Acute Renal Failure

•  ↑ of Cr by ≥0.5 mg/dL or ↑ of Cr by ≥20% over 2 wks

•  Prerenal

• Renal hypoperfusion resulting in ↓ GFR

• Causes

• Hypovolemia, ↓ cardiac output, liver failure, sepsis

• Renal vasoconstriction (ACE/COX inhibitors)

•  Intrinsic (renal)

• Damage to renal parenchyma

• Causes

• Acute tubular necrosis (ATN)—causes include ischemia & toxins (aminoglycosides, myoglobin, IV contrast)

• Acute interstitial nephritis (AIN)—usually caused by drugs (NSAIDs, b-lactams, sulfonamides, rifampin)

• Glomerulonephritis

• DIC

• TTP

•  Postrenal

• Outflow obstruction (must have bilateral obstruction, unilateral obstruction if only one kidney present, kinked Foley)

• Causes

• Nephrolithiasis, BPH, prostate cancer, neurogenic bladder

•  Treatment

• Treat underlying disorder

• Avoid nephrotoxic drugs

• Fenoldopam & low-dose dopamine (controversial) may help prevent or treat ARF by dilating renal arteries & ↑ RBF & GFR

•  Dialysis if indicated due to:

• Acidosis

• Electrolyte disturbances (hyperkalemia)

• Intoxication (methanol, ethylene glycol)

• Volume overload

• Uremia

Chronic Renal Failure

•  Either GFR <60 mL/min/1.73 m² or evidence of kidney damage (abnormal urinalysis, imaging or histology) for ≥3 mos

•  Causes:

• Hypertension

• Diabetes mellitus

• Glomerulonephritis

• Polycystic kidney disease

• Renovascular disease

•  Treatment

• ACE inhibitors/ARBs may slow progression of diabetic renal disease

• Erythropoietin for anemia

• Dialysis as indicated (hemodialysis/peritoneal dialysis)

• Phosphate binders for hyperphosphatemia

• Renal transplantation

For a list of commonly used diuretics, see Chapter 2H-56, Clinical Characteristics of Commonly Encountered Diuretics

ANESTHESIA FOR PATIENTS WITH RENAL DISEASE

Effects of Anesthesia on Renal Function

•  Reversible ↓ in RBF, GFR, urine production during regional & general anesthesia can occur despite maintenance of normal BP/volume status

•  RBF & GFR will usually return to normal within several hours postop

Indirect Effects of Anesthesia

•  Anesthetic agents & sympathetic blockade (during regional techniques)

→ Hypotension & myocardial depression → ↓ RBF & GFR

•  Hydration before anesthesia may lessen hypotension and changes in RBF

Direct Effects of Anesthesia

•  Fluorinated agents can cause direct renal toxicity (fluoride impairs kidney’s ability to concentrate urine & causes tubular necrosis)

• Fluoride production negligible with halothane, desflurane, & isoflurane

• Sevoflurane & enflurane release fluoride (no clinical evidence of renal damage)

•  Sevoflurane reacts with carbon dioxide absorbents to form compound A (shown to cause renal damage in rat models)

• Low fresh gas flows should be avoided with sevoflurane (use flows of ≥1 L/min)

• Consider avoiding sevoflurane in pts with renal insufficiency (theoretical risk of nephrotoxicity)

•  Common IV agents do not cause changes in GFR

MEDICATIONS TO AVOID OR USE WITH CAUTION IN RENAL FAILURE

•  Lipid-insoluble, ionized drugs, & water-soluble metabolites of hepatically metabolized drugs are renally excreted & may accumulate in renal failure

•  Highly protein-bound drugs can accumulate if patient is hypoalbuminemic

UROLOGIC SURGERY

Cystoscopy/Ureteroscopy/TURBT

General Considerations

•  Indications: Need for biopsies, laser lithotripsy, extraction of stones, placement of ureteral stents

•  Pts commonly elderly with comorbid medical conditions

•  Irrigation fluids often used to improve visualization & for flushing

• Sterile water: Hypotonic, causes hemolysis & hyponatremia when absorbed systemically; safe with electrocautery

• Nonelectrolyte solutions (glycine, sorbitol, mannitol): Slightly hypotonic, can cause hyponatremia if absorbed in large volumes; safe with electrocautery

• Electrolyte solutions (NS, LR): Isotonic, do not cause hemolysis when absorbed systemically; cannot be used with electrocautery

Anesthetic Technique

•  Positioning: Lithotomy

•  Usually GA, can use local/MAC/regional (T10 level necessary for instrumentation of lower GU tract), consider using LMA

•  Muscle relaxation not usually necessary (consider ETT with relaxation if surgeon anticipates working near obturator nerve)

•  Minimal to no postop pain; short-acting opioids (fentanyl) usually sufficient

Complications

•  Peroneal nerve injury from lithotomy position (causes foot drop)

•  Bladder perforation: Extraperitoneal perforation is more common; signs and symptoms include nausea, diaphoresis & inguinal, retropubic or lower abdominal pain

Transurethral Resection of the Prostate (TURP)

General Considerations

•  Indications: Relief of bladder obstruction from enlarged prostate (typically BPH)

•  Typically elderly pts with comorbid medical conditions

•  Opening of venous sinuses may lead to absorption of large amounts of irrigation fluid (see cystoscopy above) & can result in TURP syndrome (see below); fluid absorption dependent on duration of procedure, number of sinuses opened (related to prostate size), peripheral venous pressure, & height of irrigation fluid

