How To Calculate Peritoneal Dialysis Exchange
Clin J Am Soc Nephrol. 2018 Mar 7; thirteen(3): 483–485.
Crafting the Prescription for Patients Starting Peritoneal Dialysis
Keywords: peritoneal dialysis, Humans, renal dialysis, Prescriptions, Kidney Failure, Chronic
Introduction
At present, approximately 10%–11% of patients with ESKD worldwide choose to perform peritoneal dialysis (PD). Whereas the initial hemodialysis prescription tends to exist relatively compatible and standardized, the initial PD prescription lends itself to a more individualized arroyo. In this article, an initial approach to the prescription of PD is discussed.
Deciding on a PD Modality
Equally a first step, the patient must make up one's mind whether to practise PD in a style that uses strictly manual exchanges, known equally continuous ambulatory PD (CAPD), versus i using a cycler, known as automated PD (APD). The physician can assist the patient with this decision past assessing the responses to the following questions:
-
Must his/her dialysis be arranged around a work schedule and, if so, what are the piece of work hours?
-
Is the patient comfy with the use of mechanism or would s/he prefer a strictly manual method?
-
When does he/she commonly go to sleep and ascend?
-
Is s/he willing to exist connected to a machine, and therefore exist "tethered" in place for an hour or ii before and/or after usual sleep hours?
The medico and patient must work together to design a prescription that best fits the patient's lifestyle and achieves the desired clinical goals. The ensuing discussion addresses some of the factors to consider in crafting this prescription.
Considerations Regarding the Initial PD Prescription
Deciding on Timing and Duration of Handling, Dwell Volume, and Number of Cycles
The timing and duration of treatment should be tailored to the individual patient's lifestyle, matching the patient'southward wake–sleep pattern and all-around the demand to keep employment. Rarely exercise patients sleep more 8 hours; an APD prescription that ties the patient down for longer periods may crusade him/her to retire for the evening early on and lose precious family time. Similarly, the patient who wishes to continue working should not be expected to perform a manual exchange during work hours.
Patients are by and large able to tolerate intraperitoneal volumes of one.25–1.5 L/m2 BSA. As intraperitoneal force per unit area is lowest when supine, intermediate when erect, and highest when sitting, patients will often tolerate larger volumes when recumbent at night than when upright during the day (i). Dwell volumes need not be prescribed in increments of 0.v Fifty. Patients performing CAPD can estimate volumes of intermediate volume and the currently available cyclers for APD can hands exist programmed to deliver volumes in increments of 0.i L. Note that increasing fill book is often preferred past the patient over increasing the number of dwells and has a greater effect on increasing small-scale solute clearance.
Intendance should be taken non to prescribe more than four or 5 exchanges per APD session. Each exchange requires xv minutes (at to the lowest degree) of drain and fill time, during which no dialysis occurs. Furthermore, although beneficial for small solute clearance, rapid exchanges adversely affect clearance of sodium (due to sodium sieving), phosphorus, and center molecules.
Incremental PD
Although the definition of incremental PD varies between authors, the term generally refers to the practise of using balance kidney function (RKF) to attain the total desired solute removal, and initially prescribing but a modest dose of PD. This may take any of several forms: prescribing a smaller total volume of fluid (east.grand., only ii or iii CAPD exchanges daily); using only part of the day (e.one thousand., nocturnal APD with a dry twenty-four hour period); or performing PD for fewer than 7 days per calendar week (2). Many patients observe this a more acceptable manner to begin RRT and, in fact, this may attract some patients to PD in the first place. Kinetic simulation of incremental PD demonstrated that patients with a GFR equally low as 4–v ml/min per 1.73 g2 could be successfully managed in this fashion (3). Equally RKF declines the PD prescription may be increased incrementally as needed to farther augment solute clearance. Recent reports regarding the employ of incremental dialysis accept demonstrated skilful clinical outcomes (two,four).
Some patients initiate RRT because of volume overload rather than the need for solute clearance. They may often be managed with just two or three dextrose-based exchanges overnight. Keeping the patient dry during the solar day has the advantage of avoiding the risk of fluid absorption during the long day dwell. Even more simply, some patients volition reach the boosted ultrafiltration needed with the use of a unmarried long dwell of icodextrin, which may exist done manually and, at the patient'southward discretion, may be performed during the day or overnight. As the patient becomes resistant to increasing doses of diuretics, the PD prescription is increased as needed to further broaden book removal.
