Advanced 1: UROLOGY

Mechanims of Anemia in Renal Failure:

• decr RBC production (low Hct)
• uremic toxins inactivate erythropoeitin - released by juxtoglomerular network
• bone marrow response suppressed
• RBC lifespan reduced d/t change in blood pH

Treatment:

• recombinant erythropoeitin
• adequate iron intake
• cautious RBC transfusion d/t antigen sensitization
• pt will need frequent blood draws - vascular access for dialysis; use non-dominant arm

Hemotologic changes:

• uremic pts have tendency to bleed (uremia-end products of metabolism normally found in urine is found in blood --> urine in blood)
• Plt counts only mildly reduced but the quality of the platelet is also reduced (decr pH)
• Treatment:
• proper dialysis, on schedule (PD --> HD)
• desmopressin incr F VIII (8) levels if bleeding; DDAVP 0.3 mcg/kg --> vasopressin (synthetic)
• cryoprecipitate

UROLOGIC PROCEDURES:

• 20% of anesthetic procedures
• elderly
• comorbidities
• lithotomy
• transurethral approach
• > 60% males

MOST COMMON PROCEDURES:

• hematuria
• infections
• obstruction
• biopsy
• kidney stone removal
• stent placement or removal

HIGH TECH:

• Lasers - eye protection
• fluoroscopic guidance - lead
• robotic procedures
• lots of water

What influences absorption of IV fluids:

1. height of fluid
2. duration

* do not share IV pole with irrigation soln

POSITIONING

LITHOTOMY

• Requires 2 ppl to properly position pt legs up and down --> obturator nerve damage
• Common peroneal nerve injury if thigh rests on vertical steel strap support
• Loss of dorsiflexion of food (foot drop)
• Legs allowed to rest on medially placed support may compress saphenous nerve
• numbness of medial calf
• candy cane leg holder - only use for short duration (<90 min)
• Extreme flexion on thigh may:
• injure obturator nerve
• may cause posterior stretch of sciatic nerve
• femoral nerve
• Compartment syndrome with rhabdomyolysis after long procedures can occur
• Most common injury associated with lithotomy is brachial plexus
• Other physiologic derangements:
• decr FRC --> atelectasis
• trendelenberg --> restricts diaphragmatic excursion
• legs up --> incr venous return; may stress weak ventricle
• MAP incr but CO does not

Obturator Nerve:

-Sensory innervation of skin of medial thigh

-motor innervation of adductor muscles of lower extremity

LATERAL FLEXED

• kidney rest
• dependent (down) leg flexed, nondependent leg extended
• axillary role 3 fingers beneath axilla to protect brachial plexus
• bed is then flexed, kidney rest elevated to achieve optimal surgical visualization

Physiologic derangements:

• FRC reduced in dependent lung, but incr in nondependent (up) lung
• VQ mismatching
• non-dependent lung receives greater V and less Q --> atelectasis
• dead space ventilation occurs as case progresses
• kidney rest inhibits R-sided return, adding to hypotension and venous pooling in lower extremities
• pneumothorax d/t inadvertent entry into pleural space intraop --> post op CXR
• access to IVs and vascular structures are limited; insert all lines prior to positioning
• No LMA; ETT only

TURP: TRANSURETHRAL RESECTION OF THE PROSTATE

Approach acceptable for prostate btwn 40-50 gm
Pt should be carefully eval for coexisting cardiac and pulmonary dx and renal dysfunction
Long standing urinary obstruction can lead to renal dysfunction (hydronephrosis)
Procedures carries 3% mortality rate

Complications:

• hemorrhage
• TURP syndrome
• bladder perforation
• hypothermia
• septicemia (bacteria from bladder into blood stream)
• DIC
• MI
• pulm edema

Cutting loop inserted through resectoscope via urethra
continuous irrigation
prostate contains extensive venous sinus network (bleeding)
sinuses opened in prostate capable of absorbing large amount of irrigating fluid --> > 2 L leads to TURP syndrome (dilutional hyponatremia, hypoosmolality, hypotonicity - cell lysis)

TURP Syndrome:

• hyponatremia
• hypoosmolality
• fluid overload
• pulm edema/CHF
• hypotension
• hemolysis

S&S:

• Headache
• restlessness
• confusion
• dyspnea
• arrhythmia - afib
• hypotension
• seizures
• usually manifestation of circulatory overload, H2O intoxication and solute toxicity from irrigating fluid absorption

*Fluid absorbed at 20 ml/min
~ 1200 ml absorbed in 1 hour
~ 1800 ml absorbed in 90 min
> 90 min is danger zone

EKG Changes:
-widening QRS and ST elevation when Na < 115 mEq/L
-<100 mEg/L --> vtach, vfib, acute hemolysis

TURP, cont.

