Renal Volume Disorders Notes PDF

RENAL Last edited: 9/10/2024 3. VOLUME DISORDERS I. PATHOPHYSIOLOGY II. COMPLICATIONS OF III. DIAGNOSTIC APPROACH TO IV. TREATMENT OF VOLUME DISORDERS A....

RENAL Last edited: 9/10/2024 3. VOLUME DISORDERS I. PATHOPHYSIOLOGY II. COMPLICATIONS OF III. DIAGNOSTIC APPROACH TO IV. TREATMENT OF VOLUME DISORDERS A. HYPOVOLEMIA VOLUME DISORDERS VOLUME DISORDERS A. HYPOVOLEMIA B. HYPERVOLEMIA A. HYPOVOLEMIA A. HYPOVOLEMIA B. HYPERVOLEMIA B. HYPERVOLEMIA 00:38 I. Pathophysiology A. Hypovolemia 1. Pathophysiology: a) Poor Intake ↓Intake of food and fluids → Fluid absorbed across GIT into ECF → ↓Extracellular fluid → ↓Circulating blood volume b) Renal Fluid Loss Polyuria → ↓Extracellular fluid → ↓Circulating blood volume c) Extrarenal Fluid Loss Excess GI/Skin losses → ↓Extracellular fluid → ↓Circulating blood volume d) Third Spacing Movement of fluid from the vascular compartment into a tissue space → ↓Circulating blood volume 2. Causes of Hypovolemia: 08:21 b) Extrarenal Losses 12:52 c) Third Spacing a) Renal Losses i) Loop/Thiazide Diuretics i) GI Losses i) Pancreatitis or Look for prior episodes of large urine output Vomiting Severe sepsis with diuretic overuse in history Excessive NGT suctioning Systemic inflammation causes Diarrhea capillary leakage of fluid into ii) Osmotic Diuresis (e.g. mannitol tissue spaces or hyperglycemia in DKA) ii) Skin Losses Look for prior episodes of large urine output Severe skin burns with hyperglycemia in DKA or mannitol use in Excess diaphoresis (e.g. fevers) ICP crisis in history Volume Disorders RENAL : Note #3 1 of 9  B. Hypervolemia 03:45 1. Pathophysiology b) ↑Fluid Retention a) ↑Fluid Administration i) CHF ↑Intravascular fluid administered → ↑Extracellular fluid → ↓Cardiac output → ↑RAAS activity → ↑Sodium and water ↑Circulating blood volume retention → ↑Extracellular fluid b) ↑Fluid Retention ↑Renin-angiotensin-aldosterone system activity and ↑ADH activity → ↑Sodium and water retention → ↑Extracellular fluid → ↑Circulating blood volume ii) Cirrhosis Portal hypertension → Splanchnic vasodilation → ↓EABV → ↑RAAS activity → ↑Sodium and water retention → ↑Extracellular fluid Hypoalbuminemia → ↓Oncotic pressure → ↑Third spacing of Na-rich fluid in interstitial spaces 17:06 2. Causes of Hypervolemia: a) ↑Fluid Administration i) Used in Volume Resuscitation Look for history of LR or NS infusions/bolus therapy iii) CKD ↓↓GFR → Inability to excrete water and ↑RAAS activity → ↑Sodium and water retention 2 of 9 RENAL : Note #3 Volume Disorders  25:27 II. Complications of Volume Disorders A. Hypovolemia Hypotension Pathophysiology: o ↓Extracellular fluid → ↓Circulating blood volume → ↓Preload → ↓SV → ↓CO → ↓BP → ↓Organ perfusion Presentation: o Tachycardia  Most commonly, sinus tachycardia o Altered Mental Status  Confusion, Lethargy, or Delirium o Prerenal AKI  Oliguria  ↑Creatinine  FeNa < 1% and BUN/Cr >20:1 o Lactic Acidosis  Lactate > 2 o ↓Skin turgor, Dry mucous membranes  Skin turgor → Takes a prolonged time for the skin tenting to return to normal  Dry mucous membranes → Look for fissures/cracks in the tongue o Cold, Pale, Mottled Extremities  Due to reflexive vasoconstriction from hypotension Volume Disorders RENAL : Note #3 3 of 9 B. Hypervolemia 37:38 Edema Pathophysiology: o ↑Extracellular fluid → ↑Circulating blood volume or ↑Shifting of fluid from plasma into interstitial spaces Presentation: i) Weight Gain v) Jugular Venous Distention  One of the most helpful parameters in determining  Bulging of the jugular vein due to ↑CVP hypervolemia ii) Pulmonary edema  Symptoms: Dyspnea, Paroxysmal nocturnal dyspnea, Orthopnea  Signs: Hypoxia and Rales on auscultation vi) Ascites  Fluid accumulation in the peritoneal cavity causes abdominal distention, fluid wave test (+), or shifting dullness iii) Peripheral Edema  Usually causes lower extremity edema that causes pits when compressed 42:51 vii) Prerenal AKI  