030306 Renal Pa Tho Physiology Handout

The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Renal Physiology II Donald M. Voltz, M.D.

Acid/Base Regulation

Titratable Acids • • • •

Ammonia Phosphoric acid Sulfuric acid Hydrochloric acid

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Regulation of Arterial Pressure

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Macula Densa • Sympathetic stimulus • Flow of chloride • Pressure

Macula Densa Feedback

Regulation of Arterial Pressure

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Renal Endocrine Functions

Kidneys as Endocrine Organs • renin-angiotensin system • erythropoietin • metabolism of vitamin D to calcitriol

Renin – Angiotensin System

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Erythropoietin Hypoxia

Hypocalcemic Response

Renal Function

http://cms.nursingcenter.com/dev/upload/static/230543/200301nur61.gif

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Assessing Renal Function • • • •

Creatinine clearance as an estimate of GFR BUN Creatinine / BUN ratio (ex. >20:1) Creatinine clearance <50 and <25

Assessing Renal Function • Mathematically

http://www.oqp.med.va.gov/cpg/DM/DM3_cpg/images/creatinines.gif

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

The Renal System & Anesthesia

Systems Involved Cardiac- Decreased CO = decreased RBF including regional anesthesia • Neuro- Light anesthesia = increased sympathetic outflow • Endocrine- reflect physiologic changes Increased ADH?

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Effects of Anesthesia on Renal Function Induction and Maintenance Agents ƒ ƒ ƒ ƒ ƒ ƒ

Volatile Fluoride toxicity Methoxyfluoride Enflurane Sevoflurane STP Propofol

Effects of Anesthesia on Renal Function

IV Drugs

ƒ Anti-dopaminergic drugs-phenothiazines, droperidol, metoclopramide, ACEI, dyes, aminoglycosides, lithium, amphoterocin B, cyclosporine ƒ N-acetylcysteine benefits?

Effects of Renal Dysfunction on Anesthetic Drugs • Decreased protein binding • Acidosis

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

• • • • • • • •

Effects of Renal Dysfunction on Anesthetic Drugs

Barbiturates Benzodiazepines Vapors Nitrous oxide Muscle relaxants Anticholinergics H2 Blockers Narcotics

Effects of Anesthesia on Renal Function Surgical effects ƒ Pneumoperitoneum, cross clamping and direct ureteral injury

Diuretics • Decrease re-absorption of Na+ and H20 • Results in increased volume at the expense of electrolyte disturbances

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Osmotic • • • • • • • • •

Increase osmotic gradient Mannitol - filtered and excreted Greater H20 than Na+ Hyponatremia to hypernatremia Electrolytes Decreased ICP Jump start kidneys Oliguric to non-oliguric Central pontine myelinolysis

Loop • Interfere with Na+/K+/2Cl- at thick ascending portion • Furosemide • Bumetanide • Ethacrynic acid • CHF, hypertension, oliguria, hypercalcemia • Electrolyte disturbances

Thiazide • • • • • • •

Increase Na+ excretion at the distal tubule Weak HCTZ Metolazone Indapamide Some carbonic anhydrase activity CHF, hypertension and hypercalcemia

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Potassium Sparing • • • • • •

Aldosterone antagonists Anti-androgenic Spironolactone Work only if aldosterone levels are high Liver Failure CHF

Carbonic Anhydrase Inhibitors • Affects proximal tubule Na+ and H+ reabsorption which results in HCO3- wasting • Alkalinization of urine • Decreases intraocular pressure • Decreases HCO3-

Other Diuretics • Methylxanthines • Cardiac glycosides

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Pathology

Pathological Conditions • Hyponatremia • Hypernatremia • Edema

• Electrolyte disturbances • Anemia • Azotemia

– Intracellular – Extracellular • Angioedema • Lymphedema

– CHF

Azotemia • Pre-renal • Renal • Post-renal

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Renal Pathology

Renal Pathology

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Renal Pathology

Renal Functions Waste Removal

Regulation of Electrolytes

Acid-Base Balance

Fluid Regulation

Blood Pressure Regulation

Hormone Production

Case Studies for Renal Pathophysiology

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Clinical Case 58 year-old male scheduled for thrombectomy of his left arm AV-graft. • Hypertension • ESRD – on HD qM,W,F (last 3 days ago0 • Diabetes Mellitus

Case 1

Renal Concerns? – – – – –

Fluids Electrolytes Acid-Base Balance Hormones Blood Pressure Regulation

Fluid Balance • Unable to remove excess free water • May present with Pulmonary Edema • Dialysis to restore patients to less than “dry” weight

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Electrolytes

K+ HCO3-

Complications of Renal Failure • • • • • • • • • • • •

Pericarditis, cardiac tamponade Congestive heart failure Hypertension Platelet dysfunction Gastrointestinal loss of blood; duodenal or peptic ulcers Hemorrhage Anemia Hepatitis B, hepatitis C, liver failure Decreased functioning of white blood cells and immune system Infection Peripheral neuropathy Seizures

• • • • • • • •

Encephalopathy, nervous system damage, dementia Weakening of the bones, fractures, joint disorders Permanent skin pigmentation changes Skin dryness, itching/scratching with resultant skin infection Changes in glucose metabolism Changes in electrolyte levels Decreased libido, impotence Miscarriage, menstrual irregularities, infertility

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The Physiology of Anesthesia Practice Donald M. Voltz, MD 03 March 2006

Treatment of Renal Failure • • • •

Hemodialysis Peritoneal Dialysis Kidney Transplantation Nothing

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