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Emergent dialysis may also be required.

Metabolic acidosis should be corrected by either bicarbonate administration or dialysis therapy.

Coagulopathy of chronic renal failure is best controlled preoperatively by adequate dialysis. Heparin may be withheld during emergency treatment. Bleeding tendencies during or after surgery may also be controlled by the administration of fresh frozen plasma or deamino -8-D- arginine vasopressin (DDAVP).

Pericarditis and pericardial effusion should be resolved before the administration of a general anesthetic because of impaired cardiac output and the risk of pericardial tamponade.

Postoperative dialysis

Dialysis should be withheld for 24 hours postoperatively, if possible, because it requires the use of heparin, acutely lowers the platelet count, and causes transient hypotension and hypoxia during treatment.

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Dialysis should be performed emergently for the following:

Hyperkalemia unresponsive to medications

Metabolic acidosis with the inability to give sodium bicarbonate

Severe volume overload

Signs of uremia (e.g., pericarditis, mental status changes, asterixis)

Peritoneal dialysis patients require temporary vascular access for hemodialysis following abdominal procedures.

Continuous arteriovenous or venovenous hemofiltration may be indicated in patients with massive volume overload. This treatment modality uses hydrostatic transport through a semipermeable membrane to permit water and solute removal. The filtrate composition is similar to that of plasma.

D

Operative management follows the same basic principles as those for any surgical patient. Patients with renal failure are susceptible to appendicitis, cholecystitis, diverticulitis, and peptic ulcer disease. In addition, they may require surgery for problems related specifically to their disease, such as vascular access procedures and urologic procedures.

Fluid and electrolyte management must be monitored closely.

Anesthesia. The altered metabolism and excretion in chronic renal failure must be taken into consideration.

Benzodiazepines with a long half -life may tend to accumulate and lead to prolonged sedation.

Muscle relaxants

Succinylcholine administration leads to increases in serum potassium and is contraindicated in hyperkalemic patients.

Certain antibiotics and diuretics may further prolong drug action at the neuromuscular junction; this situation can lead to postoperative recurarization (recurrent paralysis) with catastrophic results.

Atracurium undergoes enzymatic degradation independent of renal function and may be the agent of choice in patients with renal failure.

All currently used inhalational agents decrease GFR and urinary excretion of sodium, with variable effects on renal blood flow.

E Perioperative management

Residual renal function , which may be adversely affected by a surgical procedure, is best protected by the following maneuvers:

Correction of volume excess or deficits and any accompanying electrolyte disorder can be achieved by either medical management or the use of dialysis.

Avoid intraoperative hypotension.

Once adequate intravascular volume resuscitation is ensured, maintenance of diuresis may simplify fluid management in perioperative patients with preservable renal function.

Infections, especially urinary tract infections, should be treated.

Nephrotoxic drugs (e.g., aminoglycosides, vancomycin, intravenous contrast, angiotensin -converting enzyme inhibitors) should be avoided when possible.

Dialysis patients with no preservable renal function should be treated similarly.

Nephrotoxic drugs may be used safely if blood levels are followed and other side effects (e.g., ototoxicity) are monitored.

A urinary bladder catheter should not be used in patients with oliguria or with no preservable renal function.

General medical management

Medication dosages should be carefully adjusted for the level of renal function.

Anemia is well tolerated by these patients.

A hematocrit of 20%–25% (i.e., 7–8 g/dL) is adequate for most major surgical procedures.

Perioperative transfusions should be given during dialysis to minimize hyperkalemia.

Supplemental steroids should be given in the perioperative period to patients on long-term steroid therapy (e.g., renal transplant patients).

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Persistent coagulopathy may be addressed with DDAVP, conjugated estrogens, or transfusion of cryoprecipitate.

Malnutrition

Elective surgery for patients with malnutrition should be postponed until their nutritional status improves.

After emergency surgery, nutritional requirements should be supplied intravenously, adhering to appropriate volume and protein restrictions until adequate oral intake is possible.

