Symposium on Biliary Tract Disorders
PRE-OPERATIVE ASSESSMENT FOR BILIARY TRACT SURGERY R. Shields Department of Surgery, University of Liverpool
Summary. The pre-operative approach to the patient with prolonged jaundice due to a long-standing obstruction of the bile duct is, we find, very similar to that of the patient with hepatic parenchymal disease who requires surgery for the treatment ofportal hypertension. Complex and sophisticated tests of liver function are not required and a reasonable assessment of the patient's ability to withstand operation may be made by estimating the serum ammonia and bilirubin and the plasma glucose and albumin. Particularly useful in this assessment is the Child's classification (Child, 1964). This is based on 3 clinical and 2 laboratory tests. On this basis the patient may be assigned to I of 3 groups. Patients who belong to Child's group A have good hepatic reserve and are similar to individuals who have been deprived ofno more than 30 per cent oftheir liver function. Patients ofChild's group C, on theother hand, are similar to patients who have lost 90 to 95 per cent ofliverfunction and operation in them carries a considerable risk. Moreover, because of their basic disease, the liver may have no regenerative powers andfurther improvement in liver function cannot be expected. These patients are hardly ever operable, although certain supportive measures may improve their general status and they may eventually be operated upon but considerable risks must be recognised. In an intermediate position are the patients who belong to group B of the Child's classification. These patients have evidence of hepatic dysfunction and require the energetic and detailed preparation described below.
THE potential benefits of biliary surgery may be vitiated if the operation, no matter how well performed technically, is carried out at the wrong time in the unprepared patient. A complex reconstruction of the biliary tract for stricture, or resection of the head of the pancreas in an older patient who has been ravaged by infection and prolonged obstruction of the bile ducts, demands very careful and precise pre-operative assessment particularly the effect upon the patient of the underlyingdisease. However, the commonestoperation upon the biliary tract is cholecystectomy and, when this operation is performed electively upon a thin and fit, young or middle-aged patient for uncomplicated disease of the gallbladder, no more preparation or assessment is required than would be for any other similar abdominal procedure of intermediate severity. The salient features of the pre-operative assessment and preparation of a patient for an operation upon the biliary tract are con-
sidered under the following headings: disorders of coagulation; fluid and electrolyte balance-hepato-renal syndrome; drug metabolism; antibiotic prophylaxis; nutrition; pre-operative temporary drainage. Coagulation disorders The following tests are essential-platelet count, prothrombin time, partial thromboplastin time and thrombin time (this last test may detect fibrin degradation products of which many circulate in the blood in high concentration in biliary tract disease). Abnormalities in the prothrombin time and the partial thromboplastin time indicate deficiencies in factors I, II, V, VII, VIII, IX and X. As far as coagulation disorders are concerned, there are basically 2 clinical problems in these patients. First, there is the patient who has been over-anticoagulated and therefore is low in factors II, VII, IX and X. In practice these are easy to replace. Secondly, in patients with parenchymal liver disease
249
Symposium on Biliary Tract Disorders
there is usually a more generalised deficiency in clotting factors, although factor VIII may be present in the blood in increased amounts. Several of these factors can be replaced fully but usually only partial replacement of factors I and V are possible. In these patients cryoprecipitate of plasma is used to supply fibrinogen, and Prothromplex to supply factors II, IX and X with or without factor VII. It is the practice for every jaundiced patient to receive parenteral vitamin K1 . Abnormalities in clotting usually return to normal within 48 hours. If there is no response, the reasons are twofold-a deficiency of other clotting factors (vitamin K supplies only factors II, VII, IX and X) or the parenchymal damage to the liver is so great that the liver is not able to respond to the injection of vitamin K. Fluid and electrolyte balance-hepato-renal syndrome The term hepato-renal syndrome was coined to describe the association between liver and kidney disease, particularly patients dying of uraemia after biliary