Adequate perfusion oxygenates and nourishes bodytissues and depends in part on a properly functioningcardiovascular system.
Adequate blood flow depends on1. the efficient pumping action of the heart2. patent and responsive blood vessels3. and adequate circulating blood volume
Factors that influence the rate and adequacy of blood flow Nervous system activity blood viscosity metabolic needs of tissues
Anatomic and Physiologic Overview The vascular system consists of two interdependent systems. right side of heart pumps blood through lungs to pulmonary circulation left side of heart pumps blood to all other body tissues through systemic circulation. The blood vessels in both systems channel the blood from the heart to the tissues and back to the heart Contraction of the ventricles is the driving force that moves blood through the vascular systems.
Arteries distribute oxygenated blood from the left side of theheart to the tissues, whereas the veins carry deoxygenated bloodfrom the tissues to the right side of the heart.Capillary vessels, located within the tissues, connect the arterialand venous systems and are the site of exchange of nutrients andmetabolic wastes between the circulatory system and the tissues.Arterioles and venules immediately adjacent to the capillaries,together with the capillaries, make up the microcirculation.The lymphatic system complements the function of the circulatorysystem. Lymphatic vessels transport lymph (a fluid similar to plasma), and tissue fluids (containing smaller proteins, cells, and cellular debris) from the interstitial space to systemic veins.
Arteries and Arterioles Arteries thick-walled structures that carry blood from heart to tissues. Aorta : diameter of approximately 25 mm (1 inch) divide into smaller arteries that are about 4 mm (0.16 inch) in diameter by the time they reach the tissues. Within the tissues, the vessels divide further, diminishing to approximately 30 µm in diameter; these vessels are called arterioles.
Layers or walls of arteries andarterioles1. Intima: an inner endothelial cell layer2. Media : a middle layer of smooth elastic tissue3. Adventitia :an outer layer of connective tissue.
Layers or walls of arteries andarterioles1. Intima an inner endothelial cell layer a very thin layer, provides a smooth surface for contact with the flowing blood
Layers or walls of arteries andarterioles2. Media a middle layer of smooth elastic tissue makes up most of the vessel wall in the aorta and other large arteries of the body. composed chiefly of elastic and connective tissue fibers that give the vessels considerable strength and allow them to constrict and dilate to accommodate the blood ejected from the heart (stroke volume) and maintain an even, steady flow of blood.
Layers or walls of arteries andarterioles3. Adventitia an outer layer of connective tissue. a layer of connective tissue that anchors the vessel to its surroundings. much less elastic tissue in the smaller arteries and arterioles, and the media in these vessels is composed primarily of smooth muscle.
What controls the diameter of the blood vessels? Smooth muscle controls the diameter of the vessels by contracting and relaxing. What influence the activity of smooth muscle? Chemical, hormonal, and nervous system factors influence the activity of smooth muscle.
Capillaries Capillary walls lack smooth muscle and adventitia composed of a single layer of endothelial cells. This thin-walled structure permits rapid and efficient transport of nutrients to the cells and removal of metabolic wastes. Distribution varies with the type of tissue. skeletal tissue, which is metabolically active, has a denser capillary network than does cartilage, which is less active.
Veins and Venules walls of veins are thinner and considerably less muscular. wall of the average vein amounts to only 10% of the vein diameter, in contrast to 25% in the artery. Walls are composed of three layers, although these layers are not as well defined.
Veins have thin and less musculature. Is this an advantage or not? Why or why not? The thin, less muscular structure of the vein wall allows these vessels to distend more than arteries. Greater distensibility and compliance permit large volumes of blood to be stored in the veins under low pressure. Approximately 75% of total blood volume is contained in the veins. That is why veins are also called Capacitance vessels
What stimulates the veins to constrict? Sympathetic Nervous System innervates the vein musculature can stimulate venoconstriction thereby reducing venous volume and increasing the volume of blood in the general circulation
Contraction of skeletal muscles in extremities creates the primary pumping action to facilitate venous blood flow back to the heart.What facilitate venous blood flow back to the heart?
