College Answer

a) What is a TIPS procedure and why is it used in patients with portal hypertension?

The hepatic vein is accessed via the internal jugular vein and IVC. A needle is then passed to connect the hepatic vein with the large portal vein near the centre of the liver, the needle tract  dilated  and  a stent  inserted  to maintain  the tract and form  the shunt  between  the higher pressure portal vein and the lower pressure hepatic vein.   This reduces portal hypertension.

b) What are 2 recognised indications for this procedure?

a)     Variceal bleeding that has failed endoscopic and pharmacological treatment. b)  Refractory ascites

c) Excluding mortality list 5 COMMON complications of TIPS procedure

•   thrombosis
•   occlusion of the stent
•   capsular puncture
•   bleeding
•   encephalopathy
•   stent migration

d) Describe  one  classification  system  used  in assessing  severity  of chronic  liver disease and outline its utility.

Either: Childs-Pugh score
Classified A,B or C by a composite of Total bilirubin, albumin, INR, ascites and hepatic encephalopathy.  Originally  used for prognostication  for surgery  – also used for prognostication  in  chronic  liver  disease  and  prediction  of  likelihood  of  complications  of cirrhosis

Or: MELD score severity scoring system for assessing severity of chronic liver that uses the serum  bilirubin,  creatinine  and INR. Initially developed  to predict  three month survival  in patients post TIPS. Now used for prognosis of liver disease and prioritizing liver transplant recipients

Discussion

The first 3 parts of this question are reasonably straightforward.

• TIPS is the transjugular intrahepatic portosystemic shunt, a conduit for portal venous blood to bypass the ineffective liver and thereby relieve portal hypertension.

Indications for TIPS:

• Refractory ascites
• Refractory rebleeding in variceal disease
• Hepatorenal syndrome
• Hepatopulmonary syndrome
• Hepatic vein thrombosis
• Hepatic veno-occlusive disease
• Portal vein thrombosis

Technical complications of TIPS:

• Vascular access complications
• Hepatic damage (through-and-through puncture): risk of intraperitoneal haemorrhage is 1-2%
• Haemobilia (damage to the biliary tree)
• Shunt stenosis or thrombosis (it happens in up to 70%)
• Shunt migration
• Hepatic vein stenosis (this can sabotage a future transplant)

Complications from portal venous shunting:

• Worsening hepatic encephalopathy
• Bilirubin rise: the diseased liver doesn't even get a chance to metabolise it
• Ischaemic hepatitis: the liver gets much of its oxygen from the portal vein, and even in spite of the hepatic arterial buffer response there is a risk of ischaemic hepatitis.
• Tricuspid endocarditis (organisms may now travel directly from the leaky gut into the systemic circulation)
• Haemolysis (due to the direct shearing effect of being in contact with the shunt)
• "Unmasked" cardiomyopathy: the TIPS returns splanchnic blood to the heart and acts as a volume challenge, and if there was pre-existing cardiomyopathy, it may be dramatically revealed in this manner.

The last part of the question is far from straightforward. How does one "briefly outline the utility" of something like the Childs-Pugh scoring system?

The system itself has existed since the 1970s, and it includes in its assessment the albumin level, the prothrombin time, the bilirubin, the presence of encephalopathy and the presence of ascites.

It seems the main point is prognosis. The utility of the scoring systems in general has been to estimate the expected lifespan of a cirrhosis patient, which has implications for liver transplantation. However, in the ICU, the overall mortality for cirrhosis patients is about 43%, irrespective of Childs-Pugh score. In general, SOFA and APACHE are better systems for predicting in-ICU mortality than the liver-specific scoring systems.

Thus, the answer to the "briefly outline utility" question should look like this:

Classification system:

• Childs-Pugh scoring system for cirrhosis
• Uses bilirubin, albumin, ascites, encephalopathy and INR to stratify the severity of cirrhosis according to risk of mortality and morbidity, particularly in the context of preoperative assessment

Its utility, briefly:

• Pre-transplant risk stratification
• Pre-TIPS risk stratification
• Helps estimate prognosis in untreated liver disease
• Does not discriminate survivors and non-survivors among cirrhosis patients admitted to ICU.