The Management of Acute Hepatic Failure SHEILA SHERLOCK SP PARBHOO
Total Page：16
File Type：pdf, Size：1020Kb
Postgraduate Medical Journal (July 1971) 47, 493-498. Postgrad Med J: first published as 10.1136/pgmj.47.549.493 on 1 July 1971. Downloaded from The management of acute hepatic failure SHEILA SHERLOCK S. P. PARBHOO Departments of Medicine and Surgery, Royal Free Hospital, London W.C.1 Summary TABLE 1. Royal Free Hospital fulminant hepatitis Acute fulminant hepatitis leads to complex bio- 1959-70 chemical and circulatory disturbances including coma. Number 83 These can be predicted to some extent by knowledge Viral hepatitis 63 of the functions of the normal liver cells. Ineffective Drugs 19 Halothane 6 haemostasis, coma, hypoglycaemia, electrolyte abnor- Amine oxidase inhibitor 9 malities, hypotension and renal circulatory failure are Anti-TB 3 particularly important. Paracetamol 1 Management should be governed by the abnor- Fatty liver pregnancy malities found in the individual patient. Fluid overload Survived 9 (12%Y) and sedation must be avoided. More complex methods Died 74 of temporary hepatic support such as exchange trans- fusion or perfusion of the isolated pig's liver should sonality. The patient may show episodes of anti- Protected by copyright. only be considered after simpler methods of correction social behaviour or character disturbance. Night- have been attempted for a reasonable period of time mares, headache and dizziness are other inaugural and found wanting. non-specific symptoms. Violent behaviour is common The prognosis of acute hepatocellular failure in children, who may also have fits. The acute reaching the stage of deep coma is very poor, the organic reaction with delirium and clouding of mortality being about 80-90 %. consciousness rapidly progresses to coma. Tremor may be transient and overlooked. Fetor hepaticus ACUTE hepatocellular failure must be distinguished is a good sign. Daily estimation of hepatic size is from chronic failure for the more elaborate pro- very useful in patients with acute virus hepatitis: a cedures of temporary hepatic support such as shrinking liver is a danger signal. If possible, an exchange blood transfusion or the isolated perfused electroencephalogram should be done, when slowing liver are not justifiable in the presence of chronic of the mean frequency is anotherearly danger signal. irreversible liver disease. A careful search must The serum transaminase, serum bilirubin or blood http://pmj.bmj.com/ therefore be made for evidence of underlying chronic ammonia levels are not particularly helpful as liver disease such as a prolonged history, a large hard prognostic signs. liver, gross ascites, marked splenomegaly and vascular spiders on the skin. The most frequent Failure of the Krebs-Henselheit cycle cause of acute hepatocellular failure is acute virus Enzymes involved in this cycle are found in the hepatitis but an identical picture can be related to mitochondria (Fig. 1). These enzymes are responsible drugs particularly hydrazine amine oxidase inhibitors for the metabolism of ammonia, which is produced such as phenelzine (Nardil) or to exposure, usually in the gut and to a much lesser extent by the kidney on September 30, 2021 by guest. multiple, to the anaesthetic agent halothane (fluo- and stomach, to urea. In liver cell failure therefore thane) (Peters, et al., 1969; Klion, Schaffner & one would expect an accumulation of ammonia in Popper, 1969). Suicidal attempts using paracetamol the blood and a reduction in the blood urea con- are increasing as a cause of acute hepatocellular centration. This is indeed so for blood ammonium failure. It may also follow surgical shock with or levels are raised in fulminant hepatitis (Phear, without Gram-negative septicaemia and fatty liver Sherlock & Summerskil, 1955) and in a series of of the last trimester of pregnancy. (Table 1). fulminant hepatitis patients seen at the Royal Free Prognosis is poor, the condition being fatal in Hospital, seven of twenty-nine had a blood urea 90 % of cases if deep coma ensues. level of less than 15 mg/100 ml. In the later stages, blood urea rises due to failure of renal excretion and Danger signals in viral hepatitis to absorption of digested blood from the gut. The One of the earliest signs is change in the per- connection between blood ammonium and hepatic 494 Sheila Sherlock and S. P. Parbhoo Postgrad Med J: first published as 10.1136/pgmj.47.549.493 on 1 July 1971. Downloaded from Glucose metabolism Fatty acid synthesis Soluble fraction FIG. 2. The soluble fraction contains enzymes concerned FIG. 1. Diagram of the hepatocyte at a subcellular level. with glucose metabolism. The mitochondria contain the enzymes of the Krebs- Henseleit cycle. Failure results in high blood ammonia and low urea levels. given via anticubital or femoral vein into the coma has been much discussed (Gabuzda, 1967). In innominate vein or vena cava. Alternatively, 20% general, the connection is more tenuous in acute laevulose may be used; this is less irritant to the hepatocellular failure than in the chronic encephalo- veins. Alertness