Bicuspid valves.Do veins have them? Some veins are equipped with valves. In general, veins that transport blood against the force of gravity, as in the lower extremities, have one-way bicuspid valves that interrupt the column of blood to prevent blood from seeping backward as it is propelled toward the heart. Valves are composed of endothelial leaflets, the competency of which depends on the integrity of the vein wall.
Lymphatic Vessels are a complex network of thin-walled vessels similar to the blood capillaries. collects lymphatic fluid from tissues and organs and transports the fluid to the venous circulation.
Lymphatic Vessels converge into two main structures: (1) thoracic duct and (2) right lymphatic duct These ducts empty into the junction of the subclavian and the internal jugular veins. The right lymphatic duct conveys lymph primarily from the right side of the head, neck, thorax, and upper arms. The thoracic duct conveys lymph from the remainder of the body. Peripheral lymphatic vessels join larger lymph vessels and pass through regional lymph nodes before entering the venous circulation. The lymph nodes play an important role in filtering foreign particles.
Arms Assessment • Observe arm size and venous pattern; also look for edema • Observe for coloration of the hands and arms • Palpate the client’s fingers, hands, arms, and note the temperature • Palpate to assess for capillary refill time • Palpate for radial pulse • Palpate the ulnar pulse • palpate the brachial pulses if suspect arterial insufficiency • Palpate the epitrochlear lymph nodes • Perform the Allen Test34 Maria Carmela Domocmat, RN, MSN 9/9/2012
Legs Assessment • Observe skin color while inspecting both legs from the toes to the groin • Inspect distribution of hair • Inspect for lesions or ulcers • Inspect for edema • Palpate edema • Palpate bilaterally from temperature of feet and legs35 Maria Carmela Domocmat, RN, MSN 9/9/2012
Legs Assessment • Palpate the superficial inguinal lymph nodes • Palpate the femoral pulses • Auscultate the femoral pulses • Palpate the popliteal pulses • Palpate the dorsalis pedis pulses • Palpate the posterior tibial pulses • Inspect for varicosities and thrombophlebitis • Check for Homan’s sign36 Maria Carmela Domocmat, RN, MSN 9/9/2012
Special Tests for Arterial or Venous Insufficiency • Position change test for arterial insufficiency • Ankle-Brachial pressure index (ABPI) • Manual compression test • Trendelenburg test37 Maria Carmela Domocmat, RN, MSN 9/9/2012
Assessment Health History and Clinical Manifestations Intermittent Claudication Changes in Skin Appearance and Temperature Pulses Diagnostic Evaluation
Intermittent claudication A muscular, cramp-type pain in the extremities consistently reproduced with the same degree of exercise or activity and relieved by rest experienced by patients with peripheral arterial insufficiency.
Pathophy Caused by inability of arterial system to provide adequate blood flow to tissues in the face of increased demands for nutrients during exercise. As the tissues are forced to complete the energy cycle without the nutrients, muscle metabolites and lactic acid are produced. Pain is experienced as the metabolites aggravate the nerve endings of the surrounding tissue.
Usually, about 50% of the arterial lumen or 75% of thecross-sectional area must be obstructed before intermittentclaudication is experienced.When the patient rests and thereby decreases the metabolicneeds of the muscles, the pain subsides.The progression of the arterial disease can be monitored bydocumenting the amount of exercise or the distance a patientcan walk before pain is produced.
Rest pain Persistent pain in the forefoot when the patient is resting indicates a severe degree of arterial insufficiency and a critical state of ischemia. is often worse at night and may interfere with sleep. frequently requires that the extremity be lowered to a dependent position to improve perfusion pressure to the distal tissues.
The site of arterial disease can be deduced from the locationof claudication, because pain occurs in muscle groups belowthe disease.As a general rule, the pain of intermittent claudication occursone joint level below the disease process.Calf pain may accompany reduced blood flow through thesuperficial femoral or popliteal artery, whereas pain in thehip or buttock may result from reduced blood flow in theabdominal aorta or the common iliac or hypogastric arteries.
