Renal Flashcards
These factors will result in prostaglandin synthesis by the kidneys
Renal ischemia, renal hypotension, and physiological stress
This common drug used for post-op pain relief should be avoided in those at risk for medullary ischemia. Why?
Ketorolac (Toradol)
This is because it is a powerful NSAID, which drastically reduces prostaglandin synthesis, putting the kidneys at risk for ischemia
Low dose dopamine will do this, but not this
Will have positive inotropic effects, which increase UO.
Will not decrease the incidence of ARF, dialysis, or mortality
The kidneys are able to autoregulate over this range of MAPs
80-180
Some say up to 200
Either way, kidneys are very sensitive to a reduction in MAP
Also, may be higher than 80 if the patient has chronic HTN
Surgical stimulation can cause release of this hormone
ADH
This will cause a drop in UO
This will cause aldosterone release
baroreceptor response to volume depletion
In hypotension, blood will be shunted (towards/away) from the kidneys
Away from the kidneys! Towards the vital organs
What ion are we concerned about in renal failure?
Floride. Free fluoride ions cause tubular injury and loss of concentrating ability (can result in ARF)
Ranking of volatile agent effects on the kidney
Methoxy>Enflu>Sevo>Iso>Des>Halo
MESID H
We prefer the use of these IAs in renal failure patients
Iso and des
These have negligible effects on renal function
This is the minimum amount of gas flow that should be given with Sevo
2L to prevent compound A formation
BUN > ___ is indicative of decreased GFR
50
These factors may cause GFR to rise despite a normal GFR
High protein diet
GI bleed
Febrile illness
Dehydration
What is the most common cause of high BUN
CHF secondary to the reabsorption of BUN
Low CO causes lows kidney perfusion.
Kidneys try to correct perceived fluid deficit by reabsorbing urea.
There is a __-__ hour lag time after a change in GFR before the increase creatinine levels are seen
8 - 17
What test is the most reliable estimate of GFR?
Creatinine clearance
Why is anemia common in renal failure?
1) Decreased EPO production
2) Build-up of toxins decreases the lifespan of RBCs
Chronic renal patients will usually have an increased or decreased CO?
Increased to compensate for the anemia
Hemoglobin levels as low as __-__ are common for renal patients, so don’t freak out
5-8
Renal patients usually have fucked up coags. Which coags are fucked up and why?
PT, PTT, and bleeding time.
These are fucked up because they have shitty vWF. Treat this by replacing vWF.
How can you treat the fucked up coags seen in renal dysfunction?
Replace the vWF!
1) Desmopressin .3-.4mg/kg over 30 min)
- Desmopressin will increase the release of vWF from endothelial cells
2) Cryoprecipitate (remember that this contains factor VIII, XIII, fibrinogen, and whaddup –> vWF!)
The hyperkalemia seen in RF can result in these EKG changes
Peaked T waves, ST depression, prolonged PR interval and QRS complex, heart block, and V-fib
Hypermagnesemia resulting from RF can cause
Coma and CNS depression
Prolongs the duration of NMBs
Why do we use a microdripper to give fluids in renal patients?
To make sure we don’t fluid overload them
Why does RF cause HTN?
1) Renin release by the diseases kidney
2) High intravascular fluid volume d/t inappropriate handling of sodium and water
RF can lead to ____ pericarditis and cause
uremic pericarditis
tamponade
Hypocalcemia causes this on EKG
Prolonged QT
Digitalis toxicity produces this on EKG
Shortened QT and depressed ST
These meds are excreted via the kidneys unchanged and are contraindicated in RF
Gallamine (100% renal elimination) and phenobarbital
Is UO predictive of post-op renal insufficiency?
No
What can happen if you give too much fluid to your anuric renal patients?
CHF and pulmonary edema
UO during surgery should be maintained at this rate
0.5cc/kg/min
If it falls, we can give 5mg of lasix
A 50% increase in plasma creatinine means
A 50% reduction in GFR
This is the source of creatinine
Skeletal muscle
We are concerned about K+ when it is over
5
When is vasopressin released?
Released by the posterior pituitary in response to high serum osmolarity and acts on the kidneys
This is the dose for low-dose dopamine
1-2mcg/kg/min
Effect of neuraxial anesthesia in renal dysfunction
• T4-T10 sympathectomy will decrease the release of catecholamines, renin, and vasopressin (ADH)
o This is because we’re causing vasodilation and blocking the sympathetic response!
o Make sure to pre-hydrate before placement!
