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Coexisting conditions > Renal > Flashcards

Renal Flashcards

1
Q

What are the major functions of the kidneys?

A
  • Control fluid and ion balance
    • volume, osmolarity, pH, mineral composition
  • remove wastes from circulation
  • gluconeogenesis
  • endocrine function/hormone
    • fluid balance- Renin, prostaglandins, kinins
    • RBC production- EPO
    • bone- 1, 25 dihydroxyvitamin D3
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2
Q

Autoregulation

What do our anesthetic techniques cause?

A
  • Autoregulation of RBF and GFR maintained with MAP between 80-180
  • All agents and most techniques cause decreased:
    • GFR
    • UOP
    • RBF
    • electrolyte excretions
  • All major kidney functions affected, usually reversible after procedure
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3
Q

What is considered oliguria?

What are the causes?

A
  • UOP < 0.5 ml/kg/hr or < 30 ml/hr
  • Prerenal
    • hypovolemia
    • decreased CO
  • renal
    • renal ischemia
    • nephrotoxic drugs
    • release of hemoglobin or myoblobin (in rhabdo, will clog glomeruli)
  • Post renal
    • bilateral ureteral obstruction
    • extravasation due to bladder rupture
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4
Q

What affects do anesthetics have on normal renal function (hormone release)?

A
  • ADH release due to surgical stimulation
    • will decrease UOP
  • aldosterone release- from baroreceptor response to volume depletion
  • Autoregulation may be affected under GA
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5
Q

Hypotension caused by agents under GA causeses blood to _____. What happens next?

A
  • shunt away from the kidney
    • any decrease in RBF causes release of Renin which leads to vasoconstriction and SNS stimulation further decreases RBF
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6
Q

Prostaglandins:

What do they do?

When are they produced?

What drug does affects prostaglandins?

A
  • prostaglandins have protective effect agains renal ischemia (local vasodilators)
    • oppose the actions of angiotensin II, SNS, ADH to balance the decrease in RBF and increase UOP
  • Production of prostaglandins is promoted in renal ischemia, renal hypotension, and physiologic stress
  • Ketoralac should be avoided in pts a risk for medullary ischemia because it inhibits the productions of prostaglandins, increasing risk of ischemic damage
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7
Q

Does Low dose dopamine decrease ARF?

dose

A

NO. It does not decrease incidence of ARF, dialysis, or mortality, but it does have inotropic effects with diuretic activity.

Does not protect the kidney b/c it does not increase BF to the deep loops of henle where the metabolic demand is.

1-2 mcg/kg/min

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8
Q

What does spinal and epidural anesthesia do to Renal function?

A
  • T4-T10 sympathectomy will decrease release of catecholamines, renin, and vasopressin
  • Key to maintenance of renal blood flow and GFR is you have to maintain renal perfusion pressure
    • fluid boluses
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9
Q

What VA do we avoid with renal patients? Why are these agents more concerning?

A
  • Methoxy > Enflurane > Maybe Sevo
  • these agents create free fluoride ions during metabolism that can cause tubular injury and the loss of concentrating ability
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10
Q

Which VA are very low risk to the kidney?

A
  • Isoflurane and Desflurane
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11
Q

What is the most up to date rule regarding Sevo flows?

A
  • FDA recommends flows of 2L
  • if running 1-2 L, should not use for more than 2 MAC hours
  • no clinical evidence of injury from compound A
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12
Q

How do PIP and PEEP affect the kidney?

how can these changes be overcome?

A
  • The higher the PIP and PEEP, the greater the decrease in RBF, GFR, and Urine flow rate
  • Hydration will overcome these changes by improving CV function
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13
Q

What response would you expect the body to have to a decreased preload, CO, and arterial hydrostatic pressure

A
  • SNS activation
  • RAAS activation
  • promotion of vasopressin release
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14
Q

What are the clinical features of Chronic Renal failure?

A
  • long term dialysis is required when Cr > 3 mg/dl (GFR < 30 ml/min)
  • Generalized edema- may need to administer higher doses of water soluble drugs
  • high concentrations of non-protein nitrogens
    • creatinine, urea, uric acid
  • High concentration of phenols, sulfates, phos, and potassium
  • Osteomalacia- vit D must be converted by liver and kidneys before it is able to promote Ca absorption
  • Pruritis
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15
Q

Why are renal pts anemic?