Changes in Skin Appearance andTemperature Adequate blood flow warms the extremities and gives them a rosy coloring. Pallor Due to inadequate blood flow whiter or more blanched appearance (esp when the extremity is elevated) Rubor reddish blue discoloration of the extremities, may be observed within 20 seconds to 2 minutes after the extremity is dependent. suggests severe peripheral arterial damage in which vessels that cannot constrict remain dilated. Even with rubor, the extremity begins to turn pale with elevation. Cyanosis a bluish tint on the skin is manifested when the amount of oxygenated hemoglobin contained in the blood is reduced.
Other changes Additional changes resulting from a chronically reduced nutrient supply include loss of hair brittle nails dry or scaling skin Atrophy Ulcerations
Edema Gangrene may be apparent bilaterally appear after prolonged, or unilaterally severe ischemia and is related to the affected represent tissue necrosis. extremity’s chronically In elderly patients who are dependent position inactive, gangrene may be because of severe rest pain. the first sign of disease.
Pulses Determine presence or absence & quality of peripheral pulses is important in assessing the status of peripheral arterial circulation Absence of a pulse indicate that site of stenosis is proximal to that location. Ex: Occlusive arterial disease
How do you assess pulse? Pulses should be palpated bilaterally and simultaneously comparing both sides for symmetry in rate, rhythm, and quality.
How can you prevent committing the mistake of taking your own pulse for that of the patient? Use light touch avoid using only the index finger for palpation,because this finger has the strongest arterialpulsation of all the fingers. The thumb should not be used for the samereason.
Doppler ultrasound flow studies When pulses cannot be reliably palpated, use of a microphone-like, hand-held Doppler ultrasound device, called a transducer or probe, may be helpful in detecting and assessing peripheral flow. Continuous-wave (CW) Doppler ultrasound device
Procedure supine position with head of bed elevated 20 to 30 degrees legs are externally rotated, if possible, to permit adequate access to the medial malleolus. Acoustic gel is applied to the patient’s skin to permit uniform transmission of the ultrasound wave (electrocardiogram gel is not used because it contains sodium, which may dissolve the epoxy that covers the transducer’s tip). tip of Doppler transducer is positioned at a 45- to 60-degree angle over the expected location of the artery and angled slowly to identify arterial blood flow. Excessive pressure is avoided because severely diseased arteries can collapse with even minimal pressure.
CW Doppler is more useful as a clinical tool when combined with ankle blood pressures, which are used to determine the ankle- brachial index (ABI), aka: ankle-arm index (AAI). ABI is the ratio of ankle systolic BP to the arm systolic BP. an objective indicator of arterial disease that allows the examiner to quantify the degree of stenosis. With increasing degrees of arterial narrowing, there is a progressive decrease in systolic pressure distal to the involved sites.
Measuring the ankle systolic pressure with a continuous-wave Dopplerprobe, pneumatic cuff and gauge.This reading would be compared with that at the brachial artery.Since pressure drops with increasing arterial stenosis, an ankle-brachialindex of less than 0.95 would be considered abnormal.
ABI supine position (not seated) for at least 5 minutes. appropriate- sized BP cuff is applied to ankle above malleolus. Identify arterial pulse at posterior tibial and dorsalis pedis obtain systolic ankle pressures in both feet. If pressure in these arteries cannot be measured, pressure can be measured in the peroneal artery, which can also be assessed at the ankle .Diastolic pressures cannot be measured with a Doppler.
To calculate ABI, the ankle systolic pressure for each foot isdivided by the higher of the two brachial systolic pressures;
Let’s practice! Compute the ABI for patient M who has the ff systolic pressures: Right brachial: 160 mm Hg Left brachial: 120 mm Hg Right posterior tibial: 80 mm Hg Right dorsalis pedis: 60 mm Hg Left posterior tibial: 100 mm Hg Left dorsalis pedis: 120 mm Hg ABI =highest systolic pressure for each ankle / highest brachial pressure
Let’s practice! Compute the ABI for patient M who has the ff systolic pressures: Right brachial: 160 mm Hg Left brachial: 120 mm Hg Right posterior tibial: 80 mm Hg Right dorsalis pedis: 60 mm Hg Left posterior tibial: 100 mm Hg Left dorsalis pedis: 120 mm Hg The highest systolic pressure for each ankle (80 mm Hg for right, 120 mm Hg for left) would be divided by the highest brachial pressure (160 mm Hg). Right: 80/160 mm Hg = 0.50 ABI Left: 120/160 mm Hg = 0.75 ABI
Normal findings In general, systolic pressure in ankle of a healthy person is same or slightly higher than brachial systolic pressure, resulting in an ABI of about 1.0 (no arterial insufficiency).ABI of 0.95 to 0.50 : mild to moderate insufficiencypatients with ischemic rest pain have an ABI of less than 0.50,and patients with severe ischemia or tissue loss have an ABI of0.25 or less.
