Hemodynamics disorder

Question 1

What are the factors that regulate the fluid balance in the capillaries?

Answer 1

1) Capillary hydrostatic pressure: This is the pressure created by the water gradient, which usually tries to take blood from the capillary into the interstitial fluid

2) Palma colloid osmotic pressure: Pressure created by the proteins (mainly albumin) in the blood vessel which tries to keep the water inside the blood vessel

• The lymphatics collect extra fluid that seeps into the interstitium

Question 2

What is meant by edema?

Answer 2

It is the collection of fluid in the interstitial tissue spaces

Question 3

What are the common locations of edema?

Answer 3

1)Peripheral

2) Cerebral

3) Pulmonary

Question 4

What are the special types of edema?

Answer 4

1) Hydrothorax (pleural effusion) in the pleura

2) Hydroperitoneum (ascites)

3) Anasarca (generalized severe swelling all around the body)

Question 5

What are the different physiologic changes that cause edema?

Answer 5

1) Increased hydrostatic pressure

2) Reduced plasma osmotic pressure (hypoproteinemia “like in liver disease”)

3) Lymphatic obstruction

4) Sodium retention (can be caused by steroids)

5) Inflammation (due to increased vascular permeability “but the edema here will have an exudate full of proteins and cells”)

Question 6

What are the causes of increased hydrostatic pressure?

Answer 6

1) Impaired venous return:
- Congestive heart failure
- Venous obstruction (like in thrombosis, or mass)

2) Arteriolar dilation
- Like in heat

Question 7

What are the different causes of reduced plasma osmotic pressure?

Answer 7

• Can occur due to the reduction in the synthesis of proteins, Excessive loss of proteins, or insufficient intake

1) Malnutrition
2) Gastroenteropathies
3) Liver cirrhosis
4) Glomerulonephropathies (losing a lot of proteins)

Question 8

What are the causes of lymphatic obstruction?

Answer 8

• Usually localized

1) Infection or inflammation
2) Neoplastic obstruction (elephantiasis)
3) induced in cancer treatment when removing it

Question 9

What is the difference between a transudate and an exudate?

Answer 9

Transudate is usually when there is a change in the forces controlling the water balance with low specific gravity and low protein content, however, exudate occurs in inflammation where they are due to the increased vascular permeability-increasing the protein content and specific gravity

• You can use this information to check for inflammation and cancer

Question 10

What is meant by hyperemia?

Answer 10

It is an active process due to an increased flow in the arteriolar side, it leads to the engorgement of oxygenated blood resulting in erythema, like when you exercise

Question 11

What is meant by congestion?

Answer 11

It is a passive process due to an obstruction where the blood will collect on the venous side mainly, it will be filled with deoxygenated blood and it can be:

1) Isolated (local congestion)
2) Systemic venous obstruction, like in heart failure

Question 12

What is meant by hemorrhage?

Answer 12

• It is the extravasation of blood due to the rupture of the vessel
• It could be external or internal resulting in petechiae, purpura, ecchymosis

Question 13

What is meant by the hemostasis of blood

Answer 13

• Its main function is to maintain blood in a fluid state and produce rapid and localized hemostatic plugs at sites of vascular injury

Question 14

What are the requirements for a normal hemostasis?

Answer 14

1) Normal integrity of blood vessels

2) Adequate number of platelets

3) Normal amount of coagulation factors

4) Normal amount of coagulation inhibitors

Question 15

What are the phases of hemostasis?

Answer 15

1) Vasoconstriction (transient)

2) Primary hemostasis (formation of a platelet plug due to the exposure of the subendothelial matrix)

3) Secondary hemostasis
- Activation of coagulation factor, converting prothrombin to thrombin and thus fibrinogen to fibrin cementing the plug

4) Activating the antithrombic effect to limit the plug into the site of injury only via tissue plasminogen acrtivator

Question 16

What are the factors that cause thrombosis?

Answer 16

• VIRCHOWS TRIAD:

1) Endothelium injury

2) Abnormal flow
- Aneurysm
- Ulcerated atherosclerotic plaque
- Sickel cell anemia which causes vascular occlusion

3) Hypercoagulability
- Primary (genetic, like the mutation of the prothrombin gene)
- Secondary (sitting in bed for a long time, obese people, etc)

Question 16

What is meant by thrombosis?