tract operations. There is no doubt that there is an increased risk of acute renal failure after operations in patients with obstructive jaundice and that this renal failure carries a poor prognosis. In the kidney of experimental animals and of patients with biliary tract obstruction, there is evidence of glomerular and tubular damage but the cause is quite obscure. Recently it has been suggested that renovascular fibrin deposition associated with endotoxaemia may be responsible. Before and during the operation it is possible to take certain preventive measures which will avoid post-operative oliguria leading to the hepato-renal syndrome. Certain causative factors are clear, e.g. old age, infections, hypoalbuminaernia. It is also claimed that in patients with obstructive jaundice, there is pre-operative evidence of a decreased maximal urinary concentrating ability, and a significantly reduced haematrocrit; the glomerular filtration rate is low and there may be high concentrations in the serum of circulating fibrin degradation products. 250
Careful attention to fluid and electrolyte balance is important. Sodium and potassium balance should be re-established and there should be an adequate fluid intake. Particular attention should be paid to sodium balance particularly if mannitol is to be given intravenously during and immediately after operation. Attention must also be paid to potassium balance for there is always a risk in these patients (particularly if diuretics are being given) that potassium will be lost in the urine, and hypokalaemia and alkalosis will develop. Before, during and after operation it is necessary to measure the serum creatinine, urine osmolality and urine output. In this last respect a catheter should be inserted into the bladder and the urine output determined half-hourly. The aim is that the patient should pass at least 25m1. urine every 30 minutes. In patients, whose serum bilirubin exceeds 120 umol, per 1., mannitol infusions should be given at a rate of 2 m1. 20 per cent solution per kg. body weight before and after operation. Diuretics such as frusemide should be avoided because there is a considerable risk that plasma volume will become depleted and, after an initial diuresis, renal failure may supervene due to the oligaemia. Drug metabolism in bepato-biliary disease The metabolism of drugs, administered to patients with liver disease about to undergo operation, may be altered either because of liver cell damage or because of the obstruction of the bile duct. In bepato-cellular dysfunction the following disorders may be recognised. Delay in drug detoxication. Many drugs are metabolised in the liver and therefore, in parenchymal liver disease, have to be given with great care. Most substances which are detoxified or metabolised in the liver are first hydroxylated and then conjugated with glucuronic or sulphuric acid. The effectiveness of many drugs and the duration of their action depends on this rate of metabolic conversion. Examples of such drugs, which may be given to a patient about to undergo operation, are thiopentone, morphine, atropine and local anaesthetic agents.
Symposiwn on Biliary Tract Disorders
Brain metabolism is abnormal in patients and, secondly, if jaundice develops after with liver disease. The brain becomes ex- an operation during which these drugs have tremely sensitive to a variety of centrally- been given, the diagnostic picture will be acting agents, for example, barbiturates. confused. Carbohydrate metabolism. In patients with Coagulation problems. These have already been referred to and obviously will modify severe parenchymal liver disease there may the use of anti-coagulants. be insufficient hepatic stores of glycogen and Fluid overload. The complications of fluid the patient is therefore particularly susceptoverload are common in liver disease and the ible to fasting hypoglycaemia. Therefore problem may be exacerbated by drugs; for before and during the operation a glucose example, large amounts of sodium can solution should be infused continuously. Fat inadvertently be given by administering large may replace the glycogen in the liver cells doses of intravenous penicillin. and therefore certain anaesthetics, being fatHypoproteinaemic. Many drugs bind to soluble, may accumulate in the liver in protein. For example, relaxants such as amounts greater than usual, possibly leading tubocurarine bind to globulin and, if the to higher hepatic concentration of toxic albumin-globulin ratio is reversed, more tubo- anaesthetic metabolites. In bile duct obstruction or in any form of curarine than usual may be required. In this cholestatic liver disease, drugs which would context it should