Doppler ultrasonography used to measure brachial pressures in both arms. Both arms are evaluated because the patient may have an asymptomatic stenosis in the subclavian artery, causing brachial pressure on the affected side to be 20 mm Hg or more lower than systemic pressure. The abnormally low pressure should not be used for assessment.
Exercise testing used to determine how long a patient can walk and to measure the ankle systolic blood pressure in response to walking. walks on a treadmill at 1.5 mph with a 10% incline for a maximum of 5 minutes. normal response : little or no drop in ankle systolic pressure after exercise. (+) claudication : ankle pressure drops Combining this hemodynamic information with the walking time helps the physician determine whether intervention is necessary.
Duplex ultrasonography is a combination of the Doppler technology with pulse-echo imaging. After sending off ultrasound pulses into the tissue, the instrument converts the echoes received from various locations into dots of varying strength, forming an image of the blood vessel. The gold standard for diagnosing venous thrombosishttp://www.surgery.hku.hk/vdc_diagnostics.php
Duplex ultrasonography helps determine level and extent of disease Is universally employed to evaluate the venous system. image and assess blood flow evaluate the runoff status of the distal vessels locate the disease (stenosis versus occlusion), determine anatomic morphology and the hemodynamic significance of plaque causing stenosis.
Duplex ultrasonography noninvasive requires no patient preparation. equipment is portable, making it useful anywhere for initial diagnosis or follow-up evaluations.
Transverse view of an abdominal aortic aneurysm.Longitudinal scan of an atheroscleroticplaque in the internal carotid artery.
Duplex ultrasonography Carotid and Vertebral Scan Detection for Deep Vein Indications: Stroke Thrombosis Transient ischaemic attack Indication: lower limb oedema / High risk screening pain Abdominal Scan Evaluation of Venous Valve Indications: Severe hypertension Competence Abdominal aortic aneurysm Indications: Varicose vein Graft Surveillance Venous ulcer Stent Surveillancehttp://www.surgery.hku.hk/vdc_diagnostics.php
Computed tomography (CT) provides cross-sectional images of soft tissue and can identify area of volume changes to an extremity and compartment where changes take place. CT of a lymphedematous arm or leg, for example, demonstrates a characteristic honeycomb pattern in the subcutaneous tissue.
In spiral (also called volumetric) CT scan the scan head moves circumferentially around the patient as the patient passes through the scanner, creating a series of overlapping images that are connected to one another in a continuous spiral Scan times are short; however, the patient is exposed to x-rays, and contrast agent usually must be injected toadequately visualize the blood vessels.Using computer software, the slicelike images arereconstructed into three-dimensional images that can berotated and viewed from multiple angles.
Computed tomographic angiography(CTA) a spiral CT scanner and rapid intravenous infusion of contrast agent are used to image very thin (1-mm) sections of the target area; the results are configured in three dimensions so that the image closely resembles a regular angiogram CTA shows the aorta and main visceral arteries better than it shows smaller branch vessels. Scan times are usually between 20 and 30 seconds. Requires large volume of contrast agent limits the usefulness of this study in patients with allergy to the contrast agent or with significantly impaired renal function.
