Week 7 - Vascular disorders and problems of circulation

Question 1

What is the function of the vascular system?

Answer 1

To meet the circulatory needs of the tissues.

Question 2

How does it work?

Answer 2

Blood flows from high pressure areas to low pressure.

From arterial to venous.

Question 3

Peripheral flow rate is affected by:

Answer 3

1. Haemodynamic resistance: blood viscosity, vessel diameter
2. Regulation of peripheral vascular resistance: e.g. vasoconstriction
3. Movement of fluid across the capillary wall: hydrostatic & osmotic force, metabolic needs.

Question 4

Peripheral Arterial Disorders (PAD), clinical manifestations:

Answer 4

• Intermittent claudication
• Pulses diminished or absent
• Oedema - none/minimal
• Skin changes

Question 5

Peripheral Venous Disorders (PVD), clinical manifestations:

Answer 5

• Pain: aching to cramp like relieved by activity/elevation
• Pulses usually present
• Oedema - present/
• Skin changes

Question 6

Intermittent Claudication - Signs & symptoms

Answer 6

• Muscular/cramping (ischaemic) type pain

• precipitated by exercise, resolves within 10 mins of rest.
• Must be reproducible.

Question 7

Intermittent Claudication - Causes

Answer 7

• Lack of blood supply of O2/nutrients when increased demand

* Caused by arterial supply failure

Question 8

Peripheral Arterial Disease (PAD) - Causes

Answer 8

• Atherosclerosis (accumulation of plaque)

* Arteriosclerosis (hardening of arteries)

Question 9

Peripheral Arterial Disease - nursing diagnoses

Answer 9

• Altered peripheral tissue perfusion
• Chronic pain
• Risk for impaired skin integrity
• Knowledge deficient

Question 10

Nursing interventions for Altered Peripheral Tissue Perfusion

Answer 10

• Protection of extremities and avoidance of trauma
• Good hygiene - moisturisers
• Reg. inspection of extremities
• Podiatric care
• Good nutrition
• Weight reduction

Question 11

What is an aneurysm?

Answer 11

An aneurysm is a localised sac or dilation formed at a weak point in the wall of the aorta (or any artery really).

Question 12

Risk factors for Venous thromboembolism - DVT

Answer 12

1. Venous stasis (HF, paralysis). 2. Venous endothelial damage (trauma).
2. Hypercoagulability of the blood (smoking/the Pill). 4. Age. 5. Pregnancy.

Question 13

DVT pathophysiology

Answer 13

RBCs/WBCs/platelets/fibrin clump together to form a thrombus.

Question 14

Drug therapy for DVT

Answer 14

• Unfractionated heparin (sodium heparin) IV infusion
• LMW heparin (enoxaparin).
Minimise venipuncture (pressure 10 mins+ after injection)

Question 15

Anticoagulant Drugs

Answer 15

• heparin • dalteparin & enoxaparin (LMWHs)

* warfarin

Question 16

What are the low-molecular-weight heparins (LMWHs)?

Answer 16

• dalteparin and enoxaparin (used in pregnancy)

These have fragments 1/3 the size of standard heparin. They have a range of 4000-6000 in molecular weight.

Question 17

Heparin mechanism of action

Answer 17

The anticoagulant affect is had by heparin combining with antithrombin III, a naturally occurring anti-clotting factor in the plasma. This complex is then able to act more rapidly at multiple sites, inactivating thrombin factor IIa, IXa, Xa, XIa and XIIa. Inactivation of Xa (intrinsic & extrinsic pathway) prevents the conversion of prothrombin to thrombin, so inhibiting the formation of fibrin from fibrinogen.

Question 18

Signs of heparin overdose

Answer 18

• Bruising, nosebleeds or excessive bleeding from minor cuts, brush of teeth or menstrual period.

Question 19

Blood flow rate?

Answer 19

Flow rate = ΔP/R (pressure difference ÷ resistance)

Question 20

What is the most important factor determining resistance in the vascular system?

Answer 20

• Vessel radius

Question 21

Vasodilators

Answer 21

• histamine • bradykinin • prostaglandin

Question 22

How to calculate the ankle-brachial index (ABI)

Answer 22

• Cuffs are placed on both arms and both legs above the malleolus
Using a doppler the highest systolic pressure from each arm is ÷ by the highest systolic pressure in both feet.
(systolic from the feet is via posterior tibial or dorsal is pedis)
Ankle systolic is usually higher in a healthy person.