Chapter 21 Peripheral Vascular System and Lymphatic System

Key Points 21-1 Chapter 21: Peripheral Vascular System and Lymphatic System Key Points This section discusses key points about the structure and function of the peripheral vascular and lymphatic systems.  The vascular system consists of the vessels of the body, which transport fluid, such as blood or lymph. o Arteries carry blood from the heart. They are strong, tough, tense vessels designed to withstand the pressure created with each heartbeat. Arteries contain elastic fibres that allow their walls to stretch with systole and recoil with diastole. Some arteries are accessible to examination. These include the temporal, carotid, brachial, ulnar, radial, femoral, popliteal, dorsalis pedis, and posterior tibial arteries. o Veins drain deoxygenated blood and waste products from the tissues and return it to the heart. They are thinner and more passive than the arteries. Veins contain intraluminal valves. Veins that are accessible to examination include the jugular veins; the superficial and deep veins in the arms; and the superficial, deep, and perforator veins in the legs.  Three mechanisms keep blood moving toward the heart in the venous system. o First, blood moves from the low-pressure system of the veins through the contraction of skeletal muscles that milk the blood back toward the heart. o Second, blood moves because of the pressure gradient caused by breathing. o Third, blood moves because intraluminal valves keep it flowing in one direction.  Veins are called capacitance vessels because they can stretch and hold more blood when blood volume increases. This compensatory mechanism reduces stress on the heart.  Risk factors for venous stasis include standing, sitting, or bed rest because of the absence of the milking action of walking. Other risk factors are hypercoagulation, vein wall trauma, varicose veins, obesity, pregnancy, and genetic predisposition.  The lymphatic system is a separate system that retrieves fluid from tissue spaces and returns it to the bloodstream. The right lymphatic duct empties into the right subclavian vein. The thoracic duct drains the rest of the body. The lymphatic system has three major functions: Key Points 21-2 o First, it conserves fluid and plasma proteins that leak out of capillaries. o Second, it is a major part of the immune system that defends against disease. o Third, it absorbs lipids from the intestinal tract.  Lymph nodes are small oval clumps of lymphatic tissue located at intervals along the vessels. They filter fluid before it is returned to the bloodstream and remove harmful organisms. In lymph nodes, pathogens are exposed to lymphocytes, which mount an antigen-specific response to eliminate the pathogens. With local inflammation, the nodes in the affected area become swollen and tender.  Four major groups of lymph nodes are accessible to inspection and palpation: o The cervical nodes that drain the head and neck o The axillary nodes that drain the breast and upper arm o The epitrochlear node in the antecubital fossa o The inguinal nodes in the groin  The spleen, tonsils, and thymus aid the lymphatic system. o The spleen, in the left upper quadrant of the abdomen, destroys old red blood cells, produces antibodies, stores red blood cells, and filters organisms from the blood. o The palatine, adenoid, and lingual tonsils are located at the entrance to the respiratory and gastrointestinal tracts. They respond to local inflammation. o The thymus, behind the sternum in the mediastinum, develops T lymphocytes in the immune system in children but serves no function in adults.  Developmental considerations: o Infants and children: Lymph nodes are relatively large in children, and the superficial ones are often more easily palpable. o Pregnant women: Hormonal changes cause vasodilation and a decrease in blood pressure. The vascular related changes can cause edema, varicosities, and hemorrhoids. o Older adults: Rigid Vessels result in arteriosclerosis, and they have an increased risk for peripheral artery disease. This section presents critical points about subjective and objective assessments of the peripheral vascular system and lymphatic system.  To obtain subjective data, ask questions that investigate these topics: o Leg pain or cramps o Skin changes on the arms or legs o Swelling in the arms or legs o Lymph node enlargement Key Points 21-3 o Medication use  To obtain objective data, first assess the arms. o Inspect the hands and arms, noting the skin colour, temperature, texture, and turgor. Also, check for size changes, lesions, edema, and clubbing. o After assessing the capillary refill, palpate the radial pulses, noting their rate, rhythm, vessel wall elasticity, and force (or amplitude). Similarly palpate the brachial pulses. o Check for the epitrochlear nodes, which are not normally palpable. o If you need to assess the collateral circulation before cannulating the radial artery, perform the modified Allen test.  Next, assess the legs. o Inspect the legs, noting the colour, hair distribution, venous pattern, and size, and check for lesions or trophic skin changes. If the lower legs look asymmetrical, measure the calf circumference. o Then, palpate the temperature of the feet and legs. o After palpating the inguinal nodes, palpate the femoral, popliteal, posterior tibial, and dorsalis pedis pulses, grading them on a four-point scale. o Check for pretibial edema. If it’s present, grade it with a four-point scale or the method used by your facility. ♣ Weight gain >2.5 kg in 24 hours is cause for immediate concern. ♣ Daily weight is a better indicator of fluid status than intake and output. o Perform the manual compression, colour change, and leg strength tests. o Using the Doppler ultrasound stethoscope, assess the peripheral pulses, and determine the ankle-brachial index.  Expect findings to vary among patients in different developmental stages. For example, in healthy infants and children, lymph nodes commonly are easily palpable. In pregnant women, diffuse bilateral pitting edema and varicose veins may appear in the legs. In older adults, the dorsalis pedis and posterior tibial pulses may be difficult to find, and trophic changes are likely to be present.  Incorporate health promotion when assessing the peripheral vascular system. For instance, discuss ways to prevent foot problems and more serious disorders. Teach the patient the principles of good foot care, such as checking the feet every day, keeping blood flowing to the feet, wearing shoes that fit comfortably, and keeping the skin soft and smooth. Key Points 21-4 o Consult foot care guidelines endorsed by the Podiatric Medical Society and the American Diabetes Association.