CHAPTER MISSION Build the first PD prescription from clinical goals and physiology: decide when dialysis is truly needed, measure what the kidneys still contribute, select CAPD or APD deliberately, choose fill volume/dwell/exchange number/osmotic strategy, protect a new catheter during urgent start, and reassess early enough that an initial prescription never becomes an unexamined permanent prescription.

Figure 6.1 — The initial PD prescription control panel.

Every prescription combines fill volume, dwell time, exchange frequency, osmotic strength and modality. Changing one lever can improve one target while worsening glucose exposure, intraperitoneal pressure or treatment burden.

MASTER PRINCIPLE The correct initial prescription is not the largest prescription that achieves a clearance number. It is the least burdensome prescription expected to meet the person’s current clinical goals safely, with an explicit plan for escalation as residual kidney function, membrane behavior and life circumstances change.

0. One-page chapter map

Table 6.1 — The eight decisions that govern a safe PD start.

Decision	Core question	Bedside output
1. Need	Why does this person need dialysis now?	Clinical indication, not eGFR alone
2. Readiness	Is the catheter, patient, home and training pathway ready?	Safe start pathway
3. Kidney contribution	What urine volume and residual clearance remain?	Incremental vs fuller starting dose
4. Modality	Does CAPD or APD fit physiology and life better?	Named modality architecture
5. Dose architecture	What fill, dwell, exchanges and total volume are required now?	Initial prescription
6. Volume plan	How will sodium and water balance be achieved?	Osmotic + diet/diuretic strategy
7. Urgency	Is this a traditional start or urgent start?	Access-protection protocol
8. Verify	Did the delivered treatment achieve the goals without excess burden?	Early reassessment + escalation trigger

Learning outcomes

Initiate dialysis using a composite clinical assessment rather than an isolated eGFR threshold.
Build an initial PD prescription from patient goals, body size, residual kidney function, volume status and expected membrane physiology.
Distinguish the physiologic strengths and limitations of CAPD and APD at the start of therapy.
Choose fill volume, dwell duration, exchange number and osmotic strategy by mechanism and trade-off.
Use incremental PD deliberately when residual kidney function and clinical goals permit, with an explicit escalation plan.
Use weekly Kt/V urea as a small-solute metric without confusing it with the total definition of high-quality dialysis.
Start PD urgently with a fresh catheter using a low-pressure strategy and recognise when urgent HD or another modality is safer.
Reassess the first prescription using symptoms, volume/sodium balance, urine, laboratory trends, treatment delivery and burden.

EVIDENCE POSTURE KDIGO 2024 recommends starting dialysis from a composite assessment of symptoms, signs, quality of life, preferences, GFR and laboratory abnormalities. ISPD 2020 reframes PD as high-quality goal-directed care, while the 2019 solute/fluid update retains weekly Kt/V ≥1.7 mainly as a low-certainty practice point, especially for anuric adults. Incremental PD is supported as a person-centred strategy when residual kidney function is meaningful, but comparative evidence remains heterogeneous. Urgent-start PD can avoid temporary HD in selected patients but carries increased mechanical-risk concerns and requires a protected low-pressure start. [1–8]

1. Starting dialysis is a clinical transition—not an eGFR event

The decision to start PD begins before a bag is chosen. KDIGO 2024 states that dialysis initiation should be based on the combined pattern of symptoms, signs, quality of life, patient preferences, kidney function and laboratory abnormalities. The relevant clinical question is therefore not “Has the eGFR fallen below X?” but “Has kidney failure created a problem that cannot be acceptably controlled without kidney replacement therapy?” [1]

Table 6.2 — Findings that can make dialysis clinically necessary.

