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The initial contribution of RRF to total solute clearance depends on when PD is started and the initial prescription. The literature and the NKF DOQI guidelines recommend initiation of dialysis when RRF approximates 10% of normal renal function or an approximate Curea = 7 or Ccreatinine 14 ml/min. This level of RRF is equivalent to a weekly Krt/V ~ 1.75 to 2.0. If the PD prescription provides a Kpt/V ~ 2.0, the contribution of RRF is 50%. Regardless of the rate of deterioration of RRF, it is imperative to periodically measure both the delivered dose of PD and RRF and make upward adjustments to the dose as RRF is lost.
Gradual versus full implementation of dialysis
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Experience has shown that most of the loss occurs in the first 18 months. The clinical team must make an effort to establish a routine to track both parameters at periodic intervals. The patient must be made aware from the beginning of therapy that adjustments will be required that may result in alternate therapy and sometimes in inconveniences or even retraining in another dialytic modality. Resistance to change in therapy has prompted many clinicians to prescribe an initial dialysis dose assuming total anuria, thus providing additional therapy early in the course of PD and avoiding changes later on.
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