Renal system lecture Flashcards
Renal anatomy
BUN
- 10 - 20 mg/dL
- inversely related to GFR
- does NOT increase until GFR is reduced by 50%
- end product of protein metabolism
- can be altered by various factors
- late indicators of renal disease !!
serum creatinie
- product of muscle metabolism
- inversely related to GFR
- entire elimination by glomerular filtration (almost)
- used as a marker of glomerular function
- 0.7 - 1.5 mg/dL
creatinine is a metabolite of
creatine, which is a major muscle constituent
creatinine is eliminated almost entirely by
glomerular filtration, it is a reliable indicator of glomerular filtration
If BUN and creatinine are both elevated that means
more if only one was elevated
increased ratio seen with: increased urea input, decreased blood volume
creatinine clearance renal dysfunction
mild: 50 - 80 mL/min
moderate: < 25 mL/min
dialysis when cc 10
must lose half of the kidney function before BUN changes
BUN creatinine ratio
10:1
Creatinine clearence
- specific test for GFR
- most reliable assessment tool for renal function
- measures the ability of the glomeruli to excrete creatinine
- need 24-hour urine sample
- 95 - 150 mL/min
anesthetics potential to affect GFR, RBF & urinary output
- general anesthesia: causes a temporary depression of RBF, GFR, UO, and electrolyte secretion
- catecholamines: decrease renal perfusion and increase renal vascular resistance
- volatile anesthetics: decrease CO & SVR –> decreased perfusion pressure –> increased renal vascular resistance –> decreased RBF
- sevoflurane: fluoride ions may accumulate after prolonged effect, but do not have a nephrotoxic effect like methoxyflurane did
- opioids & nitrous: same changes as seen with volatile anesthetics
regional anesthetics on renal function
- magnitude is related to the degree of sympathetic blockade and BP depression
- high levels of SAB: impair venous return, diminish CO, reduce renal perfusion
- thoracic levels of epidural: moderate reduction in RBF and GFR (if epi is in LA; no effect seen without epi)
Cystoscopy
- the use of instrumentation to examine the urinary tract
- used for diagnostic or therapeutic procedures
- lithotomy position
- standard monitors
- multiple anesthetic techniques used
- duration: 15 - 30 mins
what is the most stimulating part of a cystoscopy procedure
putting the scope in, and this can occur several times during the procedure
Autonomic hyperreflexia
- occurs if an injury is above T5/T6
- triggered by cutaneous stimulation or visceral stimulation
- quadriplegic or paraplegic patients may undergo repeated cytos
what happens with brain signaling during AH
- noxious stimuli below the level of the injury on the spinal cord send signals to the brain and the body is only signaling above the area of the spinal cord injury
- red, sweaty, and vasodilated above the spinal cord injury
- cold, clammy, vasoconstriction below the spinal cord injury
what is the reason AH will occur under GA?
light anesthesia, deepen the anesthetic
consider a-line for close monitoring BP