Domain	Examples	Why it matters
Uremic syndrome	Anorexia, nausea, fatigue, cognitive/neurologic symptoms, serositis/pruritus in context	Signals toxin/physiologic burden not controlled conservatively
Volume/BP	Persistent congestion or hypertension despite optimized medical therapy	Dialysis may be required for sodium/water control
Electrolyte/acid-base	Medically resistant hyperkalaemia or acidosis	Immediate safety issue
Nutrition	Progressive nutritional deterioration despite appropriate intervention	Kidney failure may be driving catabolism/intake failure
Quality of life / goals	Symptoms or treatment burden unacceptable to the person	Patient-centred indication

THRESHOLD DISCIPLINE KDIGO notes that dialysis often—but not invariably—begins when GFR is approximately 5–10 mL/min/1.73 m². This is descriptive context, not a stand-alone trigger. [1]

2. Before the first exchange: define the baseline

Table 6.3 — Pre-start baseline dataset.

Domain	What to document	Prescription consequence
Clinical indication	Symptoms, volume, BP, potassium, bicarbonate, nutrition	Defines the problem the prescription must solve
Urine/RKF	24-h urine volume and residual clearances when feasible	Determines how much support kidneys still provide
Body size	Weight, body surface area context, abdominal tolerance	Influences fill and clearance requirement
Access	Catheter function, wound, leak risk, break-in interval	Traditional vs urgent-start pathway
Home/training	Technique competence, caregiver support, supplies, cycler readiness	CAPD/APD feasibility and safety
Lifestyle goals	Work, sleep, travel, treatment burden priorities	Modality architecture
Volume inputs	Dietary sodium, fluid intake, diuretic use if responsive	Avoids solving intake problems only with glucose

BEDSIDE TRANSLATION Write the initial prescription only after writing the clinical targets. A prescription without named targets cannot be judged successful or unsuccessful.

3. The prescription is a set of physiologic levers

Chapter 1 established the transport physiology. At initiation, the same five levers are converted into a practical order: fill volume, dwell time, number of exchanges, osmotic agent/strength and modality timing. Each lever changes more than one outcome.

Table 6.4 — Lever → intended effect → cost.

Lever	Potential benefit	Trade-off / failure mode
Fill volume ↑	More effective contact area and per-exchange clearance	Higher intraperitoneal pressure, discomfort, leak/hernia risk
Dwell longer	More small-solute equilibration	Glucose gradient decays; long dwell may lose UF in rapid transport
More exchanges	Renews gradients; increases daily clearance	More burden, connections and glucose exposure
Stronger glucose	More crystalloid osmotic force	More glucose absorption/exposure
Icodextrin long dwell	Sustained long-dwell UF	Specific monitoring/safety issues; not a short-dwell substitute
APD	Shorter repeated nocturnal cycles; scheduling flexibility	Short dwells may limit slower-solute equilibration; alarms/sleep burden
CAPD	Longer stable dwells; simple technology	Daytime exchanges and connection burden

4. CAPD or APD for the initial architecture

Figure 6.2 — CAPD and APD: two timing architectures.

CAPD and APD use the same membrane and osmotic principles. The choice changes when and how often gradients are created, not the fundamental physics.

Table 6.5 — Starting architecture: CAPD versus APD.

Question	CAPD may fit when…	APD may fit when…
Daily-life pattern	Daytime exchanges are acceptable	Night-time treatment better preserves daytime activity
Dwell physiology	Longer dwells likely to work well	Shorter cycles may better fit rapid transport or nocturnal schedule
Technology	Simple gravity system preferred	Cycler competence/support available
Sleep	Night free of machine preferred	Machine sleep burden acceptable
Assistance	Manual exchange support available	Caregiver/remote support favors cycler workflow

DO NOT AUTOMATE APD is not intrinsically “stronger” dialysis and CAPD is not an inferior fallback. Match timing architecture to transport, RKF, volume target and the person’s life.

5. Fill volume: enough contact, not unnecessary pressure

Initial fill volume should be individualized. Larger volumes can recruit effective peritoneal surface area and increase per-exchange clearance, but also increase intraperitoneal pressure. Body habitus, comfort, hernia/leak risk, respiratory tolerance and a fresh catheter matter. A new urgent-start catheter is a different pressure environment from a healed chronic catheter.

Table 6.6 — Fill-volume reasoning.

