Edematous Diseases May 3, 2013 Neil A Kurtzman, MD

Edema CHF AGN Nephrotic Syndrome Cirrhosis

Irrespective of disease, the cause of edema is always renal salt retention

John Peters – 1948 A normal kidney retains salt in patients with CHF Volume must be contracted

The kidney retains salt when volume is contracted It excretes salt when volume is expanded What is the volume compartment the kidney recognizes?

Volume Candidates Blood volume Interstitial volume Extracellular volume

Peters invented a volume compartment EABV

Effective Arterial Blood Volume A concept not a measurable entity Normal EABV is that amount of arterial filling that assures adequate organ perfusion Its state is inferred from history, PE, and lab values

EABV Vomiting Diarrhea Sweating Hemorrhage CHF Some forms of nephrotic syndrome Cirrhosis

EABV History PE – BP Low urine Na High uric acid Increased BUN:Cr

CHF CO inadequate Circulation underfilled EABV decreased Kidney retains salt and water Edema

AGN vs CHF Edema + Pulmonary Edema + Urine Na Low CVP High Heart size Increased S3 + EDP High ______________________________________ These patients have different diseases

AGN vs CHF (cont) AGN CHF BP rises falls Facial edema + - Renin low high Aldosterone low high AVP low high

AGN vs CHF (cont) AGN CHF Digitalis - + CO high low A-V O2 Δ low high A-V pH Δ low high

Characteristics of Edematous Diseases Primary Secondary Nephritic CHF Renal Failure Cirrhosis NS NS ECF vol high high Plasma vol high high BP high low CO high low to high

Characteristics of Edematous Diseases 2 Primary Secondary Nephritic CHF Renal Failure Cirrhosis NS NS GFR low* low RBF nl* lower FF low high Renin low high Aldo low high

Characteristics of Edematous Diseases 3 Primary Secondary Nephritic CHF Renal Failure Cirrhosis NS NS SNS activity Nl Increased ADH Low High FNa Excretion Low Low

Primary Salt Retention Salt retention EABV BP Edema Renin Aldo AVP

Consequences of Primary Salt Retention Facial edema Normal Na Hypertension

Secondary Salt Retention

Consequences of Secondary Salt Retention Dependent edema Hyponatremia BP falls Hypokalemia Metabolic alkalosis

Nephrotic Syndrome – Low EABV Plasma volume may be reduced High renin Renal underperfusion Increased Na excretion after vol expansion or water immersion Increased SNS activity BP rises after remission

Nephrotic Syndrome – High EABV Plasma vol nl or increased Low renin No response to vol expansion Low FF BP falls after remission

Implications for Diuretic Rx Patients with nephritic edema will respond CHF – depends on Starling curve NS will respond if EABV is high Cirrhosis - rarely does any good

Conclusions Edema always results from renal salt retention Primary edema – EABV is expanded Secondary edema – contracted EABV cause the salt retention

Secondary Salt Retention

Characteristics of Edematous Diseases Primary Secondary Nephritic CHF Renal Failure Cirrhosis NS NS ECF vol high high Plasma vol high high BP high low CO high low to high

Characteristics of Edematous Diseases Primary Secondary Nephritic CHF Renal Failure Cirrhosis NS NS GFR low* low RBF nl* lower FF low high Renin low high Aldo low high

Characteristics of Edematous Diseases Primary Secondary Nephritic CHF Renal Failure Cirrhosis NS NS SNS activity Nl Increased ADH Low High F Na Excretion Low Low