Anesthesia and Renal Failure
In renal failure, the induction dose of
which of the following should be
decreased ?
•
•
•
•
Propofol
Ketamine
Thiopental
Etomidate
Induction Anesthetics
• Propofol: undergoes hepatic
biotransformation into inactive metabolites; in
renal failure duration of action is not affected
• Ketamine: hepatic metabolism and
redistribution are responsible for termination
of the anesthetic effects and <3% is excreted
unchanged in the urine, so duration is not
affected by renal failure
Induction Anesthetics
• Thiopental: 85% is protein bound and in the
setting of uremia the free fraction is almost
doubled, so the induction dose should be
decreased
• Etomidate: 75% is protein bound so the free
fraction increases in renal failure; however
this increase is not clinically significant
In renal failure, the induction dose of
which of the following should be
decreased ?
•
•
•
•
Propofol
Ketamine
Thiopental
Etomidate
Volatile Anesthetics
• Nitrous Oxide: elimination is through
exhalation, so it is not affected by renal failure
Fluoride Induced Nephrotoxicity
• Metabolism of sevoflurane, isoflurane,
methoxyflurane, enflurane and halothane
results in production of fluoride ions
• Nephrotoxicity is a result of 2 factors: the peak
fluoride concentration (with above 50 uM
toxic threshold) and the area under the curve
of serum fluoride concentration versus time
Fluoride Induced Nephrotoxicity
• Isoflurane: 20 MAC-hours of isoflurane could
lead to serum flouride levels above 50uM,
however no postoperative renal dysfunction
was detected
• Sevoflurane: regularly 7% of patients who
receive sevoflurane will have serum flouride
levels above 50uM. Yet, no clinically significant
renal dysfunction was detected
Fluoride Induced Nephrotoxicity
• Methoxyfluane and enflurane might cause
renal dysfunction especially when associated
with hypovolemia, shock and renal
vasoconstriction
Sevoflurane and compound A
• Sevoflurane is degraded in basic carbon
dioxide absorbents, such as Barium Hydroxide
and Soda lime, into a vinyl ether called
compound A
• Compound A was proven to be nephrotoxic
when it reaches certain thershold levels that
differ among different animal species
Sevoflurane and compound A
• Human studies have not associated
sevoflurane with any detectable postop
impairment of renal function
• Some clinicians recommemd that fresh gas
flow rate be al least 2L/min to avoid release of
compound A
The duration of action of which of the
following is not affected by renal
failure?
•
•
•
•
•
Succinylcholine
Rocuronium
Vecuronium
Doxacurium
Cisatracurium
Renal Failure and Succinylcholine
• Succinylcholine: its duration of action is not
significantly prolonged, so its use is justified in
rapid sequence induction
• Renal failure patients are more prone to
hyperkalemia and succinylcholine results in an
increase in serum potassium levels in normal
subjects (0.5mEq/L). Therefore, serum potassium
levels should be checked and normalized.
• Use of a continuous infusion is not recommended
since its major metabolite succinylmonocholine is
active and dependent on renal excretion
Intermediate acting Muscle Relaxants
• Vecuronium: has an active metabolite (3desmethyl vecuronium) that accumulates in renal
failure causing an intubating dose to last around
50% longer
• Rocuronium: pharmacokinetic studies on patients
with renal failure had conflicting results with
respect to the duration of action
• Atracurium and cisatracurium metabolism is
independent of renal and hepatic function, so
they are recommended in renal failure
Laundanosine
• It is a breakdown product of Hofmann
elimination (of atracurium and cisatracurium)
that was found to cause seizures in
experimental animals.
• However, intensive care patients with renal
failure receiving prolonged infusions of
atracurium did not have any seizures
Long acting muscle relaxant
• Doxacurium and pipecuronium have reduced
plasma clearance and prolonged duration of
action in renal failure patients
The duration of action of which of the
following is not affected by renal
failure?
•
•
•
•
•
Succinylcholine
Rocuronium
Vecuronium
Doxacurium
Cisatracurium
Which of the following opioids is safe
in renal failure
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•
•
•
•
Meperidine
Fentanil
Sufentanil
Morphine
Remifentanil
Opioids and Renal Failure
• Morphine undergoes hepatic metabolism to
morphine-3-glucuronide and morphine-6glucuronide. These metabolites can
accumulate in renal failure and result in
narcosis and respiratory depression
• Merperidine is metabolised to normeperidine
which might accumulate in renal failure
patients and result in CNS toxicity (seizures).
Opioids and Renal Failure
• Fentanyl and alfentanyl are good choices in
renal failure since their metabolites are
inactive and the change in their free fraction is
not clinically significant
• Sufentanil has an active metabolite that might
accumulate in renal failure upon chronic use
and result in prolonged narcosis
Opioids and Renal Failure
• Remifentanil clearance is not affected by renal
failure
• It is metabolized to remifentanyl acid, which
would accumulate in renal failure, but is 4,600
times less potent
• Thus, the clinical implications are limited
Which of the following opioids is safe
in renal failure
•
•
•
•
•
Meperidine
Fentanil
Sufentanil
Morphine
Remifentanil
TURP syndrome
• In around 1.5 % of TURPs excessive
absorption of the irrigating solution may lead
to several symptoms described as TURP
syndrome
• Several irrigation solutions are available for
use during TURP, such as glycine, sorbitol,
mannitol and distilled water
TURP syndrome
• The signs and symptoms can be divided into
those common to all irrigating solutions and
those peculiar to certain solutions.
• Excessive absorption of any of the solutions
might lead to fluid overload and hyponatremia
Common Signs and Symptoms
• Fluid overload might manifest as hypertension,
bradycardia and pulmonary edema especially in
congestive heart failure patients
• Hyponatremia (if Na<120mEq/L) could present
with ECG changes such as widening of QRS
complex, ST elevation, ventricular fibrillation and
CNS changes from confusion and nausea to coma
Glycine Solutions
• Glycine is an inhibitory neurotransmitter in
the cortex and retina
• Excessive absorption might lead to seizures
and post-op blindness that resolves when
glycine blood levels decrease
Other solutions
• Distilled water might lead to hemolysis and
hyponatremia.
• Glucose solutions might cause hyperglycemia
• Sortibol solutions could lead to hyperglycemia
and lactic acidosis
Prophylactic measures
• To decrease fluid absorption, it is
recommended to:
1) Limit resection time to < 1 hour
2) Suspend the irrigating bag <30cm above
the table at the beginning of the procedure
and < 15cm at the final stages of resection
TURP Syndrome Treatment
• When symptoms and signs of TURP syndrome
occur:
1. Stop using the irrigation solution
2. If pulmonary and cardiac symptoms are
present, place the patient in reverse
Trendelenberg position to alleviate
symptoms by pooling blood in the lower
extremities
3. Electrolyte analysis: Sent blood for
electrolytes, creatinine, glucose and ABGs
HyponatremiaTreatment
• If patients are symptomatic and have serum
[Na] < 120mEq/L, they should be corrected
with hypertonic saline at a rate < 100ml/hr till
they are asymptomatic or serum [Na] >
120mEq/L
• Then hyponatremia is managed with fluid
restriction and loop diuretic (furosemide)
Thank You