During this time, PD was offered exclusively as in-hospital modality (often offered as a last resort to patients who were not candidates for extracorporeal treatment). A typical “treatment” included instillation of PDS manually by nursing staff several times during the day (requiring multiple changes of entire sets), thus risking contamination and subsequently peritonitis. The first use of PD in ESRD patient was reported in the late 1950s. The patient felt better after just 1 day of treatment. PD was therefore continued on as needed basis with frequent monitoring of plasma chemistry. This patient survived for 6 months after which she decided to discontinue the treatment and passed away [3]. Despite the initial success, long-term PD was frequently associated with recurrent episodes of peritonitis. This, together with the inability to gain permanent access to the abdomen slowed its widespread use. In the 1950s and early 1960s, Normal Deane introduced a prosthesis that was used to keep the catheter track patent in between treatments. This prosthesis represented a significant improvement in the care of these patients, thus obviating the need for recurrent catheter insertion with attendant risk of perforation. Instead the patient would come to the unit twice a week and a stylet catheter was slipped through the permanent track after removal of the Deane’s prosthesis. Oreopoulos et al. [2] used this method in about 40 patients over 2–3 years.
Introduction of the Tenckhoff catheter in 1968 is considered a paradigm shift in the use of PD for ESRD patients. The original Tenckhoff catheter was made from Silastic and represented a technical modification of the curled Palmer catheter. It had an open end and numerous side holes in its terminal part. The 2 Dacron felt cuffs offered protection against infection along the subcutaneous tract: one just outside the peritoneum, and the other in the subcutaneous tissue. The curled section of the Palmer catheter was replaced by a straight intra-abdominal part. Description of various modifications of the original Tenckhoff catheter is beyond the scope of this book but can be found in an excellent review by Twardowski [13].
Another significant contribution towards providing PD as a home-based therapy was the introduction of the cycler machines that could be programmed to provide multiple PD exchanges at home on several days of the week. A detailed description of cyclers will be discussed elsewhere in the book.
The Birth of Continuous Ambulatory PD
In 1978, based on their work on theoretical mass transfer, Popovich and Moncrief described a continuous form of PD known as portable/wearable equilibrium dialysis technique. The investigators cited good biochemical control and liberal dietary and fluid intake as major advantages of such a technique. Oreopoulos et al. [14] at Toronto Western Hospital were the first to use PDS supplied in plastic bags (instead of glass bottles originally used by Popovich and Moncrief). Following the availability of PDS in plastic bags, Oreopoulos et al. [14] from Toronto Western Hospital developed a meticulous protocol for CAPD.
Introduction of Y Set in PD
Italian investigators led by Umberto Buoncristiani were unable to reproduce lower peritonitis rates in their PD patients despite adopting the Toronto Western Hospital CAPD protocol. They subsequently observed that with the use of a “Y” set and “flush before fill” technique, the possibility of contamination occurring during the spiking of bags could be significantly reduced [15]. As a result of this technique, they noticed a significant reduction in peritonitis rates. Although it took several years for investigators to adopt the “Y-set,” it has proven to be the single most significant factor in preventing peritonitis in CAPD patients (from 1 every 3–4 patient-months to 1 every 30–35 patient-months) [15].
PD Dose
During early days of PD, the dose of PD was primarily determined by plasma chemistry, anemia indices, and clinical parameters. PD was often prescribed for 10 h for few days of the week. In the 1980s, Popovich-Pyle introduced the concept of mass transfer area coefficient that calculated the maximum theoretical clearance of a solute by diffusion [16]. In the 1990s, Haraldsson [17] re-examined urea kinetics in PD. This research was seminal in leading to the development of guidelines underscoring the minimal urea clearance necessary for PD, thus providing guidance on dialysis dosing in PD. Later, Bargman et al.’s [18] reanalysis of the CANUSA study highlighted the importance of residual renal function in determining patient outcomes in PD.
Over the last few years, there has been a re-emergence of the concept of incremental PD, it not only provides adequate dialysis but also emphasizes the importance of preservation of residual renal function and minimizes therapy burden [19]. Progressive loss of residual renal function adversely impacts the clearance of middle and large molecules. A majority of patients have to switch to hemodialysis once they become anuric. This is especially relevant in those on continuous PD with maximum prescribed fluid volumes. In this context, the concept of Continuous-Flow PD (CFPD), first described by Shinaberger et al. [20] becomes relevant. CFPD offers a mode of PD with a continuous flow-through of dialysate into and out of the peritoneal cavity. This technique requires either 2 PD catheters or a double-lumen catheter. Dialysate is infused through one port and is simultaneously drained from the second. Table 2 summarizes the advantages and disadvantages of this modality. Detailed reviews can be found elsewhere [21].
Table 2. Continuous-Flow Peritoneal Dialysis (CFPD): advantages and disadvantages, adapted from Ref. [21]
Unplanned and Urgent Start PD
Approximately, 30–40% patients (in North America, Europe) start dialysis without a functioning permanent access, that is, an arteriovenous fistula or a PD catheter. A sudden deterioration in renal function due to superimposed acute kidney injury with subsequent non-recovery, lack of in-depth discussions between the patients and nephrology team regarding “personalized best fit modality,” and inadequately functioning arteriovenous fistula at the start of hemodialysis lead to increased use of intravenous catheters for dialysis (a major determinant of morbidity and mortality in ESRD). Several studies across the world [22–24]