CRITICAL CARE AND ORGAN PROTECTION
| PERIOPERATIVE MANAGEMENT OF THE PATIENT RECEIVING RENAL REPLACEMENT THERAPY— Neal H.
Cohen, MD, Vice-Dean, Academic Affairs, University of California, San Francisco, School of Medicine
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| Traditional management strategies: once aortic cross-clamp removed, critical to maintain renal perfusion, optimize
intravascular volume, and improve renal perfusion pressure; optimizing and maintaining intravascular volume—
challenging due to large volume of crystalloid and clotting parameters, and probably, blood transfusion; patient extravasates
fluid administered and returns to intensive care unit (ICU) significantly edematous, perhaps with decreased
intravascular volume; “administration of more volume in a patient with renal dysfunction, who is already grossly
edematous, can be very difficult”; optimizing renal perfusion pressure—also difficult due to history of cardiac disease;
patient may not tolerate cardiac and vasopressor medications without suffering significant compromise; maintain
urine flow; experience suggests nonoliguric renal failure easier to manage than oliguric renal failure, but outcome may
not be significantly different; administer diuretics, although resulting hearing loss may contribute to posttraumatic
stress disorder in ICU patient; loop diuretics and mannitol frequently administered intraoperatively and postoperatively
to improve renal perfusion; dopamine and fenoldopam also used routinely
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 | Minimize management that may further complicate renal function: avoid nephrotoxic drugs (eg, aminoglycosides); minimize
use of drugs that require renal clearance; adjust drug dosages (eg, vancomycin) to ensure adequate levels; if postoperative
angiography used to monitor perfusion, minimize use of contrast material if possible; consider alternative
renal protection strategies, eg, N-acetylcysteine, particularly in patient who receives contrast
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| Renal replacement therapy (RRT): includes traditional intermittent hemodialysis and continuous RRT (CRRT; more
common in ICU; occasionally used in operating room [OR]); general indications include—persistent fluid overload and
persistent oliguria (<150 to 200 mL per 12 hr); electrolyte imbalance (monitor and carefully manage potassium, phosphate,
magnesium, and calcium); acid-base abnormalities; uremia (focus on complications, rather than specific blood urea nitrogen
[BUN] level)
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| Traditional intermittent hemodialysis: represents solute clearance based on diffusion over solute gradient; countercurrent
mechanism results in rapid fluid removal (as result of high flow of dialysate) and clearance of potassium; large
molecules (eg, insulin, drugs, glucose) not well removed by traditional dialysis; clearance depends on relationship between
blood flow (BF) and dialysate flow (“the higher the dialysate flow, the greater the clearance”); can adjust dialysate concentration
to better clear solutes; dialysate high in glucose, so monitor patient’s glucose; some CO2 removal through system;
on occasion, patient develops respiratory depression due to decreased Pco2 , respiratory rate, and minute ventilation; requires
careful control of blood gases, particularly in critical care setting
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| Hemofiltration: designed primarily to remove fluid; involves blood under pressure, passing across highly permeable
membrane; depends on solute drag; fluid moves across membrane based on pressure gradient; solute clearance accompanies
fluid flow; more effectively removes large molecules (but not potassium) than does traditional dialysis; amount of
ultrafiltrate produced and eliminated dependent on membrane used and size of pores, BF rate, and, to some extent, hematocrit
(“the lower the hematocrit, the more fluid will be removed”); BF rates through circuit 6 to 12 L/hr; ultrafiltrate produced
at rate of 1 to 2 L/hr; solutes cleared most effectively include urea, creatinine, some electrolytes, some cytokines,
heparin, ammonia, and some toxins and pesticides; things not filtered include albumin, protein-bound drugs (eg, benzodiazepines),
platelets, and cellular material; vancomycin and similar drugs have plus/minus clearance through hemofiltration;
replace fluid based on patient needs by adjusting bicarbonate or lactate concentration, sodium, potassium, and other
solutes
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| Membrane adsorption: facilitates clearance of pro- and anti-inflammatory cytokines and other compounds; patient at
high risk of developing sepsis or septic-like physiology may benefit from early initiation of RRT, independent of fluid
and electrolyte status; may also influence drug clearance and have significant influence on sedative and analgesic requirement
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| Additional comments: RRT traditionally dialysis; usually intermittent hemodialysis 3 times per week (perhaps daily
for short period); transitional intermittent dialysis approaches provide lower flows and lower fluid removal in more hemodynamically
stable manner; peritoneal dialysis has almost no relevance for most ICU and surgical patients; advantages
of intermittent hemodialysis—initiation by ICU or OR physician not required; readily available, used routinely,