• Key to maintenance of renal blood flow and GFR is you have to maintain renal perfusion pressure – fluid boluses etc.
o Remember that proper RBF is dependent on MAP
Effect of PPV on renal function, and how we can over come this
• The higher the PIP and PEEP the greater the decrease in RBF, GFR, and urine flow rate
o Probably because PPV will decrease venous return and CO
We can overcome this by hydrating.
Creatinine Clearance
Normal is 125mL/min
•
What may a CXR show in the patient with renal failure?
• LVH
o Determine presence of hypertensive cardiovascular disease
• Pericardial effusion (from uremic pericarditis)
• Uremic pneumonitis- RF patients have chronic pulmonary edema → fluid overload, shitty heart function, and leaky capillaries
Avoid these NMBs in renal failure
d-tubocurarine, metocurine, gallamine
What is the most common cause of death in renal failure?
Infection
Make sure to use aseptic technique!!
IAs for RF
Halothane
Avoid- High K+ & acidosis-> myocardial irritability
Enflurane
Avoid- fluoride concern
Sevoflurane
Controversial: some practitioners remain concerned regarding Compound A and fluoride
Isoflurane/Desflurane
Volatile agents ideal-no dependence on kidney for elimination
Accelerated induction and emergence seen with severe anemia
Anemia results in decreased solubility of the IA
Ventilation goals in RF
Hypoventilation exacerbates acidosis
Hypercapnia predisposes to cardiac arrhythmias from acidosis
Alkalosis shifts oxy-hgb curve to left- less O2 available to tissues
Overall, we want to maintain normal acid/base balance
Remember too that they are anemic and we want to do this to keep the O2 dissociation curve to the right!!
Remember that high PIP and PEEP will decrease RBF
This is the pressor of choice for renal pts
Ephedrine
What’s the deal with H2 blockers and renal failure?
H2 blockers are highly dependent on renal excretion
When does cystoscopy require more than local anesthesia?
If the bladder if being inflated (consider RA or GA)
Lithotomy position for cystoscopy puts you at risk for these nerve injuries
All major legs nerves except LFC
Sciatic, common peroneal, femoral, saphenous, and obturator
RA for cystoscopy
Need T10 block
Spinal preferred d/t brief nature of the surgery
Will not abolish the obturator reflex (can only be blocked by muscle relaxants, which we don’t use with a regional technique)
GA for cystoscopy
Short case (15-20 min) LMA ok to use
S/S associated with TURP syndrome
headache, restlessness, confusion, seizure, dyspnea, cyanosis, arrhythmias, hypotension with bradycardia
Irrigating fluids used for TURP
glycine, sorbitol, or mannitol
How to prevent TURP syndrome
Limit irrigating fluid height to 40cm above prostate (job of the urologist)
Limit resection time to less than 1 hour
Treatment for TURP syndrome
EARLY DETECTION!!
Fluid restriction
Loop diuretic
To correct fluid overload and hyponatremia
Hypertonic solution if hyponatremia present. 100cc 3% saline over 1-2 hours. Administer based on patients serum sodium (Ideally >120)
Hyponatremia occurs d/t large absorption of this fluid that doesn’t contain lytes
Results in cerebral edema
Treat seizures with midazolam, thiopental or phenytoin (if glycine used consider a trial of magnesium)
Intubate if pulmonary edema has occurred (from volume overload)
Regional blockade level needed for ESWL
T6
Why is GA preferred for ESWL?
Ability to control diaphragmatic excursion (Jet ventilation)
Coagulation considerations in RF
o Increased bleeding despite normal PT, PTT, and Bleeding Time
• Caused by release of defective von Willebrand factor
• Rx- Desmopressin (0.3-0.4 mg/kg over 30 min) or cryoprecipitate
o Blood warmer- set up and have ready to go
When is vasopressin released?
It’s released by the posterior pituitary in response to an increase in serum osmolarity
Something to remember before doing neuraxial anesthesia in renal failure
• T4-T10 sympathectomy will decrease the release of catecholamines, renin, and vasopressin (ADH)
o This is because we’re causing vasodilation and blocking the sympathetic response!
o Make sure to pre-hydrate before placement!
