Renal Flashcards
Exam 3
~____% of total body weight is water
60
- varies w/ gender, age, body fat %
- ↑Muscle=↑Water
Intracellular fluid makes up ___ of TBW, while extracellular fluid makes up ___
2/3
1/3
Extracellular fluid includes ______ and ______. What are their respective amounts?
ISF - 3/4
Plasma - 1/4
Osmolar homeostasis is mainly mediated by osmolality-sensors in the?
anterior hypothalamus
Osmolar homeostasis does what 3 things?
- Stimulate thirst
- Cause Pituitary Release of Vasopressin (ADH)
- Cardiac atria releases ANP→act on kidney to ↓Na+/H20 reabsorption
Volume homeostasis is mediated by?
juxtaglomerular apparatus - sense changes in volume
What is the response to dec volume by volume homeostasis?
↓Vol @ JGA triggers Renin-Angiotensinogen-Aldosterone system (RAAS)→Na+/H20 reabsorption
What are the normal values of sodium? What is too low/high for surgery?
135-145 mEq/L
- ≤125 or ≥ 155, want correction prior to elective case
What are the 3 potential underlying causes of hypo/hypernatremia?
- Hypovolemic
- Euvolemic
- Hypervolemic
___% of hospitalized pts are hyponatremia. What are the causes?
15%
- over fluid-resuscitation
- ↑endog vasopressin → inc H2O reabsorption
Hyponatremia d/t hypovolemia causes and differentiation
- Renal losses (urine Na > 20) - diuretic excess, mineralocorticoid deficiency, salt-losing nephritis, renal tubular acidosis, metabolic alkalosis, ketonuria, osmotic diuresis
- Extrarenal losses (urine Na < 20) - vomiting, diarrhea, 3rd space losses, burns, pancreatitis, muscle trauma
Hyponatremia d/t euvolemia causes and differentiation
- Salt-restricted diet (urine Na < 20)
- Other (urine Na > 20) - glucocorticoid deficiency, hypothyroidism, high sympathetic drive, drugs, SIADH
Hyponatremia d/t hypervolemia causes and differentiation
- Avid Na reabsorption (urine Na < 20) - nephrotic syndrome, cardiac failure, cirrhosis
- Renal loses (urine Na > 20) - acute or chronic renal failure
Hyponatremia d/t hypervolemia S/S
peripheral edema, rales, ascites
Neuro S/S of hyponatremia
start with HA and confusion
- N/V, fatigue, muscle cramps
The most severe consequences of hyponatremia include? What is the serum Na level?
Seizures, coma, and death
< 120 mEq/L
What is the tx for hyponatremia?
- Treat underlying cause (look at volume status), electrolyte drinks, NS, diuretics
- Hypertonic/3% NaCl: 80ml/hr over 15h (max 1.5 mEq/L/hr, check Na+ q4h while replacing)
Rapid correction of hyponatremia occurs at what rate and can cause what syndrome?
Rapid correction >6 mEq/L in 24 h)
Osmotic Demyelination Syndrome (often permanent neuro damage)
What is the treatment for hyponatremic seizures?
3-5ml/kg of 3% over 20 min, until seizures resolve
What are the common causes of hypernatremia?
- Excessive evaporation
- Poor oral intake (very young, very old, altered mental status)
- Overcorrection of hyponatremia
- Diabetes insipidus - loss of dilute urine
- GI losses
- Excessive sodium bicarb (treating acidosis)
Hypernatremia d/t hypovolemia causes and differentiation
- Renal salt and water loss (urine Na > 20) - osmotic or loop diuretics, postrenal obstruction, intrinsic renal disease, profound glycosuria
- Extrarenal salt and water loss (urine Na < 20) - diarrhea, GI fistulas, burns, sweating
Hypernatremia d/t hypovolemia s/s
Dec skin turgor, flat neck veins, dry mucous membranes, orthostatic hypotension, tachycardia, oliguria
Hypernatremia d/t euvolemia causes and differentiation
Urine Na variable
- renal water loss: DI (central, nephrogenic, or gestational)
- extrarenal water loss: insensible losses (respiratory tract, skin)
Hypernatremia d/t hypervolemia causes and differentiation
Urine Na > 20 - sodium gains
- hyperaldosteronism, Cushing’s, hypertonic dialysis, IV sodium bicarb, NaCl tablets, hyperalimentation, hypertonic saline enemas, salt water drowning
Hypernatremia d/t hypervolemia s/s
peripheral edema, rales, ascities
What are the general s/s of hypernatremia?