What Hgb is normal for a renal pt?

what are the Hgb/Hct goals for these pts

A
  • Anemic because of decreased production of EPO
    • EPO therapy is helpful in improving this anemia, however it causes HTN or makes current HTN worse
  • Hgb 5-8 g/dl
  • Goal:
    • Hct 36-40%
    • Hgb> 12 g/dl in females and >13 g/dl in males
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16
Q

What changes would you expect to see in the coagulopathies of a pt with renal disease?

What is the cause?

What does this mean?

A
  • Increased bleeding time DESPITE normal PT, PTT, and platelet count
    • b/c platelets are not normal
    • usually from defective von-willebrand factor
    • can be treated with DDAVT or Cryo
  • Pts at risk for GI bleed, hemorrhagic pericarditis, and subdural hematoma
17
Q

What does hyperkalemia cause?

A
  • peaked T waves
  • prolonged PR interval and QRS
  • heart block
  • v-fib
18
Q

what causes hypocalcemia?

What causes metabolic acidosis?

What does hypermagnesemia cause?

A
  • hypocalcemia due to hyperphosphatemia
  • hypermagnesemia can lead to coma and CNS depression
  • metabolic acidosis due to inability to excrete H ions
19
Q

What causes systemic HTN in renal pts?

What is the BP goal?

How can this be achieved?

A
  • intravascular volume expansion and activiation of the RAAS
    • at risk for CHF, MI, and stroke
  • BP goal <130/85
    • ACE inhibitors or angiotensin receptor blockers
    • Hold the morning of surgery
20
Q

What are some nervous system abnormalities seen in renal pts?

A
  • Uremic neuropathy- maybe dont do regional
  • Uremic encephalopathy
    • anywhere from mild irritability to coma
    • usually reversed when dialysed
  • mixed motor/sensory polyneuropathy
    • ascending neuropathy that stops at knee or elbow
    • median nerve and common peroneal nerves most often seen
  • End stage may see parathesias in feet and lower extremety weakness
21
Q

How do infections affect pts with renal disease?

How do infections usually originate?

what can we do about it?

A
  • Of pts on HD, 25% die per year
    • 1/2 of those deats are caused by infections
    • 1/2 are caused by CV instability
  • usually originates as a pulmonary infection
  • associated with uremia
  • ASEPTIC TECHNIQUE!!
22
Q

What is ARF?

A
  • sudden deterioration in renal function
    • increased serum Cr > 0.5 mg/dl means a 50% decrease in Cr clearance
    • pt may be oliguric (<400 ml/day) or nonoliguric (>400 ml/day)
23
Q

What are the three categories of ARF?

A
  • Pre-renal: decreased blood supply to kidneys from CHF, low CO/BP, or low blood volume
    • seen in shock syndromes
  • Intra-renal: abnormality within the kidney
  • Post-renal: obstruction of urinary collecting system by renal calculi, etc
24
Q

What pts are at high risk for ARF following anesthesia?

A
  • Pre-op renal insufficiency
  • pre-op CHF or atherosclerosis
  • cardiac events peri-op (inadequate BP/CO)
  • Sepsis and/or emergency surgery, trauma (MODS)
  • elderly
  • ESLD
  • hypovolemia
  • nephrotoxic exposure
  • CPB
  • aortic clamping
  • liver or kidney transplant procedures
  • nephrectomy procedures
25
Q

What are the physiologic effects of ARF?

A
  • Retention of water and waste products, electrolytes, in the blood and CSF
    • HTN, CHF, Pulm edema
    • RBCs diluted- Hct 20-30%
    • GI bleeds- anorexia, nausea, and ileus
    • hyperkalemia- can be fatal
    • metabolic acidosis
    • neurological changes from confusion to coma
    • uremia induces immune suppression–>infection
26
Q

Do we want to take a pt in ARF to the OR?

A

NO. Only if it is an emergency! These pts are very sick!

Keep MAP > 65

27
Q

What are the goals for a dialysis pt?

A
  • Avoid infection!
  • preserve vascular access
    • avoid IV in non-dominant arm and upper portion of dominant arm
  • Remember pre-op dialysis clears many medications
    • may need to redose
28
Q

What kinds of medications are easily cleared in Dialysis?

A
  • Low weight
  • <90% PB
  • water soluble
29
Q
A

Coexisting conditions (34 decks)

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