Hemodynamic disorders, Thromboembolism and shock (from Robbins Basic Pathology)

PART 1

edema

• altered endothelial function

• raised vascular hydrostatic pressure

• plasma protein content decreased

life-threatening hypoxia

• edema with fluid filled alveoli

hemostasis

-process of blood clotting -prevent excessive bleeding after blood vessels damaged

Inadequate hemostasis leads to

1. hypotension

2. shock

3. death

Inappropriate clotting leads to

-thrombosis

-embolism -causing ischemia death

(infarction) thromboembolism leads to

1. myocardial infarction

2. pulmonary embolism

3. cerebrovascular accident (Stroke)

hyperemia and congestion

-raised blood volume within a tissue

hyperemia VS congestion

active VS passive process

Acute Pulmonary congestion

1. blood-engorged alveoli

2. variability in alveolar septal edema

3. intra alveolar haemorrhage

chronic pulmonary congestion

1. thickened and fibrotic septa

2. alveolar space with macrophage (laden with hemosiderin- heart failure-cells/phagocytosed red blood cells)

acute hepatic congestion

1. distended central vein and sinusoids

2. necrosis of centrally located hepatocytes

3. less severe hypoxia at the periportal hepatocytes due to proximity to the hepatic arterioles, they will develop reversible fatty change.

chronic passive congestion of the liver

1. red brown central region of the hepatic lobules, depressed (cell loss)

2. surrounded by uncongested tan, fatty liver (nutmeg)

3. centrilobular necrosis, hemorrhage , hemosiderin laden macrophage

edema

accumulation of body fluid in the interstitial spaces

effusion

extravascular fluid accumulate in body cavities

Examples of effusions

1. pleural effusion (hydrothorax)

2. pericardial effusion (hydropericardium)

3. peritoneal cavity (hydroperitoneum, ascites)

anasarca

1. severe / massive generalised edema

2. profound swellings of the subcutaneous tissue

3. accumulate in body cavities

Factor affecting fluid movement

1. vascular hydrostatic pressure

2. colloid osmotic pressure (induced by plasma protein)

net outflow fluid

drain by lymphatic vessels

edema fluid accumulation aetiology

1. increased vascular hydrostatic pressure ( due to impaired venous return, arteriolar dilation)

2. decreased osmotic colloid pressure

3. inflammation- increased vascular permeability

4. lymphatic obstruction

5. Na+ retention

transudate caused by imbalanced of pressure (protein poor)

exudate caused by injury or inflammation (protein rich due to increased vascular permeability)

elevated hydrostatic pressure aetiology

impaired venous return

1. DVT (distal leg)

2. congestive heart failure (raised venous hydrostatic pressure due to decrease cardiac output leading to systemic venous congestion)

3. cardiac/ renal / hepatic failure

decreased osmotic pressure

due to albumin loss 1. nephrotic syndrome

2. leaky glomerular capillaries

3. liver cirrhosis (decreased albumin synthesis)

• increased water and sodium retention by the kidney do not correct the plasma volume deficit, in contrary in exacerbate edema

lymphatic obstruction

1. compromised resorption of fluid from the interstitial spaces

2. elephantiasis: parasitic infection filariasis (massive edema of the lower extremity, external genitalia) with inguinal lymph node and lymphatic fibrosis

decreased plasma albumin aetiology

malnutrition, hepatic synthesis, nephrotic syndrome

decreased renal blood flow leads to

1. activation of RAAS

2. vicious cycle

3. does not solve the underlying problems while exacerbate edema

excessive salt and water retention due to

1. post-streptococcal glomerulonephritis

2. acute renal failure

most common location of edema

1. lungs

2. subcutaneous tissues

3. brain

recumbent -lying down

dependent edema

edema most pronounced in leg when standing edema most pronounced in sacrum when lying down

edema due to renal dysfunction/ nephrotic syndrome

1. initial manifestation in loose CT

2. eg: eyelids, periorbital edema

blood-tinged- blood streak

brain edema

1. sulci narrow

2. gyri swell

subcutaneous edema

1. potential underlying cardiac/ renal diseases (eg: left ventricular failure, renal failure, respiratory distress syndrome, lung infection and inflammation- interfering the normal ventilatory function which leads to death)

2. significant edema can impair wound healing and infection clearance

3. may lead to brain herniation through the foramen magnum

4. increased intracranial pressure leads to brain stem vascular supply compressions. This in turn leads to medullary center ischemic injury compromising respiration and other important functions

Hemorrhage is extravasation of blood

Hemorrhage main etiology

1. damage to the blood vessels

2. defective clot formation

Chronic congested tissue leads to capillary bleeding

Hemorrhage in specific etiology

1. trauma

2. atherosclerosis

3. inflammation

4. neoplastic erosion of vessel wall

Hemorrhagic Diatheses

A collective term for risk of hemorrhage

1. Inherited or acquired defects

2. Defects in blood vessels walls, platelets, coagulation factors.

Hematoma

hemorrhage accumulate within a tissue range from trivial injury (bruise) to fatal (massive retroperitoneal hematoma from ruptured Dissecting Aortic Aneurysm)

jaundice after massive hemorrhage due to massive breakdown of rbc and hemoglobin

Petechiae

1-2mm diameter -hemorrhage into the skin, mucous membranes or serosal surfaces

causes of petechiae

1. thrombocytopenia

2. defective platelet functions

3. loss of vascular wall support

4. vitamin c deficiency

purpura

larger (3-5mm)

causes of purpura

1. could be same as petechiae

2. trauma

3. vasculitis

4. increased vascular fragility

ecchymoses

larger (1-2cm)

bruises (subcutaneous hematoma)

color changes of bruises

1. hemoglobin (red-blue) to bilirubin (blue-green)

2. hemosiderin (golden brown)

little impact if there is

rapid blood loss up to 20% blood volume slow blood loss of greater than 20% blood volume

massive blood loss leads to

1. hypovolemic shock

chronic/ recurrent external blood loss leads to iron deficiency anemia (loss of iron in hemoglobin) due to

1. peptic ulcer OR

2. menstrual bleeding

hematoma

internal bleeding does not result in iron deficiency as a result of recycling of phagocytosed red blood cells.

Part 2

Hemostasis & Thrombosis