Renal Assessment Flashcards
Which fluid volume is more immediately altered by the kidneys?
ECF Volume
Where are osmolality sensors located?
What happens when they are activated?
Anterior Hypothalamus
When activated, stimulate thirst and causes release of ADH from the pituitary gland
What maintains volume homeostasis?
Juxtaglomerular apparatus
Decreased volume @ JGA activates the RAAS system –> Na+ and H2O absorb
What does ADH cause?
Water and sodium retention
When would you delay elective surgery for hyponatremia?
≤125 and ≥ 155
What are some causes of hypovolemia-related hyponatremia?
- Diuretics
- GI loss
- Burns
- Trauma
What causes euvolemic hyponatremia?
- Salt-restriction
- Endocrine-Related (Hypothyroid, SIADH)
What causes hypervolemic hyponatremia?
- AKI/CKD
- HF
Most of the time, patients will be hypervolemic and hyponatremic
What is the severe result of hyponatremia?
Seizure, coma, death
What are some s/s of Na+ < 120 meq/L?
- Headache
- Restless
- Lethargy
- Seizures
- Brain-stem herniation
- Respiratory arrest
- Death
Na+ correction should not exceed ____ meq/L/hr
1.5 mEQ/L/hr
Rapid correction of greater than ____ meq/L in 24 hours can cause osmotic demyelination syndrome leading to permanent neurological damage
Never exceed > 6 meq/L in 24 hours
What is the treatment for hyponatremic seizures?
Medical emergency
3-5 mL/kg of 3% saline over 20 minutes until the seizure resolves
How often should you check Na+ levels during repletion?
q 4 hours
Whaat are some common causes of hypernatremia?
- Excessive evaporation
- Poor oral intake
- Overcorrection of hyponatremia
- DI
- GI losses
- Excessive sodium bicarb from treating acidosis
What are causes of hypovolemic hypernatremia?
Renal or GI losses
What are causes of euvolemic hypernatremia?
DI and Insensible losses
What are causes of hypervolemic hypernatremia?
- Increased Na+ intake
- Hyperaldosteronism
- Cushing’s Dx
What are symptoms of hypernatremia?
- Orthostasis
- Lethargy
- Restless
- Muscle tremors/twitching/spasticity
- Seizure
- Death
What should you assess first when deciding how to treat hypernatremia?
Assess Volume status
What is the treatment if you are hypovolemic and hypernatremic?
NS
What is the treatment if you are euvolemic and hypernatremic?
Water replacement (PO or D5W)
What is the treatment if you are hypervolemic and hypernatremic?
Diuretics
To avoid cerebral edema, seizures and neuro damage, what rate do you want to decrease serum Na+ by?
≤ 0.5 mmol/L/hr and ≤ 10 mmol/L per day
Serum K+ reflects the _______ K+ regulation more than the total body K_
Serum K+ reflects the transmembrane K+ levels
Aldosterone and K+ have what type of relationship?
Inverse relationship
Causes distal nephron to secrete K+ and reabsorb Na+
How does renal failure affect K+ levels?
K+ excretion declines (hyperkalemia)
K+ excretion then shifts towards the GI system in renal failure.
What are 3 major categories for causes of hypokalemia?
- Renal loss (Diuretic, hyperaldosterone)
- GI loss (N/V/D, malabsorption)
- Transcellular shift
What can cause an intracellular shift of K+ leading to decreased serum K+?
- Alkalosis
- B-agonist overuse
- Insulin overuse
What are cardiac and neuromuscular affects of hypokalemia?
Muscle cramps/weakness & Dysrhythmias (U-wave)
Each 10 meq IV K+ will increase serum K by _____ mmol/L
0.1 mmol/L
Does PO or IV K+ move the needle faster when repleting K+?
PO is more effective
What are some causes of hyperkalemia?
- Renal failure
- Hypoaldosteronism
- RAAS inhibitors
- Sux
- Acidosis
- Cell death (Trauma, tourniquet use)
- MTP
What are some NM symptoms of hyperkalemia?
Skeletal muscle paralysis, decreased fine motor function
What are the progressive CV symptoms of hyperkalemia?
