Perioperative Management of the Patient with Chronic Renal Failure

Last Updated: November 22, 2002

Chronic renal failure (CRF) refers to decline in the glomerular filtration rate (GFR) caused by a variety of diseases such as diabetes, glomerulonephritis, and polycystic kidney disease. Patients with CRF have a high prevalence of hypertension. Whether hypertension is a cause or a result of CRF remains debatable. CRF may be categorized as mild (GFR of 60-89 mL/min/1.73 m2), moderate (GFR of 30-59 mL/min/1.73 m2), severe (GFR of 15-29 mL/min/1.73 m2), or end-stage renal disease (ESRD) (hemodialysis or peritoneal dialysis is initiated as the GFR falls to <15 mL/min/1.73 m2). Some patients with CRF eventually receive kidney transplantation before (a few cases) or after (majority of recipients) initiation of hemodialysis or peritoneal dialysis.

The progression of renal disease from one stage to the next; the need for emergent or maintenance dialysis; prevention and management of fluid, electrolyte, and acid-base imbalances before and after surgery; and the high cardiac risk are issues that must be addressed before a patient with CRF proceeds for elective surgery.

Patients with CRF have a higher incidence of coronary artery disease (CAD) and peripheral vascular disease (PVD) compared to the general population. This is because they have the traditional risk factors for CAD, such as advanced age, diabetes, hypertension, and lipid disorders, and they have a higher prevalence of hyperhomocystinemia, abnormal calcium phosphate metabolism, and, perhaps, uremic toxins. Based on the updated American College of Cardiology/American Heart Association (ACC/AHA) guidelines on perioperative cardiovascular evaluation of noncardiac surgery, patients with a creatinine level greater than or equal to 2 are considered to have a clinical predictor of at least intermediate pretest probability of increased perioperative cardiovascular risk. This increased risk warrants detailed cardiovascular surveillance before intermediate- or high-risk surgery.

An early nephrologic evaluation is mandatory to assess renal function and the need for renal replacement therapy perioperatively. Thus, the cardiologist, nephrologist, surgeon, primary care physician, nursing staff, and, sometimes a transplant nephrologist, must work as a team to recommend strategies for reducing cardiac and renal risks for the planned procedures (ie, noncardiac).

Pathophysiology

Impairment of the excretory function of the kidney results in an elevation in blood urea nitrogen (BUN), creatinine, and various protein metabolic products. Impairment in the synthetic function results in a decrease in the production of erythropoietin (causing anemia) and active vitamin D-3 (causing hypocalcemia, secondary hyperparathyroidism, hyperphosphatemia, and renal osteodystrophy). Impairment in synthetic function also results in a reduction in acid, potassium, salt, and water excretion (causing acidosis, hyperkalemia, hypertension, and edema) and in platelet dysfunction (leading to an increase in bleeding tendencies [see Azotemia]).

The aforementioned complications that are associated with a decline in renal function and uncontrolled hypertension or blood sugar levels must be identified and corrected perioperatively. Drugs normally excreted by the kidney accumulate in patients with CRF, exerting their toxicity in the kidney and other organs. Therefore, dosage adjustments or drug avoidance is a key pathophysiologic principle in patients with CRF. Of note is the avoidance of meperidine (Demerol) in patients with CRF because the active metabolite (normeperidine) can accumulate and cause seizures.

CRF can be associated with excess surgical morbidity, the most important of which include acute renal failure, hyperkalemia, volume overload, and infections. The above underscore the need for early involvement of a nephrologist.

Drugs that may cause hyperkalemia include the following:

 

Effect of anesthesia in persons with CRF

The administration of general anesthesia may induce a reduction in renal blood flow in up to 50% of patients, resulting in the impaired excretion of nephrotoxic drugs. In addition, the function of cholinesterase, an enzyme responsible for breaking down certain anesthetic agents, may be impaired, resulting in prolonged respiratory muscle paralysis if neuromuscular blocking agents are used. N-acetyl-procainamide, a metabolite of procainamide, accumulates in persons with CRF and, when used in combination with H2-blockers, causes prolongation of the QTc. The dose should be adjusted, or a substitute drug should be used.