to the possibility of hypoglycaemia pathy following portacaval shunting. Nevertheless, is an important practical consideration in theProtected by copyright. efforts must be made to reduce it for the blood management of fulminant viral hepatitis. ammonia also reflects the level of other nitrogenous and also possibly toxic products of bacterial meta- Albumin synthesis bolic action in the intestines. The patient is therefore This is a function of the ribosomes of the rough given no protein by mouth and the colon is emptied endoplasmic reticulum (Fig. 3). Reduced synthesis by a high enema and by a magnesium sulphate of albumin has been shown in patients with liver purge. The enema should be of neutral or slightly disease (Tavill, Craigie & Rosenoer, 1968). After acid pH as alkaline solutions favour the absorption recovery from hepatocellular failure, intravenous of ammonia from the colon. Lactulose, a dissacharid salt-poor albumin is often useful for replenishing the not altered by intestinal lactase should be given in a reduced pool of albumin. The dose required is of the dose of 40 ml twice daily by mouth. The lactulose order of 25 g daily until the serum albumin con- is split by colonic bacteria to organic acids so making centration is normal. the contents of the colon more acid and preventing http://pmj.bmj.com/ ammonia absorption. Neomycin is given in a dose of 1 g daily by mouth four times a day. Hypoglycaemia Glycogen granules are stored in the hyaloplasm (Fig. 2). Glycogenolysis is effected by an enzyme on the rough reticulum, glucose-6-phosphatase (Fig. 3). Hypoglycaemia is rare in most forms of on September 30, 2021 by guest. human liver disease, but may complicate fulminant virus hepatitis, especially in children. In one large MNWAM series, two of twenty-nine patients with acute WWv\J hepatocellular failure had blood glucose levels less than 40 mg/100 ml (Jones et al., 1967). Hypogly- Rough caemia may sometimes be very persistent and reticulum intractable (Samson, et al., 1967). It is essential that Protein synthesis the blood glucose be measured repeatedly in patients Glucose - phosphatose with fulminant hepatitis. This should be done at least 4-hourly. At least 1600 calories are supplied as FIG. 3. The rough reticulum is responsible for protein daily glucose drinks or as 20% glucose through synthesis and contains the enzyme glucose-6-phos- a gastric drip. Twenty per cent or 40% dextrose is phatase. Management of acute hepatic failure 495 Postgrad Med J: first published as 10.1136/pgmj.47.549.493 on 1 July 1971. Downloaded from Blood coagulation (Table 2) pathy). This problem is treated by using fresh blood Failure of the blood to clot is particularly impor- (which contains platelets) for transfusion and by tant in patients with fulminant hepatitis and bleeding platelet-rich transfusions. Fibrinolysis is in fact is a frequent cause of death. It is shown by bruising usually of minor importance although a shortened in tissues, bleeding from mucous membranes, from half-life of 131I-fibrin has been shown in patients the gastro-intestinal tract and into the brain. The with fulminant hepatitis (Rake et al., 1970). Intra- patient in acute hepato-cellular failure often dies vascular clotting and consumption of fibrin is shown by the finding of proteolytic degradation products TABLE 2. Clotting problems. Monitor platelets, in the peripheral blood (fibrin-split products) and prothrombin time these should be searched for in the presence of a Treatment Corrects profound haemorrhagic diathesis. These products interfere with platelet aggregation (Thomas, Ream Vitamin K, Bile salt deficiency (10 mg i.m.) Pro., VII, X & Stuart, 1967) and also interfere with normal Stored blood Pro., VII, IX, X fibrinogen polymerization. If they are found the Fresh whole blood V, VII, IX, X, platelets cautious use of heparin (10,000 units intravenously Fresh frozen plasma V, VII, IX, X given continuously over 4 hr) must be considered. Platelet infusions Platelets Calcium gluconate Citrate intoxication Its use must be monitored by thrombin consumption (10 ml/l) tests and by tests for fibrin-split products. Heparin Fibrinolysis Finally the transfusion of large quantities of stored (2000 units 6-hourly) Consumptive coagulopathy blood or plasma raises the possibility of citrate intoxication. This would be expected to be more bleeding from everywhere and in spite of all thera- common in those with hepatic disease for the liver peutic efforts. The causes of this failure of blood metabolises citrates. High concentrations of serum clotting are multiple and complex. The liver syn- citrate have been observed during multiple transfu- Protected by copyright. thesises most of the factors concerned in blood sions in patients with liver disease and these may coagulation. They have a short half-life and rapidly depress the serum ionic calcium. Intravenous calcium become deficient when liver cell function fails. This gluconate supplements should be given (10 ml slowly is reflected in the one-stage prothrombin time being for each litre of concentrated blood transfused).