- Peaked T wave
- Loss of P wave
- Prolonged QRS
- Sine waves
- Asystole
How much does Sux increase serum K+ by?
0.5-1 meQ/L
If possible, when do we want renal patients to be dialyzed by?
24 hours prior to surgery
What are the interventions for hyperkalemia?
- Calcium (initial)
- Hyperventilation (2nd fastest)
- Insulin (10 units with 25 g D50)
-Bicarb, Loop Diuretics, Kayexelate
How does Ca++ work for hyperkalemia?
quickly stabilizes the cell membrane to pump the brakes on volume loss
What should you avoid if you are hyperkalemic?
- Succs
- Hypoventilation
- LR and K+ containing fluids
___ increase in pH decreases K+ by _____ mmol/L
0.1 pH increase decreases K+ by 0.4-1.5 mmol/L
Where is 99% of Ca++ stored? Where is the other 1%?
Bone
ECF (1%)
____ % of plasma Ca++ is protein bound to albumin and _______
60% is bound to albumin making it inactive
Which type of calcium is physiologically active?
plasma ionized calcium
What is normal ionized Ca++ levels?
1.2-1.38 mmol/L
Ionized Ca++ levels are affected by what?
Albumin levels and pH
Alkalosis has what effect on free ionized Ca++ levels?
Alkalosis causes decreased ionized Ca++ levels
What are the 3 hormones that regulate Ca++ levels?
- Parathyroid hormone
- Vitamin D
- Calcitonin
What is parathyroid hormone’s effect on Calcium regulation?
PTH:
1. increases GI absorption
2. Increases renal absorption
3. Regulates bone/bloodstream levels of Ca++
What are causes of hypocalcemia?
1. Decreased PTH secretion (complication from thyroid/PT surgery)
2. Magnesium deficiency
3. Vit. D deficiency
4. Renal failure (Kidney not responding to Vit. D)
5. MTP
What can a drop in PTH levels cause?
Larngospasm - need to check baseline and routine PTH levels during surgery
How does Mg affect Ca++ levels?
Mag is required for PTH production
How does Vitamin D affect Ca++ levels?
Vit. D is required for GI calcium absorption
How is MTP affecting Ca++ levels?
Stored blood have citrate in them, which binds to Ca++ in order to prevent clotting
After how many units of blood should you check a Ca++ levels?
4 units
If you have a hyper-parathyroid syndrome, what is the serum Ca++ level?
Cancer level?
< 11
> 13
When extubating someone after parathyroidectomy, what should you always be prepared for?
Laryngospasm
Hypercalcemia causes what NM symptoms?
CV symptoms?
Hypotonia & decreased DTR
CV: Short QT-interval
Hypocalcemia causes what Nerological symptoms?
CV symptoms?
Neuro: Irritability, Paresthesia, Seizures
CV: Myocardial depression, Prolonged QT-interval
What are symptoms of hypo-magnesium
Muscle weakness/excitation, seizures, Polymorphic VT or Torsades
What is the initial treatment for Torsades or hypo-mag induced seizures?
2 g of Mag sulfate
Hypermagnesium is less common and mostly due to what?
Patients on a mag drip who are over treated
How do you treat hypermagnesium
Diuresis
IV Ca++ to stabilize membrane
Dialysis
What symptoms would you see with different Mag levels?
4-5 mEq/L: Lethargy, N/V, Flushing
> 6: Hypotension, Decreased DTR
> 10: Paralysis, apnea, heart block, cardiac arrest
Kidneys are located retroperitoneal between ____
T12-L4
Each kidney has how many nephrons?
~ 1 million
The outer cortex of the kidney receives what % of RBF?
90%
Which part of the kidney is at risk for developing necrosis in response to hypotension?
Loop of Henle
What are the Primary functions of the kidney?
- Regulates EC Volume, osmolarity, composition
- Regulates BP (Long-term)
- Excretes toxin/metabolites
- Maintains acid/base
- Produces hormones
- Glucose homeostasis
Through what 2 methods does the kidney regulate volume and BP?
- RAAS = Increases Na and water absorption
- ANP = Increases Na+ and water excretion
What hormones do the kidney produce?
