Anesthesia for Urologic Surgery Flashcards
how much cardiac output do the kidneys receive?
20-25%
nephron location
outer cortex
inner medulla
three processes of kidney that contribute to homeostasis
- filtration
- reabsorption
- excretion (tubular)
normal GFR
125 mL/min
normal urine specific gravity
1.000-1.025
increased GFR
- caused by increased renal blood flow
- dilation of afferent
- constriction of efferent
decreased GFR
- caused by decreased renal blood flow
- constriction of afferent
- dilation of efferent
renal hormones include…
- aldosterone
- antidiuretic hormone
- angiotensin
- atrial naturetic factor
- vitamin D
- prostaglandins
anesthetic drugs effect on renal function
- depress normal renal function
- renal blood flow may decrease by 30-40%
- impairment of autoregulation
general anesthesia associated with decrease in…
- renal blood flow
- GFR
- urinary flow
- electrolyte secretion
spinal and epidural
- all the same as general anesthesia
- magnitude of change parallels the degree of sympathetic block and blood pressure depression
volatile anesthetic effects on kidneys
- all cause mild increase in renal vascular resistance
- compensatory mechanism in response to decreases in cardiac output and SVR
- historically, methoxyflurane caused high fluoride ion concentrations and nephrotoxicity
prevention of effects of volatiles on kidneys
- preop hydration
- decreased concentrations of volatiles
- maintenance of blood pressure
- all attenuate reductions in renal blood flow and GFR
sevoflurane and the kidneys
- not associated with nephrotoxocity even though it has been associated with high fluoride levels
- degraded by absorbents to form compound A (vinyl ether)
- potential exists for compound A nephrotoxocity
what can the CRNA do to decrease risk of compound A nephrotoxicity?
- high gas flows (1 L/min FGF for 2 MAC hours)
- decrease gas concentration
- use of carbon dioxide absorbents
isoflurane and desflurane
-not associated with nephrotoxicity
fluoride ion toxicity
- fluoride interferes with active transport of sodium and chloride in the loop of Henle
- potent vasoconstrictor
- potent inhibitor of many enzyme systems (ADH)
- causes nephrotoxicity thorugh proximal tubular swelling and necrosis - related to dosage, duration, and peak fluoride concentrations
S/S fluoride ion nephrotoxicity
- polyuria
- hypernatremia
- serum hyperosmolality
- elevated BUN and Cr
- decreased Cr clearance
acute kidney injury
- renal functional or structural abnormality that occurs within 48 hours
- increase in Cr 0.3 mg/dL or 50% increase
- UOP < 0.5 mL/kg/hr x6 hours
AKI risk increased by what?
- hypovolemia
- electrolyte imbalance
- contrast dye
prerenal AKI
- hypoperfusion of kidneys without parenchymal damage
- ex = hemorrhage, N/V/D, diuretics, sepsis, shock, CHF, NE, NSAIDs, ACE-I
intrinsic AKI
- result of damage to renal tissue
- ex = tubular injury d/t hypoperfusion, myoglobin, chemo, infection, lymphoma, toxemia of pregnancy, vasculitis
postrenal AKI
- due to urinary tract obstruction
- ex = renal calculi, peritoneal mass, prostate/bladder urethra tumor, fibrosis, hematoma, strictures
risk factors for AKI
- aging (>50 years of age)
- preop renal dysfunction
- comorbidities - cardiac failure, hepatic failure, DM, HTN
- surgical procedures
- emergency of high risk procedures
surgical procedures that put patient at increased risk for AKI
- cardiac bypass
- aortic cross clamp
- arteriography
- intra-aortic balloon pump
emergency or high risk procedures that put patient at risk for AKI
- ruptured AAA
- ischemic time
- large volume of blood transfused
AKI preoperative treatment
- fluid deficit replacement with balanced salt solution (to minimize ADH and RAAS)
- attenuation of surgical stress (neuraxial, opioids)
- patient monitoring considerations - art line, TEE, CVP, foley catheter