be noted that a third of the tubocurarine that is administered also be- normally be excreted into the biliary tract and become involved in an enterohepatic comes bound to the liver. Deficiency in pseudocholinesterase. Al- circulation may be affected, for example, though the concentration of this enzyme in digitoxin. Also there may be a failure of the blood may be easily estimated, it is so absorption of fat-soluble drugs from the gut. Two other points should be made as far as frequently low in hepato-cellular disease that relaxants such as succinylocholine should not anaesthesia is concerned. Firstly, before, be given. Succinylocholine, which blocks during and after operation hepatic anoxia motor end-plates, is broken down by pseudo- must be avoided. This may easily occur during cholinesterase and therefore, if the concentra- an operation when cardiac output falls as a tion of this enzyme is low or indeed if it is result of the anaesthetic. In this respect absent, there will be a very protracted halothane is safer because of its less profound effect on cardiac output. Cyclopropane is recovery from succinylocholine relaxation. Hyperdynamic circulation. In patients with particularly dangerous because of the marked liver disease there is often a hyperdynamic splanchnic venous congestion which it procirculation, which is believed to be a compen- duces. Secondly, halothane is particularly safe satory and beneficial response. Indeed, it is a in these patients. Halothane jaundice is idiogood prognostic sign because the greater the syncratic and occurs only rarely. However, increase in cardiac output, the greater is the halothane should be avoided because, if chance of survival after operation. This help- jaundice occurs post-operatively, the surgeon ful response, however, may be blunted by will frequently blame the anaesthetic agent as anaesthetics which can depress the circulation. the cause rather than any other factor. Hepatotoxicity. There is no evidence that Antibiotic prophylaxis patients with liver disease are more liable to Antibiotics should be administered prophysuffer untoward effects from potentially lactically where complex biliary surgery is hepatotoxic drugs as long as the hepatotox- contemplated. The evidence supporting the icity is of the hypersensitivity kind, e.g. prophylactic use of antibiotics is now overhalothane. If the toxicity is dose-related, whelming for 2 main reasons: (1) in complex however, this does not hold true, e.g. chloro- biliary tract surgery the intestine may be form. In practice all potentially hepatotoxic opened for an anastomosis with the bile duct drugs should be avoided, firstly, because and (2) there is some evidence that the renal those who have already a diminished hepatic failure associated with obstructive jaundice reserve are at a greater risk of liver damage may be the result of the absorption of endo251
Symposium on Biliary Tract Disorders
toxin from the patient's own bowel. In these patients the reticulo-endothelial function of the liver may be significantly impaired and, with the use of antibiotics to alter and modify the intestinal flora, peripheral endotoxaemia may be avoided. There is some evidence that bile salts also may reduce the anaerobic flora in the gut. Nutrition In the severely malnourished patient, some time should be spent in correcting nutritional deficiencies. Where there is evidence of protein deficiency, and particularly where the serum albumin is low, the patient should be placed on as high a protein diet as possible, that is, as much as ammonia tolerance will permit. If the plasma albumin is particularly low, infusions of plasma or salt-poor albumin may be necessary. It is possible to increase the dietary intake of nitrogen in these patients by the oral administration of an antibiotic, e.g. neomycin, in order to suppress the bacterial population in the colon and therefore limit the intestinal absorption of free ammonia.
252
Pre-operative temporary drainage Occasionally, operative intervention in a patient with biliary tract obstruction becomes urgent, particularly if infection in the liver and bile ducts cannot be controlled. Such patients may not be fit enough for a lengthy operation and temporary drainage of the bile duct may be carried out using a trans-hepatic tube inserted percutaneously into the liver at the time of percutaneous trans-hepatic cholangiography. This manoeuvre is particularly valuable in patients in whom investigations are incomplete or in whom immediate operation is contra-indicated.
ACKNOWLEDGEMENTS. I wish to thank Drs. Christopher Wells and Frank Boulton of the Departments of Anaesthesia and Haematology of this University for helpful advice.
