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Nephrology ClearanceDr. JC E. Loren Dept. of Internal Medicine Southern Philippines Medical Center February 14, 2011

PRE-OPERATIVE PREPARATIONSI. FLUID STATUSAND EXTENT OF UREMIAA. FLUID STATUSAvoid OVERHYDRATION Avoid DEHYDRATION

B. EXTENT OF UREMIA Dialysis 12-24 hours plateletplanned surgeryfibroblast response to - affects before the function, Advisable to have 2-3 sessions of dialysis before the procedure to ensure a well tissue injury, and the immune system dialyzed status Watch out for dehydration, hypokalemia AND - for elevtive procedure:

II. ELECTROLYTE DISORDERSA. SERUM POTASSIUM LEVEL - should be at the lower range of normal (4 meq/L) - prevention of hyperkalemia: > furusemide > salbutamol nebulization > Regular Insulin + D5 water > Kalimate sacchet - post dialysis potassium prior to surgery should be 3.0 (dialysate should contain at least 2 meq/L)

II. ELECTROLYTE DISORDERS A. SERUM POTASSIUM LEVEL - special cases like patients on: DIGITALIS/HEMODYNAMICALLY UNSTABLE PATIENTS ------- higher K on the dialysate is recommended (3 meq/L) - in severely catabolic/bleeding patients, the rate of rise in the serum potassium value is greater than 1.0 1.5 meq/L/day. AGGRESSIVE LOWERING OF POTASSIUM IS WARRANTED - prevention of hypokalemia to prevent arrythmia during anesthesia induction

II. ELECTROLYTE DISORDERSB. SERUM SODIUM LEVEL > mild hyponatremia is common in seriously ill patients > use of dialysate high in sodium > avoid hypotonic solution

III. ACID BASE STATUSGOALS: 1. correct pH rather than the HCO3 level 2. mild preoperative acidosis is safer than alkalosis

IV. HEMATOCRIT LEVEL AND COAGULATION PROFILE Hct level: minimum of Hct at 20 35% is acceptable If time permits, prior to major surgical procedure, the Hct should be corrected by erythropoietin therapy

IV. HEMATOCRIT LEVEL AND COAGULATION PROFILE COAGULATION Uremic platelet dysfunction and deficient platelet vessel wall interaction The best screening test is Bleeding Time Measures to shorten the BT: A course of intensive hemodialysis or PD to maximize reversal of the uremic state Administration of desmopressin (DDA VP), cryoprecipitate, or coagulated estrogen Transfusion of red cells or the administration of ERYTHROPOIETIN to raise the hematocrit to at least 30%

IV. HEMATOCRIT LEVEL AND COAGULATION PROFILEDrugs that inhibit platelet function - aspirin and dipyridamole must be avoided for at least 2 weeks prior to surgery

IV. HEMATOCRIT LEVEL AND COAGULATION PROFILE Heparin effects from previous dialysis: Heparin t is beteewn 1 2.5 hrs Defer surgery at least 12 hours from the last dialysis (which used heparin) For emergency surgery, dialyzed the patient without heparinization No problem with PD

INTRAOPERATIVE1. PROTECTION OF THE VASCULAR ACCESS 2. ANESTHESIAA. PREMEDICATION- commonly used drugs (diazepam, atropine, fentanyl) can be used in normal dosage in dialysispatients - best to check the pharmacokinetics to detremine if a dosage reduction is required

INTRAOPERATIVEB. MUSCLE RELAXANTS Non- depolarizing: > Tubocurarine, the least affected by the renal failure but the duration of action is still prolonged > Gallamine should not be used because its elimination is completely dependent on the kidneys > Metocurine, pancuronium may offer certain hemodynamic advantage over curare but their half lives are greatly prolonged in renal failure

INTRAOPERATIVEB. MUSCLE RELAXANTS Depolarizing: > Succinylcholine can be given in usual dosage but closely monitor the potassium (the drug causes intracellular K release) > Decamethonium should be used with great caution