• slightly hypotonic, non-electrolyte irrigation solution are optimal
• Glycine 1.5% (230 mOm/L)
• Sorbitol-Mannitol combo
• hypotonic soln prone to systemic absorption
• solute absorption is influenced by pressure = height of irrigating fluid bag and duration of procedure
• most procedures about 1 hour
• pts with limited cardiac reserve are at risk for fluid overload
• absorption results in acute H2O intox, dilutional hyponatremia, hypoosmolality resulting in neurologic manifestations
• symptoms of hyponatremia become evident below 120 mEq/L
• Na below 100 mEq/l results in acute intravascular hemolysis

Complications based on irrigating fluid composition:
Glycine --> hyperglycinemia, hyperammonemia

• Hyperglycinemia:
• CNS tox
• circulatory depression
• glycine [ ] > 1000 mg/l possible; normal is 15 mg/L
• transient postop blindness (glycine intox) - neuroinhibitory element - affects optic nerve
• metabolizes to ammonia via hepatic pathways
• blood ammonia levels > 500 micromol/L --> CNS tox (normal 25 micromol/L)

Sorbitol or Dextrose solns--> hyperglycemia

• extreme in DM
• absorption may cause acute intravascular volume overload

Mannitol --> acute intravascular volume expansion

*can't use saline or LR bc elytes disperse electrical energy
*H2O is too easily absorbed --> good visibility, hypotonicity causes lysis of RBCs, acute H2O intox, restricted to bladder tumors only

Treatment of TURP syndrome:
*recognition is key - easier with regional anesthesia

• stop irrigation
• tx hypoxemia and hypoperfusion
• ETT until mental status stabilizes
• hyponatremia --> seizures
• tx: hypertonic saline, benzos, thiopental, phenytoin (10-20 mg/kg) no faster than 50 mg/min
• volume overload - precipitous drop in SpO2
• hypertonic saline soln: 3-5% given in order to correct serum Na level no faster than 100 mEq/hg
• tx may possibly exacerbate circulatory overload
• symptoms are results of water access not Na loss
• Diuresis with lasix is indicated

Other TURP Complications:

• Hypothermia
• large volumes of irrigation fluid are employed
• irrigation fluid should be warmed prior to use
• bear huggers should be used with temp monitoring
• postop shivering undesirable
• dislodge clots and promotes bleeding
• incr O2 utilization
• Bladder Perforation (1% occurance)
• Causes:
• overdistention of bladder
• friable tissue
• pt moves unexpectedly
• S&S:
• sudden poor return of irrigation fluid
• sudden hypo/hypertension with reflex decr HR
• regionalized pt c/o generalized discomfort in abdomen, N/V, restlessness
• DIC
• may develop dilutional thrombocytopenia
• may develop DIC d/t release of prostate thromboplastins
• pts with metastatic disease may develop DIC from fibrinolysis d/t tumor fibrinolytic enzymes released during surgery (vasoactive prostaglandins released when damaging prostate)
• Coagulopathy
• Fibrinolysis should be treated with Amicar 5 gm loading followed by 1 gm/hg IV
• transfusion of RBC and products
• Admin of heparin +/-
• Septicemia
• prostate may be colonized with bacteria and harbor chronic infection
• surgical manipulation results in flood of organisms into bloodstream
• bacteremia ensues
• prophylactic antibiotics --> gentamycin and Ancef given prior to TURP
• Obturator Reflex: T10 regional
• regional does not abolish obturator reflex (external rotation and adduction of hip following stim to nerve by electrocautery current via bladder wall - transparietal stim) - knees come toward surgeon
• only reliably blocked by NMB and G/A only
• can also use 3-in-1 block (Winnies block) to block reflex: lateral femoral cutaneous, femoral and obturator nerve

Anesthesia for TURP:
Regional anesthea at T10 sensory is ideal

• decr incidence of postop thrombosis
• doesn't mask TURP syndrome or bladder perf
• no difference to G/A in blood loss, postop morbidity and mortality
• metastatic disease in L-spine is CI to spinal
• G/A most commonly done (case < 1 hr)
• LMA
• decr sat = early sign of fluid overload
• ischemic EKG changes
• temp monitoring
• blood loss difficult to assess
• ~ 300 ml
• procedures > 90 min and rxn of prostate > 45 gm have resulted in blood transfusion

EXTRACORPOREAL SHOCKWAVE THERAPY (ESWL) - LITHOTRIPSY
Results in fragmented kidney stones which can be passed in urine
Pts formally lowered into H2O bath --> high intensity shockwaves
Today, gel interface --> low intensity shockwaves
Pts should be positioned so waves are focused on stones, not on lungs or heart

Urinary stents may be placed prior to lithotripsy to fascilitate passage of broken kidney stone
Peri-nephric hematomas are not uncommon