REFERENCE Child, C. G. (1964) In Major Problems in Clinical Surgery, Vol. 1: The Liver and Portal Hypertension (edited by Child, Co G.). Philadelphia: W. B. Saunders, pi
PRE-OPERATIVE ASSESSMENT FOR BILIARY TRACT SURGERY R. Shields Department of Surgery, University of Liverpool
Summary. The pre-operative approach to the patient with prolonged jaundice due to a long-standing obstruction of the bile duct is, we find, very similar to that of the patient with hepatic parenchymal disease who requires surgery for the treatment ofportal hypertension. Complex and sophisticated tests of liver function are not required and a reasonable assessment of the patient's ability to withstand operation may be made by estimating the serum ammonia and bilirubin and the plasma glucose and albumin. Particularly useful in this assessment is the Child's classification (Child, 1964). This is based on 3 clinical and 2 laboratory tests. On this basis the patient may be assigned to I of 3 groups. Patients who belong to Child's group A have good hepatic reserve and are similar to individuals who have been deprived ofno more than 30 per cent oftheir liver function. Patients ofChild's group C, on theother hand, are similar to patients who have lost 90 to 95 per cent ofliverfunction and operation in them carries a considerable risk. Moreover, because of their basic disease, the liver may have no regenerative powers andfurther improvement in liver function cannot be expected. These patients are hardly ever operable, although certain supportive measures may improve their general status and they may eventually be operated upon but considerable risks must be recognised. In an intermediate position are the patients who belong to group B of the Child's classification. These patients have evidence of hepatic dysfunction and require the energetic and detailed preparation described below.
THE potential benefits of biliary surgery may be vitiated if the operation, no matter how well performed technically, is carried out at the wrong time in the unprepared patient. A complex reconstruction of the biliary tract for stricture, or resection of the head of the pancreas in an older patient who has been ravaged by infection and prolonged obstruction of the bile ducts, demands very careful and precise pre-operative assessment particularly the effect upon the patient of the underlyingdisease. However, the commonestoperation upon the biliary tract is cholecystectomy and, when this operation is performed electively upon a thin and fit, young or middle-aged patient for uncomplicated disease of the gallbladder, no more preparation or assessment is required than would be for any other similar abdominal procedure of intermediate severity. The salient features of the pre-operative assessment and preparation of a patient for an operation upon the biliary tract are con-
sidered under the following headings: disorders of coagulation; fluid and electrolyte balance-hepato-renal syndrome; drug metabolism; antibiotic prophylaxis; nutrition; pre-operative temporary drainage. Coagulation disorders The following tests are essential-platelet count, prothrombin time, partial thromboplastin time and thrombin time (this last test may detect fibrin degradation products of which many circulate in the blood in high concentration in biliary tract disease). Abnormalities in the prothrombin time and the partial thromboplastin time indicate deficiencies in factors I, II, V, VII, VIII, IX and X. As far as coagulation disorders are concerned, there are basically 2 clinical problems in these patients. First, there is the patient who has been over-anticoagulated and therefore is low in factors II, VII, IX and X. In practice these are easy to replace. Secondly, in patients with parenchymal liver disease
249
Symposium on Biliary Tract Disorders
there is usually a more generalised deficiency in clotting factors, although factor VIII may be present in the blood in increased amounts. Several of these factors can be replaced fully but usually only partial replacement of factors I and V are possible. In these patients cryoprecipitate of plasma is used to supply fibrinogen, and Prothromplex to supply factors II, IX and X with or without factor VII. It is the practice for every jaundiced patient to receive parenteral vitamin K1 . Abnormalities in clotting usually return to normal within 48 hours. If there is no response, the reasons are twofold-a deficiency of other clotting factors (vitamin K supplies only factors II, VII, IX and X) or the parenchymal damage to the liver is so great that the liver is not able to respond to the injection of vitamin K. Fluid and electrolyte balance-hepato-renal syndrome The term hepato-renal syndrome was coined to describe the association between liver and kidney disease, particularly patients