- Orthostasis
- Restlessness
- Lethargy
- Tremor/Muscle twitching/spasticity
- Seizures
- Death
What is the tx for hypernatremia?
Route cause, Assess volume status (VS, UOP, Turgor, CVP)
- Hypovolemic: normal saline
- Euvolemic: water replacement (po or D5W)
- Hypervolemic: diuretics
When treating hypernatremia, Na+ reduction rate should be equal or less than _______ to avoid what?
Want Na+ reduction rate ≤0.5 mmol/L/hr, and ≤ 10 mmol/L per day to avoid cerebral edema, seizures, and neurologic damage
What are the 3 major causes of hypokalemia?
renal or GI loss and transcellular shift
- also DKA, HCTZ, and excessive licorice
Normal values for K+? Values for elective sx?
3.5-5 mEq/L
- K+ < 5.5 mEq/L on elective surgery
Serum K+ reflects ________ more than total body K+
transmembrane K+ regulation
Aldosterone causes the distal nephron to secrete ___ and reabsorb ___
Secrete K+ and reabsorb Na+
- Aldosterone inversely affects K+
In renal failure,K+ _______ declines
Excretion - excretions shift toward GI system
What causes hypokalemia d/t increased renal potassium loss?
TZDs, loop diuretics, mineralocorticoids, high-dose glucocorticoids, abx (-cilins), drugs that deplete Mg (aminoglycosides), surgical trauma, hyperglycemia, and hyperaldosteronism
What causes hypokalemia d/t excessive GI potassium loss?
- Vomiting and diarrhea
- Zollinger-Ellison syndrome,
- Jejunoileal bypass
- Malabsorption
- Chemo
- NG suction
What causes hypokalemia d/t transcellular potassium shift?
- B-adrenergic agonists, tocolytic drugs (ritodrine), insulin
- alkalosis (Respiratory/Metabolic)
- familial periodic paralysis
- hypercalcemia or hypomagnesemia
What are the s/s of hypokalemia?
Generally cardiac and neuromuscular:
- Muscle weakness/Cramps
- Ileus
- Dysrhythmias, U wave
What is the tx for hypokalemia?
- Underlying cause
- Potassium PO > IV (CVC); IV may require days
- Generally, K+ given @ 10-20mEq/L/hr IV
- Each 10 meq IV K+→↑Serum K+ by ~0.1 mmol/L
- Avoid excessive insulin, β-agonists, bicarb, hyperventilation, diuretics
What are the causes of hyperkalemia?
- Renal failure
- Hypoaldosteronism
- Drugs that inhibit RAAS or K+ excretion
- Depolarizing NMB (Sux - 0.5-1 mEq/L)
- Acidosis (Respiratory/Metabolic)
- Cell death (trauma, tourniquet)
- Massive blood transfusion
What are the s/s of hyperkalemia?
- Chronic may be minimally symptomatic (malaise, GI upset)
- Skeletal muscle paralysis,↓fine motor
- Cardiac dysrhythmias
What is the EKG progression of hyperkalemia?
- peaked T wave
- P wave disappearance
- prolonged QRS complex
- sine waves
- asystole
What is the tx for hyperkalemia?
- Dialyze within 24h prior to surgery (ALSO initially causes hypovolemia)
- Calcium- 1st initial treatment
- Hyperventilation (↑pH by 0.1 →↓K+ by 0.4-1.5 mmol/L)
- Insulin +/- glucose (10u IV: 25g D50) works in 10-20 min
- Bicarb
- Loop Diuretics
- Kayexalate (hrs to days)
- Avoid Sux, hypoventilation, LR & K+ containing IV fluids
How much calcium is stored in the ECF vs in bones?
Only 1% body’s Ca++ is in ECF; 99% stored in bone
___% of plasma Ca++ is PB to albumin and rendered inactive
60% - Only ionized plasma Ca++ is physiologically active
What are the normal iCa levels?
1.2-1.38 mmol/L
Ionized Ca++ level is affected by ____ and ____
albumin levels and pH
↑pH/Alkalosis→↑Ca++ binding to albumin (therefore ↓iCa++)
Which 3 hormones regulate Ca++? What are their functions?
- Parathyroid hormone: ↑’s GI absorption, renal reabsorption, and regulates bone/bloodstream levels
- Vitamin D: augments intestinal Ca++ absorption
- Calcitonin: promotes storage of Ca++ in bone
What are the 5 causes of hypocalcemia?
- ↓Parathyroid hormone (PTH) secretion
- Magnesium deficiency
- Low Vit D or disorder of Vit D metabolism
- Renal failure (kidneys not responding to PTH)
- Massive blood transfusion (citrate preservative binds Ca++)
What are the main two causes of hypercalcemia?