Finding	Interpretation	Action direction
Comfortable, healed access, larger body size	Potential to tolerate standard/larger fills	Titrate to clearance/volume need
Pain, dyspnoea, reflux, leak or hernia concern	Pressure burden may be excessive	Reduce fill and reassess cause
Urgent start / fresh catheter	Leak risk is amplified by pressure	Use lower volumes and recumbent position
Low clearance with small fills	Surface-area recruitment may be inadequate	Increase volume if anatomically tolerated

6. Dwell time: decide what you want the dwell to accomplish

Figure 6.3 — What changes during a glucose dwell.

Dwell time is a trade between solute equilibration and preservation of osmotic force.

Table 6.7 — Dwell-time mismatch patterns.

Pattern	Mechanism	Prescription implication
Short dwell + poor creatinine/urea equilibration	Insufficient time for diffusion	Lengthen dwell or increase exchange strategy when clinically needed
Long glucose dwell + poor UF in rapid transport	Glucose absorbed before drain	Shorter glucose dwell and/or long-dwell icodextrin strategy
Long dwell + good clearance + good UF	Appropriate match	Do not change because another patient uses a different schedule
APD many very short cycles + biochemical shortfall	Too little effective dwell time	Reassess cycle number, fill, total time and daytime component

7. Exchange number and total dialysate volume

Increasing exchanges renews concentration gradients and usually increases peritoneal small-solute clearance. The correct starting number is therefore not a ritual four exchanges for every CAPD patient or a fixed cycler program for every APD patient. It is the number required to achieve current goals at acceptable burden, taking RKF into account.

Table 6.8 — Before adding exchanges, ask why.

Problem	First question	Why blindly adding exchanges may fail
High urea/creatinine burden	Is delivered treatment complete and RKF falling?	Missed treatments or RKF loss may be the actual event
Edema	Is sodium/volume removal the dominant problem?	More low-osmotic exchanges may add clearance without enough net sodium/water removal
Poor APD clearance	Are dwells too short?	More cycles can make each dwell even shorter
High burden	Could a smaller incremental schedule meet goals?	Full-dose treatment may be unnecessary while RKF is substantial

8. Osmotic prescription: water removal is a separate target

The osmotic component of the prescription should be designed from sodium and volume needs, not from small-solute clearance alone. Glucose concentration should be the minimum needed to achieve the intended UF pattern, alongside dietary sodium management, fluid intake assessment and diuretics when residual urine is responsive. Icodextrin is physiologically suited to a long dwell when sustained UF is needed. [2,3]

Table 6.9 — Osmotic strategy by clinical problem.

Clinical problem	Physiologic direction	Trade-off
Euvolemic with useful urine	Avoid unnecessary hypertonicity	Preserves lower glucose exposure
Mild chronic positive balance	Review sodium/intake and diuretic response first	May avoid escalating glucose
Long-dwell UF failure from rapid glucose absorption	Consider sustained long-dwell osmotic strategy	Requires correct agent use and monitoring
Acute congestion	Increase water/sodium removal safely	Avoid chronic hypertonic rescue becoming permanent default

9. Residual kidney function changes the starting dose

Figure 6.5 — Total kidney replacement support.

A person starting PD often receives substantial continuous clearance and sodium/water excretion from their own kidneys in addition to PD.

Residual kidney function is not simply an extra line in the adequacy calculation. It contributes continuous solute excretion, sodium and water removal and has a strong association with outcomes. Therefore a patient with substantial RKF may require less peritoneal dialysis initially than an otherwise similar anuric patient.

Table 6.10 — What RKF changes at the bedside.

If RKF is…	Initial implication	What must be monitored
Substantial and stable	Incremental regimen may meet goals	Urine, residual clearance, symptoms, volume, labs
Falling	The same PD prescription becomes a smaller total therapy	Escalation trigger and repeat total assessment
Minimal/absent	PD carries nearly all clearance/volume responsibility	Fuller prescription; Kt/V and UF context become more important
Uncertain	Do not guess	Measure urine volume and residual clearance when feasible

10. Incremental PD: start with what is needed now

Figure 6.4 — Incremental PD is a staircase, not a permanently low dose.

Incremental treatment requires planned escalation. Without monitoring, “incremental” becomes inadvertent underdialysis.

