVD. |
| As ischaemia increases in severity, the ABPI value will _______. | Increasing ischaemia --> decreasing ABPI value. |
| What are the likely implications for healing of a low ABPI value? | Healing is unlikely to occur as there is severe PVD. |
| Sever PVD would be indicated by a ABPI value of what ? | Severe PVD would be indicated by an ABPI value of <0.5. |
| What is the main limitation of ABPI for patients with diabetes? | As many as 30% of patients with diabetes have Medial Arterial Calcification.Calcification results in vessels becoming stiff and offering greater resistence to external compression.This causes overestimation of intra-arterial pressure and thus falsely high |
| True or False?Patients with normal ABPI readings may still have medial arterial calcification. | True. |
| Describe the waveform for mono, bi and triphasic pulses. | - |
| How can the following conditions affect the vascular flow to the lower limb:a) diabetes mellitusb) hypertensionc) cigarette smokingd) systemic lupus erythematosuse) poor diet | a)b)c)d)e) |
| Define cyanosis | Cyanosis describes a discoloration of tissue that can occur when there is stagnation of blood in the veins.Blue-grey colour. |
| Define erythema | Erythema (def) = bruising |
| What is haemosiderosis and what might it indicate? | Haemosiderosis is a discoloration of the skin caused by brown deposits of iron from the process of haemolysis.It is an indication of venous insufficiency. |
| What is pallor? | Pallor is a lack of colour. It is one of the cardial signs of vascular insufficiency in the lower limb. |
| What is telangectasia? | Telangectasia are permanently dilated arterioles, which appear like small "worms" under the skin. |
| Describe the main clinical features of arterial insufficiency. | The 6 cardinal signs of Arterial insufficiency:Pallor, pulselessness, perishing cold,parasthesia, paralysis, painIntermittent ClaudicationRest PainNo swelling, collapsed veins, painful ulcerationSkin atrophied and hairless |
| Describe the main clinical features of venous insufficiency. | Clinical signs of Venous insufficiency:Skin warm, steady pain, retains sensationModerate swelling, tender filled veinsOedema & pigmentation (haemosiderosis)Scaling/scarred cyanotic skin |
| What are CHILBLAINS? | Chilblains (perniosis) is a vasospastic response to prolonged exposure to cold. Starts as a bruise-->purple lesion-->ulcer |
| Explain why intermittent claudication occurs. | Intermittent claudication occurs during activity. There is insufficient arterial supply to the leg muscles, therefore cramping ensues. Venous insufficiency prevents respiratory metabolites being carried away from the muscles. |
| What is rest pain and why does it occur? | Even when lying with legs at the same level as the heart arterial insufficiency is so bad that blood cannot reach the limbs. The legs must always be kept in dependency. It indicates critical limb ischaemia. |
| What are night cramps and why do they occur? | Night cramps occur when warm bedclothes increased metabolic demand of the tissues which cannot be met because blood supply is inadequate. Toxic metabolites accumulate and ischaemic pain is experienced. |
| Explain why varicose veins arise. | Venous varicosities occur when venous valves fail and backflow of blood occurs. Gravity pulls blood downwards and the relatively inelastic venous walls start to bulge outwards. |
| What is ATROPHIE BLANCHE? | Atrophie blanche is white patches on the skin around the ankles, caused by strangled microcirculation. |
| What are the clinical signs of haemosiderosis? | Haemosiderosis causes brown areas of staining of the skin of the legs and ankles.The body deposits iron complexes in the skin due to increased hydrostatic pressure. |
| What features of telagectasia would enable its recognition in clinic? | Telangectasia features:dilated microvessels around the medial malleoli. |
| What impact would temperature have on Doppler results? | High and low room temperatures can alter peripheral resistance and can affect how easy it is to detect pulses. |
| When would you measure the ABPI of a patient? | ABPI is measured when PVD is suspected. It provides a more accurate reflection of severity of PVD if carried out correctly. |
| Are there any contraindications to measuring ABPI? | Do not measure ABPI:- immediately following vascular surgery- if patient has arterial insufficiency |
| In what position should your patient be to measure their ABPI? | Patient should be prone for at least 10 minutes, and remain so throughout the process. |
| Describe two different techniques for applying the sphygmomanometer cuff to your patient. | 1) contour wrap 2) parallel wrap |
| Why do we need to take four readings to measure the ABPI? | - |
| Which readings should be used to calculate the ABPI? Why? | Use the highest systolic reading from both arms and highest systolic reading from both ankles to calculate ABPI.Why???? |
| Why might you get a weak Doppler signal? | Doppler signals may be attenuated by:fat, haematomas, scar tissue. |
| At what angle must the Doppler probe be applied to the skin? | 45-60 degree angle to the artery, facing towards the heart (against the direction of the bloodflow) |
| What frequency of soundwaves is most appropriate for detecting pedal arteries? | High frequency soundwaves of between 8-10 MHz should be used to detect pedal arteries. |
| How does a Doppler probe work? | Doppler equipment has two crystals. One emits soundwaves and the other receives them back. The difference in frequency between the waves emitted/received is emitted as a sound, which reflects the velocity of the moving objects. |
| What do Doppler waveforms represent? | The biphasic or triphasic waveform occurs because the main blood vessels in the leg are elastic and are dilated by the increased pressure during systole. This creates a reservoir of blood which empties during diastole. The volume of blood in the reservoir |
| What is venous insufficiency? | Venous insufficiency results from either (a) valve damage or (b) venous distension. If valves leak, veins become incompetent and blood falls back under gravity as calf muscles relax, increasing venous pressure because of the column of blood being supporte |
| What are the three sounds of a triphasic waveform? | 1st sound - systole (forward flow as blood ejected from heart)2nd sound - reverse flow (elastic distension of arteries)3rd sound - forward flow as arteries rebound |
| What is a biphasic waveform? | In a biphasic waveform, the second (backwards) wave is lost, because the arteries have lost their elasticity. Both remaining waves are also dampened. |
| Apart from PVD, why might you hear only a biphasic waveform? | If someone is tachycardic, the heart is beating too rapidly for reverse flow to occur. |
Created by:
georgealbertjnr
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