Renin, EPO, Calcitrol, Prostaglandins
What is the function of EPO?
EPO is involved in RBC production (many renal patients are often on EPO supplements)
Function of Calcitrol?
Maintains serum Ca++
What is the function of prostaglandins?
Inflammatory modulators, vasodilatory effects, enhance renal blood flow
What are the kidney’s role in glucose homeostasis?
Kidneys play a role in gluconeogenesis and filtration/reabsorption of glucose
What is the best measure of renal function over time (for trending) and what is a normal value?
GFR (125-140 ml/min)
GFR accuracy is heavily influenced by what?
Hydration status
GFR decreases by _____ mL/min per decade after age 20
10 mL/min per decade
What is the most reliable measure of GFR (acute changes) and what is the normal value?
Creatinine clearance (110-140 mL/min)
Is creatinine filtered or absorbed?
Freely filtered
Serum creatinine is ______ related to GFR
Inversely related
Double in your serum creatinine can mean a drop in GFR of ____ %
50% (Probably means AKI)
What is normal serum creatinine and some stats about it?
Normal: 0.6-1.3 mg/dL
-Lower in female, higher in males (correlates with muscle mass)
-Can be influenced by high protein diet, supplements, and muscle breakdown
What could a low BUN value mean?
Malnourished or volume diluted
What value tells us how well the kidney is reabsorbing urea, and what is a normal value?
BUN
Normal: 10-20 mg/dL
What could a high BUN value mean?
High protein diet, dehydration, GI bleed, trauma, muscle wasting
What is BUN:Creatinine ratio indicative of? and what is normal value?
Normal: 10:1 ratio
-Urea nitrogen is reabsorbed and creatinine is not reabsorbed
Indicative of hydration status
What is normal protein content in the urine and what suggests glomerular injury or UTI?
Normal: < 150 mg/dL
UTI/Injury: > 750 mg/day
What value measures the nephron’s ability to concentrate urine? What is normal value?
Specific Gravity
Normal: 1.001-1.035
-Compares 1 mL urine to 1 mL distilled water
What is a good sign that a patient is “dry”?
Orthostatic pressure changes
What is a late sign of volume loss?
Drop in UOP
Definition of Oliguria?
< 500 mL in 24 hours
IVC collapse of greater than ____ % indicates fluid deficit and fluid responsiveness
50%
What is a hallmark sign of AKI?
Azotemia: Build up of nitrogenous waste products (urea, creatinine) due to failure to excrete or maintain fluid homeostasis
What is the biggest risk factor for AKI? Other risk factors?
Pre-existing Renal disease
-Age, CHF, PVD, DM, Sepsis (HypoTN), Jaundice, Major surgery, IV contrast
What are the 4 diagnostic criteria for AKI?
- SCr increase by 0.3 mg/dL in 48 hrs
- SCr increase by 50% in 7 days
- Decreased CrCl by 50%
- Abrupt oliguria (not always seen)
Hemorrhage, Surgery, Burns, Cardiogenic shock, Aortic clamping, Thromboembolism are examples of what type of Azotemia?
Pre-renal Azotemia
Glomerulonephritis, vasculitis, contrast dye, myoglobinuria are examples of what type of azotemia?
Renal Azotemia
Nephrolithiasis, BPH, clot retention, bladder carcinoma are examples of what type of azotemia?
Post-renal Azotemia
Pre-renal Azotemia is the most common and reversible because the patient is still reabsorbing
Na+ and H2O
Treatment for Pre-renal Azotemia?
Restore RBF: Fluids, mannitol, diuretics, maintain MAP, pressors?
What is the BUN:Cr ratio for pre-renal and Renal AKI?
Pre-Renal: >20:1
Renal: < 15:1
In renal AKI, there is ______ urea reabsorption in the PCT leading to ____ BUN levels
Decreased urea reabsorption leading to decreased BUN levels
In renal AKI, there is ____ creatinine filtration leading to ____ serum Cr levels
Decreased Cr filtration leading to increased Serum Cr levels
In post-renal AKI there is increased nephron tubular hydrostatic pressure and reversibility is dependent on
Duration
What is a hallmark symptom of post-renal AKI?