ISPD goal-directed prescribing supports incremental PD as a way to reduce treatment burden when residual kidney function and clinical state make a lower peritoneal dose sufficient. Evidence comparing incremental with standard-dose PD suggests broadly similar survival and technique outcomes in selected incident patients, but definitions vary and evidence for better RKF preservation is inconsistent. A balANZ analysis found similar slopes of RKF and urine decline with incremental and full-dose starts. [2,6,7]

Table 6.11 — Incremental PD is appropriate only if all four elements exist.

Element	Requirement
Clinical suitability	No uncontrolled uremic, electrolyte, nutritional or volume indication requiring greater dose
Kidney contribution	Meaningful RKF/urine documented
Monitoring	Scheduled reassessment of urine, residual clearance and clinical goals
Escalation plan	Predefined triggers to add exchanges, days, volume or modality intensity

COMMON TRAP “Incremental” describes a monitored strategy. A low prescription without measurement and escalation is simply an unverified prescription.

11. Small-solute clearance: useful metric, incomplete definition

The 2019 ISPD solute/fluid update concluded that available studies support weekly Kt/V urea of at least 1.7, especially in anuric adults, but explicitly graded this as a low-certainty practice point. The 2020 goal-directed recommendations emphasize that this number should not replace assessment of symptoms, volume, nutrition, biochemical control, RKF and treatment burden. [2,3]

Table 6.12 — How to use Kt/V without misusing it.

Use it to…	Do not use it to…
Quantify small-solute removal	Declare the whole patient “adequately dialyzed”
Detect change after RKF loss or prescription change	Ignore congestion or symptoms because target is met
Support dose adjustment in anuric/low-RKF states	Force unnecessary exchanges in a clinically well person with significant RKF
Verify delivered rather than merely prescribed dialysis	Assume peritoneal and renal clearance have identical biological value

KEY NUMBER Weekly Kt/V urea ≥1.7 remains a commonly used small-solute practice point, especially for anuric adults; it is not a complete definition of high-quality PD. [3]

12. Volume and sodium: prescribe the patient, not the drain bag

Table 6.13 — Initial volume assessment.

Data	Question	Meaning
Weight trend	Is there a credible baseline/dry-weight trajectory?	Detects cumulative balance
Blood pressure	Is BP rising with congestion or driven by another mechanism?	Supports but does not prove volume excess
Edema / lungs / symptoms	Is there clinical congestion?	Patient-important target
Net PD UF	What does the peritoneum remove?	Only one part of total output
Urine volume	What do kidneys still remove?	Critical early in PD
Sodium/fluid intake	Is input overwhelming a reasonable prescription?	Prevents glucose-only escalation

13. Traditional start versus urgent-start PD

A conventional break-in period after catheter insertion reduces mechanical stress on the new access. Urgent-start PD generally refers to commencing within 14 days of catheter placement. SAGES 2023/2024 suggests traditional start over urgent start in adults when clinically feasible, based on very low-certainty evidence; however, urgent-start PD remains an important strategy when dialysis cannot wait and avoidance of a temporary HD catheter is desirable. [4,5,8]

Flowchart 6.2 — Urgent-start PD.

A fresh catheter should be treated as a vulnerable wound-access system. Lower fill volumes and recumbent exchanges reduce intraperitoneal pressure while dialysis intensity is built according to clinical need.

Table 6.14 — Urgent-start priorities.

Priority	Bedside principle
Patient safety	Do not force PD if severe instability or an indication requires a faster/more controllable modality
Catheter protection	Recumbent position and low fill volumes initially
Clearance	Use repeated exchanges according to biochemical/uremic need
Volume	Select osmotic strength according to congestion while limiting pressure burden
Leak surveillance	Inspect wound and drain pattern; abdominal wall/genital swelling may indicate leak
Escalation	Increase fill/intensity as catheter/wound tolerance permits under local protocol

SAFETY BOUNDARY Exact urgent-start fill volumes, exchange schedules and escalation rates are protocol- and catheter-specific. This chapter teaches the low-pressure physiologic strategy; the treating unit’s urgent-start pathway and procedural team govern the exact regimen.

