Useful Knowledge For Patients With Chronic Kidney Disease

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Chronic Kidney Disease

Reena Julka and Ashok Reddy

Chronic kidney disease (CKD) affects 5% of the general population [1]. In the United States, hemodialysis-dependent end-stage renal disease has increased by 20% since 2000 [2]. In a systematic review and metaanalysis, CKD was an independent risk factor for postoperative mortality and cardiac events—with a similar strength of association with diabetes, stroke, and coronary disease [1]. However, patients with CKD can safely undergo surgery with appropriate medical management.

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PREOPERATIVE EVALUATION

In the preoperative setting, it is important to document the history of existing renal disease, severity (e.g., chronic kidney disease stage), history of transplant, and etiology of disease. Information including baseline creatinine and any major problems in the past (e.g., renal
failure during admission for sepsis) is vital. Preoperative measurement of the serum creatinine and electrolytes is appropriate for all these patients.

CKD affects renal drug elimination, drug absorption, drug distribution, and non-renal clearance [3]. The normal creatinine clearance (CrCl) is generally >100 mL/min. Patients need adjustments to the most commonly used medications when the CrCl falls below 50 mL/min.
Glomerular filtration rate and/or CrCl is estimated using the Modification of Diet in Renal Disease (MDRD) study or using Cockcroft–Gault equation. These estimates are less accurate in certain circumstances including when patients have more or less muscle mass [4]. Also, these estimates assume that the patient is at a steady-state—thus in patients with rapidly rising creatinine, the calculations overestimate the patient's renal function [4].

The major morbidity and mortality in patients with end-stage renal disease (ESRD) is cardiovascular disease- the largest single cause being fatal arrhythmias [2]. It is estimated that left ventricular hypertrophy is as high as 30% in patients with CKD not yet on dialysis. Additionally, the incidence of pulmonary hypertension in patients with ESRD may be as high as 40%[2]. These comorbid conditions lead to the importance of a thorough preoperative cardiovascular and pulmonary risk assessment. Care for patients with hemodialysis dependent ESRD or a history of renal transplant should be coordinated with a nephrologist.

COMMON MANAGEMENT ISSUES

Hemodialysis
It is preferred that hemodialysis (HD) is carried out on the day before surgery to minimize any risks from anticoagulation and from unresolved fluid or electrolyte shifts [2]. Informing inpatient nephrology teams about HD patients on the day of surgery can be useful if there
are major issues with fluid or potassium control in the postoperative setting.

In the preoperative setting, a history of vascular access (right or left arm, history of clotting, or history of stenosis) can provide useful information to staff and clinicians involved in the patient's care. In general, HD catheters should not be used for purposes other than dialysis. Documenting a patient's usual dialysis days and length of time is helpful information in coordinating hemodialysis care.

Fluid and Electrolyte

Recording the "dry weight" prior to surgery is helpful in managing the patient's volume status. Patients who are above their dry weight are at risk of pulmonary edema and poorly controlled HTN while those who are under their dry weight are at risk of hypotension in the postoperative setting. Common electrolyte disturbances include hyperkalemia and metabolic acidosis. In general, these should be monitored and treated in the pre-and postoperative setting to reduce the risk of ventricular arrhythmia.

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Medications

Reviewing the medication list looking for drugs that may impair renal function or which require dose adjustment according to the patient's estimated CrCl is important.

■ Useful resources include Micromedex®, e-books, and textbooks such as the ACP guide for renal dosing [5], and pharmacists are essential resources for dose adjustment recommendations depending on the medication and the patient’s estimated CrCl. CHAPTER 18: CHRONIC KIDNEY DISEASE 125 VII

■ Certain antibiotics (vancomycin, aminoglycosides, etc.) not only need dose adjustment but also close monitoring in the inpatient setting.
■ Avoid nonsteroidal anti-inflammatory agents (NSAIDs) if possible.
■ Morphine and meperidine have metabolites that can accumulate with renal insufficiency. Hydromorphone and fentanyl are the preferred narcotic agents for patients with renal insufficiency.
■ Enoxaparin is impaired by renal insufficiency—use with caution in patients with CKD (dose adjustments are available but close monitoring of anti-factor Xa is recommended).
■ Use caution reinstituting ACE inhibitors and ARBs—monitoring renal function and electrolytes closely in the postoperative period.

