SICU Case Discussion—Perioperative Renal Failure in Cardiac Surgery

Intern 許惠晴 Resident 李惠琴 醫師V.S. 張家昇 主任

Name: 莊先生Age: 82Sex: maleChart No.: 16448408Date of admission: 2008/03/04

Basic Data

Present Illness

Sudden onset of upper back pain since 3 AMIntolerable pain without radiation brought to 埔基 H. CT: aortic dissection experienced bilateral legs numbness and right leg weakness transferred to our hospital On admission: severe back pain; not able to move his right leg; bedside doppler failed to sense blood flow over bilateral dorsal pedis, bilateral popliteal and right femoral artery.

Present Illness

Leg CTA: 1) Aortic dissection at lower abdominal aorta, 2) PAOD of both lower limb from bilateral external iliac arteriesType B aortic dissection was diagnosed sent to OR

Past History

RCC, pT2N1M0 s/p R't radical nephrectomy + hilar lymph node excision + R't adrenalectomy on 96/10/02 3V-CAD s/p PTCA + stent to RCA Complete AV block s/p TPM in 96/08 Chronic renal failure Hypertension Gout

Lab data on 2008/03/04

RBC Hb HCT PLT. 3.41 9.9 29.4 143 WBC Seg Lymph Mono. Baso. Eos. 9.07 87 8.9 2.4 0.1 0.9 GPT Bil-T Glu-AC 14 0.55 166 BUN CREA NA K eGFR 40 2.57 136 5.1 19.4

Operative MethodRight axillo-femoral; femoral-femoral bypass

Operative Findingsno pulsation of rt’ common femoral arterydissection with intramural hematoma over lt’ common femoral artery equal artery pressure over bilateral subclavian artery

Hyperkalemia(K:6.5) and oliguria were noted at OR ABG: PH 7.36, PaO2 274.5, PaCO2 38.6, HCO3 22.4, O2 sat 100.0% Acute renal failure Consult nephrologist for CVVH

Perioperative Renal Failure in Cardiac Surgery

Incidence of Peri-operative ARF

occurs in up to 30% of all patients who undergo cardiac surgery, dialysis occurs in approximately 1%7% after abdominal aortic reconstruction 3% after elective infrarenal aortic reconstruction, mortality greater than 40% Acute tubular necrosis accounts for nearly all renal dysfunction and failure after aortic reconstruction. The degree of preoperative renal insufficiency remains the strongest predictor of postoperative renal dysfunction.

Acute perioperative renal failure is most likely to occur in patients who have renal insufficiency before surgery, are older than 60 years, and have preoperative left ventricular dysfunction

General Measures to Prevent ARF

Optimization of systemic hemodynamics— maintenance of intravascular volume the mos

t effective means of renal protectionHemodynamic monitoringAvoid over-hydrationAvoid nephrotoxinUse isosmolar contrast agents

Pharmacologic Intervention to Prevent ARF after Cardiac Surgery

Increase renal blood flow— low dose dopamine, fenoldopamInduce natriuresis—ANP, mannitol, diureticsBlock inflammation—Pentoxifylline, N-acetylcysteineOther—Clonidine, diltiazem, prophylactic hemodialysis

Loop diuretics and low-dose dopamine (1 to 3 μg/kg/min) have been advocated to protect the kidneys by increasing renal blood flow and urine failed to show benefit

Fenoldopam mesylate

A selective dopamine type 1 agonist that preferentially dilates renal and splanchnic vascular beds; has shown some early promise as a renal-protective agent .causes natriuresis and increases renal blood flow and urine output

Atrial natriuretic peptide

anaritide increases natriuresis by increasing GFR as well as by inhibiting sodium reabsorption by the medullary collecting duct significant reduction in the incidence of dialysis at day 21 after the start of treatment (low rate, prolonged infusion)

Mannitol

to induce an osmotic diuresisimproves renal cortical blood flowreduce ischemia-induced renal vascular endothelial cell edema and vascular congestionacting as a scavenger of free radicalsdecreasing renin secretionincreasing renal prostaglandin synthesis

N-acetylcysteine (N-AC)

shown to block inflammation and oxidant stress in cardiac surgery patientmay hold promise as a simple, nontoxic protective measureNot proven yet.

Prophylactic hemodialysis

Single studyCreatinine > 2.5 mg/dlPerioperative prophylactic dialysis vs. Dialysis only when postoperative ARF that indicated the procedureMortality: 4.8 vs.30.4% Need more study

Inh. Sym. tone

Inh. InflammPrevent vasospasm

Continuous Renal Replacement Therapy

Arteriovenous: external shunt, without the absolute need of a blood pumpVenovenous: catheter, require a blood pumpCVVH: hemofiltration; removal of fluid and waste occur by entirely by convection or bulk flow, transmembrane pressure governs the amount of fluid and dissolved waste being ultrafiltered across the membrane

Continuous renal replacement therapy(CRRT)

Renal Replacement Therapy

Blood Pump

Replacement Fluid (RF)/Dialysate (D)

Intraoperative Use

Slow continuous ultrafiltration(SCUF)

Yes/no None Yes

Continuous arteriovenous hemodialysis(CAVHD)

No D No

Continuous arteriovenous hemodiafiltration(CAVHDF)

No RF/D No

Continuous venovenous hemofiltration(CVVH)

Yes RF Yes

Continuous venovenous hemodialysis(CVVHD)

Yes D Yes

Continuous venovenous hemodiafiltration(CVVHDF)

Yes RF/D Yes

Reference

Brenner & Rector's The Kidney, 7th ed.Miller's Anesthesia, 6th ed. Acute Kidney Injury Associated with Cardiac Surgery, Mitchell H. Rosner, Clin J Am Soc Nephrol 1: 19–32, 2006.