Fluorinated compounds such as methoxyflurane and enflurane are nephrotoxic and should be avoided in patients with CRF. Succinylcholine, a depolarizing blocker, causes hyperkalemia.

Effect of surgery in persons with CRF

Hyperkalemia may be precipitated by tissue breakdown, blood transfusions, acidosis, ACE inhibitors, beta-blockers, heparin, rhabdomyolysis, and the use of Ringer lactate solution as a replacement fluid. Ringer lactate solution contains potassium, which is often disregarded but can cause fatal hyperkalemia. Third-space fluid loss, diarrhea, vomiting, and nasoenteric suction result in both volume contraction and hypokalemia. Hypokalemia is sometimes followed concomitantly with hypomagnesemia.

Most patients with CRF have chronic acidosis; surgical disease can further complicate the acidemia. Such patients are at a higher risk for hyperkalemia, myocardial depression, and cardiac arrhythmia.

Hypocalcemia and hyperphosphatemia may be caused by rhabdomyolysis. Hyponatremia may occur from hypotonic fluids or inappropriate secretion of antidiuretic hormone.

Approach to patients with peripheral arterial disease

Peripheral arterial disease (PAD) is a significant risk marker for the presence of CAD. Epidemiological studies have shown the incidence of CAD in patients with PAD to be 25-90%, depending on age group. CAD is largely asymptomatic in more than 50% of patients with PAD, largely due to the limited functionality of these patients and the presence of intermittent claudication and congestive heart failure (CHF).

In a study of 1886 patients older than 62 years who lived in a nursing home, CAD was present in 58% of patients and cerebrovascular disease was present in 34% of patients. Using the noninvasive diagnostic test, ie, the ankle-branchial index (ABI), the prevalence rate of PAD was 2.5% in patients younger than 60 years and 18.8% in patients older than 70 years.

In the Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (ie, CAPRIE) study, more than 19,000 patients were enrolled who had manifestations of a form of atherosclerotic disease (ie, recent stroke, recent myocardial infarction [MI], established PAD with an ABI of 0.85 or less). An analysis of the patients showed that 25% had disease in 2 or more areas, 11.9% had PAD and associated CAD, and 3.3% had all 3 manifestations of cardiovascular disease.

Usually, patients with PAD are older, and, depending on the presence of risk factors such as hypertension, diabetes mellitus, or hyperlipidemia, they are a particularly high-risk group for concomitant CAD.

Conduct a thorough history and physical examination because these are essential in the evaluation of patients with CRF prior to surgery. Obtain information on the following during the history and physical examination:

 

  • Blood pressure and blood sugar trends

     

  • Presence of anemia

     

  • Radio-contrast exposure

     

  • Prior surgical experiences

     

  • Bleeding tendencies

     

  • Allergies

     

  • Use of potentially nephrotoxic drugs

     

  • Nutritional and volume status

     

  • Significant cardiac history

     

  • Presence of comorbid disease

     

  • Functional capacity

Other important history

Obtain the patient's history related to the following conditions because this information is important in the perioperative treatment of patients with CRF:

 

  • Stable or unstable angina

     

  • Arrhythmias (atrial fibrillation)

     

  • Comorbid disease (eg, pulmonary disease, history of stroke, transient ischemic attacks)

Obtain the patient's functional capacity by using simplified questions of usual daily activities (eg, climbing flights of stairs, playing tennis, shoveling snow in the winter). Strenuous activities such as swimming, tennis, or basketball have estimated energy requirements of at least 10 metabolic equivalents (METs).

Also inquire about the patient's history of previous surgeries, which helps to determine the effects of general anesthesia and the presence of allergies to medications.

Perform a thorough physical examination, particularly to obtain evidence of volume overload and cardiovascular abnormalities (eg, murmurs, carotid bruits, pericardial effusion, abnormal peripheral pulses). Note the presence or absence of hair on the lower extremities because this information may herald undiagnosed PAD. Record all extremity blood pressures, and calculate the ABI.

