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Flashcards in Physiology Portal HTN Deck (22)
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1
Q

Go over slides for recap

A

xx

2
Q

List consequences of portal HTN.

A

Oesophageal varices
Hepatic encephalopathy
Ascites
Impaired liver function

3
Q

What are varices?

A

Dilation of pre-existing blood vessels.

4
Q

What does portal hypertension lead to?

A

Shunting of blood from the portal vein to the systemic (venous) circulation

5
Q

What may happen to varices?

A

Thin-walled varices may rupture with increased venous pressure (15-20mmHg)
Also can be torn by bulky food passing through the oesophagus

6
Q

What does bleeding from varices cause?

A

Follows on from rupture.
Steady regular bleeding may cause anaemia
In severe cases, acute haemorrhage may occur
Haematemesis = vomit up blood

7
Q

How do we treat haemodynamic changes found in portal HTN?

A

Destruction of varices - sclerotherapy or banding
Drug therapy - vasoconstrictors diminish portal vein inflow from the GI tract
Surgery - shunt surgery, TIPS (transjugular intrahepatic portosystemic shunting), transplantation

8
Q

What causes hepatic encephalopathy?

A

Reduced hepatic detoxification
Toxins (NH3) bypass liver via shunts (protein)
Cerebral dysfunction/neuropsychiatric symptoms

9
Q

What is ascites and what causes it?

A

Accumulation of peritoneal fluid
Increased hydrostatic pressure
Low COP - albumin

10
Q

Define hepatic encephalopathy.

A

Cerebral dysfunction associated with liver failure.
Gradual/chronic - acute/fulminant
Neuropsychiatric symptoms/signs

11
Q

What are the signs of hepatic encephalopathy?

A

Chronic - personality changes, sleep changes, incoordination, asterixis (hand flap)
Acute - rapid progression from altered mental state –> coma, seizures, cerebral oedema

12
Q

What is the pathogenesis behind hepatic encephalopathy?

A

Hepatic detoxification - reduced capacity/bypasses the liver
Blood-brain barrier changes in permeability

13
Q

What toxins are involved in hepatic encephalopathy and how?

A

Ammonia
Gut bacteria vs proteins/urea = normal detoxification
Normally liver detoxifies.
In liver failure we can’t detoxify or it doesn’t get to the liver due to shunt = increased levels in systemic circulation

14
Q

What is the function of astrocytes in hepatic encephalopathy?

A

Usually detoxify ammonia, but increased levels of ammonia overwhelm the astrocytes
This leads to glutamine accumulation/Na-K-ATPase
Resulting in swelling/BBB impaired

15
Q

What other toxins can cause hepatic encephalopathy?

A

Mercaptans (sulfur containing compounds)
GABA-like compounds
Short chain FAs, aromatic AAs
Manganese

16
Q

List precipitating factors for hepatic encephalopathy.

A
GI bleed (more protein in GI tract) 
High protein intake
Constipation 
Metabolic
Infection
Alcohol/neurodepressants
Shunts (TIPS)
17
Q

How do you diagnose hepatic encephalopathy?

A

Overall picture/history of liver disease
Exclude other causes
Impaired neuropsychological performance
Asterixis (flapping tremor)
Elevated serum ammonia concentrations
CSF - increased protein
EEF (electro-encephalic gram) - reduced frequency

18
Q

What is the management for hepatic encephalopathy?

A
Care 
Precipitating factor treatment 
Lactulose - laxative for constipation 
Antibiotics
Diet - decrease proteins 
P-V shunt (TIPS) 
Transplant
19
Q

What is ascites and what disorders cause it?

A

Excess of peritoneal fluid - common complication of cirrhosis/portal HTN

20
Q

Describe why ascites is serious.

A

Median survival 2 years from onset of ascites
Survival depends mainly on liver function
Spontaneous Bacterial Peritonitis in 25% of cases
Low urinary sodium and SBP predict high mortality

21
Q

What is the pathophysiology behind ascites?

A

Increased hydrostatic pressure - lymph loss
Reduced COP
Sodium and fluid retention

22
Q

What is the management for ascites?

A
Limit sodium intake
Bed rest
Diuretics - spironolactone 
Paracentesis - drains ascites 
P-V shunt (TIPS) 
Transplant