Renal Assessment Flashcards
Expected GFR for someone with Chronic Kidney Disease (CKD)
GFR < 60 ml/min/1.73 m2 for 3 months
Expected GFR for someone with Chronic Renal Failure (CRF)
15 ml/min/1.73m2
ESRD defined
loss of renal function for 3 months or more
DM accounts for half of cases & HTN for 1/4
Co-morbidities of renal dysfunction
CV disease
HTN
electrolyte issues
Perioperative considerations for the patient with ARF.
pts requiring surgery with ARF are VERY ILL.
don’t take these patients to the OR without careful consideraton
Dialysis will be required in the following situations:
oliguria fluid overload hyperkalemia severe acidosis metabolic encephalopathy pericarditis coagulopathy refractory GI symptoms drug toxicity
Hemodialysis vascular access set up
AV fistula = cephalic vein anastomosed to radial artery
Jugular or femoral vein for emergency access
Pre operative dialysis assessment
- optimization, optimization, optimization!
- dialysis should occur day of surgery or day before surgery
- review dialysis flowsheet if available
- amount of fluid “taken off”
- pre and post dialysis eights compare with the day of surgery wt
- Note POST dialysis chemistry: serum K < 5.5 mEq/L
consider that these patient’s obviously just had fluid removed and you don’t want to fluid overload them in surgery, but their potential level of dehydration IMMEDIATELY post dialysis + vasodilation from VA may cause hypotension/hemodynamic instability and warrant some fluid
Which kinds of drugs will be removed by dialysis?
low molecular weight
water soluble
non protein bound
READILY CLEARED BY DIALYSIS, so some drugs may need to be administered POST dialysis so they are not removed during dialysis.
RF: neuro assessment
UREMIC ENCEPHALOPATHY -asterixis -myoclonus -lethargy -confusion -seizures -coma AUTONOMIC NEUROPATHYD - hemodynamic instability PERIPHERAL NEUROPATHY - document pre op
What is disequilibrium syndrome? Anesthetic considerations?
- can occur s/p dialysis
- transient CNS disturbance after rapid decrease in ECF osmolarity compared with ICF osmolarity
- dementia
If noted, may want to discuss pts status with surgical team and delay surgery if necessary
RF, hematological assessment: reasons for anemia
typical Hgb = 6-8 g/dL
- decreased erythropoietin production
- dec RBC production & cell life span
- GI blood loss, hemodilution, bone marrow suppression
- excess PTH replaces bone marrow with fibrous tissue
RF, hematological assessment: anemia compensation
- *most patients tolerate the anemia well (except CAD)**
- increased 2,3 DPG
- metabolic acidosis also favors a rightward shift
RF, hematological assessment: other hematological considerations
Impaired platelets (qualitative)
- dec plt factor III activity
- dec adhesiveness & aggregation
- possibly related to release of defective von Willebrand factor??*
- –administration of DDAVP may be helpful in improving von willebrand factor
Impaired WBC function - INFECTIONS!!
dialysis = residual anticoagulation VS promotion of hypercoagulable state
hypocomplementemia with dialysis
Aseptic technique
INFECTION COMMON CAUSE OF DEATH! - over the top vigilant
care with ETT - prone to pulmonary infections
IVs, line insertion
try and preserve blood vessels on the NON DOMINANT ARM in case they may need an AV fistula on that arm eventual. So try and put IVs on the DOMINANT arm
RF: CV assessment
- inc CO
- –compensation for dec O2 carrying capacity
- HTN - NA retention, renin angiotensin activation
- LVH common
- CHF with pulmonary edema after limits of compensation reached
- Deposition of calcium
- –in the conduction system & on the heart valves
-Arrhythmias - electrolyte imbalances
- Uremic pericariditis
- –can be asymptomatic, chest pain, tamponade, usually secondary to inadequate dialysis
-Accelerated CAD, PVD
RF: fluid balance assessment
- fluid overload VS intravascular depletion s/p dialysis/aggressive diuretic therapy
- body weight
- VS (orthostatic hypotension & tachycardia)
- atrial filling pressures
-mucous membranes; ask, “Do you get dizzy when you stand up?”