- Hyperparathyroid serum Ca++ <11
- Cancer serum Ca++ >13
What are the less common causes of hypercalcemia?
- Vit D intoxication
- Milk-alkali syndrome (excessive GI Ca++ absorption)
- Granulomatous diseases (sarcoidosis)
What are the s/s of hypocalcemia?
paresthesias, irritability, HoTN, seizures, myocardial depression, prolonged QT-I, post-parathyroidectomy-hypocalcemia-induced-laryngospasm
What are the s/s of hypercalcemia?
confusion, lethargy, hypotonia, abd pain, N/V, short QT-I
- chronic = hypercalciuria and nephrolithiasis
What are the causes of hypomagnesemia?
- Low dietary intake or absorption
- Renal wasting
What are the s/s of hypomagnesemia?
- Muscle weakness or excitation
- Seizures
- Ventricular dysrhythmia (Polymorphic V-tack/Torsades De Pointes)
What is the tx for hypomagnesemia?
- d/o severity of sx
- Slower infusions for less severe
- Torsade’s/seizures→ 2g Mag Sulfate
What are the causes of hypermagnesemia?
Very uncommon, generally due to over-treatment
- Pre-eclampsia/Eclampsia
- Pheochromocytoma
What are the s/s of hypermagnesemia with dosing intervals?
4-5 mEq/L: Lethargy, N/V, Flushing
>6 mEq/L: HoTN, ↓DTR
>10 mEq/L: Paralysis, apnea, heart blocks, cardiac arrest
What is the tx for hypermagnesemia?
- Diuresis, IV Calcium (stabilize cell mbrn), Dialysis
- Check mag level at regular intervals if on gtt
Between which vertebrae can the kidneys be found?
Located retroperitoneal btw T12-L4
The right kidney is slightly ______ to left to accommodate the ______
caudal, liver
The _______ is the structural/functional unit of the kidney; each kidney has ___
nephron, 1 mil
The kidneys receive __% of CO. Which layer receives most of the RBF?
20%, cortex (85-90% of RBF)
Which portion of the kidney is especially susceptible to de RBF?
Medulla
What are the 3 main hormones the kidney produces? What are their roles?
- EPO involved in RBCs production
- Calcitriol maintains serum Ca++
- PG’s key inflammatory modulators, vasodilatory effects, maintain renal blood flow
What is a normal GFR? What is GFR best at measuring?
125-140 mL/min
- Best measure renal function over time
What is a normal creatinine clearance? What is it the most reliable measure of?
110-140 mL/min
- GFR bc creatinine freely filtered, not reabsorbed
What is a normal serum creatinine level? How does it relate to GFR?
0.6-1.3 mg/dL
- SC inversely related to GFR
Which renal function lab is best for detecting acute changes?
Serum creatinine
_______ is the renal function lab that correlates with muscle mass
serum creatinine
What is the normal BUN? What does a high or low BUN mean?
10-20 mg/dL - affected by diet
- Low BUN could mean malnourished or volume-diluted
- High could mean ↑protein diet, dehydrated, GI bleed, trauma, muscle wasting
What is the normal BUN:creatinine ratio? What does it measure?
10:1
- hydration status
What level is considered proteinuria?
<150 mg/dL
>750mg/day could suggest glomerular injury or UTI
What is the normal urine specific gravity? What does it measure?
1.001-1.035
- measures nephron’s ability to concentrate urine; compares 1 mL of urine to 1 mL of water
What is a normal UOP? What is considered oliguria?
- UOP- 30 ml/hr; 0.5-1ml/kg/hr
- Oliguria: <500mL in 24h
What are the different methods to monitor volume?
- US to assess IVC
- CVP, RAP
- LAP, PCWP
- PAP
- SVV
IVC collapse of __% indicates fluid deficit
50%
AKI effects __% hospitalized pts & __% ICU pts
20%, 50%
What is the hallmark of AKI?
Azotemia: buildup of nitrogenous products s/a urea, creatinine
What are the risk factors of AKI?
Pre-existing renal disease, age, CHF, PVD, DM, sepsis (hypotension), jaundice, major operative procedures, IV Contrast
What is the diagnostic criteria for AKI?
- ↑SCr by 0.3 mg/dL within 48 h
- ↑SCr by 50% within 7 days
- ↓Creatinine clearance by 50%
- Abrupt oliguria *although not always seen in AKI
What are the physical s/s of AKI?
- Asymptomatic
- Malaise
- HoTN
- Hypovolemic or hypervolemic
What are the 3 types of AKI?
