Elimination & Detox 2: Renal Dz & Anesthesia Flashcards
3 main functions of KIDNEY?
- FILTRATION to REMOVE METABOLIC PDTS/TOXINS from BLOOD & EXCRETE IN URINE
- MAINTENANCE of HOMEOSTASIS for BODY FLUIDS, ELECTROLYTE & ACID-BASE BALANCE
- SECRETION OF HORMONES
HORMONES secreted by the kidney help achieve… (4)
- ERYTHROGENESIS (making RBCs)
- CALCIUM METABOLISM
- REGULATION OF BLOOD PRESSURE
- REGULATION OF BLOOD FLOW
kidney requires a HIGH amount of ____ because….
OXYGEN, because 25% of ALL CO IS USUALLY DIRECTED TO IT
AUTOREGULATION of the kidney..
= definition?
3 benefits?
= can INDEPENDENTLY MAINTAIN RENAL BLOOD FLOW in a NARROW RANGE DESPITE FLUCTUATIONS IN SYSTEMIC BP
3 benefits?
1. maintenance of HIGH OXYGEN DELIVERY during STATES OF LOW PERFUSION
- helps STABILIZE FILTERED LOAD/GFR IS AT STEADY RATE
- PROTECTS GLOMERULAR CAPILLARIES from HIGH SYSTEMIC PRESSURE
PROCESS of AUTOREGULATION by kidneys? (4)
- AFFERENT arteriole carries fluid from SYSTEMIC vasculature INTO GLOMERULUS
- as PRESSURE increases from FLUID IN AFFERENT arteriole, it STRETCHES THE WALL & NON-SELECTIVE CATION CHANNELS will OPEN IN RESPONSE
- once channels open, RELEASES CALCIUM to cause CONTRACTION OF SMOOTH MUSCLE IN VESSEL WALL
- overall, can REDUCE BLOOD FLOW GOING TO KIDNEY IN HIGH PRESSURE STATES
what is the AUTOREGULATORY RANGE of the KIDNEYS?
what happens if we go ABOVE this range?
what happens if we go BELOW this range?
60 - 150 mmHg MAP
if we go >150 mmHg, AUTOREGULATION LOSES ABILITY TO CONTROL FLOW, see increase in FLOW & PRESSURE
if we go <60 mmHg, KIDNEYS CANNOT MAINTAIN BLOOD FLOW & OXYGEN DELIVERY
METABOLIC CHANGES that occur with RENAL IMPAIRMENT… (5)
- ABILITY OF KIDNEYS to EXCRETE WATER & SODIUM can be impaired
- REGULATION of ELECTROLYTE HOMEOSTASIS
- underlying METABOLIC ACIDOSIS
- HYPOALBUMINEMIA
- INABILITY to PROCESS WASTE causes them to ACCUMULATE
what is the BIGGEST ELECTROLYTE RISK regarding KIDNEYS when UNDER GA? why?
HYPERKALEMIA, which can induce LETHAL CARDIAC ARRHYTHMIAS from ALTERING REPOLARIZATION OF MYOCARDIAL CELLS
HEMATOLOGIC changes in RENAL IMPAIRMENT… (2)
- DECREASED PRODUCTION of EPO –> NON-REGEN ANEMIA (decreased production)
- ABNORMAL PLATELET FUNCTION, NOT REPRESENTED ON PT/PTT or ANY CBC; just BLEEDS A LOT
5 CLINICAL SIGNS from RENAL DZ…
three are GI, two are more general
- NAUSEA
- VOMITING
- INAPPETENCE
- DEHYDRATION
- DELAYED WOUND HEALING
4 CARDIOVASCULAR changes from RENAL IMPAIRMENT? (last one has 3 subs)
- CHRONIC ARTERIAL HYPERTENSION
- shift in AUTOREGULATORY RANGE
- RENAL INJURY & DISEASE PROGRESSION from HYPERTENSION (outside auto regulatory range)
- LONG-TERM ARTERIAL HYPERTENSION can cause STRUCTURAL CHANGES IN MYOCARDIUM such as…
–> LEFT VENTRICULAR HYPERTROPHY
–> DIASTOLIC DYSFUNCTION
–> VALVULAR INSUFFICIENCY
4 RESPIRATORY CHANGES with RENAL IMPAIRMENT…
GENERALLY…
- PULMONARY EDEMA & PLEURAL EFFUSION from VOLUME OVERLOAD
- DECREASED FUNCTIONAL RESIDUAL CAPACITY (from PULMONARY EDEMA/PLEURAL EFFUSION)
- DECREASED PULMONARY COMPLIANCE (from PULMONARY EDEMA/PLEURAL EFFUSION)
- INCREASE in VENTILATION-PERFUSION MISMATCH (from PULMONARY EDEMA/PLEURAL EFFUSION)
GENERALLY, we don’t tend to see many RESPIRATORY CHANGES with renal impairment
DRUGS & RENAL IMPAIRMENT…
drugs that undergo RENAL ELIMINATION…
what 3 CBC findings contribute to a REDUCTION in PROTEIN-BINDING? what is the significance of this?
