portal hypertension
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It is defined as a portal venous pressure above 7 mmHg; however, clinical features or complications do not usually develop until the portal venous pressure exceeds 12 mmHg
Clinical features
The clinical features of portal hypertension result principally from portal venous congestion and collateral vessel formation
Splenomegaly is a cardinal finding, and a diagnosis of portal hypertension is unusual when splenomegaly cannot be detected clinically or by ultrasonography
Collateral vessels may be visible on the anterior abdominal wall and occasionally several radiate from the umbilicus to form a caput medusae. Rarely, a large umbilical collateral vessel has a blood flow sufficient to give a venous hum on auscultation The most important collateral vessel formation occurs in the oesophagus and stomach, and this can be a source of severe bleeding. Rectal varices also cause bleeding and are often mistaken for haemorrhoids
Fetor hepaticus results from portosystemic shunting of blood, which allows mercaptans to pass directly to the lungs
Ascites can occur as a result of portal hypertension when intrahepatic sinusoidal distension is present, as occurs with post-hepatic portal hypertension or cirrhosis. Pre-sinusoidal portal hypertension does not cause ascites, as there is no distension of the sinusoids
The most important clinical feature of portal hypertension is variceal bleeding, which commonly arises from oesophageal varices located within 3-5 cm of the oesophagogastric junction, or from gastric varices
Bleeding from varices at other sites is comparatively uncommon but most often occurs from varices in the rectum or intestinal stomas
Complications of portal hypertension
Variceal bleeding: oesophageal, gastric, other (rare)
Congestive gastropathy
Hypersplenism
Ascites
Iron deficiency anaemia
Renal failure
Hepatic encephalopathy
Investigations
The diagnosis is often made on clinical grounds. Portal venous pressure measurements are rarely needed for clinical assessment or routine management
Pressure measurements are usually made by using a balloon catheter inserted using the transjugular route (via the inferior vena cava into a hepatic vein and then hepatic venule) to measure the wedged hepatic venous pressure (WHVP)
Thrombocytopenia is common due to hypersplenism, and platelet counts are usually in the region of 100 × 109/L; values below 50 × 109/L are uncommon
Leucopenia occurs occasionally
endoscopic examination of the upper gastrointestinal tract to determine gastro-oesophageal varices
US often shows features of portal hypertension, such as splenomegaly and collateral vessels, and can sometimes indicate the cause, such as liver disease or portal vein thrombosis
CT and MRI angiography can identify the extent of portal vein clot and are used to identify hepatic vein patency
Management
Management of variceal bleeding
saline (1-2 L) :Extracellular volume replacement
Banding ligation and sclerotherapy: It stops variceal bleeding in 80% of patients and can be repeated if bleeding recurs. Banding is repeated every 1-2 weeks until the varices are obliterated - Pharmacological reduction of portal venous pressure
Terlipressin is the current drug of choice and releases the vasoconstrictor (vasopressin) , over several hours in amounts sufficient to reduce the portal pressure without producing systemic effects. It is given in a dose of 2 mg i.v. 6-hourly until bleeding stops, and then 1 mg 6-hourly for a further 24 hours
Balloon tamponade
a Sengstaken-Blakemore tube possessing two balloons which exert pressure in the fundus of the stomach and in the lower oesophagus respectively .Current modifications incorporate additional lumens to allow material to be aspirated from the stomach and from the oesophagus above the oesophageal balloon5- Transjugular intrahepatic portosystemic stent shunting (TIPSS) - Portosystemic shunt surgery
Hepatic encephalopathy
IT is a neuropsychiatric syndrome caused by chronic liver disease
Features include changes of intellect, personality, emotions and consciousness, with or without neurological signs
The earliest features are very mild but, as the condition becomes more severe, apathy, inability to concentrate, confusion, disorientation, drowsiness, slurring of speech and eventually coma develop. Convulsions sometimes occur
Examination usually shows a flapping tremor , inability to perform simple mental arithmetic tasks or to draw objects such as a star (constructional apraxia), and, as the condition progresses, hyper-reflexia and bilateral extensor plantar responsesHepatic encephalopathy rarely causes focal neurological signs, and if these are present, other causes must be sought
Fetor hepaticus, is usually present
Pathophysiology
Hepatic encephalopathy is thought to be due to a disturbance of brain function provoked by circulating neurotoxins that are normally metabolised by the liver
nitrogenous substances produced in the gut are normally metabolised by the healthy liver. Ammonia has traditionally been considered an important factor and ammonia-induced alteration in astrocyte glutamine and glutamate concentrations may be important. Recent interest has focused on ?-aminobutyric acid as a mediator, along with other factors such as octopamine, amino acids, mercaptans and fatty acids which can act as neurotransmitters.
Disruption of the function of the blood-brain barrier is a feature of acute hepatic failure and may lead to cerebral oedema.
Investigations
The diagnosis can usually be made clinically
an electroencephalogram (EEG) shows diffuse slowing of the normal alpha waves with eventual development of delta waves.
The arterial ammonia is usually increased in patients with hepatic encephalopathy.
Management
The principles of management are to treat or remove precipitating causes and to suppress the production of neurotoxins by bacteria in the bowel.
Dietary protein restriction is rarely needed and is no longer recommended as first-line treatment because it is unpalatable and can lead to a worsening nutritional state in already malnourished patients.
Lactulose (15-30 mL 8-hourly) is a disaccharide which is taken orally and reaches the colon intact, to be metabolised by colonic bacteria. It produces an osmotic laxative effect, reduces the pH of the colonic content, thereby limiting colonic ammonia absorption, and promotes the incorporation of nitrogen into bacteria.
Lactitol is a rather more palatable alternative to lactulose, with a less explosive action on bowel function.
Neomycin (1-4 g 4-6-hourly) is an antibiotic which acts by reducing the bacterial content of the bowel
Chronic or refractory hepatic encephalopathy is one of the main indications for liver transplantation.