INTRAOPERATIVEANESTHETIC AGENTS: Can be safely given in renal failure without dose adjustment: HALOTHANE and NITROUS OXIDE Enflurane and methoxyflurane should be avoided since its metabolite yield OXALATE and FLUORIDE (NEPHROTOXIC)

INTRAOPERATIVE3. FLUID AND ELECTROLYTE MANAGEMENT Most patients with renal failure have heart disease Volume status and cardiac filling pressure need to be carefully monitored Potassium-containing IV fluids should not be given routinely intra-op

4. INTRAOPERATIVE HEMODIALYSIS - for patients undergoing bypass

POST-OPERATIVE meticulous monitoring of fluid and electrolyte balance decision whether hemodialysis is necessary should be made on a daily basis any dialysis post op especially from vascular or ophthalmic surgery should be done without using heparin

Common problems encountered post-op are:I. HYPERKALEMIA

Dialysis for K > 6 meq/L URGENT therapy for life threatening hyperkalemia: NaHCO3 Clucose + insulin Albuterol (Reduction of K level ranges from 0.5 to 1.0 meq/L, duration of effect is 2 hours)

II. HYPERTENSIONRefelects increased volume Withdrawal of antihypertensive drugs

Common problems encountered post-op are:III. HYPOTENSION - reflects the hemorrhage or fluid deprivation due to preoperative dehydration - pericardial effusion IV. FEVER - any fever persisting 24-48 hours after surgery may be an indication of infection - uremic patients are in the state of immunodepression - careful adjustment of antimicrobial dose and to the metabolic load associated with administration of certain of these drugs

Common problems encountered post-op are:VI. PULMONARY - dialysis patients have stiff hypertrophied hearts that require a relatively high filling pressure for optimal function but at the same time suffer from the increased capillary permeability (due to uremia)------PULMONARY EDEMA

ANEMIA OF RENAL FAILUREErythropoetin therapy (EPOTEIN ALPHA or BETA) Uses: restores erythropoiesis brings back to normal the electrocyte survival and viability increases elasticity, deformability and antioxidant enzymatic system of RBC higher Red Cell superoxide dismutase/total glutathione peroxidase uremic BT shortened

ANEMIA OF RENAL FAILURE anemia starts to occur once GFR is down to 2035ml/min 7% of patients with renal failure DO NOT need treatment for anemia normal EPO level: 8-18 mu/cc goal of therapy: Hct 28-33% Recommended dose: 50-300 IU/kg 3x a week T1/2 of IV = 4-13 hours T1/2 of SQ = 24 hours EPO Alpha and Beta differs in their oligosaccharide moiety (more in Alpha) but NO difference in pharmacokinetics and efficacy

DRAWBACK IN EPO THERPY: EXACERBATION OF HYPERTENSIONRecommendation: can occur during the first 4 months of therapy while the Hct is increasing avoid rate of rise in the Hgb of >3 g/dl in any 4 week period each time dosage is increased, the increment shou8ld not exceed 30 IU/kg 3x a week reason for the Hypertension:- Correction of Hct losses the reactive vasodilatation broughtn about by chronic hypoxemia of anemia

EFFECT OF RENAL FAILURE ON HEMOSTASIS BLEEDING TIME is a predictor of bleeding Platelet are adequate in renal failure but function is impaired

UREMIA = BLEEDING TENDENCY AND THROMBOSISI. BLEEDING TENDENCY IN UREMIA Associated with excessive formation of NO NO inhibits platelet aggregation Stimulation of TNF alpha and IL-1 beta CRD (defect in platelet function):

Decreased total platelet gp!b Defect in gp 11b III a complex

II. ABNORMALITY OF COAGULATION AND FIBRINOLYSIS: (thrombotic tendency) increased Fibrinogen (activates fibrinolysis) Increased Factor VIII C Decreased antithrombin C Decreased protein S and C