Abnormal calcium metabolism is observed in secondary and tertiary hyperparathyroidism, which is prevalent in patients with ESRD. In one retrospective study, the annual incidence of severe valvular heart disease was estimated at 15-19 cases per 10,000 patients who were on dialysis. Of these patients, the most common etiology was calcific valvular disease in 69% and endocarditis in 19%. Calcific valvular disease manifested primarily as aortic stenosis endocarditis and mitral regurgitation, which could be due primarily to calcific valvular disease or secondary to endocarditis; therefore, a history of syncope, heart failure, or chest pain should imply not only ischemic heart disease but also the possibility of significant aortic valvular disease. These patients benefit from preoperative noninvasive imaging, ie, transthoracic echocardiography.

Laboratory studies and other tests

 

  • Perform a CBC count, particularly to investigate for the presence of anemia of CRF, which can be treated with recombinant erythropoietin therapy. This therapy helps optimize the hematocrit value prior to elective surgery.

     

  • Conduct iron studies to determine if an iron deficiency or anemia is present, which can be treated with intravenous iron therapy. Also perform a thorough gastrointestinal and gynecologic evaluation to investigate the cause of the iron deficiency.

     

  • Study the patient's serum chemistry results, including potassium, magnesium, and phosphate concentrations, to establish the level of renal function and electrolyte concentrations. Also obtain digoxin and other drug levels.

     

  • Perform a urinalysis to help detect a urinary infection or active glomerular disease (red and white blood cells and their casts).

     

  • Perform a baseline electrocardiogram (ECG) to investigate for arrhythmias, conduction system abnormalities (eg, left bundle-branch block), evidence of silent MI or ischemia, electrolyte abnormalities (eg, hypokalemia, hyperkalemia), and hypocalcemia or hypercalcemia.

Imaging studies and other specific noninvasive testing

 

  • Obtain a chest radiograph to help rule out volume overload or active pulmonary disease.

     

  • Conduct noninvasive diagnostic testing on patients who are about to receive intermediate-risk procedures and have a poor functional capacity or on patients with minor clinical predictors who are about to receive high-risk surgery and have poor functional capacity. Noninvasive assessment can be achieved using the tests described below.

     

    • Exercise ECG testing: Patients who are able to achieve greater than 85% of the maximum predicted heart rate with good exercise capacity (>6 METs) without showing ischemic changes in the ECG findings or developing hypotension are at a very low risk of a perioperative infarct. Test results also help estimate the functional capacity of the patient. Limitations include difficulty interpreting ECG findings in the presence of bundle block, hypertensive ECG changes, and the effect digoxin. The test has a sensitivity and specificity of 68% and 77%, respectively; however, in patients with renal disease, this testing is much less applicable because of limitations in exercise capacity and baseline ECG abnormalities.

       

    • Stress thallium or sestamibi testing: Advantages of this test are its applicability in patients with abnormal ECG findings, left ventricular hypertrophy, or documented CAD. A positive test result is documented as perfusion defects on images in combination with ECG findings. This combination of findings bolsters the clinical picture and has an overall sensitivity and specificity of 92% and 93%, respectively. This study has limitations in patients who are unable to attain their target heart rates, and some clinicians consider the findings to be of low predictive value in patients with diabetes and ESRD.

       

    • Persantine or dipyridamole pharmacologic myocardial perfusion imaging with thallium or sestamibi: This study is used in patients who are unable to exercise and/or are undergoing major vascular or orthopedic procedures. Positive test results are quantified as reversible defects. Fixed defects do not convey risk. The finding of a reversible dilated left ventricular cavity is also considered a high-risk profile. Several randomized studies have shown that the results of this test can help predict the risk of a perioperative cardiac event in patients with ESRD. Limitations include patients with pulmonary obstructive disease, use of theophylline, and critical carotid stenosis.

       

    • Dobutamine stress echocardiography: This test is used to detect wall motion abnormalities on echocardiography findings after infusing dobutamine to increase the heart rate to at least 85% of the maximal heart rate. Findings include wall motion abnormalities and ECG changes at different infusion rates. This study is found to be comparable to the Persantine thallium study in several randomized trials. Limitations include patients who are obese, have severe chronic obstructive pulmonary disease, and have severe hypertension and arrhythmias. In one study, a negative test result in selected patients helped identify a very low-risk population, with a 97% probability of no cardiac complications after surgery.