Estimating the Minimum Necessary Dialysis Dose to Achieve Acceptable Small Solute Clearance
Recognizing that Kt/5urea is an imperfect mensurate of dialysis adequacy, information technology may nonetheless be useful equally a starting point from which to estimate the initial volume of dialysis fluid to prescribe (5). Standardized weekly Kt/Vurea in PD is expressed as:
(1)
in which Durea and Purea are the urea concentrations measured in dialysate and plasma respectively; DV, the bleed book per day, is the algebraic sum of the instilled volume and net ultrafiltration; and Vdurea, the volume of distribution of urea, is assumed to be total body water (TBW). Let united states of america examine the application of this equation in two scenarios: patients without or with significant RKF.
A. The Patient with Well-nigh No RKF.
Let u.s.a. begin by because an anuric patient, for example, a patient who has failed hemodialysis. Recall that the target for weekly Kt/Vurea recommended past the International Club for Peritoneal Dialysis is 1.7 (6). Therefore, the daily Kt/V would need to exist i seventh of this, or 0.243; for the sake of simplicity, this may be rounded to 0.25. Thus, for daily Kt/Five to equal 0.25, the post-obit relationship pertains:
(2)
The maximum ratio of Durea/Purea obtainable is i. Although not achieved in practice (certainly not when performing APD with multiple short dwells) if we assume this to exist the case, the DV needed to achieve the daily Kt/V of 0.25 is then equal to 0.25TBW (note that using the common approximation that TBW=0.6×weight [kg] will generally overestimate TBW, thereby partially compensating for the overestimate of D/Purea). This value, minus some arbitrarily selected value for net ultrafiltration (1 L is a reasonable first approximation), would and then be the minimum volume of dialysis fluid i could prescribe and promise to have adequate small solute removal. So, if our patient weighs eighty kg, we would estimate an initial prescription of at least 11 L of dialysis fluid ([80×0.six×0.25] − one). Therefore, we might initially prescribe four nightly exchanges of 2.5 L each and a last fill of 1 L.
B. The Patient with Significant RKF.
For the patient coming to PD with RKF, this approach may be adapted by measuring the daily residual urinary Kt/Five (Uurea/Purea×urine volume/TBW), subtracting the resulting value from 0.25, and using this number instead of 0.25 in Equation two to solve for DV. So, if the same eighty kg patient has a plasma urea of l mg/dl and produces one L of urine daily with a urea concentration of 240 mg/dl, the daily residue urinary Kt/Vurea would be (240/50×1/48)=0.1. Subtracting this from 0.25 so substituting 0.15 in place of 0.25 in Equation 2 yields an estimate of seven.2 L for the needed DV. Assuming the same 1 50 of daily UF one would need a dose of just 6.2 50 of dialysate; one might therefore prescribe just three nightly exchanges of 2.one Fifty each. This approach may feel cumbersome at kickoff only, once used with frequency, becomes easy to apply and applied.
Other Considerations
Urgent Start PD
Urgent first PD—the initiation of PD within two weeks of catheter placement in a patient with no prior planned RRT—has become increasingly prevalent in the past few years. Because of the concern of leakage effectually a newly placed catheter, the volume of fluid infused is generally smaller than for standard PD. The volume is tailored to body size: 1 algorithm is for patients with body surface expanse <i.65 m2 to brainstorm with 750 ml; those up to 1.8 thoutwo, yard ml; and larger patients receive 1250 ml. The total dialysis time and number of exchanges may be adjusted depending on the caste of residuum GFR and the severity of uremic signs or symptoms (seven).
Tidal PD
Some patients may feel discomfort in the pelvic/rectal region when draining. This is likely due to the catheter approaching and irritating the rectum or other next viscus every bit intraperitoneal volume decreases. This awareness generally diminishes over time but may be problematic early on in the course of PD, particularly in patients on APD who are attempting to sleep during the performance of their dialysis. The solution may be to use tidal PD. In tidal PD, the abdomen is non fully drained at the end of each dwell. Rather a residual volume (ordinarily 15%–25%) is kept in the abdomen at the terminate of each dwell as a cushion; this helps to prevent the catheter from irritating a viscus. Apparently, the dialysate and ultrafiltrate cannot continue to accumulate indefinitely and must be drained at some bespeak; this is done in the morn when the patient is awake and therefore more tolerant of the discomfort.
Is CAPD Preparation Necessary for Patients on APD?
One question often raised regarding PD training relates to the need for preparation in manual exchange techniques (CAPD) for patients who cull to perform APD. The argument has been fabricated that if patients are not trained in the performance of manual exchanges, they volition be incapable of dialyzing in the consequence of a natural disaster such as a hurricane or tornado, during which electrical power is lost. Although there is some merit to this concern, it should be recognized that patients on APD are trained to bleed and disconnect manually. The inability to connect manually and perform CAPD exchanges is generally not problematic every bit patients can commonly safely tolerate a day or ii without dialysis (recollect that patients on hemodialysis get nearly 72 hours without dialysis over the weekend), past which fourth dimension power will almost certainly have been restored. Note likewise that training in APD only is standard in areas where assisted APD is available.