removes fluid, and may correct electrolyte abnormalities; disadvantages—involves dramatic fluid and electrolyte shifts,
resulting in dysequilibrium syndrome and contributing to patients’ delirium and agitation; contributes to changes in central
nervous system (CNS) fluid volume, resulting in cerebral edema and altered mental status; hypovolemia
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| Continuous RRT: more common in ICU; also used on selected patients in OR; essentially “go slow” dialysis and fluid
removal; may be instituted through arterial and venous system or venovenous system (used in most cases; provided
through single catheter; removes, filters, and replaces blood); catheter diameter and length important; if diameter too
large, excess fluid removed, vessels collapse, and flow obstructed; catheter must be deep enough to ensure adequate
flow (ideally near superior vena cava [SVC]-right atrial junction without stimulating sinoatrial [SA] node); usually
double-lumen catheter, but 2 catheters may be used as long as arterial port that brings blood from patient to machine
more distal from heart than distal port (in atrium) that returns blood from machine to patient
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| Hemofiltration: blood pumped to membrane, fluid removed, and filtered blood comes back to patient; dialysate added to
circuit through another pump, creating concentration gradient across membrane; so patient’s blood undergoes dialysis
through diffusion and hemofiltration through pressure gradient; replacement fluid can be added and modified to normalize
patient or to optimize electrolyte and fluid balance
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| Slow continuous ultrafiltration (SCUF): eliminates replacement fluid; designed to slowly remove fluid from intracellular
and extracellular volume (without dialysate or replacement fluid); can remove 6 to 7 L of fluid per day; patient who has
extravasated large amount of fluid in OR may benefit from SCUF therapy by improving overall fluid balance, minimizing
potential for bed sores, skin irritation, and breakdown of abdominal wounds
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| Clinical indications: dialysis used for acute renal failure; ultrafiltration used for fluid overload; solute imbalance or toxicity
managed by adjusting replacement fluid; less hemodynamic instability than with intermittent dialysis
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| Advantages: mimics normal kidney; maintains hemodynamic stability; allows precise control of volume status, electrolytes,
acid-base status, and uremia; minimizes volume and osmolar shifts, and facilitates clearance of middle-sized and
large molecules; can remove liters of fluid in otherwise hemodynamically unstable patients requiring vasopressors who
do not respond to traditional measures; therapeutic benefits—can be adjusted to patient’s specific needs; maintains
hemodynamic stability or minimizes instability; provides solute removal and tighter control of fluids and electrolytes;
may have benefit in sepsis, ingestion of dialyzable toxins and drugs, shock, and management of altered intracranial
compliance; advocated as treatment for hypothermia and hyperthermia by rewarming fluid coming back into patient or
allowing exposure hypothermia
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| Limitations: include systemic bleeding; vascular access complications; hypothermia; mistakes in fluid balance calculations;
bed rest requirement; transport to computed tomography (CT) area (each time system taken down, ≈200 mL of blood lost
by retention in membrane); mechanical complications; specialized training required; cost (mostly related to labor); anticoagulation
generally required (heparin used most commonly; goal for partial thromboplastin time [PTT] 1.5 to 2.0 times
normal value, measured in venous return limb); some patients develop heparin-induced thrombocytopenia or have increased
bleeding risk; alternative anticoagulants include regional citrate anticoagulation (may develop metabolic acidosis;
high citrate concentration can chelate calcium, causing hypocalcemia and possibly myocardial dysfunction); saline bolus
(occasionally used; may be ineffective at decreasing fibrin deposition and decreasing clogging of filter)
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| Effect on outcome: current evidence suggests no survival benefit; recovery benefit may optimize management; improved
management of solutes and volume status clearly facilitated by CRRT; ultimate value unknown
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| PROTECTING THE HEART —Lee A. Fleisher, MD, Robert D. Dripps Professor and Chair, Department of Anesthesia,
and Professor of Medicine, University of Pennsylvania School of Medicine, Philadelphia
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| Perioperative concerns: hypotension not shown to be most associated with perioperative ischemia or infarct; myocardial
ischemia may or may not be end product (certain episodes of ischemia may be preconditioning and may protect heart
from prolonged episode of ischemia; inhalational anesthetics may mimic brief episodes of ischemia and be protective for
final insult); myocardial infarction (MI) of more concern; troponin leak may have long-term implications
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| Determinants of ischemia: supply side (eg, blood supply and vasoconstriction; anemia and hypoxia); demand side
(eg, tachycardia; contractility issues; diastolic volume and blood pressure); if ischemia prolonged (30 min to 2 hr), infarct