Magnetic resonance angiography(MRA) performed with a standard MRI scanner but with image- processing software specifically programmed to isolate the blood vessels. The images are reconstructed to resemble a standard angiogram, but because the images are reassembled in three dimensions, they can be rotated and viewed from multiple angles. no contrast agent is necessary useful in patients with poor renal function or allergy to contrast agent. Scan time is long, and motion artifacts are common, restricting the use of the test to relatively short segments of the vascular system
Angiography An arteriogram produced by angiography may be used to confirm the diagnosis of occlusive arterial disease when considering surgery or other interventions. involves injecting a radiopaque contrast agent directly into the vascular system to visualize the vessels. The location of a vascular obstruction or an aneurysm (abnormal dilation of a blood vessel) and the collateral circulation can be demonstrated. Usually, patients experience a temporary sensation of warmth as the contrast agent is injected, and local irritation may occur at the injection site.
Risks/ complications immediate or delayed allergic reaction to the iodine contained in the contrast agent. Manifestations include dyspnea, nausea and vomiting, sweating, tachycardia, and numbness of the extremities. Any such reaction must be reported to the physician at once; treatment may include the administration of one or more of epinephrine (adrenaline), antihistamines, or corticosteroids. Additional risks include vessel injury, bleeding, and CVA (brain attack, stroke).
Air plethysmography (APG) Is a pneumatic plethysmograph designed for non- invasively measuring venous function and absolute volume changes in the lower extremities. Changes in volume are measured with the patient’s legs elevated, with the patient supine and standing, and after the patient performs toe-ups (patient extends ankle while standing; stands on tip-toes). provides information about venous filling time, functional venous volume, ejected volume, and residual volume. useful in evaluating patients with suspected valvular incompetence or chronic venous insufficiency.
Influence of high-heeled shoes on venous function in young womenhttp://www.sciencedirect.com/science/article/pii/S0741521412001176
Air- Air-Plethysmography (APG) Detection for Chronic Venous Obstruction Measurement of Venous Reflux Indications: Varicose veins Venous ulcer Quantifies volume change in a limb caused by alterations in BP. This information would indicate the presence of obstruction by venous thrombosis and the degree of venous reflux in the lower limb as a result of chronic venous insufficiency.http://www.surgery.hku.hk/vdc_diagnostics.php
Contrast phlebography Also known as venography involves injecting radiographic contrast media into the venous system through a dorsal foot vein. If a thrombus exists, the x-ray image discloses an unfilled segment of vein in an otherwise completely filled vein. Injection of the contrast agent may cause a brief but painful inflammation of the vein. generally performed if patient is to undergo thrombolytic therapy
Lower limb phlebography (two projections): Contrast material fills the deep veins of the leg and passes through the perforate branches (arrow) into the superficial veins (double arrow). The veins are dilated in the region of the varicosity.
Lymphangiogram used to evaluate the possible spread of cancers and the effectiveness of cancer therapy. X-rays may also help determine the cause of swelling in an arm or leg and check for parasitic diseases. performed by injecting blue dye into an area to be tested. blue dye helps to locate the lymphatic vessels where the catheter will be placed. Once the lymph vessels are found, contrast medium is injected through the catheter and X-rays are taken to monitor its progress as it spreads through the lymph system up the legs, into the groin, and along the back of the abdominal cavity. The next day, another set of X-rays is taken.
Lymphangiography Procedure a lymphatic vessel in each foot (or hand) is injected with contrast agent. A series of x-rays are taken at the conclusion of the injection, 24 hours later, and periodically thereafter, as indicated. The failure to identify subcutaneous lymphatic collection of contrast agent and the persistence of contrast agent in the tissue for days afterward help to confirm a diagnosis of lymphedema.
Lymphoscintigraphy is a technique that is used to determine the sentinel lymph node Aka: lymphoscintigram, lymphangiogram a reliable alternative to lymphangiography. used to diagnose lymphedema and lipedema.http://breastcancer.about.com/od/breastcancerglossary/g/lymphoscintig.htm
Lymphoscintigraphy Procedure A radioactively labeled colloid is injected subcutaneously in the second interdigital space. The extremity is then exercised to facilitate the uptake of the colloid by the lymphatic system, and serial images are obtained at preset intervals. a computer records the path of the radioactive material towards the draining lymph nodes. The blue dye will assist the surgeon in finding the sentinel lymph nodes, which will be removed and tested for metastasis. No adverse reactionshave been reported.http://breastcancer.about.com/od/breastcancerglossary/g/lymphoscintig.htm