Endocrine Functions of the Kidney by sammyc2007

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									Endocrine Functions of the Kidney
 Secretion
 Metabolism

 Target

organ

-

renin insulin parathormone aldosterone antidiuretic hormone (ADH)

Renal Function
flow = 20 - 25% of cardiac output Glomerular filtration rate (GFR) = 125 ml/min (normal young adult) Urine output = 1500 ml/24 hr
Blood

Renal Function Tests
urea nitrogen – normal value 10 - 20 mg/dl – renal dysfunction > 50 mg/dl  Plasma creatinine – normal value 0.7 - 1.5 mg/dl  Creatinine clearance – normal value 110 - 150 ml/min
 Blood

Creatinine Clearance
Cp
mg x

Vp = Cu
ml

x

Vu
ml

/dl

/min

mg

/dl

/min

Creatinine Clearance
Measure:

Cp = 1mg/dl Cu = 100 mg/dl 24 - hour urine volume = 1440 ml (Vu = 1 ml/min)
~

~

~

~

Creatinine Clearance
Cp 1
x

Vp = Cu CL = 100

x

Vu
x

x

1

CL = 100 ml/min

Effects of Anesthetic Drugs on Renal Function
Decreases

in RBF, GFR, urine

output Nephrotoxicity (Fluoride ionpolyuria)

Chronic Renal Failure Etiology
Chronic Diabetic

glomerulonephritis nephropathy

Pyelonephritis

Chronic Renal Failure Circulatory Changes
(erythropoietin deficiency)  Coagulopathy – Platelet dysfunction – Systemic heparinization  Hypertension (renin release) – Vasoconstriction (angiotensin II) – Sodium retention (aldosterone)
 Anemia

Chronic Renal Failure Metabolic Changes
 Metabolic

acidosis (phosphate, sulfate

retention)
 Hyperkalemia

 Hypermagnesemia
 Hypocalcemia

(from phosphate

retention)

Chronic Renal Failure Immunosuppression
phagocyte activity Effects of drugs
Decreased

Postoperative Problems Chronic Renal Failure
Recurarization Hypertension Sensitivity Cardiac

to opioids

dysrhythmias

Causes of Perioperative Oliguria Prerenal (Decreased RBF)
Hypovolemia Decreased

cardiac output

Causes of Perioperative Oliguria Renal (Acute Tubular Necrosis)
ischemia Nephrotoxic drugs Myoglobinuria Hemoglobinuria
Renal

Causes of Perioperative Oliguria Postrenal (Obstructive Uropathy)
ureteral obstruction Extravasation from bladder rupture Prostatism
Bilateral

Differential Diagnosis of Perioperative Oliguria
Urine sodium Urine osmolarity Urine/plasma osmolarity
Prerenal Renal < 40 > 40 > 400 250-300 > 1. 8 <1.1

Patients at Risk of Perioperative Renal Failure
Renal disease Liver disease Hypovolemia Sepsis Multiple trauma Congestive heart failure Advanced age

Operative Risks of Renal Failure
Abdominal

aneurysm resection bypass

Cardiopulmonary

Treatment of Acute Renal Failure
Challenge Dopamine infusion –(3-5 mcg/kg/min) Diuretics –Mannitol 12 . 5 g –Furosemide 5 mg
Fluid

Renal Disease (1)
Glomerulonephritis

– Acute (often post-streptococcal) – Goodpasture syndrome (vasculitis) – Nephrotic syndrome (gross proteinuria) – Interstitial nephritis (drug allergy)

Renal Disease (2)
Polycystic Fanconi Bartter

kidneys

syndrome

syndrome

Renal Disease (3)
Renal Uric

hypertension

acid nephropathy syndrome

Hepatorenal

Anesthesia for ESWL
Immobilization Analgesia

to T6 (regional

technic) Effects of water immersion Cardiac dysrhythmias (shock waves)

TURP Syndrome
Cardiovascular

changes

(hypervolemia) CNS disturbances, dysrhythmias (dilutional hyponatremia)

TURP Syndrome Signs of Hemodilution
Serum

sodium decreased

» < 120 mEg/L
Hematocrit

Anesthesia for TURP
Spinal preferred (level to T 10)
detection of excessive fluid absorption Early detection of bladder perforation Postoperative analgesia (opioid)
Early

Renal Transplantation Preoperative
Hemodialysis Blood

glucose value (diabetic patient)

Renal Transplantation Intraoperative
5% glucose with 0.45% NaCl Mannitol: 12.5 g increments
Fluid:

Renal Insufficiency
Threshold

= loss of 60% of nephrons Uremia = loss of 90% of nephrons

Anesthetic Induction
CNS

hypersensitivity

Hypovolemia

Fluid Management
hydration (balanced salt solution 10-20 ml/kg) Intraoperatively 3-5 ml/kg/h Maintain urine output > 0.5 ml/kg/h Avoid diuretics
Preoperative

Fluid Management (Anuric Patient)
Replace

insensible losses with

5% D/W

Renal Transplantation Hazards and Complications
arrest (acute hyperkalemia) Acute immunologic rejection (DIC) Hematoma Delayed signs of rejection (fever, oliguria)
Cardiac


								
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