Management of Anesthesia in a Renal pt Flashcards
If pt is oliguric, what would you expect their GFR to be?
At what GFR do you see reduced clearing of unchanged drugs?
- Oliguric = GFR probably 5-15 ml/min
- Reduced clarance of unchanged drugs with GFR < 50 ml/min
What is important to know when dosing drugs for pts in renal failure?
Which drugs bind more in chronic renal failure?
- Know Cr clearance/estimated GFR
- determine VD- Is the ECF increased, decreased, or nml
- this will effect water soluble drugs
- protein binding is altered in chronic renal failure
- acidic drugs bind less, basic drugs bind more
How will you expect renal failure to affect Atropine and glycopyrrolate?
Scopalomine?
potential for accumulation if multiple doses given because 50% is excreted unchanged in urine.
Scopalomine usually not given d/t CNS effects
How will you expect renal failure to affect benzodiazepines?
- You would use shorter acting benzos and titrate carefully
- midazolam 60-80% cleared by kidneys in form of active metabolite and highly protein bound
- start with low dose
How will you expect renal failure to affect phenothiazines?
- Droperidol
- has alpha blocking ability- may accentuate hypotension
- not usually a problem if only small doses given
How will you expect renal failure to affect H2 blockers?
- highly dependent on renal excretion
- metoclopramide will accumulate in renal failure
What is the BEST choice of opioid for a pt in renal failure?
what do you want to avoid?
- fentanyl is best!
- avoid:
- morphine- active metab and highly PB avoid repeat dosing
- meperidine- active metab can cause sz!
- hydromorphone- active metab accumulates
- Remifentanyl also ok to use
- Alfentanyl and sufentanyl- not necessarily bad, but takehome is that fentanyl is the best
What induction agents should be used with RF?
- TPL- highly PB, free fraction can be 2x normal in pt with RF
- propofol, ketamine, etomidate- no major clinical changes
- just might be more sensitive, administer slowly
- dexmedetomidine- highly PB, longer lasting, low BP not ideal
What muscle relaxants should be avoided in RF?
d-turbo
metocurine
gallamine
pancuronium
piepcurium
doxicurium
Which NMB are ok for one dose but not ideal in a pt with RF?
Vec and Roc
about 30% renal excretion; may see prolonged effect
Which NMB are best for a pt in RF?
Would you want to give succ to apt with RF?
- Atracurium
- Cisatracurium
- mivacurium
- **nml dosing appropriate
- Use Succ with CAUTION!
- single dose ok if K is normal
- DO NOT give if K >5
- gtt problematic- active metabolite succinylmonocholine
How much can Succ increase a K level?
by 0.5-1 mEq/L
How will you intubate a pt with RF?
- Avoid Succ
- Use lidocaine
- may need beta-blockers to control HTN
- these pts will have delayed gastric emptying and increased gastric volume
- consider full stomach protocol with RSI
What should you consider when positioning the pt with RF?
- They are prone to fractures d/t hypocalcemia
- They are prone to nerve injury d/t uremic neuropathy
- Distal symmetric mixed motor and sensory polyneuropathy
- median nerve and common peroneal nerves most often seen
How should you provide the maintenance anesthesia for pts with RF?
What if they are hypertensive?
How do you want to ventilate?
- Avoid Halothane and Enflurane d/t free flouride concern
- Sevo controversial
- Isoflurand and Desflurane ideal
- fentanyl combined with N2O, O2, and agent
- If hypertensive, increase IA or administer NTG or hydralazine
- Ventilate to maintain normocapnia
Would a renal patient have a accelerated or slowed induction?
Accelerated induction AND emergence because of their severe anemia
Which way does alkalosis shift the oxy-hgb curve?
to the left
less O2 available to the tissues
What should you know about the reverasal agents in RF?
- They will have prolonged half lives because they are all heavily excreted renally
- endrophonium 75%
- neostigmine 50%
- pyridostigmine 75%
- althought effect will be prolonged, it is not a big deal because so is the effect of the relaxants
How should you manage the fluids for a pt in RF?
- may need to pre-hydrate, even pts that were jsut dialysed
- Use NS or 1/2 NS, NO LR!
- there is debate about this, LR has K in it, NS moves K from ICF to ECF, which is better?!?
- Use 500 ml bag and micro gtt
- maintain uop at 0.5 ml/kg/hr
- lasix 5 mg can be given if uop drops
- Uop is NOT predictive of postoperative renal insufficiency
- anuric pts have a narrow margin of safety for fluids
- may develop CHF or pulm edema post op
How do you wnat to monitor a pt in RF?
- Do not measure BP in arm with fistula
- A-line needed for major cases
- CVP or PA pressures for cases with a large anticipated fluid shift or EBL
What is the benefit of doing regional for a shunt placement?
the sympathometic dilation will make it easier for surgeon to place shunt
What are the concerns for regional in RF pts?
- if pt has altered mental status from uremic encephalopathy, they may be unable to sit still for procudures
- coagulopathy concern
- infection/pH changes will make anesthetic less effective
What is better to support CV depression in a pt with RF, fluids or vasopressors?
What are the renal affects of Alpha and beta adrenergics?
- Fluids first!
- Alpha adrenergics (phenylephrine)- results in greatest interference with renal circulation
- Beta adrenergics- do not result in renal vasoconstriction, but increase myocardial irritability
In septic shock, severe hypotension, etc. renal auto-regulation is impaired. What medication can be renal protective?
- Nor-epi, if it increases MAP > 60 mmHg
In Summary,
What are your priorities for GA of a pt with RF?
- schedule surgery for post dialysis
- NO LR, use K free solution in microdrip tubing
- Do not use extremity with AV fisutla for BP or IV
- CV disease likely- A-line, swan
- maintain preload
- hypotention
- Gi prophylaxis
- Muscle relaxants- use ones with little to no renal elimination
How should the RF patient be managed post-operatively?
- recurarizaition can occur due to ineffective metabolism of other drugs (antibiotics)
- HTN common: NTG or sodium nitroprusside
- ECG monitoring
- continue O2
- antibiotic continuation
