Module 3 -Path continued

Question 1

What is the etiology of a nitrogen embolism/ the bends/Caisson’s Disease

Answer 1

Deep sea diving without Caisson’s chamber or deeper than 10meters

Question 2

What is the pathogenesis of a nitrogen embolism?

Answer 2

O2, N2 dissolve in high amounts in blood and tissues due to high pressure –> sudden resurfacing releases N2, O2 –> O2 reabsorbed, N2 bubbles out –ruptures tissues and forms emboli in vessels –> platelets adhere to N2 ,form secondary thrombi and aggravate ischemia

Question 3

In regards to nitrogen emboli, what are the effects if found in the brain, muscles/joints, or lungs

Answer 3

Brain = death 
Muscles/Joints = bends 
Lungs = edema and hemorrhage (chokes)

Question 4

What is Caisson’s Disease?

Answer 4

Persistent (Chronic) gas emboli in bones –> necrosis in femur, tibia, and humerus

Question 5

What is the treatment for Caisson’s Disease?

Answer 5

Pressure chamber (slow decompression)

Question 6

What is an air embolism?

Answer 6

150mL of air in venous circulation through neck wounds, thoracentesis, cut jugular vein, hemodialysis, child birth, abortion

Question 7

What is the pathogenesis for air embolism?

Answer 7

Air bubbles coalesce and obstruct flow of blood in right ventricle, lungs and brain
Frothy mixture in right ventricles –> ineffective ejection –> may occlude large vessels

Question 8

Where does a white infarct occur?

Answer 8

Solid organs with single blood supply (no dual or collateral circulation)

Question 9

What is the pathogenesis for a white infarct?

Answer 9

Arterial occlusion –> decreased O2 supply –> white infarct (wedge shaped) –> ischemic coagulative necrosis

Question 10

In the heart what is the common etiology for a white infarct?

Answer 10

Occlusion of LAD due to atherosclerosidic plaque with superimposed thrombus and this causes an MI and a pale infarct

Question 11

In the kidney what is the common etiology for a white infarct? And how would you get a white or pale infarct in the kidney?

Answer 11

Unilateral - asymptomatic
Bilateral –> decreased urine output
Hypovolemic show because this leads to acute ischemia

Question 12

In the spleen what is the common etiology for a white infarct?

Answer 12

Sickle cell disease

Question 13

Where do Red (hemorrhagic) infarcts occur?

Answer 13

Loose tissues with collateral/dual blood supply (lungs, small bowl, testicles)
Reperfusion injury via TPA ( free radical damage)
Venous obstruction via testicular torsion (testicular veins are torsed)
Coagulative necrosis

Question 14

If a red infarct occurs in the lungs what is this usually do to?

Answer 14

Usually due to Major pulmonary embolus (from DVT) + compromised bronchial artery –> hemorrhage/congestion – >red infarct –> coagulative necrosis

Question 15

In the GI system if there is a red infarct the area is referred to as a watershed area, where is the exact location in the GI tract?

Answer 15

Splenic Flexure (where SMA ends, IMA begins) most vulnerable to hypoxia

Question 16

In the small intestine a red infarct is caused by what?

Answer 16

Volvulus, obstruction, or intersusception (proximal bowel goes into the distal bowel)

Question 17

A cerebral infarct is usually do to what?

Answer 17

Atherosclerosis with superimposed thrombus in vertebro-basilar artery
(thrombo-emboli in the internal carotid/MCA are less common)

Question 18

In regards to a cerebral infarct explain the progression of necrosis that will be seen

Answer 18

12-24 hours: Coagulative necrosis/hemorrhage due to reperfusion
24-48 hours: microglia engulf necrotic material –> Gitter cells
Then you have liquefactive necrosis and gliosis of surrounding area

Question 19

What are key findings of a Myocardial infarction?

Answer 19

Coronary atherosclerosis with superimposed thrombosis
Left anterior descending is the commonest involved
Coagulation necrosis
Initially blotchy , later pale scar tissue
Cardiac enzymes raise in serum
Presents with severe chest pain

Question 20

In a white infarct where is the site of occlusion on gross specimen?

Answer 20

Apex!

Question 21

What is the most accurate test for an MI?

Answer 21

Troponin I (does not lower until 7-10 days post MI) 
however if a patient is admitted to the floor post MI and you think they are experiencing another MI, what test would you order???? CK-MB because trop will most likely still be high (CK-MB has a much shorter window)

Question 22

In the lab slides the picture on the left shows what kind of morphological changes of an MI ?

Answer 22

Acute MI: 1-3 days because no nucleus in myocardial fibers: coagulative necrosis and this is irreversible and lots of neutrophils

Question 23

In the lab slides the picture to the right shows what kind of morphological changes of an MI?

Answer 23

Granulation tissues and collagen so this shows up between 10-14 days post MI. Type III collagen and angiogenesis

Question 24

What is the most common cause of death when a person experiences an MI?

Answer 24

Arrhythmia’s due to damage to the purkinje fibers

Question 25

In the GI system the patient experiences a red infarct, what is the last place that will get blood?

Answer 25

Mucosa (last place to get oxygenated blood)

Question 26

A red infarct is a surgical emergency why?

Answer 26

because the walls are soo weak they are ready to perforate

perforation –>peritonitis –> gram negative septic shock from e.coli –> DIC

Question 27

What are findings on exam of a GI red infarct?

Answer 27

abd pain
blood diarrhea
fever
absent/reduced bowl sounds

Question 28

What diagostic tools would you do an a patient with a GI red infarct?

Answer 28

Exploratory laparotomy

Angiogram

Question 29

best investigation for a stroke?

Answer 29

First do a CT to rule out hemorrhagic stroke

then do an MRI to look for ischemic stroke