Renal pathophysiology part II Flashcards
Glucose is freely filtered at
the glomerulus
reabsorbed in the proximal tubule
Glycosuria signifies that the ability of the renal tubules to
reabsorb glucose has been exceeded by an abnormally heavy glucose load & is usually indicative of diabetes mellitus
Conditions that cause elevated serum creatinine include
ketoacidosis
cefoxitin
flucytosine
other drugs- aspirin, cimetidine, probenecid, trimethoprim
Conditions that cause decreased creatinine include
advanced age
cachexia
liver disease
A good measure of GFR is
creatinine clearance
The best measure of glomerular function is
glomerular filtration rate
- normal is 125 mL/min
- people are asymptomatic until GFR decreases to <30-50% of normal
Blood urea nitrogen is not
a direct renal function
it is influenced by exercise, bleeding, steroids, & tissue breakdown
-is elevated in kidney disease once GFR is reduced to ~75%
Serum creatinine is due to
muscle tissue turnover and dietary intake of protein
****creatinine is freely filtered at the glomerulus and is neither reabsorbed nor secreted
The best mechanism that we have to assess kidney function is
serum creatinine
Describe ECG in patients with renal disease.
ECG reflects the toxic effects of potassium excess more closely than determination of the serum potassium concentration
will see peaked T waves*
Small or indiscernible P waves
Clinical situations that contribute to increased K+ in renal failure patients include
protein catabolism hemolysis hemorrhage tx. of stored RBCs metabolic acidosis
How long are RBCs stored in blood bank?
42 days
During blood storage, there is a slow but constant leakage of
potassium from the cells that results in a plasma level of potassium increase by 0.5-1.0 mmol/L/ per day of refrigerator storage
The risk of potassium overload in patients requiring a blood transfusion can be minimized by
selecting only blood collected less than 5 days ** prior to transfusion and by washing *** any unit of blood immediately before infusion to remove extracellular potassium
The use of potassium absorption ______ during transfusion may also decrease potassium loading
filters****
Factors that also play a role in the increase of potassium levels with transfusion are
the rate and volume***** of transfusion as well as the patient’s circulating pre-transfusion blood volume
Imaging studies in renal disease include
ultrasound, CT, & MRI
Ultrasound in renal disease provides
noninvasive, minimal patient prep, assesses kidney size, hyponephrosis, vasculature, obstructions, & masses
CT in renal disease is used to
detect stones of all kinds, masses may be evaluated using contrast
MRI in renal disease is used to
provide detailed tissue characterization, nice alternative to a contrast CT, reduced radiation exposure (e.g. pregnant)
Gandolinium is a paramagnetic IV contrast agent used commonly in MRA
Describe how general anesthesia effects renal function
PPV & decreased CO–> depression of renal blood flow, GFR, urinary flow, & electrolyte secretion
Describe how regional anesthesia effects renal function
parallels with degree of SNS blockade, decreased venous return, & decrease in blood pressure
Indirect effects perioperative effects on renal function include
circulatory, endocrine, SNS, patient positioning
Describe the direct effect perioperative effects on renal function.
medications that target renal cellular function
Describe how surgery effects renal function.
causes stress & catecholamine release, fluid shifts, secretion of vasopressin & angiotensin
Describe how fentanyl is affected by renal failure.
not grossly altered by renal failure but a decrease in plasma protein binding may result in higher free fractions
Describe how meperidine is affected by renal failure
active metabolite normeperidine is dependent on renal excretion- accumulation can lead to CNS toxicity & seizures
Describe how morphine is affected by renal failure
active metabolites that depend on renal clearance mechanisms for elimination
-morphine-6-glucuronide**** is excreted via the kidney
Describe the use of morphine & hydromorphone for patients at risk or early stage of CKD, advanced CKD, & ESRD/hemodialysis.