may follow; if short and brief, may protect myocardium from later infarct; acute thrombosis alternative mechanism; unstable
angina or ischemic changes related to plaque rupture, macrophages, platelets, thrombus formation, and eventually
MI and death; use of aspirin or other anticoagulants not yet studied in perioperative period; prolonged, stress-induced infarction
occurs with higher degree of stenosis (≥70%); plaque-rupture MI occurs with lower degree of stenosis
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| McFalls study: once thought that performing coronary vascularization before major noncardiac surgery would lead to
good outcome; McFalls et al reported on coronary artery revascularization before elective major vascular surgery
(CARP) trial; randomized ≈500 patients with positive angiography (no significant left main disease) to revascularization
or nonrevascularization; found both groups had similar rate of death at 30 days, rate of infarction, and length of stay;
looking at survival out to 6 yr, those assigned to revascularization had 77% survival rate at ≈2.6 yr; survival curve almost
identical for patients not undergoing revascularization (same median survival); most revascularization for single- or double-vessel
disease; ≈66.6% of patients underwent angioplasty
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| Further studies: indicate “you can do more harm than good by attempting to protect the heart by coronary stent placement,
than by just going through surgery alone”; many believe that angioplasty alone (in highly symptomatic patient with
left ventricular [LV] dysfunction, without placement of stent for urgent surgery) may be most sensible (stent may increase
risk); optimal strategy unknown in highest-risk patients (eg, left main or triple-vessel disease); in absence of high-risk disease,
fixing heart first does not acutely protect it from subsequent perioperative events; another study found that hypothermia
increases rate of perioperative MI, angina, and cardiac arrest
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Intraoperative Pharmacologic Therapies
| Nitroglycerin: may be excellent treatment for ischemia, but appears ineffective as prophylaxis
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| β-blockers: original trial indicates atenolol associated with improved long-term survival (no short-term benefit); Poldermans
et al—looked at patients with risk factors for coronary disease who had positive stress test; excluded patients with
extensive wall-motion abnormalities; found giving bisoprolol for ≥7 days preoperatively (and continued for 30 days) had
significant effect in reduction of perioperative morbidity; average patient heart rate <60/min preoperatively, <80/min intraoperatively,
with additional intravenous (IV) metoprolol given perioperatively; patients previously on β-blockers continued
for ≤1 yr, and β-blockers not started in those not previously on them; conclusion that patients with known
coronary disease benefit from β-blockers independent of perioperative period; as number of risk factors decrease, actual
benefit from perioperative β-blockers diminishes; another study—found that when patient’s heart rate tightly controlled
with esmolol, incidence of perioperative ischemia lower; unclear whether to start β-blocker average of 37 days in advance,
morning of surgery, or near end of surgery but ensuring continuation to postoperative period; patient previously
on β-blockers or patient at high cardiac risk undergoing vascular surgery should continue taking medication; Lindenauer
et al—looked at patients with multiple risk factors and showed that in patients with Revised Cardiac Risk Index score of
0, treatment associated with increased harm; study in British Medical Journal—suggests giving atenolol (for long-acting
benefits) rather than metoprolol in perioperative period (avoids β-blocker withdrawal); speaker’s conclusion—
starting β-blocker preoperatively ideal for patient with positive stress test about to undergo vascular surgery because β-
blockers not only control heart rate, but have anti-inflammatory effects if given long enough and may decrease thrombotic
tendency; if patient has not received β-blockers on morning of surgery, give anesthetic and titrate β-blockers in by
end of surgery to control heart rate perioperatively and decrease stress and shear forces on plaque
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| α2 -agonists: appear to have some beneficial short- and long-term effects
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| Statins: anti-inflammatory properties; Poldermans et al showed reduced mortality after vascular surgery, even in subset of
patients on β-blockers; older randomized trial, in which statins started ≈30 days before vascular surgery, show significant
beneficial effect; Lindenauer used large scale cohort study of patients with multiple risk factors to show beneficial effect
of statins on perioperative death
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Educational Objectives
| The goal of this program is to educate the listener about perioperative management of the patient receiving renal replacement
therapy and strategies to reduce cardiac risk of noncardiac surgery. After hearing and assimilating this program, the participant
will be better able to:
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| 1. Describe traditional management strategies for renal replacement therapy.