AKI Perioperative treatment
- fluid replacement
- improve CO
- normalize SVR
- diuretic use to prevent oliguria NOT recommended
- early treatment of prerenal causes (10% mortality)
- post renal – good prognosis with early identification
- intrarenal AKI = most difficult to treat
prevention/management of AKI
- most common cause = prolonged hypoperfusion
- prophylaxis reduced mortality more than dialysis
- duration and magnitude of insult determines severity of AKI
treatment of AKI
- administer volume (NS) to euvolemia
- improve cardiac output by afterload reduction
- normalize systemic vascular resistance
- key strategy = minimize magnitude and duration of renal ischemia
chronic kidney disease (CKD)
- renal function decreases 10% per decade
- CKD exists when GFR is less than 60 mL/min/1.73 m2 for three months
- s/s not apparent until less than 40% of normal functioning nephrons remain
- 95% loss of renal function = uremia, CHF, volume overload
CV effects of CKD
- HTN and CHF
- 90% volume dependent
- 10% secondary to increased renin
- pericardial effusion
- ischemic heart disease most common cause of death
- pericarditis seen in patients with severe anemia
respiratory effects of CKD
respiratory depression secondary to delayed clearance
neurologic effects of CKD
- fatigue and weakness are early complaints
- autonomic neuropathy
disequilibrium syndrome
- rapid increase in brain intracellular volume –> increased sodium
- seizure, stupor, coma
hematologic effects of CKD
- normochromic, normocytic anemia - decrease in EPO, reduction in RBC life d/t dialysis, blood loss from frequent sampling
- prolonged bleeding - decrease plt function, DDAVP increases factor 8
GI effects of CKD
dialysis patients at greater risk for GI bleed, due to inflammation and mucosal changes
infection effects of CKD
- protein malnutrition
- neutrophil, monocyte and macrophage changes
- leading cause of death in dialysis dependent patients
endocrine effects of CKD
- hyperparathyroidism (hypocalcemia common so this is body’s way of compensating)
- adrenal insufficiency (because on chronic steroids)
electrolyte effects of CKD
- sodium wasting
- hypocalcemia
- hyperkalemia
hyperkalemia
- serious disturbance in patients with renal disease
- fatal dysrhythmias or cardiac standstill can occur when K+ levels reach 7-8 mEq/L
- peaked t waves
- wide QRS
- wide PR
- loss of P wave
- sinusoidal wave
treatment of hyperkalemia
- 25-50g dextrose
- 10-20 units regular insulin
- 50-100 mEq sodium bicarb
- hyperventilation
- calcium (chloride or gluconate)
physiologic effects of dialysis
- hypotension
- muscle cramping
- anemia
- nutritional depletion
preop considerations for those with CKD
- pertinent labs and diagnostics
- continue antihypertensives
intraop considerations for those with CKD
- monitoring
- regional
- general
- fluid management
postop considerations for those with CKD
dialysis with in 24 hours
fluid management for those with CKD
- UOP 0.5-1 mL/kg/hr recommended
- mildly compromised function - balanced salt solution at 3-5 mL/kg/hr with 500 mL bolus PRN
- potassium containing = contraindicated if anuric
- blood products ONLY If need increased oxygen carrying capacity
- renal insufficiency/ESRD - replace volume deficit preop; intraop loss greater than 15% replaced with colloid; NS, no fluid with K+
fluid management for dialysis patient
- insensible loss - replace with 5-10 mL/kg of D5W
- urine produced then replace with 0.45% saline
serum creatinine
- 7-1.5 mg/dL
- for every 50% reduction in GFR serum Cr doubles
BUN
blood urea nitrogen
10-20 mg/dL
BUN:Cr ratio 10:1
Cr clearance
95-150 mL/min
- most reliable test for renal function
- measures glomerular ability to excrete Cr in urine
- mild 50-80
- moderate <25
- dialysis <10
pharmacologic considerations CKD
- reduced protein binding –> increase sensitivity