Anemia

Loss of erythropoietin production as renal function declines often leads to significant anemia. Typically, nephrologists use erythropoietin-stimulating agents (ESAs) and supplemental iron (PO/IV) to target hematocrit of ~33% [6]. In the preoperative period discussion with

nephrology can be helpful in optimizing anemia prior to surgery with the knowledge that the benefit of ESAs and supplemental iron takes a number of weeks to achieve.

POSTOPERATIVE MANAGEMENT

Postoperative management includes diligent medication monitoring as described above. Dose adjustments in antibiotics are often required, as is avoidance of NSAIDs. Adequate volume resuscitation after major surgeries is essential. Resumption of chronic ACE-I or ARB medications should be started with care once the renal function is established to be stable post-op. Many patients require diuretics chronically to maintain their volume status, and typically need diuretics resumed post-op provided they are not volume depleted.

For patients who receive hemodialysis, care is best managed in consultation with a nephrologist. Patients may require additional dialysis or ultrafiltration depending on the volume load received intraoperatively and the patient's clinical stability.

BLEEDING

Patients with CKD and ESRD are at risk of uremia which can cause platelet dysfunction resulting in increased perioperative bleeding [3]. This can be reduced by adequate hemodialysis. If excessive bleeding continues there are additional strategies that may be helpful, including stopping all medications that may inhibit platelet function including aspirin. Discussion with a nephrologist or a hematologist is often helpful with regard to the use of desmopressin, cryoprecipitate, or transfusion.

CONTRAST PROCEDURES

Patients with CKD may need evaluation requiring contrast media. First, consider the necessity of the procedure and any alternatives (ultrasound, non-contrast CT scan, or MRI without gadolinium). If the test is required, consider pre-hydration and the use of N-acetylcysteine prior to the contrast procedure [7]. Note however that there is practice variation with regard to radiology protocols, and more recent studies have not found benefits with the use of N-acetylcysteine [8].

■ If the patient can tolerate volume expansion with sodium bicarbonate, consider treatment before and after contrast studies. The patient should receive a bolus of 3 mg/kg of isotonic bicarbonate for 1 h prior to the procedure and continued at a rate of 1 mL/kg/h for 6 h after the procedure.
■ N-Acetylcysteine, at a dose of 1,200 mg orally twice daily, can be administered the day before and on the day of the procedure. (Note: Protocols vary between 600 and 1,200 mg twice daily.)

From: THE PERIOPERATIVE MEDICINE CONSULT HANDBOOK --Chapter 18 Chronic Kidney Disease by Reena Julka and Ashok Reddy

REFERENCES

1. Mathew A, Devereaux PJ, O’Hare A, et al. Chronic kidney disease and postoperative mortality: a systematic review and meta-analysis. Kidney Int. 2008;73:1069–81.
2. Rainor D, Borthwick E, Ferguson A. Perioperative management of the hemodialysis patient. Semin Dial. 2011;24(3):314–26.
3. Krishnan M. Preoperative care of patients with kidney disease. Am Fam Physician. 2002;66(8):1472–6.
4. Stevens LA, Coresh J, Greene T, Levey AS. Assessing kidney function—measured and estimated glomerular filtration rate. N Engl J Med. 2006;354:2473–83.
5. Aronoff GR, Bennett WM, Berns JS, Brier ME, Kasbekar N, Mueller BA, Pasko DA, Smoyer WE. Drug prescribing in renal failure. 5th ed. ACP Press; 2007.
6. KDOQI. KDOQI clinical practice guideline and clinical practice recommendations for anemia in chronic disease: 2007 update of hemoglobin target. Am J Kidney Dis. 2007;50:471–530.
7. Rudnick MR. Prevention of radiocontrast media-induced acute kidney injury. UpToDate. February 2011. http://www.uptodateonline.com. Accessed Dec 2011.
8. ACT Investigators. Acetylcysteine for prevention of renal outcomes in patients undergoing coronary and peripheral vascular angiography: main results from the randomized acetylcysteine for contrast-induced nephropathy trial (ACT). Circulation. 2011;124(11):1250–9.
Epub 22 Aug 2011.