Dialysis: Understanding the Importance of Fluid and Volume Management, Exams of Medicine

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Real Facts About Fluid Overload Venkat K. Iyer, MD, MBAAssistant Professor, Mayo School of MedicineMedical Director, Quality and Process Improvement, Mayo Clinic Dialysis System

Disclosure• None

Two major functions of dialysis^ Uremic solute removal

Excess ECF volume removal Main Process^ Diffusion

Ultrafiltration How is adequacyClearance of surrogatemeasured?solute - urea

BP control, Dry weight Quantification ofspKt/V, Std Kt/V, URRadequacy

No objective measure to quantifyadequacy of fluid removal. Trial &Error method to achieve DW Debate^ Small versus middlemolecular clearance(diffusive versusConvective clearance)

What is the best method toquantify ECF volume removal.Clinical versus Non-clinicalmethods

What is dry weight?• Lowest tolerated post-dialysis weight achievedvia a gradual reduction in post dialysis weight atwhich there are minimal signs or symptoms ofhypovolemia or hypervolemia

Dry Weight ECF volume LBM Initiation of HD^

High^

Low Adequate Maintenance HD^

Euvolemic^

Improves Acute illness^

Increases^

Decreases

Cost of Hospitalization for Volume Overload^ % of Fluid Overload admission^ 14.3 85.7^ FO admission^ •^ Arneson et al. CJASN 2010; 5(6): 1054 – 1063

25,291 pts of 176,790^ Others

% of 41,699 episodes 1008680 60 40 209 5 0 InpatientED^ Observationcare Average cost per episode

Total cost $6, $266 million

Pathophysiology of Volutrauma ChronicHypervolemia^

^ PreloadHypertensionConc LVH^ ^ Afterload

Systolicdysfunction Diastolicdysfunction

^ Arterial stiffness,so^ Sytemic VascResistance

^ LV dilatation

How does Fluid Overload cause hypertension?^ BP = CO x SVR^ ^ VR (Preload) Volume overload or Fluid overload

CHF, Compensatory neurohormonal activation^ ^ Arterial stiffness70 – 80% of hypertension in dialysis is from volume excess, 20 -30% other causes

IF Fluid Overload causes HTN then Excess volumeremoval should reduce BP: Proof?• Several observational studies have shown that reducing DWimproves BP control• Two centers practicing strict volume control have 2 – 4 %hypertension prevalence• Tassin, France• Ege University, Izmir, Turkey• DRIP trial• FHN trials

Editorial: Belding H. Scribner• “Shortly after our first patient, Mr. Clyde Shields, began long termhemodialysis in March of 1960, he developed malignant hypertension,and death seemed imminent. Since we were unable to control his bloodpressure with the few antihypertensive drugs then available, we decidedthat our only hope of saving him was to try aggressive removal ofextracellular fluid by ultrafiltration during his once weekly 24-hourhemodialysis.”• “During the subsequent weeks cramping was severe as we tried tomaximize fluid removal during each dialysis. Gradually, however, hisblood pressure came under control. Eventually he became normotensiveoff medication, and remained so until his death from a myocardialinfarction in 1971. This dramatic episode made a lasting impression onour approach to the control of blood pressure in our hemodialysispatients.”

DW Reduction in HTN HD Patients (DRIP Trial)150 chronic stable HD ptsAvg 2.6 antihypertensivesUncontrolled HTN (44h interdialytic ABPM)Intervention groupProgressive reduction inDW by 0.2 kg each HD

Control groupPrescribed DW unchanged

Volume overload and LVHVolume overload

^ PreloadLVH  Afterload

Arrthymia, SCDCHF Ischemia Proof that volume control by dialysis regresses LVH No long term trails showing equivocally that volume control leads toconsistent reduction in LVMI translating into improved outcomes

20018016014012010080 60 40 20 0 FHN Daily Trial^ FHN Nocturnal Trial

Canadian Trial Effect of Intensive versus Conventional HD on LV Mass Mean Left Ventricular Mass (g)

ConventionalbaselineConventionalStudy endIntensivebaselineIntensive Studyend Treatment Effects:^ -13.8 g^

-10.9 g^ -15.3 g

Chronic Fluid Overload and Mortality in ESRD: JASN2017; 28: 2491 - 2497

1.941.621.51^ OverhydratedMen: FO/ECF ≥ 15%Women: FO/ECF ≥ 13%1.51p < 0.0011.301.25*^

Mortality rates 2015, USRDSCardiacarrhthmia/OthersSCD49%40% CHF3%AMI/ASHDCVA5%3% ECF volume excessCKD-MBD, FGF-23Reduced vascular compliance,increased PW velocity and PPLVHSilent ischemia, decreasedcoronary flow reserve,impaired microcirculationmyocardial stunningIDHHigher prevalence of CAD, DMIneffective vasoregulation