Timing of the Start Peritoneal Equilibration Exam
Contempo data indicates that peritoneal transport status has prognostic value regarding mortality and frequency of hospitalization (8). However, considering transport characteristics may alter during the first few weeks on PD, the peritoneal equilibration examination is mostly non performed until the patient has been on PD for four–vi weeks (9). Therefore, results of the peritoneal equilibration test are not used in formulating the initial PD prescription. That said, the astute clinician, and very unremarkably the acute PD nurse, may notice that a patient has negative ultrafiltration (i.e., absorbs fluid) during a long dwell, suggesting that southward/he is a rapid transporter. The prescription should then be modified to avoid this if better ultrafiltration is needed. The contempo availability of remote monitoring of PD treatments allows for adjustment of prescriptions fifty-fifty when the patient is not physically present in the clinic.
A Concluding Thought
"(T)he secret of the intendance of the patient is in caring for the patient" (10). We must pay careful attending to the patient'southward lifestyle and his/her needs and desires. Coupled with the advisable application of physiology and sound medical judgement, this will culminate in a prescription that meets the patient'southward clinical needs and is one with which s/he is able to comply.
Footnotes
Published online alee of impress. Publication date available at www.cjasn.org.
References
ane. Twardowski ZJ, Prowant BF, Nolph KD, Martinez AJ, Lampton LM: High book, low frequency continuous ambulatory peritoneal dialysis. Kidney Int 23: 64–70, 1983 [PubMed] [Google Scholar]
2. Ankawi GA, Woodcock NI, Jain AK, Garg AX, Blake PG: The use of incremental peritoneal dialysis in a large contemporary peritoneal dialysis program. Can J Kidney Health Dis 3: 1–seven, 2016 [PMC free article] [PubMed] [Google Scholar]
iii. Guest S, Leypoldt JK, Cassin One thousand, Schreiber Grand: Kinetic modeling of incremental ambulatory peritoneal dialysis exchanges. Perit Dial Int 37: 205–211, 2017 [PubMed] [Google Scholar]
four. Sandrini One thousand, Vizzardi V, Valerio F, Ravera S, Manili 50, Zubani R, Lucca BJ, Cancarini G: Incremental peritoneal dialysis: A 10 year single-centre feel. J Nephrol 29: 871–879, 2016 [PMC gratuitous article] [PubMed] [Google Scholar]
5. Perl J, Dember LM, Bargman JM, Browne T, Charytan DM, Flythe JE, Hickson LJ, Hung AM, Jadoul Thou, Lee TC, Meyer KB, Moradi H, Shafi T, Teitelbaum I, Wong LP, Chan CT; American Order of Nephrology Dialysis Advisory Group: The use of a multidimensional measure of dialysis adequacy- moving beyond small-scale solute kinetics. Clin J Am Soc Nephrol 12: 839–847, 2017 [PMC free article] [PubMed] [Google Scholar]
6. Lo WK, Bargman JM, Burkart J, Krediet RT, Pollock C, Kawanishi H, Blake PG; ISPD Adequacy of Peritoneal Dialysis Working Grouping: Guideline on targets for solute and fluid removal in developed patients on chronic peritoneal dialysis. Perit Dial Int 26: 520–522, 2006 [PubMed] [Google Scholar]
7. Ghaffari A, Kumar V, Guest S: Infrastructure requirements for an urgent-get-go peritoneal dialysis program. Perit Dial Int 33: 611–617, 2013 [PMC free article] [PubMed] [Google Scholar]
eight. Mehrotra R, Ravel 5, Streja Due east, Kuttykrishnan S, Adams SV, Katz R, Molnar MZ, Kalantar-Zadeh K: Peritoneal equilibration exam and patient outcomes. Clin J Am Soc Nephrol 10: 1990–2001, 2015 [PMC free article] [PubMed] [Google Scholar]
nine. Johnson DW, Mudge DW, Blizzard S, Arndt G, O'Shea A, Watt R, Hamilton J, Cottingham Due south, Isbel NM, Hawley CM: A comparison of peritoneal equilibration tests performed 1 and iv weeks after PD showtime. Perit Punch Int 24: 460–465, 2004 [PubMed] [Google Scholar]
10. Peabody FW: Landmark commodity March xix, 1927: The care of the patient. By Francis Westward. Peabody. JAMA 252: 813–818, 1984 [PubMed] [Google Scholar]
Manufactures from Clinical Journal of the American Social club of Nephrology : CJASN are provided here courtesy of American Society of Nephrology
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5967680/
0 Response to "How To Calculate Peritoneal Dialysis Exchange"
Post a Comment