NR304 Chapter 21 Peripherial Vascular

Chapter 21: Peripheral Vascular System and Lymphatic System

Overview

The peripheral vascular and lymphatic systems are critical components of human physiology, playing essential roles in facilitating blood circulation and maintaining body fluid balance. These systems not only transport nutrients and oxygen to tissues but also remove metabolic wastes and help in the immune response.

Arteries and Veins

Arteries:

• Arteries are high-pressure vessels that transport oxygenated blood away from the heart to various body tissues. They receive direct pressure from the left ventricle (LV) of the heart during systole, which maintains blood circulation.

• The arterial wall structure is robust, comprising three layers: the tunica intima (inner layer), tunica media (middle muscular layer), and tunica externa (outer layer). This structure enables them to withstand high pressure.

Veins:

• Veins, in contrast, are low-pressure vessels that return deoxygenated blood back to the heart. They are equipped with valves that prevent retrograde flow, ensuring unidirectional blood movement.

• The flow in veins is supported by skeletal muscle contractions during physical activity, which compress the veins and propel blood towards the heart. Changes in intrathoracic pressure during respiration also assist in venous return.

Arteries in the Arm

Major arteries include:

• Brachiocephalic artery: Supplies blood to the right arm and head.

• Common carotid artery: Supplies blood to the head and neck.

• Subclavian artery: Supplies blood to the upper limb.

• Axillary artery: Continuation of the subclavian artery, supplies the shoulder and upper arm.

Pulses sites:

• Radial artery: Located at the wrist, commonly palpated.

• Ulnar artery: Supplied the ulnar side of the forearm and hand.

• Brachial artery: Found in the upper arm, commonly used in blood pressure measurements.

Vessels in the Leg

Major arteries and veins include:

• Aorta (abdominal): The largest artery in the body, branches into the common iliac arteries.

• Common iliac artery: Supplies blood to the pelvis and lower limbs.

• External iliac artery (Pulse site: Femoral artery): Continuation of the common iliac artery; supplies blood to the lower limb.

• Popliteal artery: A continuation of the femoral artery behind the knee (Pulse site).

• Dorsalis pedis artery: Supplies blood to the foot.

Veins:

• Great saphenous vein: The longest vein in the body, running along the length of the leg; often used for grafts.

• Femoral vein: Drains blood from the thigh.

• Popliteal vein: Located behind the knee, collects blood from the lower leg.

Venous Functionality

Capacitance:

• Veins have a larger diameter than arteries, which allows them to serve as capacitance vessels that can hold larger volumes of blood during overall circulation.

Depend on:

• Contracting skeletal muscles (calf pump): Essential for facilitating venous return from the legs.

• Intrathoracic pressure changes: Variations in pressure during breathing assist in propelling blood through the thoracic veins.

• Competent valves and open lumen: Valves ensure one-way flow of blood; any incompetence can lead to venous disorders.

Mechanism of Venous Flow

• The venous system is a low-pressure system that maintains blood flow through:

  • Skeletal muscle contractions: Helps push blood towards the heart.

  • Pressure gradients created by breathing: Diaphragm movement affects thoracic and abdominal pressure.

  • Valves: Prevent backflow, ensuring efficient blood flow.

• The calf pump acts as a significant contributor to venous return, and conditions like varicosities can lead to incompetent valves and increased venous pressure, resulting in complications like venous insufficiency.

Lymphatic System

Functions:

• The lymphatic system plays a pivotal role in maintaining fluid balance by retrieving excess fluid and plasma proteins from interstitial spaces and returning them to the bloodstream, thus preventing edema.

• It conserves fluid and plasma proteins vital for cellular activity and fluid homeostasis.

• Crucial part of the immune system, the lymphatic system filters and processes lymph, which contains immune cells and antigens.

• It also absorbs lipids from the digestive tract, facilitating dietary fat absorption.

Lymph nodes:

• Small clumps of lymphatic tissue located throughout the body, primarily in the neck, axillae, and groin; they are crucial for immune surveillance and can be inspected and palpated during physical examinations.

Lymphatic Ducts and Drainage Patterns

Ducts:

• Right lymphatic duct: Drains lymph from the right upper body into the right subclavian vein.

• Thoracic duct: Drains lymph from the remainder of the body into the left subclavian vein, playing a major role in lymphatic circulation.

Related Organs

Spleen:

• Located in the left upper quadrant, the spleen performs multiple functions:

  • Destroys old red blood cells and recycles iron.

  • Produces antibodies to help combat infections.

  • Stores red blood cells and platelets, contributing to blood volume and clotting when necessary.

  • Filters microorganisms from blood, contributing to the immune response.

Thymus:

• A gland located in the superior mediastinum, crucial for developing T lymphocytes (T cells), which are essential for adaptive immunity.

Developmental Competence

Children:

• In children, lymphatic tissues are relatively larger; lymph nodes may be palpated even in healthy individuals due to increased prevalence of infections and high immune activity.

Pregnant Women:

• Hormonal changes during pregnancy lead to vasodilation, increased blood volume, and possible dependent edema, varicosities, and hemorrhoids due to higher blood flow and pressure on pelvic veins.

Aging Adults:

• In aging adults, vascular rigidity increases, resulting in arteriosclerosis and a higher prevalence of peripheral artery disease (PAD), which can impact overall cardiovascular health.

Peripheral Artery Disease (PAD)

• Recognized as a cardiovascular risk equivalent by the American Heart Association (AHA), PAD is associated with an increased likelihood of heart attack and stroke.

• Risk factors include genetics, sedentary lifestyle, smoking, diabetes, and hypertension.

• The ankle-brachial index (ABI) is a non-invasive screening tool utilized to assess arterial flow and diagnose PAD, comparing blood pressure in the ankle with that in the arm to identify blockages.

Assessment Considerations

Key symptoms to assess:

• Leg pain/cramps: Often indicative of arterial insufficient blood flow (claudication).

• Skin changes: Monitor for color changes, temperature variations, or lesions, which may indicate vascular issues.

• Swelling and lymph node enlargement: May indicate venous insufficiency or lymphatic problems.

Objectives of Examination

• Inspect and palpate arms and legs for:

  • Color, temperature, lesions, edema, and pulses.

• Measure leg circumferences for asymmetry, which can signify deep vein thrombosis (DVT) or other vascular issues.

• Check for pretibial edema and assess overall vascular health to monitor for potential complications.

Pulses Assessment

• Use a grading scale to evaluate pulses:

  • 0: No pulse (absent)

  • 1+: Weak pulse (thready)

  • 2+: Normal pulse (easily palpable)

  • 3+: Increased pulse (full)

  • 4+: Bounding pulse (strong and pounding).

Common Abnormalities

Arterial diseases:

• Characterized by symptoms of oxygen deficit, often leading to cool, pale skin and intermittent claudication in the limbs due to reduced blood flow.

Venous diseases:

• Symptoms often include changes in skin color, edema, and signs of metabolic waste buildup due to poor venous return, leading to conditions like chronic venous insufficiency.

Health Promotion and Teaching Points

• Focus on patient education regarding foot care, especially in individuals with diabetes or peripheral neuropathy.

• Encourage regular exercise and movement to stimulate venous return and overall vascular health; highlight monitoring for skin abnormalities as preventative care.

• Promote the use of comfortable, well-fitting footwear and emphasize the importance of skin hydration to prevent breakdown and complications associated with poor circulation.