Contraindications:

• urinary obstruction below stone
• untreated infection
• bleeding disorder
• pregnancy
• relative CI: AAA & ortho implants

Cardiac considerations in ESWL:

• pacemaker and AICD at risk for arrythmia induced by shockwave
• shockwaves may damage implant device
• synchronization of shockwaves to R wavef rom monitor EKG decr incidence of arrythmia
• waves are timed at 20 ms following R wave corresponding to ventricular refractory
• asynchronous delivery of shockwaves is safe in most non-cardiac pts and speeds process
• glyco; sympathomimetic

Anesthesia for ESWL:

• Epidural to T6 sensory level assures anesthesia
• renal innervation derived from T10 to L2
• excessive air in epidural space or foam tape dissipates therapeutic shockwave
• spinal anesthesia ok
• G/A helps tolerate extremes of positioning
• extremem flexed lithotomy with T-berg
• G/A is only option with robotic prostatectomy d/t demands of positioning

RADICAL PROSTATECTOMY
*adenocarcinoma is most common CA in men

RADICAL RETROPUBIC PROSTATECTOMY:

• lower midline abdominal incision
• prostate removed with seminal vesicles, ejaculatory ducts and bladder neck
• Indigo carmine --> visualization of ureters during sx is common
• results in reduced SpO2 and possibly CV changes (vascular leaks)
• Nerve sparing technique
• significant blood loss expected --> robotic has minimal blood loss but takes 4-5 hours
• 500 ml to several liters
• clamp hypogastric artery and penile dorsal vein complex to decrease blood loss
• standard invasive monitoring; tailor to comorbidities: A line

RADICAL PERINEAL PROSTATECTOMY:

• Extreme exaggerated lithotomy
• ETT G/A required
• position interferes with diaphragmatic excursion
• neurologic injuries may result from positioning
• prophylaxis mini dose of unfractionated heparin may be used to prevent thrombosis --> does increase operative blood loss
• don't want autodonation or cell saver (don't want CA cells) - use homologous blood from blood bank

Complications:

• hemorrhage, operator nerve injuries
• ureter and rectal injuries
• urinary incontinence and impotence may occur
• sequential pneumatic leg stockings delay but do not actually reduce the incidence of DVT

ROBOTIC PROSTATECTOMY:
Limit IV fluids until resection is complete

• potentiate formation of edema in face and airway delaying extubation
• keeps excessive urine out of pelvis which obscures view
• prevents venous and gland engorgement and helps reduce operative blood loss
• swelling will normalize within first few hours postop

BILATERAL ORCHIECTOMY

• Performed to control metastatic carcinoma of prostate
• may be done under LOC/MAC via scrotum (rare)
• G/A with LMA is normal with inguinal approach

BLADDER CANCER

• age 65 y/o; 3:1 male/female
• Transitional cell carcinoma - most common malignancy of GIT
• associated with tobacco, CAD and COPD
• ameliorated with transurethral rx in low grade tumor
• may require cystectomy in high grade tumor

RADICAL CYSTECTOMY

• Major operation; significant blood loss
• incision midline, pubis to xyphoid
• all pelvic organs removed in female and male
• pelvic node dissection common; urinary diversion created
• Neo-bladders implanted - pt bowel
• surgery time 5 hours
• G/A ETT
• controlled hypotension technique reduces blood loss
• adjunctive epidural
• hypotension and postop pain control
• when threat of blood loss is gone can dose epidural
• spinal --> small contracted bowel and hyperperistalsis - restricts formation of urinary reservoir such as ileal condt by surgery.

• normothermia
• papaverin, glyco, glucagon may help reduce peristalsis so surgeon can work
• urine flowing into abdomen may result in metabolic derangements
• jejunal conduits may result in metabolic acidosis, hyponatremia, hypokalemia and hyperkalemia --> rarely used (selective absorptive characteristics)
• colonic and ilieal conduits may be associated with hyperchloremic metabolic acidosis
• the use of temporary urethral stents and maintaining high UOP helps reduce this problem
• Nephrostomy tubes with collection; urinary diversion with collection
• Artificial Neobladder
• orthotopic created bladder from ileum and colon

RADICAL NEPHRECTOMY

• GETA
• potential for extreme blood loss
• traction on major blood vessels ensues
• Aline & CVP, large bore IVs in most cases
• Mannitol given prior to surgical dissection
• controlled hypotension probably not used bc of potential to impair renal function
• reflex renal vasoconstriction of the healthy kidney may result in postop renal dysfunction

Tumor thrombus:

• hypotension not used
• heralded by arrythmias, desaturation, hypotesion
• cardiopulm bypass may be required if thrombus extends to RA
• level 3 thrombus --> PAC is CI, CVP +/-