RF: pulmonary assessment
- MV increased to compensate for metabolic acidosis
- inc pulm extravascular water = interstitial edema = widened alveolar/arterial O2 gradient
- “Butterfly wings” on CXR secondary to inc permeability of alveolar capillary membrane (edema even with normal pulmonary capillary pressure)
hyperventilation, interstitial edema, alveolar edema, pleural effusion
RF: endocrine assessment
- peripheral resistance to insulin = poor glucose tolerance
- hyperparathyroidism = prone to fractures
- abnormal lipid metabolism = accelerated atherosclerosis
- kidneys do not degrade hormones and proteins normally = inc circulating PTH, insulin, glucagon, GH, LH, PL
RF: GI/Liver Assessment
- 10 - 30% of pts will develop GI hemorrhage
- anorexia
- N/V
- hypersecretion of gastric acid + delayed gastric emptying (autonomic neuropathy)
- high incidence of Hep B and C in these patients (multiple transfusions)
- ascites with dialysis
RF, impact on drugs: effects altered due to…
- anemia
- dec serum protein (alters protein binding)
- electrolyte abnormalities (can alter effect of drug, i.e. low Na can increase risk of Li toxicity, more prone to digoxin toxicity)
- fluid retention (alters Vd of MR)
- abnormal cell membrane activity (alters pharmacodynamics or receptor/drug level)
Drugs eliminated by kidneys unchanged are ________. Examples?
CONTRAINDICATED
Gallamine, phenobarbital, LMWH (metabolized or cleared by the kidneys and NOT removed by dialysis – RISK OF BLEEDING INCREASED EVEN FURTHER and PROLONGED DOA
Best MR to choose for a patient with RF. WHY?
atracurium or cisatracurium
not cleared by the kidneys!
Things to consider when getting labs on any patient.
- will this result change my anesthetic plan??
- will the result come back in a short enough window to have a meaningful impact on my plan, if not, DON’T GET IT!
For example, (just because these patients are typically anemic) H&H may not necessarily be warranted on a short procedure with conscious sedation
Also, baseline K would be a good value to have in case you have to administer any drugs that would alter serum K levels (succ, lasix, etc. )
The NORMAL chemistry panel
Sodium (135-145 mEq/L) Potassium (3.5-5.0 mEq/L)**** Chloride (95-105 mEq/L) Sodium bicarb (venous - 19-25 mEq/L, arterial - 22-26 mEq/L) Calcium (4.5-5.5 mEq/L) Phosphate (2.4-4.7 mg/dL) Magnesium (1.5-2.5 mEq/L) Serum Osmolality (280-300 mOsm)
GFR: purpose, values
indicative of NEPHRON function
- BUN (10-20 mg/dL)
- Plasma creatinine (0.7-1.5 mg/dL)
- —GFR can decrease 50% w/o rise (Not accurate indicator especially in elderly)
- creatine clearance (110-150 ml/min)
Renal Tubular Function
Assesses concentrating ability of kidneys
- urine specific gravity (1.003 - 1.030)
- urine osmolarity (38-140 mOsm/L)
BUN: normal value, value interpretation, pit falls
- Normal: 10-20 mg/dL
- varies inversely with GFR & directly with protein catabolism
- > 50 mg/dl is indicative of a dec GFR (in patients with normal diets)
- BUN is a NOT a sensitive index b/c urea clearance also depends on the production of urea
- BUN can be abnormal despite a normal GFR due to: high protein diet, GI bleed, febrile illness
- most common cause of in BUN is CHF secondary to the reabsorption of BUN
Cr: normal value, value interpretation, pit falls
- Plasma Cr is a specific indicator of GFR - freely filtered but not reabsorbed
- 8 - 17 hour lag time after a change in GFR before the inc creatinine levels are seen
- suggestive (but not indicative) of acute renal failure
- usually a 50% inc in plasma cr reflects a corresponding dec in GFR
- skeletal muscle = source of Cr
- elderly patient - Cr levels stay normal constant due to :
- –dec muscle mass and GFR
- –If CR inc in the elderly, this may be indicative of renal failure
Creatinine clearance: what is it?, how do you measure it?, values?