14. The elective start pathway

Flowchart 6.1 — Elective PD start.

A safe elective start links the clinical indication, healed/functional access, training readiness, baseline RKF/volume assessment, initial dose and an early verification plan.

Table 6.15 — First-prescription sign-off checklist.

Check	Pass criterion
Indication	Reason for dialysis start documented
Access	Catheter usable; wound status and break-in pathway known
Technique	Patient/caregiver demonstrates safe exchange/cycler workflow
RKF	Urine and residual contribution documented or measurement planned
Solute target	Clinical/laboratory goal and clearance measurement plan documented
Volume target	Weight/BP/UF/urine strategy documented
Burden	Regimen compatible with life goals where possible
Review	Early reassessment date and escalation triggers named

15. The first days and weeks: verify what was delivered

Figure 6.6 — The first-month prescription feedback loop.

The initial prescription is a testable hypothesis. Delivered treatment and patient response must close the loop.

Table 6.16 — Early follow-up data that change the prescription.

Finding	What it may mean	Next action
Missed exchanges / cycler bypass	Delivered dose lower than ordered	Solve workflow, alarm, burden or training issue before increasing prescription
Persistent edema	Insufficient total sodium/water removal or high intake	Assess urine, UF, dwell/osmotic strategy and intake
Weight falling + dizziness	Excess fluid removal / low intake	Reduce osmotic intensity; reassess target weight
Hyperkalaemia/acidosis persists	Insufficient total clearance or ongoing catabolic problem	Verify delivery/RKF and adjust dose as needed
Good clinical control + high burden	Possible opportunity for simplification if RKF/targets permit	Reassess incremental strategy

16. Clinical problem framework: “the initial prescription is not working”

Table 6.17 — Name the phenotype before changing therapy.

Phenotype	Think first	Typical next data
Uremic/biochemical	Delivered dose, RKF, dwell/volume, catabolism	Treatment log, urine, clearance, labs
Volume overloaded	Sodium/input, urine, UF, glucose-dwell match	Weight/BP, intake, urine, UF records
Too dry/hypotensive	Excess osmotic removal, low intake, diuretics	Weight, orthostasis, urine, UF
Pain/leak	Fill pressure, catheter/wound, hernia	Exam, volume relationship, imaging if needed
Drain alarms	Constipation, catheter position, kink, fibrin	Mechanical troubleshooting
Excess burden	Over-prescription, poor timing fit, cycler issues	Goal review + delivered-data review

17. Diagnostic reasoning framework

Flowchart 6.3 — Adjusting the initial prescription.

Start with the failing clinical target, identify the responsible mechanism, change the relevant lever and verify the response.

Table 6.18 — Clinical question → data → interpretation → action.

Clinical question	Data required	Interpretation	Action
Why is clearance poor?	Delivered therapy, RKF, dwell/volume, catheter	Dose vs delivery vs kidney loss vs mechanical issue	Correct mechanism; then increase dose if required
Why is volume poor?	Intake, urine, UF, dwell/agent, transport	Input/RKF/osmotic mismatch	Sodium strategy + osmotic/dwell adjustment
Why is patient intolerant?	Fill symptoms, pressure-related features, schedule burden	Volume/geometry vs lifestyle problem	Reduce fill/change schedule/modality architecture
Why did status change suddenly?	Adherence, catheter, constipation, intercurrent illness	Acute delivery/mechanical/clinical event	Do not assume gradual membrane failure

18. Management framework: change the lever that matches the mechanism

Table 6.19 — Problem → mechanism → change → reassess.

Problem	Likely mechanism	Prescription/management direction	Reassess
Low small-solute clearance	Insufficient dialysate-time/volume or RKF loss	Increase effective volume, dwell or exchanges after verifying delivery	Symptoms, labs, clearance
Poor long-dwell UF	Rapid glucose absorption	Shorten glucose dwell / appropriate long-dwell icodextrin	UF, weight, BP
General volume overload	Positive sodium/water balance	Diet/diuretic strategy + osmotic prescription	Weight, edema, BP, urine, UF
High treatment burden	More PD than current needs or schedule mismatch	Simplify/incremental strategy if goals remain met	Clinical control + RKF
Leak/pain after start	Excess intraperitoneal pressure or access issue	Reduce fill/hold-escalation; evaluate access	Symptoms, wound, drainage

19. Retention tables

Table 6.20 — Prescription lever fingerprints.