____ ___ may INCREASE the ____ of ____ of HYDROPHILIC drugs
____ can increase the ____ of the ____ ____ ____
drugs that undergo RENAL ELIMINATION may ACCUMULATE with renal impairment
3 CBC findings that REDUCE PROTEIN-BINDING?
1. HYPOALBUMINEMIA
2. AZOTEMIA
3. ACIDEMIA
–> PROTEIN-BINDING DRUGS may be INEFFECTIVE in renal dz patients
FLUID RETENTION may INCREASE the VOLUME of DISTRIBUTION of HYDROPHILIC drugs
UREMIA can increase the PERMEABILITY of the BLOOD BRAIN BARRIER
giving BENZODIAZEPINES to patients with RENAL DZ? (3)
hint: end with how we should administer them
- BENZODIAZEPINES are HIGHLY PROTEIN-BOUND drugs
- so NORMALLY only a SMALL % of this dose SITS IN CIRCULATORY SYSTEM/BIOAVAILABLE for use
- but when DISEASED, MORE DRUG IS AVAILABLE TO BIND TO RECEPTOR & likely need DOSE REDUCTION
if BBB is ALTERED due to UREMIA in patient with kidney dz, what is an ANESTHETIC CONSIDERATION we should have? (two)
- ANESTHETIC DRUGS can ACTIVATE or INHIBIT RECEPTORS in CNS & usually CROSS BBB
- if BBB is MORE PERMEABLE to these drugs, MIGHT WANT TO GIVE A REDUCED DOSE
2 main goals for ANESTHETIC MANAGEMENT for patients with RENAL DZ?
- MINIMIZE RISK of FURTHER KIDNEY INJURY via…
–> MAINTAIN ADEQUATE RENAL PERFUSION
–> REDUCE exposure to NEPHROTOXIC COMPOUNDS - ID & OPTIMALLY MANAGE MODIFIABLE RISK FACTORS
NSAIDs & renal dz patients?
NSAIDs are NEPHROTOXIC COMPOUNDS
PRIOR to anesthesia for KIDNEY DZ patients, we should…
why?
STAGE THEIR KIDNEY DISEASE
because we have HUMAN studies that show DIRECT RELATIONSHIP BETWEEN CKD SEVERITY & PERIOPERATIVE MORBIDITY & MORTALITY
most common grading system for kidney dz in DOGS/CATS?
what 3 parameters does it examine?
INTERNATIONAL RENAL INTEREST SOCIETY for both AKI and CKD
3 parameters?
1. SERUM CREATININE & its TREND (don’t want to see it change much/increasing)
2. PROTEINURIA
3. BLOOD PRESSURE
if SERUM CREATININE is trending towards INCREASING, this can suggest…
PROGRESSION OF RENAL DZ
if an animal has STABLE RENAL DZ, how soon prior to Sx should we perform bloodwork?
if UNSTABLE, then how soon?
2 WEEKS to a MONTH BEFORE Sx
if UNSTABLE, then do b/w MUCH CLOSER TO PROCEDURE
CBC/Chem findings for RENAL DZ that we should run PRIOR to Sx? (2)
- COMPLETE BLOOD COUNT, look for ANEMIA & HEMOCONCENTRATION
- CHEMISTRY –> BUN, CREATININE, ACID-BASE balance, ELECTROLYTES
if we’re concerned that a patient with RENAL DZ also has CARDIOVASCULAR INSTABILITY, what 3 diagnostics should we look into performing?
what ELECTROLYTE value commonly found with RENAL DZ may indicate this?
- TFAST
- ECHOCARDIOGRAM
- ECG
HYPERKALEMIA can indicate this!
if we’re concerned that a patient with RENAL DZ also has VOLUME OVERLOAD, what 2 diagnostics should we look into performing?
- THORACIC RADS
- TFAST
TRUE/FALSE
PATIENTS with RENAL DZ COMMONLY have COEXISTING DISEASES, so be THOROUGH ON PE.
TRUE
in patients with RENAL DZ, RISK ASSESSMENT & MITIGATION is necessary, why?
because PATIENTS WITH RENAL DZ can be PRONE TO PERIOPERATIVE and POST-OP COMPLICATIONS
in patients with AKI, SURGERY….
SHOULD ONLY BE DONE IF IT’S LIFE-SAVING!
list the 5 RISK ASSESSMENT parameters PRIOR to Sx for RENAL DZ patients
OVERALL, the ___ of the procedure SHOULD…
- ID RESOURCES to MOBILIZE if necessary
–> O2 cages, consult specialists - determine need for ADDITIONAL TESTING
- ID patients that can BENEFIT FROM STABILIZATION (such as weight loss) to help IMPROVE SURGICAL OUTCOME
- determine need for CHANGE IN PATIENT MANAGEMENT
- FACILITATE COMMUNICATION between the TEAM
OVERALL, the VALUE of the procedure SHOULD OUTWEIGH THE RISK