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| 2. Differentiate between traditional intermittent hemodialysis and continuous renal replacement therapy (CRRT).
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| 3. Review the clinical features of CRRT.
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| 4. Explain the recent guidelines on coronary revascularization before major noncardiac surgery.
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| 5. Summarize perioperative prophylactic medical interventions to reduce cardiac risk in noncardiac surgery.
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Discussed on This Program
Atenolol [Tenormin]
Bisoprolol fumarate [Zebeta]
Dopamine HCl [Intropin, Dopamine HCl in 5% Dextrose]
Enalapril maleate [Enalaprilat, Vasotec]
Fenoldopam mesylate [Corlopam]
Fentanyl citrate [Sublimaze]
Insulin injection, regular (several trade names)
Mannitol [Osmitrol, Resectisol]
Metoprolol succinate [Lopressor, Metoprolol Tartrate, Toprol XL]
Pancuronium bromide
Vancomycin [Vancocin, Vancoled]
Suggested Reading
Durazzo AE et al: Reduction in cardiovascular events after vascular surgery with atorvastatin: a randomized trial. J
Vasc Surg 39:967, 2004; Eagle KA et al: ACC/AHA Guideline Update for Perioperative Cardiovascular Evaluation for
Noncardiac Surgery--Executive Summary. A report of the American College of Cardiology/American Heart Association
Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation
for Noncardiac Surgery). Anesth Analg 94:1052, 2002; Fleisher LA et al: ACC/AHA 2006 guideline update on perioperative
cardiovascular evaluation for noncardiac surgery: focused update on perioperative beta-blocker therapy: a report of
the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee
to Update the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery): developed in collaboration
with the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society,
Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society for
Vascular Medicine and Biology. Circulation 113:2662, 2006; Fleisher LA: Strategies to reduce cardiac risk in noncardiac
surgery: where are we in 2005? Anesthesiology 102:881, 2005; Kellum JA et al: Continuous versus intermittent
renal replacement therapy: a meta-analysis. Intensive Care Med 28:29, 2002; Kellum JA et al: The first international
consensus conference on continuous renal replacement therapy. Kidney Int 62:1855, 2002; Kiziltepe U et al: Effects of
combined conventional and modified ultrafiltration in adult patients. Ann Thorac Surg 71:684, 2001; Landesberg G et
al: Coronary revascularization before vascular surgery. N Engl J Med 352:1492, 2005; Lindenauer PK et al: Perioperative
beta-blocker therapy and mortality after major noncardiac surgery. N Engl J Med 353:349, 2005; McFalls EO et
al: Coronary-artery revascularization before elective major vascular surgery. N Engl J Med 351:2795, 2004; Morabito S
et al: Continuous renal replacement therapies: anticoagulation in the critically ill at high risk of bleeding. J Nephrol
16:566, 2003; Pastan S et al: Dialysis therapy. N Engl J Med 338:1428, 1998; Petroni KC et al: Continuous renal
replacement therapy: anesthetic implications. Anesth Analg 94:1288, 2002; Tan HK et al: Continuous venovenous
hemofiltration without anticoagulation in high-risk patients. Intensive Care Med 26:1652, 2000; Teehan GS et al: Update
on dialytic management of acute renal failure. J Intensive Care Med 18:130, 2003; Wallace AW et al: Effect of
clonidine on cardiovascular morbidity and mortality after noncardiac surgery. Anesthesiology 101:284, 2004; Wilson SH
et al: Clinical outcome of patients undergoing non-cardiac surgery in the two months following coronary stenting. J Am
Coll Cardiol 42:234, 2003.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial relationship
with the manufacturer or provider of any commercial product or service discussed. For this issue, the faculty reported
nothing to disclose.
Drs. Cohen and Fleisher were recorded at the 59th Postgraduate Assembly in Anesthesiology, presented December 9-13,
2005, by the New York State Society of Anesthesiologists, Inc. and held in New York, NY. The Audio-Digest Foundation
thanks the speakers and the NYSSA for their cooperation in the production of this program.
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