PD: Prescribing

• Done every 4 months, or unless concern or change in prescription.

  • Reported as weekly Kt/V (because PD is done nightly) and target is > 1.8 (KDIGO uses > 1.7 for adults).

  • Every 4 months, we TRY to get a 24h urine collection to include it in our Kt/V calculations for PD patient

Solution

Fill volume

Dwell time

• Recognize that solutes move back and forth from the dialysate to the blood and from the blood to the dialysate; the longer the dialysate solution sits against the peritoneal membrane, the more equilibration there will be with reabsorption and redistribution of solutes

  • With long dwells, you will lose the dextrose-related osmotic gradient, decreasing dialysis efficiency (less effective ultrafiltration, increased dialysate reabsorption)

Number of exchanges

Adequacy

• Kt/Vurea

  • Unitless measure

  • K t = D/P urea x drained volume of dialysate in 1 day

  • Multiple Kt for a day x 7 to get the weekly value

  • Divide weekly Kt by V (TBW) to get Kt/V week

    • "Since V is fairly constant and t is fixed at 1 week, increased K (or increased drained dialysate) is the only way to improve Kt/V" -Morgenstern, 2011

• Weekly dialysis Kt/V:

  • 24 hour D/P urea x 24 hour drained volume x 7

    • Divided by V

• Weekly renal Kt/V

• It's all about the "V"

  • Current best practice suggests to sex specific nomograms

Adequacy

• "Adequate dialysis is likely provided if the patient's clinical status is characterized by adequate growth, blood pressure control and nutritional status, avoidance of hypovolemia and sodium depletion and adequate psychomotor development" --> the ideal

• Adequacy = fractional solute clearance --> the reality

• Quantity of clearance refers to clearance of small easily measurable molecules felt to reflect "uremia"

• Kt/V urea

  • Fractional clearance of body urea

• Total weekly Kt/V urea

• 1997 DOQI guidelines

  • Kt/V goals (Ccr)

  • CAPD: 2.0 (60)

  • NIPD: 2.2 (66)

  • CCPD: 2.1 (63)

  • Difficult to hit these goals, particularly in kids. Resulted in some kids being switched from PD to HD.

    • Difficult to achieve both Kt/Vure and CCr in some patients, especially infants

    • Unclear which was more important

• CANUSA study

  • Showed an increase risk of mortality with declining Kt/V

    • What it actually showed was that loss of residual renal function was what was causing this effect

  • Dosing targets in adults derived from studies linking urea removal with morbidity/mortality

  • There are no large scale, prospective studies in children to define the minimally adequate dose of dialysis

• "Clinical judgment suggests that the target doses of PD for children should meet or exceed the adult standards..."

• Residual kidney function

  • Urine Kt/V urea >0.1/week

  • The minimal "delivered" dose of total (PD and kidney) small-solute clearance should be a Kt/Vurea of at least 1.8/week

  • Total solute clearance should be measured within the first month after initiating dialysis and at least once every 6 months thereafter

  • IF the patient has RKF and the RKF is being considered as part of the patient's total weekly solute clearance goal, a 24-hour urine collection for urine volume and small solute clearance determinations ***

• Meeting dosing targets

• For patients without residual kidney function

• Clinical manifestations of inadequate dialysis

  • Congestive heart failure

  • Hyperphosphatemia/excessive calcium and phosphorus product

  • Uncontrolled hypertension

  • Overt uremia (uremic pericarditis, pleuritis)

  • Repeated hyperkalemic episodes

  • Clinical or biochemical signs of malnutrition, wasting

  • ***

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