If you change…	You mainly influence…	Remember…
Fill volume	Per-exchange surface area/clearance and pressure	Pressure cost
Dwell time	Equilibration vs osmotic decay	Longer is not always better
Exchange number	Gradient renewal and total clearance	Connection/burden cost
Glucose strength	Crystalloid UF	Metabolic/membrane exposure
Long-dwell icodextrin	Sustained long-dwell UF	Different osmotic mechanism
CAPD↔︎APD timing	Distribution of dwell lengths	Same physiology, different schedule

Table 6.21 — What not to confuse.

Do not confuse	With	Correction
eGFR level	Dialysis indication	Use composite clinical assessment
Prescribed volume	Delivered dialysis	Check logs/technique
Peritoneal UF	Total fluid removal	Include urine
Kt/V target	Whole-person adequacy	Assess symptoms/volume/nutrition/goals
Incremental PD	Underdialysis	Requires monitoring + escalation
Urgent start	Full chronic prescription immediately	Use low-pressure protected start

20. Clinical pearls

The first prescription should have a reason for every exchange.
An unchanged PD prescription becomes a smaller total therapy when residual kidney function falls.
If the problem is edema, increasing urea clearance may not solve it.
If APD clearance is poor, adding more cycles can paradoxically shorten dwells further.
Use the least glucose exposure that safely achieves volume goals.
A fresh catheter converts fill volume into a wound-pressure decision.
Incremental PD is safest when the escalation trigger is written on day one.
The patient who cannot live with the prescription is not receiving high-quality dialysis even if the machine reports perfect delivery.

21. Common pitfalls—and the correction

Table 6.22 — High-frequency errors at PD initiation.

Pitfall	Why it fails	Correction
Starting because eGFR crossed a number	Ignores symptoms, goals and treatable alternatives	Use composite KDIGO assessment
Giving every patient a full-dose template	Ignores RKF and burden	Individualize; consider incremental strategy
Treating edema by glucose escalation only	May ignore sodium intake/RKF/diuretics	Assess total sodium-water balance
Assuming ordered = delivered	Misses alarms, missed exchanges and technique problems	Review treatment logs
Using Kt/V as the only success endpoint	Misses congestion, symptoms and QoL	Goal-directed review
Urgent-start full-volume ambulatory fills	Raises intraperitoneal pressure and leak risk	Low-volume recumbent start under protocol
No escalation plan for incremental PD	Creates silent underdialysis as RKF falls	Schedule RKF/clinical reassessment
Changing several variables at once	You cannot learn which mechanism mattered	Change targeted lever when clinically safe

22. Mini-cases: prescription decisions, not arithmetic

Case 1 — Symptomatic kidney failure with substantial urine

A 59-year-old with progressive CKD has anorexia, fatigue and refractory acidosis but still passes 1.6 L urine/day. Catheter is healed and training complete.

REASONING Start PD because clinical indications are present, document RKF, and consider an incremental starting regimen that meets current biochemical/volume goals with a written escalation plan rather than reflex full-dose therapy.

Case 2 — Low eGFR, clinically well

A 48-year-old has eGFR 7 mL/min/1.73 m², good appetite, controlled potassium/bicarbonate and no congestion. PD catheter is ready.

REASONING Do not start solely because eGFR is 7. Continue close monitoring and start when composite clinical indications emerge, respecting patient preferences and readiness.

Case 3 — APD with edema but acceptable clearance

A new APD patient meets the small-solute target but gains weight, has ankle edema and little net daytime UF.

REASONING This is primarily a volume/sodium problem. Review sodium intake, residual urine/diuretics, dwell physiology and long-dwell osmotic strategy instead of simply adding cycles to raise Kt/V.