       

    • Coronary angiography: This study is indicated in patients with profoundly abnormal stress test results, evidence of significant left ventricular dysfunction after echocardiography testing, the possibility of significant aortic valvular pathology, and symptoms suggestive of worsening chronic stable angina or unstable angina.

Preoperative decision making and management

Cardiovascular risk

Clinical predictors of preoperative cardiovascular risk (eg, MI, CHF, death) can be described as major, intermediate, or minor risk factors.

 

  • Major predictors

     

    • Unstable coronary syndromes - Recent MI with evidence of important ischemic risk based on clinical symptoms or the results of noninvasive testing or unstable or severe angina (Canadian Heart Association class III or IV)

       

    • Decompensated CHF

       

    • Significant arrhythmias - High-grade atrioventricular block, symptomatic ventricular arrhythmias in the presence of underlying heart disease, supraventricular arrhythmias with uncontrolled ventricular rate

       

    • Severe valvular disease

     

  • Intermediate predictors

     

    • Mild angina pectoris (Canadian Heart Association class I or II)

       

    • Prior MI based on history findings or the presence of pathological Q waves

       

    • Compensated or prior CHF

       

    • Diabetes mellitus

     

  • Minor predictors

     

    • Advanced age

       

    • Abnormal ECG findings (eg, left ventricular hypertrophy, left bundle-branch block, ST-T abnormalities)

       

    • Rhythm other than sinus (eg, atrial fibrillation)

       

    • Low functional capacity (eg, inability to climb one flight of stairs with bag of groceries)

       

    • History of stroke

       

    • Uncontrolled systemic hypertension

Surgical risk for noncardiac procedures can be divided into high-risk, intermediate-risk, or low-risk surgery. The type of surgery, the duration of the surgical procedure, and, occasionally, the choice of anesthesia can make a difference in patient outcome. Allowing the anesthesiologist to choose the mode of anesthesia is always advisable.

 

  • High risk (reported cardiac risk often >5%)

     

    • Emergency operations, particularly in elderly persons

       

    • Aortic and other major vascular procedures

       

    • Peripheral vascular procedures

       

    • Anticipated prolonged surgical procedures associated with large fluid shifts, blood loss, or both

     

  • Intermediate risk (reported cardiac risk generally <5%)

     

    • Carotid endarterectomy

       

    • Head and neck procedures

       

    • Intraperitoneal and intrathoracic procedures

       

    • Orthopedic procedures

       

    • Prostate surgery

     

  • Low risk (reported cardiac risk generally <1%)

     

    • Endoscopic procedures

       

    • Superficial procedures

       

    • Cataract surgery

       

    • Breast surgery

Patients with major clinical predictors of cardiac morbidity can be assessed using the flow chart from the ACC/AHA guidelines on preoperative management (see Image 1). Preoperatively, patients who are undergoing elective surgery can be treated by identifying their risk profile for surgery and their risk of the intended procedure, as is indicated above. Patients with decompensated heart failure or unstable coronary syndromes should have their procedures postponed until their medical management is optimized.

Patients with intermediate (see Image 2) or minor (see Image 3) clinical predictors who are undergoing elective noncardiac surgery should be evaluated based on their functional capacity and type of surgery. Functional capacity is defined in METs, which are usually self-reported; however, this capacity can also be assessed based on the results from exercise treadmill testing. Patients who achieve at least 7 METs have a significantly better prognosis. Patients with poor functional capacity should be evaluated with noninvasive testing methods, while patients with good functional capacity can proceed to surgery. Based on the updated ACC/AHA guidelines on perioperative cardiovascular evaluation of noncardiac surgery, all patients with renal insufficiency who have a creatinine level greater than or equal to 2 are considered to have an intermediate clinical predictor of increased perioperative cardiovascular risk.

 

Renal risk assessment and interventions

Patients with CRF treated conservatively

Rapidly establish the duration of CRF; level of renal function impairment; and whether the elevation in BUN and creatinine is prerenal, intrarenal, postrenal, or a combination of these on a background of CRF. Patients who are euvolemic, responsive to diuretic therapy, and/or have no significant electrolyte abnormalities or bleeding tendencies are uncomplicated and do not require dialysis before surgery.

