INDICATIONS FOR ACUTE RENAL REPLACEMENT THERAPY

Jonathan Tembo 04 Nov 2014

Outline

• History• Definitions• Modes of RRT• Indications• Summary

History

• 1861 ,Thomas Graham coins the word ’dialysis’

• In 1913, Abel, Rowntree, et al construct first artificial kidney.

• 1943, WJ Kolff and H Berk , first practical human haemodialysis machine , the Netherlands.

• The arteriovenous shunt, as described by Quinton and Scribner (1960)

3-Definitions• Hemodialysis– Hemodialysis filter

substitutes for glomerulous– Blood flows on one side of

semipermeable memb & dialysate flows on other side in counter current direction

– Electrolytes & H2O move from blood across Concentration gradient

– Diffusive clearance of small molecules

2-Definitions• Hemofiltration– Plasma forced from blood

space into effluent across semipermeable membrane by application of pressure

– Convective clearance of small & middle size molecules by solvent drag

– Serum electrolytes not changed unless replacement fluid infused into blood

1-Definitions• Hemodiafiltration– Simultaneos use of both

hemofiltration & dialysis– Convective & diffusive

clearance

3 -Modes of RRT

• Intermittent • Continuous

3

2- Modes-Intermittent

• Peritoneal Dialysis (PD)• Intermittent Hemodialysis (IHD)• Pure Ultra filtration (PUF)• Hybrid therapies– Sustained Low Efficiency Daily Dialysis (SLEDD)– Sustained Low Efficiency Diafiltration (SLEDF)– Extended Daily Dialysis (EDD)– Slow Continuous Dialysis (SCD)

1-Modes-CRRT

• Slow Continuous Ultra filtration(SCUF)• Continuous Venovenous Hemofiltration-CVVH• Continuous Venovenous hemodialysis-CVVHD• Continuous Venovenous hemodiafiltration

CVVHDF

IHD-prescription

• Access– temp dialysis catheter, tunneled cuffed

catheter(hickman), A-V fistula,A-V graft

• Treatment duration• Filter size• Blood flow rate /dialysate rate/dialysate bath• Ultrafiltration goal– Amt of fluid to be removed per session

Catheters

Advantages-IHD

Advantages

• Clearance per unit time faster– better for life threatening

indications Hyperkalaemia, toxicological

Complications

• Vascular access– Thrombosis & stenosis=loss

of bruit– Infections,Staph,Vanc– Aneurysms,CCF,

• Hypotension

CRRT

Advantages

• Slower rates of solute flux & fluid removal better tolerated hemodynamically

• Allows for increased net daily ultrafiltration

• Increased clearance

Disadvantages

• Long term immobilisation of pt

• Continuous anticoagulation• Hypothermia• Labour intensive 1:1 nursing

Indications for RRT

• Renal• Non Renal

AKI

• Uraemia =Urea in blood• Def: an abrupt (1 to 7 days) and sustained

(more than 24 hours) decrease in kidney function.– Accumulation of Urea & Creat– Increased K,PO4,non volatile acids– ± Decreased urine output

AKI-RIFLE Classification

Aetiological classification of AKI

• Pre-renal– Adaptive response of intact nephrons to volume

depletion & / hypotension– Azotaemia– Urea:Creat ratio

• Renal– Vascular– Gn– ATN

• Post renal

Indications-AKI

• Hyperkalaemia– >6.5 mmol/L or rapidly rising

• Severe acid-base disturbance– Uncompensated Severe metabolic acidosis pH <7.1

• Anuria– UO <50mL/12h– Urea >35mmol/L– Creat >400

• APO resistant to alternative therapy• Uraemic complications– Encephalopathy,myopathy,neuropathy

Hyperkalaemia

• Excessive intake• Increased production• Decreased renal excretion• Compartment shifts• Drugs• Factititious

Hyperkalaemia

5-Rhabdomyolysis

4-Indications- Rhabdomyolysis

• Breakdown of skeletal muscle and release of intracellular contents

• Myalgias,weakness, dark urine(myoglobin)• CK ≥X5• Hyper K,• Hyperuricaemia, Hyper PO4,Hypo Ca• HAGMA• AKI-myoglobinuric• Lactic acidosis• DIC

2

3-Rhabdomyolysis- Physical causes

• Trauma & compression• Occlusion/hypoperfusion of muscular vessels• Excessive muscle strain– Xs,seizure,tetanus,DT

• Electrical current• Hyperthermia– Xs, sepsis, NMS, Malignant hyperthermia

Sjambok

2-Rhabdomyolysis-Non Physical

• Drugs & toxins– Statins,fibrates,ETOH,heroin,venoms

• Infections- local & systemic• Endocrinopathies • Electrolyte abnormalities• Metabolic myopathies• Autoimmune

1-Rhabdomyolysis-Treatment

• Fluid resuscitation- 0.9% NaCl

• Urine alkalinisation with HCO3-

– pH >6.5(serum pH 7.40-7.45)– UO 3mL/kg/hr =200mL– Not shown to impact outcomes in humans

• Diuretics– Mannitol ,?acetazolamide

• RRT

Indications Non-Renal

• Toxins• Hyperthermia T > 40 °C • Na <110 and >160mmol/L

Toxicological indications– Poison Characteristics

• Small enough and lack charge will cross dialysis membrane

• Highly water soluble• Small volume of distribution (<1L/Kg)

concentrated in blood rather than tissues• Have low protein binding• Rapid redistribution from tissues• Slow endogenous elimination

Tox -The drugs

• Toxic Alcohols• Li• Salicylates• Theophylline• K+ salt OD + Hyper K

• Phenobarb coma• Valproate• Carbamazepine• Metformin lactic

acidosis

Indication- Acute fluid overlod

Complications of RRT

• Central venous access• Electrolyte abnormalities• Hypovolaemia• Hypothermia• Nutritional– Amino acids,Vitamins,trace elements

• mm

Indications -Summary

• A -Acidosis (Metabolic) refractory to HC03• E - Electrolyte imbalances- Hyper-K• I - Ingestions toxic alcohols,Salicylates,Li,• O - Overload, fluid• U - Uremia

1

References

• Polly E.Parsons,Jeanine Wiener- Kronish,Critical Care Secrets ,5th Ed, Elsevier Mosby,2013.pp307,548

• Linsay Murray et al, Toxicology Handbook,2nd Ed,2011,Elsevier,pp28-29.

• Judith E.Tintinalli,Tintinalli’s Emergency Medicine,A Comprehensive Study Guide,7th Ed,2011,McGrawHill,pp624-630

• http://renux.dmed.ed.ac.uk/EdREN/index.html,accessed 04 Dec14