Case 4 — Incremental PD after urine falls

A patient started with fewer CAPD exchanges because RKF was substantial. Six months later urine has halved and phosphate, urea symptoms and edema are worsening.

REASONING The incremental plan has reached its escalation trigger. Re-measure total support and increase PD intensity according to the failing targets; do not call the original low prescription “stable.”

Case 5 — Urgent start after catheter insertion

A patient needs dialysis within 48 hours of catheter placement because of worsening uremic symptoms and volume overload but is hemodynamically stable.

REASONING If the local urgent-start pathway supports PD, use a protected low-pressure recumbent low-fill strategy with frequent reassessment for leak and drainage; exact volumes/schedule follow local protocol.

Case 6 — The prescription looks adequate but the patient skips therapy

A cycler download shows repeated bypassed drains and shortened nights because alarms disturb sleep. Serum indices are worsening.

REASONING This is delivered-dose failure. Fix catheter/constipation/alarm workflow and treatment burden before simply increasing the programmed dose.

23. Active recall

MUST MEMORIZE

Q: What determines when dialysis should start? A: Composite symptoms, signs, QoL, preferences, GFR and laboratory abnormalities—not eGFR alone.

Q: What are the five main PD prescription levers? A: Fill volume, dwell time, exchange number, osmotic agent/strength and timing modality.

Q: Why does RKF permit a smaller initial PD dose in selected patients? A: The kidneys still provide continuous solute, sodium and water removal.

Q: What weekly Kt/V urea practice point remains commonly used? A: At least 1.7, especially in anuric adults, with low-certainty evidence.

Q: What makes incremental PD safe? A: Documented RKF, adequate current clinical control, scheduled monitoring and an escalation plan.

Q: What is the core urgent-start principle? A: Minimise intraperitoneal pressure while delivering enough dialysis—typically recumbent low-volume exchanges under protocol.

MUST REASON

Q: Why can adding APD cycles reduce efficiency? A: More cycles can shorten each dwell, limiting equilibration.

Q: Why can good Kt/V coexist with edema? A: Small-solute clearance and sodium/water balance are different targets.

Q: Why is an unchanged prescription not an unchanged treatment? A: RKF, body state, adherence and membrane physiology can change.

Q: Why should a long glucose dwell sometimes be shortened? A: Rapid glucose absorption may dissipate the osmotic gradient before drain.

Q: Why should you verify delivery before increasing dose? A: A larger prescription cannot correct missed/bypassed therapy or a mechanical drain problem.

USE AS REFERENCE

Exact local starting templates, cycler programming, urgent-start fill-volume schedules, glucose strengths, clearance collection methods and medication/diuretic dosing should be taken from current unit protocols and manufacturer instructions rather than memorized from a generic chapter.

24. Flashcards

1. Q: Dialysis-start trigger? A: Clinical composite, not eGFR alone.

2. Q: Most valuable “invisible” part of an incident PD prescription? A: Residual kidney function.

3. Q: Incremental PD without reassessment becomes? A: Potential underdialysis.

4. Q: CAPD vs APD changes what? A: Timing architecture of the same transport levers.

5. Q: More exchanges do what? A: Renew concentration gradients and usually increase small-solute clearance.

6. Q: Longer glucose dwell always better? A: No—osmotic force can dissipate.

7. Q: Net PD UF equals total fluid output? A: No—include urine.

8. Q: Kt/V is mainly a measure of? A: Small-solute urea clearance.

9. Q: Why use low fills in urgent start? A: Reduce intraperitoneal pressure and leak risk.

10. Q: First action when prescribed dose seems inadequate? A: Confirm delivered treatment and RKF.

11. Q: Volume overload + good Kt/V means? A: Treat sodium/water problem, not the number.

12. Q: Good initial prescription endpoint? A: Goals met with acceptable burden and a clear reassessment plan.

13. Q: What does stronger glucose buy? A: More crystalloid osmotic force at greater glucose exposure.

14. Q: Icodextrin is primarily useful for? A: Sustained long-dwell ultrafiltration.

15. Q: What ends an incremental phase? A: Failure of clinical/clearance/volume goals or sufficient RKF decline.

16. Q: What should every prescription change include? A: A reason and a reassessment endpoint.

17. Q: Urgent-start definition commonly used? A: PD begun within 14 days of catheter insertion.

18. Q: First-month mindset? A: Prescribe → deliver → measure → adjust.

25. Rapid differential / troubleshooting table

Table 6.23 — When the new PD prescription disappoints.