Oliguria  ↑Creatinine  FeNa < 1% and BUN/Cr > 20:1 iv) Hypertension  Often times in high circulating volume states, these patients can have resistant HTN that improves with volume removal 4 of 9 RENAL : Note #3 Volume Disorders  46:39 III. Diagnostic Approach to Volume Disorders Assess Volume status a) Obtain History and Physical Examination Indications: o Assess volume status Abnormal findings: i) Hypovolemic ii) Hypervolemic  History of fluid loss:  History of fluid retention: Renal loss: Diuretics and cerebral salt CHF, Cirrhosis, CKD, Iatrogenic fluid resuscitation wasting  Physical Exam: Extra-renal Na loss: Vomiting and diarrhea Normal skin turgor, moist membranes, distended jugular veins, ↑BP,  Physical exam: pulmonary or peripheral edema, ascites ↓Skin turgor, dry membranes, flat jugular Weight gain veins, ↓BP, ↑HR Weight loss Volume Disorders RENAL : Note #3 5 of 9  48:53 IV. Treatment of Volume disorders A. Hypovolemia 1. Replace Volume Loss Therapies: o Isotonic Solutions  0.9% Normal Saline  Lactated Ringers Solution o Hypotonic Solutions  0.45% Normal Saline  D5 Water Solution o Colloid solutions  Albumin 6 of 9 RENAL : Note #3 Volume Disorders  Indications: i) 0.9% Normal Saline iv) D5 Water Solution  Used as an initial fluid in resuscitation if hypotensive (more  Used as a maintenance fluid if hypovolemic, hypernatremic common on medical wards) and need some calories (e.g. NPO) after stabilized with isotonic solution v) Albumin ii) Lactated Ringers Solution  Used as an initial fluid in resuscitation if hypotensive (less  Used as an initial fluid in resuscitation if hypotensive (more commonly used given expensive) common in Trauma or OR) iii) 0.45% Normal Saline  Used as a maintenance fluid if hypovolemic and hypernatremic after stabilized with isotonic solution Volume Disorders RENAL : Note #3 7 of 9 Purpose: Monitoring: o Crystalloid solutions o Isotonic solutions → Monitor for improved BP, urine output  Replace Volume Loss → Restore ECF volume → Improve BP and improved creatinine and organ perfusion  0.9% Normal Saline o Colloid solutions Monitor for ↓HCO3- indicating a NAGMA  Osmotic pressure in vasculature → Pull water into vascular Monitor for ↑K+ as a result of NAGMA space → Improve ECF volume → Improve BP and organ  Lactated Ringers Solution perfusion Monitor for hypercalcemia (calcium present in solution) No risk of lactic acidosis or Hyperkalemia o Hypotonic solutions → Monitor for stable urine output and improved hypernatremia  0.45% Normal Saline and D5 Water Solution Monitor for hyponatremia with continued use Monitor glucose level with D5 in any solution 8 of 9 RENAL : Note #3 Volume Disorders  B. Hypervolemia 57:45 Remove Excess Volume Therapies: Monitoring: o Diuretics o Monitor for ↑BUN and ↑Creatinine, as this may indicate over-  Loop Diuretics (e.g. Furosemide, Bumetanide, Torsemide) diuresis and evidence of prerenal AKI  Thiazide Diuretics (e.g. HCTZ, Metolazone, Chlorothiazide) o Monitor for improvement in BUN and creatinine with the use  Potassium Sparing Diuretics (e.g. Spironolactone, Eplerenone) of Hemodialysis  Carbonic Anhydrase Inhibitors (e.g. Acetazolamide) o Monitor for Intake and output and daily weights with the goal o Hemodialysis of reaching baseline weight and negative fluid balance Indications: o Monitor for improvement in edema (pulmonary edema, o Loop Diuretics peripheral edema, ascites)  Large Volume Removal for the following: Pulmonary edema Peripheral edema Ascites Weight gain o Thiazide Diuretics  Volume removal PLUS Hypernatremia o Potassium Sparing Diuretics  Volume removal PLUS Hypokalemia o Carbonic Anhydrase Inhibitors  Volume removal PLUS Metabolic alkalosis o Hemodialysis  Refractory hypervolemia Not responsive to diuretics, usually due to severe CKD or AKI Purpose: o Remove excess fluid from ECF (i.e. interstitial spaces, cavities) → Improve features of volume overload/edema Volume Disorders RENAL : Note #3 9 of 9