Hemodynamic Disorders Flashcards
(111 cards)
What is blood hemostatis?
- Vessel Walls - balance between intravascular hydrostatic pressure and plasma colloid osmotic pressure to prevent edema
- Liquid blood - balance to prevent hemorrhage or thrombosis
**Body tries to keep us in hemostatic state to prevent these things from happening
What is edema?
Increased fluid in interstitial space or body cavities
What is hydrothorax
Pleural effusion (edema in lung)
What is hydroperitoneum
Ascites (edema in peritoneal cavity in abdomen)
What is Anasarca
Severe, generalized edema with profound subcutaneous swelling
What is Dependent edema?
Gravity dependent (common in congestive heart failure)
What is Pitting edema?
Finger pressure displaces interstitial fluid
What are the two types of edema?
Non-inflammatory - protein poor, transudate (getting water and electrolytes out but not cells b/c permeability has not increased)
Inflammatory - protein rich, exudate (leaky b.v. cause loss of proteins)
Describe the pathogenesis of edema
-Increased hydrostatic pressure
-Reduced plasma osmotic pressure
-Lymphatic obstruction (lymphatics normally return extra fluid back to the heart. So when these stop working, the extra fluid doesn’t get back and just pools in the interstitial space)
-Sodium retention
-Inflammation
Describe what normally happens in a capillary bed
-At the arterial end, fluid gets pushed out increasing hydrostatic pressure
-Interstitial fluid pressure is increased because of fluid coming out
-Plasma osmotic pressure in the venous end drops causing fluid to be pulled back in
-Fluid in the venous end is more dense because there is more protein component per volume of fluid than you had on the arterial end b/c some of this fluid has come out
-Fluid balance is eventually restored through lymphatics
**Problems occur when hydrostatic pressure on arterial end becomes excessive, or colloid osmotic pressure increases
(see slide 7)
What can cause increased hydrostatic pressure
Impaired venous return due to:
-Congestive Heart Failure (CHF) –> decreased blood to kidney stimulates renin/angiotensin pathway which worsens the peripheral edema
-Liver disease (ascites)
-Venous obstruction/compression: thrombosis, mass (external pressure), inactivity
What is the function of Renin?
Constricts renal b.v. and retains Na+ bringing in water
Describe the Renin pathway
- Any decrease in blood flow causes renin release which converts Angiotensin to Angiotensin I
- Angiotensin I flows through renal and stimulates ACE which converts Angiotensin I to Angiotensin II
- Angiotensin II causes:
-Increased Na+ reabsorption b/c of Aldosterone secretion
-Increased Na+ brings water with it
-Arteriolar vasoconstriction in the kidney
-ADH secretion from pituitary causing collection duct to absorb more water - All of this leads to increased water and salt retention. Effective circulating volume increases. Perfusion of the juxtaglomerular apparatus increases.
*The goal was to get more blood back to the kidney but if your heart is defective, then it’s not going to help.
What part of the heart stops functioning in someone with CHF? What does this lead to?
-Left ventricle
-When the left ventricle stops working, blood backs up into the lungs causing shortness of breath and tiring easily (this is the initial phase of CHF called “Left Sided Heart Failure”)
-If not treated, it will effect the R side of the heart b/c of pulmonary hypertension
After right sided-heart failure in CHF, what is the first place in gravity fluid will hit?
The liver causing enlargement of the liver
Describe what happens with Liver Disease
-Liver disease prevents blood from flowing through the heart normally
-Portal vein gets increased pressure (portal hypertension) and blood flows back to other organs leading to enlargement of the organs (intestine, stomach, spleen –> symptoms of abdominal swelling (ascites))
-With liver disease we see deoxygenated blood right around the central vein (called central lobular necrosis) b/c right on the central vein you have no oxygen so the cells die at that area. This area will gradually enlarge and then reach the portal triad and ongoing –> 1. Inferior Vena Cava, 2. Hepatic Vein, 3. Central Vein, 4. Portal Triad Vein, 5. Out to Spleen, Stomach, Abdomen
What causes reduced plasma oncotic pressure?
Decreased albumin (main blood protein) in the blood (the protein component of the blood is altered)
-Inadequate synthesis - liver disease
-Increased loss of albumin - nephrotic syndrome
What is the net result of reduced plasma oncotic pressure?
Net result is stimulation of renin-angiotensin-aldosterone pathway with Na+ and fluid retention
–> If you lose protein into your urine, the plasma oncotic pressure of blood decreases and water tends to go with it. So blood volume decrease and that stimulates renin, which tries to increase water retention but there’s no protein to go with it so you retain the water but lose it into the interstitial fluid
What causes lymphatic obstruction?
Due to inflammation or neoplastic growth
-parasitic infection (filariasis)
-breast cancer
What is Lymphadema?
Edema related to deficient lymphatics
What causes sodium and water retention?
-Acute renal failure
-Post-strep glomerulonephritis (autoimmune stimulating kidney not to work)
*Normal excretion and retention of Na+ gets thrown off. So instead of excreting the appropriate amount, you start not filtering at all and so you retain more Na+ and water over time leading to edema
What is the significance of edema in the brain
Herniation, compression of brainstem vessels, can cause death
What is the significance of edema in the lung
-Edema may occur here due to LV failure
-Causes breathing difficulty, infections
What is the significance of edema in the larynx
Airway obstruction (Ludwigs’ angina)