Answer 16

1) It is an inappropriate activation of the hemostatic process in an uninjured vessel

2) Forming a thrombus when there is a minimal vascular injury

Question 17

Describe the morphology of the thrombus

Answer 17

• It depends on its location:

1) Non-occlusive in rapid and high volume flow like in the heart or aorta, gives a structure called the line of Zahn where you see a dark layer (formed by erythrocytes) followed by a pale layer of thrombus composed of fibrins and platelet

2) Occlusive occurs in smaller arteries and veins, Accumaltes large amounts of erythrocytes, and appears redder (that’s why it is called red (due to the increased accumulation of rbc compared to the non-occlusive one) /stasis (because it is usually caused by obstruction and stasis of blood flow) thrombi

• Arterial or cardiac thrombi usually occurs at the site of endothelial injury or turbulence

Question 18

What are the different fates of thrombus?

Answer 18

1) Propagation (more obstruction, occluding larger vessels)

2) Organized and Recanalized (where they are more organized and holes will appear in them in a trial to get rid of them via inflammation and macrophages)

3) Embolised (when they are detached and pushed by the BF)

4) Dissolution (removed by the fibrinolytic activity)

Question 19

What is an emboli?

Answer 19

• Any solid, liquid, or gas that forms a mass and is carried by blood flow, arises from thrombi in 99% of the cases, other forms include, fat, gas bubbles, tumors, atherosclerotic debris, etc
• It can cause infarction due to the occlusion of BV leading to ischemia and necrosis

Question 19

What is meant by infarction?

Answer 19

An area of ischemic necrosis caused by an occlusion to a blood vessel (mainly arteries) can be due to thrombus, emboli, vasospasm, compression (due to hematoma or tumor), and torsion they are classified into:

1) Red-infarcts: Hemorrhagic

2) White infarcts: anemia

3) It can be septic or non-septic

Question 20

What is the clinical significance of thrombi and emboli?

Answer 20

It depends on their location, as venous thrombi can cause congestion and edema or worse embolize into the lungs, whereas arterial thrombi have a higher risk of occluding the coronary arteries causing a myocardial infarction

Question 20

When does a white infarction occur?

Answer 20

• When the occluded blood vessel (infarct) is in solid organs (heart, spleen, and kidney) as 1BV supplies these organs

Question 20

When doe the red infarct occur?

Answer 20

• In venous occlusions (Ovarian torsion)
• Occurs in loose tissues like the lung, which allows blood to accumulate in the infarcted area
• In tissues with a dual blood supply (like the lungs and S.I)
• In tissues that were previously congested

Question 21

What is meant by pulmonary thromboembolism?

Answer 21

In some cases like in hospitalized patients, thrombi formed in the deep veins of the leg can travel to the lung, obstructing the main pulmonary vessels which can be fatal, right side heart failure or cardiovascular collapse or pulmonary hypertension due to the blocking of one side of the lung increasing the pressure on the other side

Question 21

What is meant by systemic thromboembolism?

Answer 21

Less important than the pulmonary embolism

• They are the emboli traveling in the arterial circulation arising from the Heart, left atrium, and heart valve vegetation, traveling to the lower extremities, brain, kidney, spleen, and intestine mainly, causing the infarction of the tissue it travels to.

Question 22

What is meant by fat embolism?

Answer 22

• Occurs in cases of severe trauma with multiple fractures, releasing fat from the bone marrow into the circulation and forming an embolism that can travel into the lung and brain but it is mainly asymptomatic

Question 23

What is an Air embolism?

Answer 23

It is the entry of air bubbles into the circulation that might be due to vascular surgery, chest trauma, etc, >100ml of air needed to produce a symptom

Question 24

What is meant by shock?

Answer 24

It is a clinical syndrome that results from inadequate tissue perfusion due to:

1) Cardiogenic shock (large MI)
2) Hypovolemic shock (losing a lot of fluid “like burns, severe hemorrhage, etc”)
3) Septic shock (microbial sepsis due to for example toxins that vasodilate the BV’s)
4) Anaphylactic shock (due to allergy)
5) Neurogenic shock

Question 25

What is a cardiogenic shock?

Answer 25

1) The failure of the myocardial pump due to:
- MI
- Myocardial rupture
- Cardiac arrhythmia

2) Extrinsic compression
- Cardiac tamponade

3) Outflow obstruction
- Pulmonary embolus