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58 Cards in this Set
- Front
- Back
Both regional and general anesthesia cause reversible declines in? 4
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RPF, GFR, urine flow rate, and urine sodium excretion; alterations tend to be less with regional anesthesia
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Most anesthesia-related changes in renal function are?
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indirectly mediated
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Anesthetic agents may cause?
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cardiac depression and peripheral vasodilation, and reduce MAP below the lower limit of renal autoregulation
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Anesthesia can activate?
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activiation of the SNS(stress response) causing renal vasoconstriction
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What can anesthesia stimulate?
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hormone secretion (ADH, aldosterone) can facilitate sodium and water retention
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What are direct effects of anesthetic agents on renal function ? 3
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1. Halothane and isoflurane may reduce vascular resistance
2. Methoxyflurane - nephrotoxicity secondary to fluoride ion release 3. Possible sevoflurane nephrotoxicity |
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Eger et al. reported what with sevo?
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transient renal injury in normal volunteers administered 1.25 MAC sevo for 8 hours at a flow rate of 2 L/min
-but several other investigators have not found evidence of adverse effects of sevo on renal function |
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If nephrotoxicity occurs, it is most likely due to?
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Compound A produced by sevoflurane degradation when the agent is passed at slow rates through Baralyme CO2 absorbent
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NSAIDS and ACE inhibitors may?
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exaggerate the effects of anesthesia and surgery on renal function
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Preoperative considerations (KDOQI 2-4) assess?
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level of renal function, Ccr
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In patients in renal failure stages 2-4 what should emphasis be on?
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prevention of postoperative ARF (mortality rate of 50-60%) particularly in patients undergoing surgical procedures that increase the risk of postop ARF
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What things could you do to avoid ARF in patients in stages 2-4 renal disease already? 2
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1. Preop administration of a balanced salt solution may correct hypovolemia
2. Mannitol, low-dose dopamine, fenoldopam, or loop diuretic may be administered to maintain urine flow |
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What preoperative medications are safe to administer to a renal failure stage 2-4 patient?
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1. Benzodiazepines
2. Anticholinergic agents (atropine) 3. Histamine-2 receptor blocker |
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With the administration of benzodiazepines what things should you consider?
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that they undergo hepatic metabolism before excretion in the urine and thus safe to use; however, hypoalbuminemia may increase sensitivity due to increased free fraction of drug
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What should you consider when administering anticholinergic agents in patients with renal failure in stages 2-4?
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possible accumulation with repeated doses
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What are histamine-2 receptor blockers used for?
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to increase gastric pH
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What can an increased bleeding time be corrected by?
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administration of cryoprecipitate or DDAVP
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What is included in standard monitoring during the intraoperative time?
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urine flow rate - output greater than 0.5 mL/kg/hr is desired
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During induction of anesthesia what do you want to make sure is adequate?
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the intravascular volume is adequate, otherwise hypotension may occur on induction
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What drug may have an increased sensitivity due to increased free fraction of drug?
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thiopental
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Are the pharmacokinetics of ketamine, propofol, and etomidate significantly altered?
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no
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Is succinylcholine safe to use?
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yes, provided that serum potassium concentration is less than 5meq/L
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What neuromuscular agents are the drugs of choice?
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atracurium and cisatracurium, they are not dependent on renal clearance
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What two neuromuscular agents may be modestly prolonged?
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vecuronium and rocuronium
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What gases are considered acceptable to use during the maintenance of anesthesia?
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nitrous oxide together with either isoflurane or desflurane, some practitioners avoid sevoflurane because of concerns regarding fluroide ion release or compound A production
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Are opioids safe to administer?
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most opioids are suitable, possible avoid morphine and meperidine as active metabolites may accumulate
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Fluid therapy during maintenance of anesthesia
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administer a balanced salt solution to maintain normal or slightly expanded intravascular volume
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T or F. Symptoms of fluid overload (pulmonary congestion) are easier to treat than are symptoms of ARF.
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True
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Which antiemetics can be used?
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metoclopramide- does not depend on renal function for clearance, phenothiazenes, droperidol, and 5-HT3 receptor blockers can be used as well
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Preop considerations for patients in stage 5 renal failure (3)
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Thorough patient eval; uremia is likely
1. Evaluate intravascular volume status; hyper- or hypovolemia may be present 2. RBC transfusion may be given for severely anemic patient 3. Evaluate preoperative drug therapy |
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Premedication considerations for patients in stage 5 renal failure (3)
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1. increased sensitivity to benzodiazepines and dexmedetomidine
2. Continue preop medications, especially hypertensive agents 3. Histamine-2 receptor blocker can be used to increase gastric pH |
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Should you place the BP cuff on the arm with the fistula?
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no, invasive monitoring may be necessary
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Induction of anesthesia with patients who have nausea, vomiting, or GI bleeding should undergo?
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RSI
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What induction drugs can be used with patients in stage 5 renal failure?
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thiopental (reduced dose), propofol, etomidate, or ketamine can be used for induction
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What muscle relaxants should be used with patients in stage 5 renal failure?
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atracurium and cisatracurium
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What volatile agents are preferred in patients in stage 5 renal failure?
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isoflurane and desflurane- least effect on CO
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In patients with very low Hb what should you avoid?
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nitrous oxide- allows for administration of 100% oxygen
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Which opioid should you use and which one should you avoid in stage 5 renal failure patients?
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fentanyl is excellent opioid, avoid meperidine and morphine (accumulation)
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What other way could you maintain anesthesia intraoperatively with these patients?
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TIVA with remifentanil, propofol, and cisatracurium
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Fluid therapy for stage 5 renal patients undergoing superficial procedures with little fluid loss?
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D5W may be used to replace insensible water loss
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Procedures that cause large fluid loss or shifts require administration of?
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a balanced salt solution and/or colloid solution
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In patients with hyperkalemia what solutions should you avoid?
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glucose-free solutions and LR
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In aortic cross-clamping what is the most important determinant of RBF changes and probablitly of postop ARF?
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level of clamping
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What is the incidence of ARF after infrarenal clamping?
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5%
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What is the incidence of ARF after suprarenal clamping?
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13%
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Postop mortality is ______ times higher in patients who develop ARF than in those who do not
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4-5
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Suprarenal clamping reduces? and increases?
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RBF by 80% and increases fractional distribution of RBF to the cortex
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Infrarenal clamping reduces RBF by?
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45%
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How long does RBF remain depressed following release of clamp and return of systemic hemodynamics to normal?
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30 min or more
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What are some methods of renal protection during cross-clamping of the aorta?
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1. Dopamine (2-3 micrograms/min)
2. Fenoldopam (DA-1 receptor agonist) 3. Furosemide 4. Mannitol |
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Mannitol produces?
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diuresis and acts as a free radical scavenger
-does not necessarily improve outcomes |
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What has been found to be the most important in preventing postop ARF?
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good hydration during clamping and after clamp release
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Is intraoperative urinary output a predictor of postop renal fx?
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no
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What is the most reliable predictor of postoperative renal dysfunction after aortic cross-clamping?
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is preoperative renal dysfunction ie, elevated Scr or BUN or decreased Ccr
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What is the effect of endovascular aortic surgery on renal function?
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prevalence of renal complications similiar to that with open surgery
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Why is the endovascular approach not any better than the open approach?
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large amounts of radiocontrast dye may be used- can aggravate preexisting renal dysfunction
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What may be dislodged into the kidneys and contribute to ischemia?
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atherosclerotic debris
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What is warranted to lessen the risk of postop renal dysfunction?
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good hydration
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