Systemic disorders, such as diabetes mellitus or a thyroid disorder, should be controlled.

F

Postoperative complications are more common in patients with chronic renal failure and may include labile blood pressure, impaired wound healing, postoperative hematomas, and shunt thrombosis.

V The Surgical Patient with Liver Disease

Hepatic insufficiency increases the risk of complications and death in the postoperative period. The recognition and management of liver disease preoperatively can minimize the postoperative problems.

A Assessment of hepatic function

Liver disease should be suspected, based on the history and physical examination.

History

A prior history of jaundice, hepatitis, hemolytic anemia, parasitic infection, biliary stone disease, pancreatitis, enzyme deficiencies (e.g., α 1 -antitrypsin deficiency), or prior malignancy (e.g., gastrointestinal or breast cancer) should be considered.

A history of drug or alcohol abuse and possible exposure to infectious hepatitis agents (e.g., via tattoos, blood transfusions) or to environmental or other hepatotoxins suggest the possibility of hepatic parenchymal disease.

A history of prior hepatotoxicity after inhalational anesthesia is a risk factor for future exposure to halogenated anesthetics.

The physical examination should include an assessment of

Clinically evident features (e.g., jaundice, ascites, peripheral edema, muscle wasting, testicular atrophy, palmar erythema, spider angiomas, gynecomastia) should be examined.

Stigmata of portal hypertension , including caput medusae (dilated periumbilical vessels) or splenomegaly, should be assessed.

The presence of upper gastrointestinal bleeding, delirium tremens, or encephalopathy suggests the presence of portal hypertension and underlying cirrhosis.

Evidence of bleeding disorders should be sought.

Evidence of encephalopathy or asterixis should also be checked.

Liver size. Hepatomegaly or a shrunken liver (especially a shrunken liver with a rounded edge or with palpable nodules on its surface) may be present in liver disease. Hepatic tenderness to percussion should be assessed.

Laboratory tests can confirm the diagnosis but may be normal despite the presence of significant liver

disease.

The most useful tests are aspartate aminotransferase (AST), alanine aminotransferase (ALT), bilirubin, alkaline phosphatase, albumin, and prothrombin time.

Platelet count and bleeding time may be abnormal in patients with significant liver disease.

Hepatitis B surface antigen and hepatitis C serology should be sought if their presence is suspected, given the potential for hospital staff exposure.

A liver biopsy may be necessary preoperatively if an acute hepatitis is suspected.

B

Operative risk factors and their management in patients with pre -existing liver disease have not been fully defined, but several generalizations are useful.

Acute hepatitis. It is advisable to delay elective surgery in the patient with acute hepatitis until the hepatitis is resolved.

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Acute alcoholic hepatitis

Abstinence from alcohol for 6–12 weeks before elective surgery has been recommended.

General anesthesia is associated with an operative mortality rate of 50% or higher when portal decompressive surgery is performed.

Acute drug-induced hepatitis. The results of studies have ranged from no increase in risk to as high as a 20% morbidity and mortality rate.

Acute viral hepatitis. Elective surgery should be deferred for at least 1 month after the acute illness.

Chronic liver disease. Patients with chronic liver disease can tolerate most surgical procedures well if they are in a relatively compensated state preoperatively.

The risk appears similar to that of patients undergoing portal decompressive procedures (see ChildsPugh classification in Table 14 -1).

Emergency or abdominal surgery increases surgical risk.

Patients with decompensated cirrhosis (Childs C) have significant surgical morbidity and mortality.

Management of portal hypertension may include β -blockers, octreotide, and transvenous intrahepatic portosystemic shunting (TIPS).

Obstructive jaundice is associated with increased operative risk, especially in the presence of biliary tract infection. The increased intestinal absorption of enteric endotoxin in the absence of luminal bile salts may lead to systemic endotoxemia and a higher rate of complications.

