140 likes | 987 Views
Post-Operative Oliguria. Definitions. Oliguria - <0.5 cc/kg per hr in adult About 30-70 cc/hr Children less than 10kg: <1 cc/kg per hr Anuria - <100cc/24hrs Acute renal dysfunction – oliguria and increase in Creatinine (>1 mg/dl from baseline). Case Presentation.
E N D
Definitions • Oliguria - <0.5 cc/kg per hr in adult • About 30-70 cc/hr • Children less than 10kg: <1 cc/kg per hr • Anuria - <100cc/24hrs • Acute renal dysfunction – oliguria and increase in Creatinine (>1 mg/dl from baseline)
Case Presentation • 65y M w PVD, POD#0 s/p RLE bypass • Called by the ICU for UOP 20mL over 2hrs
General Approach • Go see patient, talk with nursing staff, get flowsheet • ABC (evaluate mental status) • Resuscitate - does pt have adequate IV access, does the pt need Foley, NGT, continuous monitoring? • H&P • Physical examination • Order appropriate labs/tests • Diagnose and treat • Communicate plan with team and patient
Case: Assessment & Resuscitation • AAOx3, afebrile, P 105, BP 100/60, O2 sat 96% RA • Tachycardic, oliguric = hypovolemia • Ensure adequate IV access • Fluid bolus • While pt is receiving bolus, continue the evaluation What are potential causes? What exam findings/tests will help you make a diagnosis?
DDx • Pre-renal (2/2 ↓ renal perfusion) • Dehydration, bleeding • Shock 2/2 sepsis, cardiogenic • Abdominal compartment syndrome • Renal artery stenosis • Post-renal (obstructive) • Obstructed Foley catheter • Extrinsic compression on ureter, bladder, urethra (BPH, CA, hematoma) • Stone • Intrinsic renal • ATN (contrast, prolonged pre-renal, toxins, rhabdomyolysis) • AIN (drugs i.e. antibiotics) • Less common in surgical population: • Vascular (Wegener’s, HUS, TTP, embolism) • Glomerular • Nephritic (red cells, red cell casts) • Nephrotic (proteinuria, edema, HTN)
H&P • Focused history: time since surgery, surgical complications, anesthesia history (any periods of hypotension during surgery?), recent medications, recent h/o contrast, check fluid balance (include operative period and even pre-operative period) • Physical: signs of bleeding, signs of dehydration, look at urine • Tip: Flush the Foley (catheter obstruction)
Labs • Initial labs: • CBC - ?bleeding? • BMP, urine Na & Cr, U/A • Note: if pt has been on diuretics, send for urea instead of Cr • Additional studies: Urine Eos, CPK, Urine myoglobin, Renal U/S • As suspected: septic workup, MI workup • Interpretation of FeNa: • Pre-renal: UNa<20, FeNa<1%, BUN/Cr >20 • ATN: UNa>40, FeNa>1%
FeNa Calculation • FENa = UNa * PCr/ PNa * UCr x 100 • Online calculators
Studies • Renal Ultrasound – evaluate renal blood flow • Central catheter to evaluate CVP, Swan-Ganz catheter • Bladder pressures (for Abd Compartment Syndrome) • Via foley, >20 abd HTN, >40 requires intervention • Bladder US or IV pyelogram
Post-Op Oliguria: Treatment • Pre-renal: resuscitation, improve CO • Post-renal: fix the obstruction • New foley, suprapubic tube, nephrostomy tube • Sepsis: resuscitate & broad-spectrum abx • Contrast-induced nephropathy: IVF, N-acetylcysteine, +/- bicarbonate • Nephrotoxin or AIN: stop the agent
Indications for Hemodialysis • Acidosis (pH < 7.10) • Electrolytes (for example, hyperkalemia) • Ingestion (toxins) • Overload (fluid overload) • Uremia
Take Home PointsWhat to do when you’re called with low UOP • Go see the patient • Always start with your ABCs • Resuscitate • Oliguria ddx: pre-renal, post-renal, intrinsic • Look for bleeding • FeNa can help