- morphine not removed by dialysis
- meperedine metabolite (normeperedine) also NOT removed by dialysis
- H2 blockers highly dependent on renal excretion
major regional anesthetic concerns for those with CKD
- intolerance
- coagulopathy
- peripheral neuropathy
- risk of infection
regional for those with CKD
- regional WELL TOLERATED
- block duration not affected by renal failure
- spinal and epidural considerations - plt count, PT/PTT, ASRA Coags
General Anesthesia and CKD
- IV drugs –> volume of distribution increased, decreased protein binding, low pH, renal excretion
- ketamine and benzos less protein bound
- propofol appears safe
- dex cleared by liver
- remi - reduced clearace in patients with ESRD
succinylcholine
- increases serum potassium 0.5 mEq/L
- succinylmonocholine (precursor to products of metabolism)
- cholinesterase deficiency in uremic patients
pancuronium
80% excreted in urine
atracurium, cisatracurium, and mivacurium
- duration not increased in renal failure
- slower onset with cisatracurium and mivacurium
vecuronium
- approximately 30% excreted via renal system
- effects rapidly revered with dialysis
rocuronium
renal failure reduces clearance by almost 40%
common urologic procedures (6)
- cystoscopy
- extra-corporeal shock wave lithotripsy (ESWL)
- transurethral resection of the prostate (TURP)
- laparoscopic/robotic urologic procedures
- open nephrectomy
- renal transplant
cystoscopy
- urologist uses cystoscope to examine urethra and bladder
- procedures can be quick or last hours
cystoscopy anesthetic considerations
- Local/MAC
- spinal - offers relaxation with real time patient assessment
- general - LMA vs ETT
cystoscopy position
lithotomy
extra-corporeal shock wave lithotripsy (ESWL)
- non-invasive treatment that uses high energy ultrasound waves to break up renal calculi (kidney stones)
- outpatient under general
- water immersion no longer used
- ECG placement important
- hematuria common
nephrolithiasis (renal calculi)
- affect 9% of population
- if calculi <5mm in diameter expected to pass without intervention
- 5-10 mm = medical management
- > 10 mm = unlikely to pass spontaneously
ESWL contraindications
- active UTI
- uncorrected bleeding disorder or coagulopathy
- distal obstruction
- pregnancy
ESWL complications
- dose-dependent hemorrhagic lesions on kidneys
- perforation, rupture or damage to colon, hepatic structures, lungs, spleen, pancreas, abdominal aorta, or iliac veins
- hematuria develops in MOST patients
- diabetes, new onset HTN or decreased renal function
ESWL anesthesia
- GA- rapid onset, can control patient movement
- spinal/epidural at T4/T6 level
- MAC
- topical LA
ESWL considerations
- d/c ASA, anticoagulants, platelet inhibitors, NSAIDs 7-10 days before
- document negative urine cx
- HCG - because ionizing radiation
- laser eye protection
purcutaneous nephrolithotomy
- procedure to remove kidney stones 25mm or smaller
- GA and post op hospitalization
- rigid scope inserted in renal calyx under fluoro
- prone or supine position
complications from purcutaneous nephrolithotomy
- pain
- fever
- UTI
- renal colic
- septicemia
- bleeding
- pneumothorax, hemothorax
- anaphylaxis
transurethral resection of the prostate (TURP)
- most common surgical procedure performed in men over 60
- scope placed through urethra to cut away obstructing lobes of the prostate
- bladder distended and continuous irrigation used
- anesthetic risks r/t patient age and associated comorbidites
medical management of BPH
alpha blocking agents
TURP anesthetic considerations
- commonly performed under general
- spinal anesthesia is anesthetic of choice because S/S complications better detected
TURP syndrome
- rare but significant complication
- mortality 25%
- large amounts of fluid absorbed through prostate
- symptoms related to a combination of water intoxication, fluid overload, and hyponatremia
