CME Live: Session Two

Curofy- India's largest community of verified doctors covered the CME-International Neonatal and Pediatric Nephrology Training Workshop live. This post was first published on the Curofy app. 

Basics of RRT

Speaker: Dr. Pranaw Jha

Dialysis process whereby soluble composition of a solution A is altered by exposing to solution B across a semipermeable membrane
-Need 2 solution- blood & dialysate 
-Semi permeable membrane

Transport mechanisms: 
Diffusion
Convection
Adsorption
Osmosis

Diffusion: 
results in random molecular motion
inversly proportional to solute ssite

Convection:
Ultrafilteration
water driven across semipermeable membrane by hydrostatic/ osmotic force
solvent swept along with it, close to concentrated gradient- solvent drag

Convective methods:
Hemofilterationlarge amount of ultrafilteration coupled with replacement fluid infusion.

Hemodiafilteration: combined HD & HF

Dialysis Modality

Dr. Siddhartha Sethi

Choice of modality
Peritoneal dialysis
intermittent hemodialysis
CRRT

PD is declining in the west, since expertise is increasing. CRRT is used

Modality of choice in India

less expertise in India
not insured in India
expensive

indication of CRRT
prevention of fluid overload

Acute peritoneal dialysis:
indication: Refractory volume overload
refract hyperkalemia
refract metabolic disease
uremia complication
dysnatemias in AKI

Apparatus: 
PD catheter
three way connector
IV sets
PD fluid bags
Drain bag

Catheter: 
Stiff catheter
two cuff tenckhoff's catheter
Cook's catheter
tenckhofs single cuff
soft thermal 

Bicarbonate dialysis
Severe lactic acidosis or hepatic failure
asepsis required
1 hr exchange time

Ultra filtration
Not more than 5-10% weight loss should be targeted

Session length: Stiff catheter are 48-72 hr affair

anuria, hypercatabolism, nutritional support

Additives: 
heparin, potassium, insulin

Disadvantage: 
Slower concentration
lower URA clearance
lower ultra filtration
risks of peritonitis

Automated PD:
warm fluids, keeps track, less infection

Prescribing HD & Mathematics

Dr. Rupesh Raina

Dialysis cannot clear solutes not present in intravascular space.

Diffusion: 

Factors:
Conc. gradient(dC)
surface area(A)
diffusivity(KO)
sum of resistance(dx/KO)
concurrent flow
time
J=KOA x dC/dx

Solutes:
Low molecular weight- uo to 300 daltons
middle molecular weight- 300- 2000 daltons
large molecular weight- 5000- 1200 daltons
serum albumin-69 366 D

Hollow fiber dialyser;
Thousands of hollow capillary sizes fibers fixed in a polyurethane capsules.
blood flows through fibers, dialysate flows around fibers

Clearance: volume of blood cleared of solute per unit time. 
( Refer pic) 

KoA 
Product of the overall mass transfer co efficient for a given solute x dialyser surface area

Ultrafilteration co efficient: ( KUf)

Volume of fluid transferred across the membrane per mmHg of pressure gradient
Low KUf denotes low permeability and low flux
high KUf denotes near complete permeability

High flux of dialyzers: KUf> 14ml/min/mmhg

Urea kinetic modeling:
Process to determine the amount of dialysis actually given
uses mathematical equation
( refer urea soup pic)

KT/V( Urea)
represnts fractional ura clearance
K= dialyzer clearance
T= time
V= volume of urea distribution

-0.5= uremic, death
-0.7= EEg abnormal
-1.0= short trm 
-1.2-1.4= long term
->1.4= better outcome

Initial hemodynamic prescription concepts; Aim to prescribe a dose of dialysis to effect a desired result

Tubing: < 10 kg- neonatal tubing 
10-20 kg- pediatric tubing
>20 kg adult tubing

SLED & CRRT

Dr. Timothy Buchman

Continuous form of renal replacement therapy that allows for hemodynamic stability

SLED: Slow Low Efficiency Dialysis

Pediatric data for CRRT: optimal use in situation of hemodynamic compromise, Hypermetabolic state, sepsis
45% survival

Pediatric data SLED: 
Heparin Anticoagulation
14 children in 16 sessions. less than 8 hours.
cheaper than CRRT

Advantages of CRRT:
Continuous in nature making decision making of medication, dosage and nutrition delivery easier. 
Hemodynamically stable

Disadvantages, of CRRT:
greater need of utilization of resources
High pharmacy costs

Adv. of SLED
less resource utilization
less expensive
hemodialysis in morning and nocturnal SLED at night

Disadvantages of SLED
may cause hemodynamic compromise
intermittent
risk of over dialysis due to minimal dialysate flow of 6 ltrs per hour