dying of uraemia after biliary tract operations. There is no doubt that there is an increased risk of acute renal failure after operations in patients with obstructive jaundice and that this renal failure carries a poor prognosis. In the kidney of experimental animals and of patients with biliary tract obstruction, there is evidence of glomerular and tubular damage but the cause is quite obscure. Recently it has been suggested that renovascular fibrin deposition associated with endotoxaemia may be responsible. Before and during the operation it is possible to take certain preventive measures which will avoid post-operative oliguria leading to the hepato-renal syndrome. Certain causative factors are clear, e.g. old age, infections, hypoalbuminaernia. It is also claimed that in patients with obstructive jaundice, there is pre-operative evidence of a decreased maximal urinary concentrating ability, and a significantly reduced haematrocrit; the glomerular filtration rate is low and there may be high concentrations in the serum of circulating fibrin degradation products. 250
Careful attention to fluid and electrolyte balance is important. Sodium and potassium balance should be re-established and there should be an adequate fluid intake. Particular attention should be paid to sodium balance particularly if mannitol is to be given intravenously during and immediately after operation. Attention must also be paid to potassium balance for there is always a risk in these patients (particularly if diuretics are being given) that potassium will be lost in the urine, and hypokalaemia and alkalosis will develop. Before, during and after operation it is necessary to measure the serum creatinine, urine osmolality and urine output. In this last respect a catheter should be inserted into the bladder and the urine output determined half-hourly. The aim is that the patient should pass at least 25m1. urine every 30 minutes. In patients, whose serum bilirubin exceeds 120 umol, per 1., mannitol infusions should be given at a rate of 2 m1. 20 per cent solution per kg. body weight before and after operation. Diuretics such as frusemide should be avoided because there is a considerable risk that plasma volume will become depleted and, after an initial diuresis, renal failure may supervene due to the oligaemia. Drug metabolism in bepato-biliary disease The metabolism of drugs, administered to patients with liver disease about to undergo operation, may be altered either because of liver cell damage or because of the obstruction of the bile duct. In bepato-cellular dysfunction the following disorders may be recognised. Delay in drug detoxication. Many drugs are metabolised in the liver and therefore, in parenchymal liver disease, have to be given with great care. Most substances which are detoxified or metabolised in the liver are first hydroxylated and then conjugated with glucuronic or sulphuric acid. The effectiveness of many drugs and the duration of their action depends on this rate of metabolic conversion. Examples of such drugs, which may be given to a patient about to undergo operation, are thiopentone, morphine, atropine and local anaesthetic agents.
Symposiwn on Biliary Tract Disorders
Brain metabolism is abnormal in patients and, secondly, if jaundice develops after with liver disease. The brain becomes ex- an operation during which these drugs have tremely sensitive to a variety of centrally- been given, the diagnostic picture will be acting agents, for example, barbiturates. confused. Carbohydrate metabolism. In patients with Coagulation problems. These have already been referred to and obviously will modify severe parenchymal liver disease there may the use of anti-coagulants. be insufficient hepatic stores of glycogen and Fluid overload. The complications of fluid the patient is therefore particularly susceptoverload are common in liver disease and the ible to fasting hypoglycaemia. Therefore problem may be exacerbated by drugs; for before and during the operation a glucose example, large amounts of sodium can solution should be infused continuously. Fat inadvertently be given by administering large may replace the glycogen in the liver cells doses of intravenous penicillin. and therefore certain anaesthetics, being fatHypoproteinaemic. Many drugs bind to soluble, may accumulate in the liver in protein. For example, relaxants such as amounts greater than usual, possibly leading tubocurarine bind to globulin and, if the to higher hepatic concentration of toxic albumin-globulin ratio is reversed, more tubo- anaesthetic metabolites. In bile duct obstruction or in any form of curarine than usual may be required. In this cholestatic liver disease, drugs which would context it should be noted that a third of the tubocurarine that is administered also