Hydronephrosis (swelling of kidney d/t build-up of urine)
Neuro complications of AKI are related to __________ build up in the blood
Protein/amino acid
Neuro symptoms of AKI are:
- Uremic encephalopathy
- Motility disorder
- Neuropathies
- Myopathies
- Seizures
- Stroke (build up of uremic proteins in the blood)
CV symptoms of AKI are
- Systemic HTN
- LV hypertrophy
- CHF
- Arrhythmias
- Pulmonary edema (late)
- Uremic cardiomyopathy (late)
Hematological signs of AKI are
- Anemia
- Decreased EPO production, Decreased RBC, decreased RBC survival
- Platelet dysfunction (vWF is disrupted by uremia)
What can you give prophylactically due to the vWF disturbance in AKI?
Prophylactic DDAVP (tachyphylaxis - choose the surgery that will have the most blood loss)
Is hypo or hyperalbumin seen in AKI?
Hypo-albumin (kidneys allowing albumin to escape)
What acid-base status will someone with AKI be in?
Metabolic Acidosis
What type of parathyroid activity will you see in AKI?
Hyperparathyroidism - PT is trying to act in overdrive in an attempt to stimulate the kidneys to reabsorb Ca++
What is the fluid of choice for renal patients?
NS
What is the pressor of choice for renal patients?
Vasopressin over alpha agonists because it constricts the efferent arteriole which helps maintain RBF
What is the use of prophylactic sodium bicarb for renal patients?
Decreases formation of free radicals and prevents ATN from causing renal failure
What drugs should you avoid in renal patients?
Demerol and Morphine (drugs with active metabolites)
What labs do you want within a couple of hours of surgery on renal patients?
Recent K+ level
What is the leading cause of CKD? Is CKD reversible?
Diabetes (38%)
HTN (26%)
CKD is irreversible
What characterizes Stage 1 CKD?
Kidney damage w/ normal or increased GFR
GFR: > 90 mL/min
Usually undiagnosed
What characterizes Stage 2 CKD?
Kidney damage w/ midly decreased GFR
GFR: 60-89 mL/min
What characterizes Stage 3 CKD?
Moderately decreased GFR
GFR: 30-59 mL/min
What characterizes Stage 4 CKD?
Severely decreased GFR
GFR: 15-29 mL/min
Dialysis starts here
What characterizes Stage 5 CKD?
Kidney Failure
GFR: <15 mL/min
Dialysis dependent
In CKD, ______ is both a cause and a consequence
Hypertension
What is the first-line medication for CKD induced HTN?
Thiazide diuretics (First line)
-May need ACE-I and ARB
What are the benefits of ACE-I and ARBs?
- Decrease BP & glomerular BP
- Decrease proteinuria by reducing glomerular hyperfiltration
- Decrease glomerulosclerosis
Which populations are at risk for silent MI?
Women and Diabetics
Whether or not to transfuse due to anemia from CKD is weighed because excess hgb can lead to
- Sluggish circulation
- Acidosis
- Hyperkalemia
What is the leading cause of death in dialysis patients?
Infection
We want a ______ within 24 hours of surgery for appropriate drug dosing
Weight pre-post dialysis
What is the best NMB on a non-RSI CKD patient?
Nimbex (metabolized in the plasma instead of renal)
What can happen if you give morphine to a CKD patient?
Life-threatening respiratory depression
What would you want to use to reverse NMB on a renal patient?
Sugammadex, Neostigmine uses renal excretion
What can happen if you give demerol to a CKD patient?
Neurotoxicity (Nervousness, tremors, muscle twitch, seizures)
-Accumulation of normeperidine due to long elimination half life (15-30 hours)
K+ level of ____ or greater results in delay of elective surgery
5.5 meQ/L or greater
What are pre-operative concerns for renal patients?
- K+ level (<5.5)
- Aspiration prophylaxis
- Anesthesia & sx will decrease RBF and GFR
- Blood loss activates baroreceptors which increase SNS outflow
- Catecholamines activate a-1 receptors which constrict afferent arteriole leading to decreased RBF
- Longer periods of hypotension (cross-clamping, hemorrhage, sepsis) all decrease RBF
