Liver Failure

Question 1

What are the common causes of acute liver failure

Answer 1

Paracetamol damage

Sudden loss of synthetic or metabolic functions

Question 2

Describe how paracetamol overuse can cause acute liver failure

Answer 2

Free radical damage to the hepatocytes caused by processing paracetamol through an alternative pathway due to blockage from overloading of the normal pathways

Question 3

How may patients survive acute liver failure

Answer 3

If they can be kept alive for long enough, their liver may gradually come back into function as there is large regenerative potential
Transplant often the only option

Question 4

What are the common causes of chronic liver failure

Answer 4

Cirrhosis
Primary liver cancer - can follow from cirrhosis or happen from other causes such as a hepatitis infection
Secondary liver cancer - metastases, often from bowel cancer

Question 5

Why does liver cirrhosis occur

Answer 5

When the liver regenerates, although the cells can regenerate, the liver architect often can’t, so if there is enough fibrosis to lose the normal liver architecture, there will be permanent loss of liver function that will result in cirrhosis

Question 6

What are the common causes of liver cirrhosis (6)

Answer 6

Multi factorial aetiology:
Alcohol
Primary biliary cirrhosis
Viral disease - chronic active hepatitis
Autoimmune chronic hepatitis
Haemachromatosis
Cystic fibrosis

Question 7

What are the signs and symptoms of liver cirrhosis

Answer 7

Often none
Acute bleed - portal hypertension and oesophageal varices
Jaundice
Oedema and ascites
Encephalopathy 
Spider naevi, pal Mary erythema

Question 8

Why is ascites a sign of cirrhosis

Answer 8

When lack of synthetic ability to produce normal plasma proteins, there will be a loss of the plasma oncotic pressure which holds fluid within the blood vessels
As this reduces fluid will more easily move into the tissues and particular from the portal vein into the peritoneum where it accumulates

Question 9

What are spider naevi

Answer 9

Small prominent arterioles which develop near the skin and become enlarged and produce a central arteriole with lots of feeder vessels coming away from them
Looks like a spider

Question 10

What is palmar erythema

Answer 10

When there is high oestrogen in the blood the patient will develop the pattern of a pale palm surrounded by erythema around the margins of the hand

Question 11

What is ascites

Answer 11

Fluid accumulation in the peritoneum due to low plasma protein synthesis producing a lower oncotic pressure within the blood vessels such that fluid moves easily from vessels out into the tissues

Question 12

How is ascites treated

Answer 12

Necessary to drain manually to release the pressure it is placing on the thorax

Question 13

What are oesophageal varices

Answer 13

Dilated and thin-walled veins in the oesophagus

Question 14

How to oesophageal varices form

Answer 14

Blood entering the portal system has no exit route as the portal vein cannot communicate with the hepatic vein so it escapes at the edge of the embryological gut at the lower oesophagus
Blood engorges as it passes through vessels in the lower oesophagus

Question 15

What are the consequences of oesophageal varices

Answer 15

May protrude into the oesophageal lumen

Are easy to rupture which will lead to a catastrophic bleed

Question 16

How is a patients survival rate affected if they stop drinking

Answer 16

Survival rate significantly reduces even if there is a second cause of liver failure eg - oesophageal varices
This is due to there being some residual liver regeneration that can take place

Question 17

What synthetic functions are lost during liver failure

Answer 17

Loss of plasma proteins will lead to problems with ascites and oedema, patient will present with swollen ankles and abdomen
Due to loss of clotting factors, if the patient develops oesophageal varices which then rupture, there is little ability for the blood to be able to clot

Question 18

What metabolic functions are lost in liver failure

Answer 18

Loss of first pass metabolism
Products of the metabolism which are toxic to the brain will not be removed and will pass, causing encephalopathy
Failure of conjugation of bilirubin will lead to jaundice

Question 19

What different tests can be used for liver function

Answer 19

Hepatic enzyme level tests - ALT, GGT

INR - most useful

Question 20

Why can hepatic cell enzyme levels be used to test liver function

Answer 20

These enzymes will escape if there is damage or inflammation more easily that if there is health in the liver
If inflammation in the liver, these enzymes will be detected more in the blood

Question 21

Why are hepatic cell enzyme tests not always useful

Answer 21

If there is a large liver producing a normal amount of enzymes we may find raised levels even though the liver is healthy
Similarly a fibrosed liver may produce a lot of hepatic enzymes but the levels measured are actually normal as there are fewer cells producing a higher amount of enzyme

Question 22

What is INR

Answer 22

Measures time taken for prothrombin to form thrombin and compares it against a control

Question 23

What is a normal INR for a patient taking warfarin

Answer 23

2-4

Question 24

What is considered a high INR for a patient with liver failure

Answer 24

1.2-1.3

Question 25

What are the effects of liver failure

Answer 25

Fluid retention - ascites and oedema
Raised INR as the liver is no longer synthesising clotting factors effectively
Portal hypertension leading to oesophageal varices
Inability to remove waste products leading to encephalopathy
Build up in the blood of unconjugated bilirubin leading to jaundice

Question 26

What treatment options are available for liver failure

Answer 26

Managing things such as alcohol consumption and infection are very important
Transplantation is the only cure
Artificial liver systems are not yet available but are starting to provide some degree of liver function

Question 27

Describe how a live transplant donor can be used in a liver transplant

Answer 27

When a liver is donated, each liver has 3 lobes each of which can be transplanted into separate people
Therefore a single lobe can be removed from a live donor and transplanted

Question 28

Why are live donor liver transplants very risky

Answer 28

It requires good division of major blood vessels supplying each lobe and that these can be identified
If this is not the case there will be catastrophic bleeding and it is likely the donor will die as a consequence

Question 29

What must a dentist remember when treating a patient at risk of liver failure (Metabolic consequences)

Answer 29

Sedatives are going to be a problem and giving IV sedation out of hospital may be risky
May be necessary to reduce doses of normal medicines because of accumulation
Paracetamol often the safest option as NSAIDS will increase bleeding risk
Always ask the physician

Question 30

What must a dentist remember when treating a patient at risk of liver failure (Synthetic consequences)

Answer 30

Remember bleeding tendency, drug binding may be reduced and there may not be gamma globulin synthesis
LA are largely metabolised in the plasma such as articaine and therefore don’t pose a problem