RENAL TRANSPLANTATION

• Dont take out old kidney unless uncontrolled renal HTN, infection or malignancy
• due to improvements in immunosuppressive therapy, cadaveric kidney implants are nearing the same 3 year survival rates as living donor grafts (80-90%)
• Absolute CI: Infection and CA
• Relative CI: > 60 y/o and severe CAD

• transplant kidney placed retroperitoneal to iliac vessels
• renal vessels anastomosed to iliac vessels and the ureter to the bladder
• CVP, Aline +/-
• increase CVP up to 15 mmHg so kidney is hit with a lot of fluid
• Heparin admin just prior to clamping iliac vessels
• IV Mannitol acts as a free radical scavenger and promotes osmotic diuresis
• lasix further promotes diuresis (60 mg)
• Pt is fluid loaded with PSS in anticipation of unclamping iliac vessels - NS only; no LR
• Use of sevo is questionable +/-
• MR: roc and atra - depend less on renal excretion
• vec may have prolonged blockade
• brisk urine flow after unclamping indicates good graft function
• If pt is oligouric, adjust fluid appropriately (UOP < 300-500 ml/day)

• Increased K+ reported after release of vascular clamps
• K+ in preservative which kidney is transported in has been implicated
• surgeons wash kidney out with large volumes of LR, but K+ levels may still be high
• seen in peds and smaller patients
• peaked T waves
• Extubated unles K-P: kidney pancrease transplant
• Immunosuppression:
• steroids
• cyclosporine
• azathioprine
• *given just prior to unclamping

RETROPERITONEAL LYMPH NODE DISSECTION (RPLND)
Usually following chemotherapy
Pts may have received bleomycin preop (chemotherapy):

• at risk for pulm insufficiency postop
• sensitive to O2 toxicity and fluid overload --> O2 at 30%, sat > 90%
• may develop ARDS
• PEEP 5-10 cmH2O
• N2O --> bone marrow suppression
• air/O2 mixture optimal

Fluid Balance:

• crystalloid
• colloid
• blood products prn
• maintain UOP 0.5-1 ml/kg/hr
• Mannitol 0.25-0.5 gm/kg
• retraction of IVC may result in reduced R sided return and hypotension

Regional:

• if epidural anesthesia utilized as adjunct document motor findings pre-block (i.e. preop weakness)
• ligation of intercostal arteries has resulted in paraplegia
• artery of Adamkiewicz (arteria radicularis magna) supplies lower 1/2 of spinal cord
• A of A is unilateral and arises generally on L side

TESTS FOR RENAL FUNCTION:

Renal tubular function

• Urine SG 1.003-1.030
• Urine osmolality 25-400 mOsm/L
• Urine Na 130-260 mEq/day

Eval of GFR

• BUN 10-20 mg/dl
• creatinine level 0.7-1.5 mg/dl
• creatinine clearance 110-150 ml/min

BLOOD UREA NITROGEN
End product of protein metabolism
Urea reabsorbed along renal tubules
*incr BUN in presence of normal Cr suggests "extra renal" cause of elevation

< 8 = overhydration or under production
> 20-40 = dehydration, incr nitrogen levels or diminished GFR
> 50 = decr GFR

Factors that influence BUN level:

• diet
• anabolic/catabolic states
• hydration status
• reabsorption of urea by nephrons
• BUN not predictable indicator of GFR
• but BUN will incr when GFR decr by 50%
• late sign

SERUM CREATININE (0.7-1.5 mg/dl)
Metabolite of creatinine phosphate --> major constituent of muscle
daily rate of Cr production is constant; determined by skeletal muscle mass
*Cr is eliminated entirely by glomerular filtration
*Cr is a reliable marker of glomerular filtration

• any disease that affects the filtration process of the kidney will incr serum Cr levels
• when creatinine levels double = 50% reduction in filtration rate of the kidneys is noted
• Causes: glomerulonephritis, pyelonephritis, DM, shock, CHF and conditions that reduce blood flow through kidneys

Creatinine Clearance (100-150 ml/min)
*The most reliable assessment of renal function
a test specific for GFR

measures the ability of the glomeruli to excrete Cr into the urine at a known serum Cr level
Disadvantages: 24 hour collected urine specimen is required; 2 hour collections may be used

HEMATOLOGIC CHANGES

• Anemia is common in renal disease
• Hct 20-30% common
• Azotemia: abnormally high levels of nitrogen-containing cmpds such as urea and creatinine; reflected in incr BUN

PRERENAL
d/t decr blood flow
decr GFR and/or excess urea production
causes: dehydration shock, decr blood volume, CHF

RENAL
d/t acute or chornic renal failure

POST RENAL
urinary tract obstruction perforation with extravasation or urine