be- normally be excreted into the biliary tract and become involved in an enterohepatic comes bound to the liver. Deficiency in pseudocholinesterase. Al- circulation may be affected, for example, though the concentration of this enzyme in digitoxin. Also there may be a failure of the blood may be easily estimated, it is so absorption of fat-soluble drugs from the gut. Two other points should be made as far as frequently low in hepato-cellular disease that relaxants such as succinylocholine should not anaesthesia is concerned. Firstly, before, be given. Succinylocholine, which blocks during and after operation hepatic anoxia motor end-plates, is broken down by pseudo- must be avoided. This may easily occur during cholinesterase and therefore, if the concentra- an operation when cardiac output falls as a tion of this enzyme is low or indeed if it is result of the anaesthetic. In this respect absent, there will be a very protracted halothane is safer because of its less profound effect on cardiac output. Cyclopropane is recovery from succinylocholine relaxation. Hyperdynamic circulation. In patients with particularly dangerous because of the marked liver disease there is often a hyperdynamic splanchnic venous congestion which it procirculation, which is believed to be a compen- duces. Secondly, halothane is particularly safe satory and beneficial response. Indeed, it is a in these patients. Halothane jaundice is idiogood prognostic sign because the greater the syncratic and occurs only rarely. However, increase in cardiac output, the greater is the halothane should be avoided because, if chance of survival after operation. This help- jaundice occurs post-operatively, the surgeon ful response, however, may be blunted by will frequently blame the anaesthetic agent as anaesthetics which can depress the circulation. the cause rather than any other factor. Hepatotoxicity. There is no evidence that Antibiotic prophylaxis patients with liver disease are more liable to Antibiotics should be administered prophysuffer untoward effects from potentially lactically where complex biliary surgery is hepatotoxic drugs as long as the hepatotox- contemplated. The evidence supporting the icity is of the hypersensitivity kind, e.g. prophylactic use of antibiotics is now overhalothane. If the toxicity is dose-related, whelming for 2 main reasons: (1) in complex however, this does not hold true, e.g. chloro- biliary tract surgery the intestine may be form. In practice all potentially hepatotoxic opened for an anastomosis with the bile duct drugs should be avoided, firstly, because and (2) there is some evidence that the renal those who have already a diminished hepatic failure associated with obstructive jaundice reserve are at a greater risk of liver damage may be the result of the absorption of endo251
Symposium on Biliary Tract Disorders
toxin from the patient's own bowel. In these patients the reticulo-endothelial function of the liver may be significantly impaired and, with the use of antibiotics to alter and modify the intestinal flora, peripheral endotoxaemia may be avoided. There is some evidence that bile salts also may reduce the anaerobic flora in the gut. Nutrition In the severely malnourished patient, some time should be spent in correcting nutritional deficiencies. Where there is evidence of protein deficiency, and particularly where the serum albumin is low, the patient should be placed on as high a protein diet as possible, that is, as much as ammonia tolerance will permit. If the plasma albumin is particularly low, infusions of plasma or salt-poor albumin may be necessary. It is possible to increase the dietary intake of nitrogen in these patients by the oral administration of an antibiotic, e.g. neomycin, in order to suppress the bacterial population in the colon and therefore limit the intestinal absorption of free ammonia.
252
Pre-operative temporary drainage Occasionally, operative intervention in a patient with biliary tract obstruction becomes urgent, particularly if infection in the liver and bile ducts cannot be controlled. Such patients may not be fit enough for a lengthy operation and temporary drainage of the bile duct may be carried out using a trans-hepatic tube inserted percutaneously into the liver at the time of percutaneous trans-hepatic cholangiography. This manoeuvre is particularly valuable in patients in whom investigations are incomplete or in whom immediate operation is contra-indicated.
ACKNOWLEDGEMENTS. I wish to thank Drs. Christopher Wells and Frank Boulton of the Departments of Anaesthesia and Haematology of this University for helpful advice.
REFERENCE Child, C. G. (1964) In Major Problems in Clinical Surgery, Vol. 1: The Liver and Portal Hypertension (edited by Child, Co G.). Philadelphia: W. B. Saunders, pi