Morphine- early stage reduce dose, advanced CKD & ESRD avoid completely
hydromorphone- early stage 1-2 mg q4 h, advanced CKD decrease to 1 mg, ESRD decrease to 0.5 mg
Describe CKD & ketamine
8% of administered ketamine is metabolized in the liver forming norketamine; norketamine is then hydroxylated into a water-soluble metabolite excreted by the kidney
most clinicians believe that dose modification for ketamine is not required for patients with decreased renal function
Describe the use of gabapentinoids (gabapentin & pregabalin) for patients with renal failure.
may increase the risk of over sedation & even coma
these agents are excreted solely by the kidney**
a reduction of 50% of the dose for each 50% decline in GFR or CCr** and increasing the time interval between the doses is advised
Describe the use of inhalational agents on renal function.
all can cause a decrease in blood pressure & the kidney respond with a compensatory increase in renal vascular resistance–> decreased renal blood flow
Describe the use of isoflurane on renal function
decreases BP (dose dependent)
Describe the use of desflurane on renal function.
with increased heart rate, may maintain a greater degree of CO and therefore renal perfusion
Describe the use of sevoflurane on renal function.
free fluoride ion metabolite
-was more pronounced & only proven with methoxyflurane & clear evidence has not been established with sevoflurane
What other metabolite is associated with sevoflurane?
Compound A
Risk of development of compound A is dependent on
duration of exposure, fresh gas flow rate, concentration of sevoflurane
Co2 absorbents containing _________ degrade sevoflurane resulting in production of
soda lime; vinyl ether called compound A
risk is higher with closed-circuit anesthesia
The sevoflurane FDA package insert states
sevoflurane exposure should not exceed 2 MAC hours at flow rates of 1 to <2 L/min.
FGF <1L/min. are not recommended
____ can be used in place of soda lime
Amsorb
non-caustic and can be disposed of in domestic waste
no production of compound A even when desiccated and low flows with sevo are safe
Propofol does not
adversely affect renal tubular function
Prolonged infusions of propofol may result in
green urine due to the presence of phenolic metabolites
-this discoloration does not affect renal function
Propofol infusion syndrome can result in
renal failure secondary to rhabdomyolysis, myoglobinuria, hypotension, & metabolic acidosis
The duration of action of muscle relaxants in patients with renal failure
may be prolonged***
Succinylcholine & patients with renal failure
can be used carefully
okay if patient has received dialysis within 24 hours & normal serum K+
Administration of succinylcholine causes a
rapid, transient increase of 0.5 mEq/L in the serum potassium concentration
- can be exaggerated to >0.5 mEq/L in the patient with renal failure
Succinylcholine’s metabolism is catalyzed by
pseudocholinesterase to yield the nontoxic end products succinic acid & choline
- the metabolic precursor of these two compounds, succinylmonocholine, is excreted by the kidneys
With sugammadex, the neuromuscular blocker complex is
excreted by the kidney**
in patients with severe renal impairment, these cylcodextrin complexes can accumulate
______ is an intermediate in the metabolism of sodium nitroprusside
cyanide; with thiocyanate being the final metabolic product
The half-life of thiocyanate is normally
more than 4 days and it is prolonged in patients with renal failure
When thiocyanate levels are more than 10 mg/100 mL
hypoxia, nausea, tinnitus, muscle spasm, disorientation & psychosis have been reported
Thiocyanate toxicity is associated with
long-term infusions (usually more than 6 days)
Describe what fluids should be considered for patients with renal failure.