Cholangitis mandates prompt decompression byendoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and biliary stenting ortranshepatic cholangicography with drainage (THC) to effectively treat sepsis.

Coagulation disorders are common secondary to diminished intestinal absorption of vitamin K. Disseminated intravascular coagulation may be present, especially in association with biliary sepsis.

Acute renal failure with renal tubular dysfunction has been reported in approximately 10% of postoperative patients, and the risk is apparently related to the degree of jaundice.

Gastrointestinal hemorrhage , especially stress gastritis, occurs in 5%–14% of postoperative patients.

Delayed wound healing and wound infection are likely to be exacerbated by associated malnutrition, malignancy, and sepsis.

Risk factors for postoperative complications in patients with obstructive jaundice [Friedman LS. The Risk of Surgery in Patients with Liver Disease. Hepatology. 1999;29:1617–1623]

Hematocrit <30%

Bilirubin >11 mg/dL

Malignancy

Hypoalbuminemia

Cholangitis

Azotemia

C Anesthetics

The liver is the primary site of much first -pass metabolism. Impaired function leads to altered drug pharmacokinetics and prolongation of effects.

All inhalational anesthetics reduce splanchnic perfusion and hepatic blood flow to some extent.

Isoflurane is associated with minimal hepatic metabolism and therefore may be the inhalational anesthetic of choice.

Halogenated inhalational agents should be avoided in patients with a history of hepatotoxicity after inhalation anesthesia.

Muscle relaxants

Neuromuscular blockade may be prolonged after the administration of nondepolarizing muscle relaxants to patients with chronic liver failure.

Atracurium undergoes peripheral enzymatic degradation, and its metabolism is unaffected by hepatic dysfunction.

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D

Perioperative management should be aimed at the treatment of potentially correctable factors.

Fluid and electrolyte balance

Care must be taken to avoid hypotension , as the compromised liver is sensitive to further ischemic insults.

Patients with cirrhosis may be in high -output cardiac failure secondary to volume overload and peripheral arteriovenous shunting.

Hypokalemia and alkalosis must be corrected.

Hypomagnesemia and hypophosphatemia are common in alcoholics and should be identified and corrected.

Impairment of lactate metabolism may result in significant acid–base disturbances.

Coagulopathy

The prothrombin time may be elevated secondary either to vitamin K deficiency in patients with obstructive jaundice or to failure of synthetic function in patients with parenchymal disease. Treatment may be instituted with vitamin K or fresh frozen plasma.

Thrombocytopenia may be present in patients with portal hypertension secondary to splenomegaly. The response to platelet transfusion may be lessened.

Prophylactic antibiotics should include coverage of biliary and enteric flora.

Stress gastritis prophylaxis should be administered.

Narcotics and sedatives that may precipitate hepatic encephalopathy must be avoided. The half -life of meperidine is significantly prolonged in patients with hepatic failure.

Hypoxemia may be present secondary to increased intrapulmonary shunting.

Encephalopathy should be treated with dietary protein restriction and the administration of intestinal antibiotics (i.e., neomycin ) and lactulose.

Ascites may be controlled with diuresis, sodium and water restriction, and judicious paracentesis.

Malnutrition, with its attendant increased risks of infection and wound complications, should be improved by adequate nutrition and treatment of current infections.

VI The Surgical Patient with Diabetes Mellitus

Diabetes mellitus affects 2%–10% of the general population. As many as one half of these patients have no symptoms until a stressful situation (e.g., sepsis, surgery) results in overt manifestations of hyperglycemia.

A Assessment of risk

There is increasing awareness that tighter glycemic control can limit long-term complications of the disease. The patient with diabetes frequently requires surgery for complications of the diabetes as well as for nondiabetic surgical problems. The patient history should emphasize the diabetes and its management, and the physical examination should focus on evidence of systemic complications.

History

The type of diabetic control used, the dosage schedule, and the adequacy of control for the patient should be determined.