Anesthetic Technique

•  Positioning: Lithotomy

•  General or regional (T10 level necessary)

• Base choice on pt’s preference, coexisting diseases

• Regional anesthesia allows for evaluation of TURP syndrome during procedure

•  Muscle relaxation not required, although patient movement should be avoided (prevent further bleeding/perforation of prostate)

•  Postop pain usually not significant

Complications

•  TURP syndrome

• Results from absorption of large volumes of irrigant fluid through venous sinuses of prostate

• → Hyponatremia & volume overload

• Signs/symptoms: Headache, confusion, nausea/vomiting, HTN, angina, seizures, coma, cardiovascular collapse

• May also see toxicity from absorption of irrigant solutes

• Glycine: Can cause transient blindness, seizures

• Ammonia: Can cause delayed awakening, encephalopathy

• Hyperglycinemia may result in CNS toxicity & circulatory collapse

• Treatment: Fluid restriction & diuretics to correct hyponatremia & volume overload; if pt has seizures/is comatose → consider hypertonic saline

•  Bladder perforation

•  Coagulopathy: Dilutional thrombocytopenia from excessive fluid absorption & DIC

•  Bacteremia: Since prostate is colonized by bacteria, bacteremia may result after instrumentation

•  Prophylactic antibiotics may ↓ risk of bacteremia/septicemia

Alternatives to TURP

•  Medical management with alpha blockers

•  Vaporization of prostate tissue with electrocautery/laser/thermocoagulation (avoid danger of TURP syndrome)

Urologic Laser Surgery

General Considerations

•  Indications: Condyloma acuminatum, ureteral strictures, BPH, ureteral calculi, & superficial carcinomas of penis, ureter, bladder, or renal pelvis

•  Different lasers may be used (CO₂/argon/pulsed dye/Nd-YAG/KTP-532)

•  Safety concerns

• Goggles should be worn by OR personnel & patient to protect eyes from an inadvertent break in laser fiber

• Lasers should be used intermittently to prevent thermal injuries

• Special masks should be worn to prevent inhalation of active HPV particles when condyloma are being treated

Anesthetic Technique

•  Positioning: Lithotomy

•  Local with MAC, general, or regional anesthesia

Open Prostatectomy

General Considerations

•  Indications: Simple prostatectomy for BPH that cannot be resected transurethrally; radical prostatectomy for prostate cancer

•  Pts often elderly with comorbid medical conditions

•  Blood loss can be significant

•  Retroperitoneal lymph node dissection is performed for staging in prostate cancer

•  Bilateral orchiectomy may be performed in symptomatic, advanced disease.

Monitoring/Access

•  Standard monitors; large-bore IV

Anesthetic Technique

Open prostatectomy

•  Positioning: Supine

•  Anesthesia: Regional, general, or combined general/epidural

•  Epidural may ↓ blood loss, improve postop pain relief, & result in recovery of bowel function more quickly

•  Experienced surgeons typically able to perform procedure under general anesthesia with minimal blood loss/small incisions

•  Surgeon may ask for methylene blue/indigo carmine to assess integrity of urinary tract

• Indigo carmine: Can cause hypertension (α-agonism)

• Methylene blue: Can cause hypotension/interfere with SpO₂ readings

Laparoscopic and robotic-assisted prostatectomy

•  Laparoscopy +/- robotic-assisted

•  Advantages: Less blood loss (vs. open), smaller incisions with less postop pain

•  Positioning: Lithotomy; steep Trandelenberg

•  Anesthesia: General endotracheal anesthesia

Cystectomy

General Considerations

•  Indications: Simple cystectomy for benign bladder disease (hemorrhagic/radiation cystitis); radical cystectomy for invasive bladder tumors

•  Pts often elderly with comorbid conditions; given the association between smoking & bladder cancer, pts may be at risk for CAD & COPD

•  After cystectomy, a urinary diversion must be constructed

• → Piece of ileum can be formed into an ileal conduit (brought out to the abdominal wall as a stoma)

• → Bladder suspension more involved operation (piece of bowel is formed into a pouch & connected to the urethra)

• Significant blood & fluid loss may occur

Monitoring/Access

•  Standard monitors; consider arterial line, central line given potential for large blood loss & fluid shifts; large bore IV

Anesthetic Technique

•  Positioning: Supine or lithotomy

•  General or combined general/epidural anesthesia

Nephrectomy

General Considerations

•  Indications: Neoplasm, transplantation, chronic hydronephrosis/infection, trauma

•  Pts undergoing nephrectomy for renal cell carcinoma, will undergo preop staging to determine if tumor involves IVC or right atrium

• Tumor may partially/completely obstruct IVC (reduces venous return & may cause hypotension); IVC may need to be clamped during resection

• Tumor may embolize to pulmonary vasculature (signs: ↓ SpO₂, hypotension, supraventricular arrhythmias)

• Complications: Venous air embolus, diaphragmatic injury (causing pneumothorax)

•  May be performed open or laparoscopically

Monitoring/Access

•  Standard monitors; consider arterial line

•  Large-bore IV (potential for significant blood loss)

Anesthetic Technique

•  Positioning: Lateral decubitus position for retroperitoneal approach/supine for transabdominal approach

•  General anesthesia or combined general/epidural anesthesia (T7–T9 level)

•  Hydration to preserve renal blood flow