Pre-renal: ↓ renal perfusion
Renal: nephron injury
Post-renal: outflow obstruction
Which type of AKI is the easiest to treat?
Post-renal
What are the causes of pre-renal azotemia?
Hemorrhage, GI fluid loss, trauma, sx, burns, cardiogenic shock, sepsis, aortic clamping, thromboembolism
What are the causes of renal azotemia?
Acute glomerulonephritis, vasculitis, interstitial nephritis, ATN, contrast dye, nephrotoxic drugs, and myoglobinuria
What are the causes of post-renal azotemia?
Nephrolithiasis, BPH, clot retention, and bladder carcinoma
What is the most common form of AKI?
Pre-renal - Anesthesia meds + volume & blood loss →↓RBF
What is the treatment for pre-renal azotemia?
Restore RBF - Fluids, Mannitol, Diuretics, maintain MAP, Pressors?
Differentiate between a BUN:Cr ratio in pre-renal vs renal AKI
Pre-Renal - BUN:Cr is >20:1
Renal - BUN:Cr often < 15:1
What are the s/s and patho behind renal azotemia?
- ↓GFR(late sx)
- ↓urea reabsorption in prox tubule →↓BUN
- ↓Creatinine filtration→↑blood creatinine
What are the neuro complications of AKI?
- Related to protein/amino acids buildup in blood
- Uremic Encephalopathy (dialysis improves)
- Mobility disorders
- Neuropathies
- Myopathies
- Seizures
- Stroke
What are the CV complications of AKI?
- Systemic hypertension
- Left ventricular hypertrophy
- CHF
- Pulmonary edema
- Uremic cardiomyopathy
- Arrhythmias
- In order of incidence HTN→ LVH→ CHF→ischemicheartdisease→ anemicheartfailure→ rhythm disturbances→pericarditis with or without effusion→cardiactamponade, uremic cardiomyopathy
What are the hematological complications of AKI?
Anemia
- ↓ EPO production
- ↓ red cell production
- ↓ red cell survival
- platelet dysfunction
What is the treatment for anemia caused by AKI?
Prophylactic DDAVP - ↑VWF & Factor VIII to improve coagulation (vWF disrupted by uremia)
What are the metabolic complications of AKI?
- Hyperkalemia
- Water/sodium imbalances
- Hypoalbuminemia (kidneys allowing albumin to escape)
- Metabolic acidosis
- Malnutrition
- Hyperparathyroidism
What is the preferred vasopressor for AKI?
Vasopressin - preferentially constricts the Efferent arteriole
How can prophylactic bicarb help AKI in anesthesia?
- Decreases the formation of free-radicals
- Prevents ATN from causing renal failure
What are the 2 leading causes of CKD?
DM and HTN
What are the 5 stages of CKD?
1: kidney damage w/ normal or inc GFR (GFR > 90)
2: kidney damage w/ mildly dec GFR (60-89)
3: mod dec GFR (30-59)
4: severely dec GFR (15-29)
5: kidney failure (GFR < 15)
GFR decreases by ___ per decade starting from age __
10, age 20
What is the first-line tx for CKD?
TZD
Which populations are high risk for silent MI?
Women and Diabetics (and CKD!)
HD vs PD for CKD?
PD is slower, less dramatic volume shifts, may be more suitable to those that cant tolerate fluid swings/vol shifts (i.e. pts w/poor cardiac function)
What is the leading COD in dialysis patients?
Infection
What is the most common SE of dialysis?
HoTN
Desmopressin peak and duration? Con?
Peak 2-4h; lasts 6-8h
Tachyphylaxis
What anesthetic meds should be avoided in a patient with CKD?
- lipid-soluble drugs (reabsorbed by renal tubular cells)
- meds w/ active metabolites (morphine and Demerol)
Which drugs are given with renal dosing based on GFR in patients with CKD?
Lipid INsoluble drugs - TZDs, loop diuretics, digoxin, abx (prolonged DoA)
Dialysis pts should be dialyzed within ___ preceding elective surgery
24h
What is the best NMB for CKD patients?
cisatracurium (Nimbex)
Which induction drugs are renally excreted?
phenobarb and thiopental
Which muscle relaxants are renally excreted?
pancuronium and vecuronium
Which cholinesterase inhibitors are renally excreted?
edrophonium and neostigmine
Which CV drugs are renally excreted?
Atropine, digoxin, glycopyrrolate, hydralazine, milrinone
Which antimicrobials are renally excreted?
Aminoglycosides, cephalosporins, penicillins, and vanco