albumin- may be protective by maintaining renal perfusion, binding of endogenous toxins & nephrotoxic drugs, & preventing oxidative damage
Hetastarch/Dextran- has been associated with AKI secondary to the breakdown of the synthetic carbs to degradation products that cause direct tubular injury & plugging of tubules
Dopamine & fenoldopam have been used to
dilate afferent and efferent arterioles and increase renal perfusion
Anti-dopaminergics & renal failure
may impair renal response to dopamine
(metoclopramide, phenothiazines, droperiodol
Renal pathophysiologies requiring surgeries include
renal cell carcinoma
renal dysplasia
polycystic kidney disease
& Wilm’s Tumor
The most common renal malignancy is
renal cell carcinoma
>80% of all solid renal masses
Renal cell carcinoma originates
in the lining of the proximal tubules
Renal cell carcinoma is refractory to
chemotherapy or radiation
The classic triad presentation of renal cell carcinoma is
hematuria, flank pain, & renal mass****
although often found incidentally ~50%
__________ is often curative for renal cell carcinoma
surgical resection
For 5-10% of patients with renal cell carcinoma, the tumor extends into
the renal vein & the inferior vena cava & right atrium
-may require CPB
Renal dysplasia is the
malformation of the tubules during fetal development
kidney consists of irregular cysts of varying sizes
The diagnosis of renal dysplasia is often made
in utero by ultrasound
Renal dysplasia is linked to
genetic mutation & illicit drug use by mother (e.g. cocaine)
Patients with renal dysplasia may also have
ureteropelvic junction obstruction & vesicoureteral reflux
______ is incompatible with survival for patients with renal dysplasia
bilateral
Renal dysplasia can lead to
chronic kidney disease, dialysis, & transplant
About 90% of patients with renal dysplasia will have
contralateral hypertrophy by adulthood
Polycystic kidney disease is
an inherited (dominant or recessive), massive enlargement of the kidneys with compromised renal function -cysts can also occur on other organs (liver, pancreas, spleen)
Polycystic kidney disease is
painful due to distension of the cysts & stretching of fascia
-hemorrhage, rupture, or infection exacerbate this pain
Most cases of polycystic kidney disease progress to
bilateral disease by adulthood
PKD involves non-functioning
fluid filled cysts that range in size form microscopic to mass-effect producing size
Complications of PKD include
hypertension due to activation of RAAS
cyst infections
bleeding
decline in renal function
Treatment of PKD includes
symptoms management, dialysis, & transplant
Wilms tumor often presents
unilaterally and a painless, palpable abdominal mass
<5% are bilateral
Wilms tumor can be associated with
congenital/genetic malformations
Beckwith-Wiedemann, & WAGR
The most common malignant renal tumor in children is
Wilms tumor
1/3rd occur in under age 1
Wilms tumor treatment
requires resection & possibly chemotherapy
capacity for rapid cases
in cases of metastasis it is usually to the lungs
Describe the stages of Wilms tumor
1- 43% of cases, limited to the kidney & is completely excised
2- 23% of cases, tumor extends beyond the kidney but is completely excised
3- 20% of cases, inoperable primary tumor lymph node metastasis
4- lymph node metastases outside of the abdominopelvic region
5- bilateral renal inolvement
Describe a total nephrectomy
the renal artery & vein are ligated and then it involves removal of the kidney, the ipsilateral adrenal gland, perinephric fat, and the surrounding fascia
-the other kidney needs to be functional
Describe a partial nephrectomy
(nephron-sparing surgery) is considered for patients with a solitary functional kidney, small lesions (<4cm), or bilateral tumors or for patients with increased risk because of other disease such as diabetes or hypertension
Prior to surgery for nephrectomy
patients have flank mass
hypertension- started on anti-hypertensives
US & CT
Biopsy- diagnosis
Anesthesia for nephrectomy include
premed
inhalation induction with peds, IV induction with adults
BP control- wide fluctuations requiring volume & vasopressors
PIVs x 2, aline, CVC placed by surgeon if chemo or by anesthesia for IV immunosuppression medication
Additional anesthetic considerations for nephrectomy include
standard risk assessment identify smoking and age risk factors note any preexisting renal dysfunction many are anemic- CBC, T&C K+-BMP regional anesthesia include blockage of nerve roots T8-L3 ERAS opioid sparing
This is released by kidney in response to anemia, hypoxia
erythropoietin
PTH causes increased _________ in exchange for phosphate
Ca2+ reabsorption
________ is secreted from adrenal cortex and causes reabsorption of Na+
aldosterone
_______ will constrict efferent arteriole & reabsorption of water
ADH/vasopressin
___________ is released due to atrial distension (fluid overload) and stimulates excretion of Na+ and water
ANP
______ causes vasodilation and Na+ excretion
dopamine- DA1 receptor