fluid overload in TURP clinical manifestations
- HTN
- bradycardia
- arrhythmia
- angina
- pulmonary edema
- CHF
- hypotension
water intoxication in TURP clinical manifestations
- confusion
- restlessness
- seizure
- lethargy
- coma
- dilated sluggish pupils
hyponatremia in TURP clinical manifestations
- CNS changes
- widened QRS
- T wave inversion
- irritability
- 120 = EKG changes
- 115 = widened QRS
- 100 = v fib or vtach
glycine toxicity in TURP clinical manifestations
- N/V
- HA
- Transient blindness
- myocardial depression
TURP irrigation solutions
- distilled water
- saline
- cytal (sorbitol and mannitol)
- glycine
complications of irrigation in TURP
- volume overload with pulmonary edema
- dilutional hyponatremia with hypoosmolality
- cardiac effects
- renal toxicity (glycine)
- hyperglycemia
- hypothermia
additional complications of TURP
- glycine absorption
- bleeding
- bladder perf
- infection
- skin burns - greater incidence with monopolar cutting devices; may impact patient with pacemaker
fluid absorption in TURP syndrome depends on
- size of resection
- duration of resection
- irrigation solution pressure
- number of venous sinuses open at one time
- provider experience
- up to 30 mL of fluid absorbed per min (so up to 8 L in two hours)
how much can 1 L of irrigant decrease sodium
5-8 mEq/L
glycine absorption can lead to….
- N/V
- fixed and dilated pupils
- HA
- weakness
- muscle incoordination
- TURP blindness
- seizures
- hypotension
TURP syndrome considerations
- prevention is key when it comes to TURP syndrome
- avoid trendelenburg
- limit resection to less than 1 hour
- place irrigating solution less than 60 cm above prostate
- monitor electrolytes
- use a regional technique with light sedation
TURP syndrome treatment
- early recognition
- correcting hyponatremia (3-5% saline no greater than 100mL/hr; increase sodium SLOWLY, goal greater than 120, rapid reversal can cause osmotic demyelination syndrome)
- 20 mg IV lasix
- labs/tests - Hct, lytes, Cr, glucose, ABG, 12 lead
- IV midaz 1 mg at a time for seizures
- intubate for pulmonary edema
- PRBCs if necessary
- investigate for DIC or primary fibrinolysis
Anesthetic concerns for laparoscopic urologic surgery
- pneumoperitoneum
- urologic system is retroperitoneal - communicates with thorax so risk for subQ emphysema
- alterations in renal and hepatic perfusion
- CO2 absorption - potential for acidosis
- extremes in patient position
- hemorrhage
two categories of robotic urologic surgery
- upper tract surgery - simple or radical nephrectomy, radical nephroureterectomy, nephron sparing surgery
- pelvic surgery - radical cystectomy, radical prostatectomy
robotic urologic surgery position
steep trendelenburg (+ lithotomy for prostatectomy), arms tucked at sides *airway assessment before extubation*
robotic urologic surgery duration
3-4 hours
robotic urologic surgery EBL
<300 mL
robotic urologic surgery additional anesthetic considerations
- limit fluids until urethra reconnected
- large bore PIV +/- art line
- additional = DVT prophylaxis, eye protection, OGT, bair hugger, antibiotics, dexamethasone, remi infusion common
nephrectomy anesthetic considerations
- open vs. laparoscopic
- lateral jack knife position
- CV compromise
- third-spacing and edema
- hemodynamic monitoring
- postop pain management
renal transplant
- mainstay tx for ESRD
- donors may be living or deceased
- most frequent solid organ transplanted today
- 5 year survival rate is 70%
- living donor - ORs are usually next door
- transplanted organ placed in R or L extraperitoneal fossa (R side preferred)
- transplanted kidney attached via vascular anastomoses of external iliac artery and vein and ureter anastomosed to bladder
- GA - prop, cis, art line, CVP monitoring
- immunosuppressant therapy