If you see…	Think…	Do now…
Persistent uremic symptoms	Underdelivery, low dose, RKF loss, catabolism	Verify delivery/RKF; assess clearance and clinical cause
Edema + good small-solute indices	Sodium/water mismatch	Review intake, urine, UF and dwell/osmotic plan
Low drain volumes	Mechanical issue or low UF	Distinguish poor drainage from true UF failure
Pain/leak after fill	Excess pressure / fresh access issue	Reduce pressure exposure and assess catheter/wound
Cycler alarms + lost dwell time	Delivered prescription failure	Solve alarm mechanism; inspect constipation/catheter
Dizziness + large UF	Excess fluid removal	Reduce osmotic intensity and reassess target weight
Stable labs but overwhelming burden	Potential over-prescription / poor schedule fit	Revisit incremental or modality architecture

26. Final revision sheet

TEN TAKE-HOME RULES 1) Start dialysis for clinical need, not eGFR alone. 2) Measure what the kidneys still contribute. 3) Name the target before choosing the lever. 4) CAPD and APD are timing architectures, not different physiologies. 5) Fill volume trades clearance against pressure. 6) Dwell time trades equilibration against osmotic decay. 7) Incremental PD requires monitoring and escalation. 8) Kt/V is a small-solute metric, not the definition of adequate care. 9) Urgent-start PD protects the fresh catheter with a low-pressure strategy. 10) The initial prescription is a hypothesis—verify delivery and patient response.

Table 6.24 — One-minute bedside synthesis.

If you see…	Think…	Do now…
Symptoms despite apparently adequate order	Delivered dose/RKF change	Check logs, catheter, urine and labs
Weight gain/edema	Positive sodium-water balance	Assess intake + urine + UF + osmotic plan
High burden with strong RKF	Possible incremental opportunity	Confirm goals then simplify cautiously
Falling urine	Total therapy is shrinking	Reassess and escalate
Fresh catheter + urgent dialysis need	Leak-pressure risk	Low-volume recumbent urgent-start pathway
Good Kt/V, poor QoL	Adequacy is multidimensional	Revisit goals and prescription burden

FINAL MENTAL MODEL Need → readiness → residual kidney contribution → modality → fill/dwell/exchanges/osmotic plan → deliver → measure symptoms/volume/labs/urine → adjust → escalate as RKF falls.

Rapid oral viva

Explain why dialysis initiation cannot be defined by one eGFR threshold.
Build an initial PD prescription for a patient with substantial RKF and mild uremic symptoms.
A new APD patient is edematous but has adequate Kt/V. Talk through your next decisions.
Explain incremental PD and its mandatory safety conditions.
Walk through an urgent-start PD strategy after catheter placement.
A patient’s urine output falls by half without a prescription change. Explain why the total treatment has changed.

SCOPE BOUNDARY This chapter establishes how to start PD and construct the first prescription. Formal adequacy calculations and RKF quantification are developed in Chapter 7; detailed volume/sodium and ultrafiltration-failure management in Chapter 8; CAPD/APD optimization in Chapter 9; urgent-start operational scenarios in Chapter 17.

27. Selected authoritative references

1. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314. https://doi.org/10.1016/j.kint.2023.10.018.

2. Brown EA, Blake PG, Boudville N, et al. International Society for Peritoneal Dialysis practice recommendations: Prescribing high-quality goal-directed peritoneal dialysis. Perit Dial Int. 2020;40(3):244–253. https://doi.org/10.1177/0896860819895364.

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SOURCE NOTE Guideline status and key contemporary evidence were checked 2 September 2026. Exact cycler programs, glucose concentrations, urgent-start fill-volume schedules, break-in instructions, diuretic doses and clearance-collection procedures remain governed by current local protocols, catheter/device instructions and individual clinical assessment.