Once the decision to pursue peritoneal dialysis (PD) is made, two primary modalities are available from which patients can choose: continuous ambulatory PD (CAPD) and ambulatory PD (APD). CAPD involves manually performed exchanges using gravity to fill and drain the peritoneal cavity, and APD involves exchanges that are performed using a cycler over several hours, typically during the night. The selection of a PD modality is dependent on an individual's lifestyle because there is no difference in patient and technique survival (1).
Subtypes of APD include continuous cycling PD (CCPD), nightly intermittent PD (NIPD), and tidal PD (TPD) (2). CCPD consists of overnight exchanges with a day dwell, and NIPD encompasses only overnight exchanges without a day dwell. TPD is an alternative form of APD in which the peritoneum is not completely drained between exchanges (Figure 1).
We use the following approach to determine modality and initial prescription. We begin with an assessment of the patient's lifestyle. Given that CCPD is a predominantly nocturnal therapy, a detailed sleep history is critical. This should include the average times when the patient goes to bed, falls asleep, and wakes up. This history can help determine the total amount of time available for cycler-assisted dialysis. In patients who report shorter sleep periods, the history is expanded to include activities immediately before and after bedtime, because some may be amenable to being performed during cycler-assisted dialysis. After understanding the patient's sleep schedule, the nephrologist and patient can work together to determine whether it would be feasible to perform exchanges during the day. This typically depends on the employment status, field, and lifestyle of the patient. The adept nephrologist will develop a prescription that works around the patient's lifestyle, allowing the patient to maintain a maximal quality of life. For example, a patient may report sleeping only 6.5 hours per night, but further history taking reveals that the patient reads for 1 hour before falling asleep and has a sleep latency of 30 minutes. This patient could reasonably receive 8 hours of cycler-assisted dialysis overnight. Volumes are titrated to tolerance, and dwell time typically targets 2 hours per exchange, which can be adjusted when transport status is determined by peritoneal equilibrium testing. Patients who are rapid transporters will benefit from shortened exchanges and slow transporters from longer exchanges (Figure 2).
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