Patients with edema, CHF, or pulmonary congestion or those who are responsive to diuretic therapy require further cardiovascular evaluation. If the results of the cardiovascular evaluation are optimal, then fluid overload can be attributed to CRF. Combination diuretic therapy can help treat these patients to achieve euvolemia prior to surgery. Patients with diabetes have a greater tendency of having volume overload or cardiovascular disease. CRF may be so advanced that the patient develops diuretic resistance, with progressive edema. Preoperative dialysis may be considered in these patients. If postoperative dialysis is imminent, the surgeons should be advised to place a temporary catheter intraoperatively. This avoids the use of femoral cannulation, which carries a higher risk of infection. Permanent vascular access placement can then be arranged when the patient is more stable.

Further deterioration in renal function can be avoided by identifying and eliminating potential nephrotoxic agents. These include substitution or dosage adjustment for antibiotics (eg, aminoglycosides, acyclovir, amphotericin), sedatives, and muscle relaxants. NSAIDs and COX-2 inhibitors should be avoided, as should radiocontrast material. Radiocontrast material can induce acute renal failure by causing vasoconstriction and direct renal tubular epithelial cell damage. Demerol (meperidine) used for postoperative pain should be avoided because accumulation of its metabolite normeperidine can cause seizures in patients with CRF, especially those on dialysis. If radiocontrast material must be used, prophylactic oral administration of the antioxidant acetylcysteine, along with hydration (0.45% saline), may reduce the risk of acute renal failure.

All drug interactions and potential nephrotoxicity must be identified and either stopped or the dose of the drug adjusted for the level of renal function. Electrolyte abnormalities must be identified and corrected perioperatively.

Patients already on dialysis or those who have a renal transplant

For patients already on dialysis, dialysis adequacy, preoperative dialysis needs, postoperative dialysis timing, and dosage requirements for all medications should be determined. Patients on hemodialysis usually require preoperative dialysis within 24 hours before surgery to reduce the risk of volume overload, hyperkalemia, and excessive bleeding. Patients with peritoneal dialysis who are undergoing abdominal surgery should be switched to hemodialysis until wound healing is complete. Peritoneal dialysis should be continued for those undergoing nonabdominal surgery.

Because of complicated drug interactions and immunosuppressive dosing, monitoring, and adjustment, a nephrologist with specialized knowledge of renal transplantation should be involved in the preoperative evaluation of patients with CRF who have received kidney transplantation. Cyclosporine or tacrolimus taken by renal transplant recipients for immunosuppression are metabolized by the cytochrome P-450 system in the liver and thus interact with a wide variety of agents. Diltiazem, hepatic 3-methylglutaryl coenzyme A reductase inhibitors, macrolides, and antifungal drugs inhibit the system, elevate drug levels, and can precipitate nephrotoxicity. Others, such as carbamazepine (Tegretol), barbiturates, and theophylline, induce the system, reduce drug levels, and can precipitate rejection. Drug levels must be monitored in this setting. Intravenous cyclosporine or tacrolimus should be given at one-third the oral dose until the patient is able to tolerate oral medications.

 

Postoperative decision making and management

No preoperative cardiac assessment is indicated for emergency surgery; however, postoperative cardiac assessment must be performed and continued for 3-5 days with daily ECGs and screening of cardiac enzyme levels to detect and treat possible perioperative MI. Perioperative MI occurs mostly within the first 72 hours; however, most occurrences are silent. The incidence rate of perioperative MI is approximately 1% but carries a high mortality rate of almost 50%.

Be aware of discordant blood testing results of total creatine kinase (CK), myocardial band enzymes of CK (CK-MB), and troponin. Total CK levels are elevated in patients with CRF, but CK-MB levels are not; thus, elevation in CK-MB levels is due to myocardial injury. Elevation of troponin levels without a corresponding elevation in total CK levels has been shown to reflect enzyme elimination kinetics due to renal failure or cross-reactivity of the troponin I assay with noncardiac antigens.

Therefore, any enzyme elevations are not diagnostic in and of themselves. The diagnosis of postoperative MI should be made based on a combination of clinical, laboratory, and ECG evidence.

Bibliography

 

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Constructed by Dr N.A. Nematallah Consultant in perioperative medicine and intensive therapy, Al Razi Orthopedic Hospital , State of Kuwait, email : razianesth@freeservers.com