- 24 hour collection most accurate although 2 hour tests also helpful
- creatinine clearance approximates GFR
Normal: 100-120 ml/min dec renal reserve: 60-100 ml/min mild renal impairment: 40-60 ml/min moderate insufficiency: 25-40 ml/min renal failure: <25 ml/min ESRD: <10 ml/min
Lab/test abnormalities common with renal failure
- assess the adequacy of dialysis
- hyponatremia (hypernatremia rare)
- HYPERKALEMIA (hypokalemia with dialysis)
- metabolic acidosis with high anion gap
- hypermagnesemia
- hypocalcemia (unclear etiology)
- hypoalbuminemia (esp with dialysis)
- hyperglycemia (if insulin resistant)
Hyperkalemia TX, calcium gluconate: dose, MOA, onset, duration, side effects
Dose: calcium gluconate 10%, 10-20 ml IV MOA: antagonizes effects on cardiac msucle onset: immediate duration: brief SE: avoid with dig therapy
Hyperkalemia TX, sodium bicarbonate: dose, MOA, onset, duration, side effects
dose: sodium bicarbonate, 50-100 mEq IV MOA: shift K into cells onset: prompt duration: short SE: Na overload
Hyperkalemia TX, glucose + insulin: dose, MOA, onset, duration, side effects
dose: glucose, 50 ml of 50% soln + insulin, 10 units regular insulin MOA: shift K into cells onset: prompt duration: 4-6 hours SE: hyperglycemia, hypoglycemia
Hyperkalemia TX, dialysis: MOA, onset, side effects
MOA: remove K from body
onset: immediate
SE: need vascular access
Hyperkalemia TX, ion exchange resin: MOA, onset, side effects
MOA: remove K from body
onset: 1-2 hours
SE: Na overload
The NORMAL CBC: RBC
male: 4.6-6.2 million/mm3
female: 4.2-5.4 million/mm3
The NORMAL CBC: HGB
male: 13.5-18 g/dL
female: 12-16 g/dL
The NORMAL CBC: HCT
male: 40-54%
female: 38-47%
The NORMAL CBC: WBC
5000-10,000/mm3
remember - RF patients are at high risk for iatrogenic infections
RF, Transfuse only when absolutely indicated: < ____ or ____________________.
< 6-7 g/dL
OR
significant intra operative blood loss
What does a normal plt ct mean in a RF patient?
Does not mean much
RF patients may have an issue with platelet QUALITY, not count
RF coagulation abnormalities: anesthesia considerations
- If regional anesthesia is planned – need a coagulation panel!!!!
- increased bleeding despite normal PT, PTT
- bleeding time is BEST screening test
-Important cause of coagulation issue - RELEASE OF DEFECTIVE VON WILLEBRAND FACTOR
RX: desmopressin (0.3 - 0.4 mg/kg over 30 min); cryoprecipitate (10 units IV over 30 minutes)
RF, labs and tests: pulmonary - chest xray
check for:
- fluid status
- –butterfly wings
- determine presence of HTN related CV disease
- pericardial effusion
- uremic pneumonitis
- enlarged heart
RF, labs and tests: CV – EKG
check for:
- hyperkalemia
- —tall T waves, ST depression, widening QRS
- hypokalemia
- —peaked or flattened t waves, prolonged PR and QT
- hypocalcemia
- —prolonged QT
- ischemia
- conduction blocks
- LVH
- digitalis toxicity
- —shortened QT interval, depressed ST
RF, labs and tests: pulmonary - ABG
check for:
-hypoxia and acid/base status especially if dyspnea noted on exam
RF, labs and tests: CV – ECHO
check for:
- ventricular EF
- hypertrophy
- wall motion abnormalities
- pericardial fluid
Bleeding time: normal value, factors assessed
3 - 10 minutes
platelet function
platelet count: normal value, factors assessed
150,000-400,000 cell/mm3
vascular integrity
prothrombin time (PT): normal value, factors assessed
10-12 seconds
I, II, V, VII, X
International Normalized Ration (INR): normal value, factors assessed
0.8-1.2
I, II, V, VII, X
Plasma thromboplastin time (PTT): normal value, factors assessed
25-35 seconds
I, II, V, VIII, IX, X, XI, XII
Activated clotting time (ACT): normal value, factors assessed
90-120 seconds
I, II, V, VIII, IX, X, XI, XII
Thrombin time: normal value, factors assessed
9-11 seconds
I, II
Fibrinogen: normal value, factors assessed
160-350 mg/dl
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