Renal / Urology Dr. Reed Flashcards
What is the hormonal response ,(“what things are released”), in response to decreased pressures and/or fluid volume to the kidneys
-A decrease in renal blood flow d/t decreased pressures or hypovolemia leads to reduced GFR, which reduces the amount of sodium and chloride sensed by the macula densa of DCT.
- Juxtaglomerular cells lining the afferent arterioles respond by releasing Renin, which activates the RAAS.
(Renin -> Angiotensin II -> Aldosterone & ADH, Vasoconstriction) - Leads to dilation of afferent arteriole and constriction of efferent arteriole -> restoring GFR
Where does the bulk of Sodium and Water reabsorption occur in the nephron?
Proximal Convoluted Tubule
65% of sodium and 65% water reabsorption into plasma.
For renin to be released from the kidney, what does it need to sensed?
- Decreased Renal perfusion pressure,
- Increased Sympathetic NS Activation (circulating catecholamines)
- Tubuloglomerular Feedback (decreased NA and Cl in DCT)
For Renin to be released, is sodium and Chloride in the Macula Densa, increased or decreased - pg 744 nagelhout
Decreased Na and Cl concentrations sensed by the Macula Densa.
( extra info - Decreased glomerular filtration causes reduced sodium ions (Na+) and chloride ions (Cl−) in the distal tubule, resulting in a reduction in the delivery of these ions to the macula densa, which are specialized cells designed to detect small changes in osmolality, triggers renin release)
What’s the best way to protect the kidneys? What are some strategies?
Preop:
-Correct fluid deficits,
-minimize ADH and RAAS activation with adequate hydration,
-minimize surgical stress - preop analgesia/anxiolysis,
-balanced salt solution IVF - NS.
-Advanced hemodynamic monitoring for pts with cardiac dysfxn.
Intraop:
-Minimize prolonged renal hypoperfusion / Maximum renal perfusion.
- Urinary Catheter for monitoring
-Fluid bolus 250mL - 500mL - if UO drops below 0.5-1mL/kg/hour
-Inotrope if necessary
Avoid nephrotoxic agents
What are normal serum BUN and Creatinine Levels
BUN: 10-20
Creatinine: 0.7-1.5
Lab Values for Prerenal Injury
BUN:Creatinine Ratio = >20:1
Urea, Sodium, and Water are Maintained
BUN would be normal or elevated.
Lab Values for IntraRenal Injury
Urea, Na, and Water reabsorption are all impaired.
BUN: Creatinine Ratio = 10-20:1 (this is the ratio, not the exact serum level of BUN)
Lab Values for Post Renal Injury
clinical scenerio, page 756, with regards to what demonstrates an indication of renal pathology. Bunch of things that look normal, pick out the abnormal
Normal BUN: 10-20
Normal Creatinine: 0.7-1.5
Normal BUN:Creatinine Ration: 10:1-20:1
Specific Gravity Normal: 1.003-1.030. (Higher more concentrated - not reabsorbing as well)
Urine Osmolality: 65-1400mOsm/L (Higher value = more solute. It could be from the kidney holding on to more water or tubular reabsorption difficulties)
Proteinuria: 3+ or 4+ is never normal suggests glomerular dysfxn
Urine Sodium Concentration (130-260mEq/day) High urine sodium - concentrated urine. either holding on to extra water or trouble reabsorbing Na.
Creatinine Clearance 110-150
Hgb/Hct
What drugs do you need to use caution with, not necessarily eliminate, but use caution with when treating renal patients?
Morphine
Fentanyl, Sufentanil, Remifentanil
Hydromorphone
Metoclopramide (reglan)
Cimetidine (H2 blocker - antacid)
Ketamine
Succinylcholine (ok if normokalemic and recent dialysis)
Vecuronium
Rocuronium
What acid-base anomalies can occur in someone in chronic renal failure
Metabolic Acidosis
decreased plasma pH and Bicarb
(acidosis causes potassium to shift form ICF to ECF - hyperkalemia)
Doing a TURP and what is going with this patient. Page 765 nagelhout
Fluid Overload
Water Intoxication or Hypoosmolality
Hyponatremia
Glycine Toxicity
Ammonia
Hemolysis
Coagulopathy
What are some control mechanisms of the glomerular filtration rate? pg 744 what controls your gfr
Glomerular Hydrostatic Pressure (Determined by Arterial BP, Afferent Arteriole Pressure and Efferent Arteriole Resistance)
Pressure in Bowman Capsule
Colloid Osmotic Pressure of plasma proteins
How and why do people develop intrinsic kidney (Intrarenal) injury?
Renal Parenchyma/tissue injury
(Mainly toxins and medullary ischemia)
Site of action of ADH in the nephron
Distal Convoluted Tubule and collecting duct - increases water absorption ONLY, not solutes.
Clinical features of TURP syndrome
-Hypertension
-Bradycardia (reflex)
-Change in mental status
CNS Depression
Change in mental status d/t hyponatremia
Nausea, Vomiting, seizures
EKG changes from hyponatremia - widened QRS, t-wave inversion, dysrhythmias
Pulmonary Edema
Hemolysis (cell swelling)
Pros and Cons of GLycine Irrigation TURP fluid
Pro: Decreased risk of TURP syndrome
Con:
Increased ammonia -> decreased LOC
Transient Post-op Visual Syndrome
-blindness / blurry vision 24-48hrs
Pros and Cons of Distilled Water Irrigation TURP
Pro: Good Surgical Visibility
Cons: Increased Risk of TURP Syndrome.
-Hyponatremia
-Hemolysis
-Hemoglobinuria->renal failure
Electrolyte disturbances from TURP syndrome
Hyponatemia
What are the autoregulatory parameters of renal blood flow? What are key contributors?
MAP = 60-160
*Myogenic mechanism
*Juxtaglomerular Apparatus &Tubuloglomerular Feedback
RAAS
Prostaglandins
ANP
SNS
Pick out renal-friendly neuromuscular blockers
Cisatrium and Atracurium
What are some surgical effects or renal blood flow (page 748)
-Reduced renal blood flow d/t sympathetic activation. (increased renal vascular resistance and decreased RBF and RFR)
-Endogenous and Exogenous catecholamines stimulate RAAS
-Laparoscopic surgeries increase ADH and Aldosterone
-Positive Pressure Ventilation and Upright positions increase ADH release
What critical complication can occur during a Nephrectomy?
Large amounts of bleeding from donor.
What are 3 determinants of glomerular hydrostatic pressure
- Arterial blood pressure
- Afferent arteriole resistance
- Efferent arteriole resistance
What is normal Fractional excretion of sodium
1-3%
What is normal urine osmolality
65-1400mOsm/L
What is normal urine sodium concentration
130-260mEq/day
What is normal specific gravitiy
1.003-1.030
What labs evaluate GFR
BUN
Serum Creatinine
Creatinine clearance (110-150)
Causes of Intra-renal azotemia (aka Intrinsic kidney injury)
Acute Tubular Necrosis (aminoglycosides, IV contrast, ischemia, myoglobin)
-Acute glomerulonephritis
-Vasculitis
-Interstitial Nephritis
Causes of post renal azotemia
Nephrolithiasis
obstructive clots
bladder carcinoma
BPH
What is the best method of renal protection following major muscle trauma?
Mannitol and keep urine pH above 5.6 with bicarb and or acetazolamide
When antagonizing rocuronium in a patient with end-stage renal disease, the dose of neostigmine should be?
the same as the patient without end stage renal disease. excretion is prolonged which is good because roc excretion is also prolonged