The propensity to develop ketosis, ketoacidosis, hyperglycemia, or hypoglycemia and a history of “brittleness” (i.e., unpredictable wide swings in blood glucose level) should be assessed.

Specific questions related to the complications of diabetes (e.g., peripheral vascular and coronary artery disease, nephropathy, neuropathy, hypertension, and retinopathy) should be answered.

The physical examination should be directed at identifying target organ involvement.

Associated cardiovascular disease , with silent myocardial ischemia, may be present.

Retinopathy is associated with diffuse small -vessel disease.

Autonomic neuropathy occurs as a result of diabetic degeneration of the autonomic nervous system. This neuropathy may manifest as the following conditions:

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Postural hypotension

Bladder -emptying problems

Impaired intestinal motility

Gastroparesis

Impotence

Cardiac autonomic dysfunction

Somatic neuropathy , with “stocking -glove” loss of sensation, increases the risks of injury (of which the patient may not be aware) to an insensate foot.

Patients with uncontrolled diabetes are susceptible to infections, and the presence of an ongoing infection should be investigated.

Laboratory studies

Elevated HbA1c levels are correlated with increased cardiovascular complications.

The patient's volume and electrolyte status should be assessed, especially in relation to the acuteness of the disease requiring surgery.

Serum glucose level and the degree of glucosuria should be determined.

The anion gap should be determined, and if it is elevated, arterial blood gases should be tested. The usual finding is low serum bicarbonate and a decreased pH secondary to

Diabetic ketoacidosis

Lactic acidosis

Retained organic acids containing phosphates and sulfates secondary to chronic renal failure

extremely high glucose levels secondary to stress or ongoing infection.

These patients require correction of the acute disease process before the diabetes can be controlled. Nevertheless, intraoperative management is often improved with a brief period to stabilize fluid and electrolyte balance.

Hyperglycemia. The serum glucose level should be monitored, and abnormalities should be treated promptly. Perioperatively, the serum glucose should be stable and within normal range, if possible.

Diabetic ketoacidosis. Patients with diabetic ketoacidosis are hyperglycemic, ketotic, and acidotic. They are also dehydrated and have decreased body stores of potassium and sodium. They may exhibit Kussmaul's respirations (rapid deep breaths).

Measured serum sodium levels decrease 1.7 mEq/dL for each 100 mg/dL that the glucose is elevated.

Massive free water deficits may occur secondary to osmotic diuresis from glucosuria.

Ketoacidosis is best corrected by the administration of intravenous fluids, insulin, bicarbonate, and potassium.

Surgery should be postponed until the ketoacidosis is at least partially resolved, as measured by an improvement in pH, hydration, and correction of electrolyte abnormalities and serum glucose levels.

Hyperosmolar nonketotic states. The stress of surgery, infection, or the high glucose load of hyperalimentation may induce a nonketotic, hyperglycemic, hyperosmolar coma in patients with adult -onset diabetes mellitus.

The hyperosmolar nonketotic state is not associated with acidosis but is otherwise very similar to diabetic ketoacidosis.

Management principles include administering intravenous fluids, insulin, and potassium as necessary as well as correcting any underlying cause.

D Operative complications

Infections. Patients with out-of -control diabetes tend to have an increased rate of infectious complications both at the surgical site and elsewhere. Complications from infections account for up to 20% of perioperative deaths in diabetic patients.

Wound healing is likely to be impaired in patients with poor glucose control secondary to changes in soft tissue matrix, granulation tissue, and microvascular disease.

If macrovascular disease is present, impaired wound healing is more likely than in patients without diabetes. However, if peripheral blood flow is adequate, wound healing is likely to proceed.

Mortality rates

The overall mortality rate for surgery in patients with diabetes is approximately 2%.

Almost 30% of deaths are a direct result of cardiovascular complications.

Almost 16% of deaths are related to sepsis , particularly from staphylococcal infections.

The mortality rate for emergency surgical procedures in patients with diabetes is several times