What does the RAA system depend almost solely on?
RBF
What is renal artery stenosis characterized by?
Intractable HTN since aldosterone is such a potent vasoconstrictor. (Aldosterone will be released due to macula densa signals)
A review: what are the possible treatments of renal failure?
Hemodialysis
Peritoneal dialysis
Renal transplantation
Nothing (pt refusal, death within 2 weeks)
What are some mechanical things to keep in mind when positioning a patient?
- Position legs simultaneously to prevent undue stress on one leg.
- Pad lateral thigh to prevent injury to the common peritoneal nerve. (Do not pad too aggressively though, since it may put too much stress on the other side)
- Do not give too much flexion at hip or you may pinch the obturator nerve.
- Do not wake up patient before legs are down (bucking may cause hip dislocation if legs are still up in lithotomy)
What are some physiological changes that occur with the lithotomy position?
Decreased FRC due to impingement on lower abdominal contents (pushes up into lungs)
Increased venous return (rise in BP); remember that BP will decrease once legs are down as venous return decreases
Increased MAP due to increased vascular resistance of the lower limbs
What is one easy way to assess lower limb perfusion (esp relevant with pts in high lithotomy position)?
Pulse ox on toe. Compare that reading to pulse ox on fingers.
In transurethral surgeries, how is the visual field cleared for the camera?
The surgical site is flooded with irrigation fluid
Why is it often important to keep patients paralyzed during GU procedures?
Ureteroscopy = camera placed up the ureter which is very small and delicate (damage can = scar off the ureter = kidney failure on that side)
- Therefore, we often have to paralyze pts for these procedures to prevent laceration of ureter by the cytoscope (can occur if patient bucks)
- Regional anesthesia (placed at or above T10 which correlates with the top of the bladder) can help as well esp with resections of tumors or prostate resections which are larger proceduresHow do the mortality rates of TURBTs compare to the mortality rates for TURPs? Why?
TURBT mortality < 1% VS TURP mortality up to 6%
Mortality rate for TURPs are much higher due to older pt population (>60 y/o) with more co-morbidities + more vascular surgical site + the prostate sits at the neck of the bladder (urethra runs right through it) so its a more delicate procedure
In TURPs, what electrolyte is of special concern?
Sodium; if pre-op levels are low, consider delaying the surgery (TURP syndrom concerns)
What are the main anesthetic concerns for TURBTs?
- Stresses of anesthesia and surgery
- Perforation of bladder
- Not a lot of venous vasculature for the absorption of irrigation fluid (unlike the prostate)
What are the main anesthetic concerns for TURPs?
- Co-existing diseases = more in TURP pts due to advanced age (30-60% have cardiac/pulmonary issues)
- Bleeding risks due to larger size of resection + more vascular tissue
- Coagulopathies due to potentially large loss of blood
- Can cause clots in ureter
- Clots can be washed upstream by irrigation fluid
What is the major concern with TURPs?
TURP Syndrome, caused by excessive systemic absorption of irrigation fluids by the patient due to vascular nature of prostate (lots of venous openings)
What factors determine how much fluid can be absorbed into the systemic circulation by the pt during a TURP?
- Size of resection (how many venous channels exposed) and how distended the bladder is
- Height of irrigation bag (determines pressure of fluids coming in)
- How long the resection takes (more time = more time venous channels are open)
Describe the composition of irrigation fluids.
Non-electrolyte to prevent conduction of electricity from the surgical tool
Iso-osmotic to prevent hemolysis
Examples of irrigation fluids:
Cytal (mannitol and sorbitol)
Glycine
What can be a side effect of glycine if absorbed into systemic circulation in excessive amounts?
Can cause temporary blindness
Hyperammonemia (high ammonium due to ammonium
being glycine’s metabolic byproduct)
What are some complications that can occur during a TURP procedure?
- Hemorrhage (irrigation fluid absorption can mask signs of blood loss, BP and HR)
- Volume overload
- Hypo osmolarity (causing hemolysis, cerebral edema, etc..)
- TURP syndrome
- Bladder perforation
- Hypothermia (irrigation fluid is cold)
- Sepsis
- DIC (from depletion of coag factors if clots keep being washed away by the irrigation fluid)
Describe TURP syndrome.
What kind of metabolic conditions can the metabolism of biomolecules in the irrigation fluid cause?
TURP Synrdome is basically severe hyponatremia due to excessive systemic absorption of irrigation fluid that can lead to cardiac conduction problems and seizures
Metabolism of biomolecules in the irrigation fluid can also lead to these conditions
- Hyperglycemia: high sugar
- Hyperglycinemia: high glycine (can cause transient blindess)
- Hyperammonemia (glycine metabolism)
- Volume expansionHow do we assess TURP syndrome and why?
Look for the following symptoms to gauge approx sodium levels:
• 140 mEq/l - normal serum sodium
• 120 mEq/l - confusion & aggitation
• 115 mEq/l - cardiac electrolyte problems, ST
elevations, QRS widening
• 110 mEq/l - hypotension, seizure, cardiac
arrhythmia’s, coma, death
**We use these criteria because sending for a blood gas often takes much longer than the onset of TURP syndrome.
In correcting TURP, why is it important to infuse sodium at a slow to moderate pace?
Correcting hypernatremia too quickly can result in central ponteine myelinolysis
What does fluid absorption depend on during a TURP?
Length of procedure (TURP pts will absorb about 20 mL/min)
Height of fluid bag
What can hyperglycinemia cause?
Cardiac and neurologic toxicity (Glycine = inhibitory NT)
Temporary blindness
High ammonium levels
How do you treat TURP syndrome?
- Stop resection.
- Treat HoTN and hypoxia.
- Eliminate excess water (fluid restrict and loop diuretics).
- Treat seizures if applicable.
- Slow treatment of hyponatremia.
