Metabolic Cost & Encapsulating

The contract between this chapter and the reader.

1. 1. Quantify the daily glucose load of PD and its metabolic consequences.
2. 2. Explain how glucose absorption drives weight gain, dyslipidaemia, and worse glycaemia.
3. 3. Recognise the paradox of glucose calories coexisting with protein-energy wasting.
4. 4. Apply glucose-sparing strategies to reduce the metabolic burden.
5. 5. Define encapsulating peritoneal sclerosis and its cocoon pathology.
6. 6. Identify the risk factors for EPS, with PD duration as the dominant one.
7. 7. Explain the two-hit pathogenesis linking chronic injury to the encapsulating phase.
8. 8. Diagnose EPS using clinical features and CT.
9. 9. Evaluate the management of EPS and the rationale for risk-stratified prevention.

A sixty-second reading. Each bullet stands alone.

• PD delivers a continuous glucose load — often in the order of 100 to 300 grams absorbed per day — with a real metabolic cost.
• That load causes weight gain, dyslipidaemia (especially high triglycerides), and worse glycaemic control.
• Glucose calories can suppress appetite, so metabolic burden and protein-energy wasting can coexist.
• Glucose-sparing strategies — icodextrin, amino-acid dialysate, and the lowest effective glucose strength — reduce the burden.
• Encapsulating peritoneal sclerosis is a rare but often fatal fibrosing cocoon that obstructs the bowel.
• The dominant risk factor is long PD duration; high glucose exposure, severe or recurrent peritonitis, and fast transport add to it.
• The two-hit model: chronic membrane injury primes the peritoneum, and a second inflammatory hit — severe peritonitis, stopping PD, or transplantation — triggers encapsulation.
• EPS often declares itself after PD has stopped or after transplantation.
• It presents as bowel obstruction with weight loss, sometimes with bloody effluent and ultrafiltration failure.
• CT is the key test: peritoneal thickening, calcification, bowel tethering, and loculated fluid.
• No single test reliably predicts EPS; long duration with a declining membrane is the current best signal.
• Management is to stop PD, support nutrition, give corticosteroids and tamoxifen, and refer obstruction to experienced surgeons.
• Risk-stratified prevention — glucose-sparing, minimising peritonitis, and considering elective transfer after long duration — is the realistic lever.

The medical core. An expert should agree the metabolic cost and EPS are fully covered here.

Why it matters at the bedside

Glucose is the engine of peritoneal dialysis and, over years, one of its costs. Day to day it drives a metabolic burden that is easy to overlook; over a long PD life it injures the membrane and, rarely, sets the stage for the most feared complication of all — encapsulating peritoneal sclerosis. Both halves of this chapter trace back to the same molecule.

The glucose load and its metabolic cost

• A substantial fraction of dialysate glucose is absorbed each day, supplying a steady stream of calories that the patient did not eat. The result is weight gain, an atherogenic rise in triglycerides, and worse glycaemic control — in diabetics and sometimes in those without prior glucose intolerance.
• Together these feed the metabolic syndrome and add to an already high cardiovascular risk, so the glucose load is treated as a modifiable exposure, not an inert vehicle.

The anorexia–wasting paradox

• Absorbed glucose blunts appetite. A patient can therefore gain fat from dialysate calories while losing muscle from poor protein intake — metabolic excess and protein-energy wasting at once. Nutrition is monitored on both axes, not by weight alone.

Reducing the metabolic burden

• Glucose-sparing is the lever: icodextrin replaces the glucose long dwell, amino-acid dialysate substitutes for one exchange and supplies protein, and the glucose strength is kept to the minimum that achieves euvolemia. Matching the dwell to transport (Chapters 1 and 2) wins the same ultrafiltration for less glucose. Lipid and glycaemic management and dietetic input complete the package.

Encapsulating peritoneal sclerosis — what it is

• EPS is a rare, serious, often fatal complication: progressive intra-abdominal fibrosis forms a fibrocollagenous cocoon that encases and tethers the bowel, producing obstruction. It is the catastrophic end of the membrane-injury spectrum, not a routine transport problem.

Why EPS happens — the two-hit model

• Years of glucose, glucose-degradation-product, and low-pH exposure denude the mesothelium, drive new vessel growth, and lay down submesothelial fibrosis — the first hit that primes the peritoneum. A second inflammatory trigger — a severe peritonitis episode, stopping PD, or transplantation — then tips the primed membrane into the encapsulating phase.

Who is at risk

• Long PD duration is the dominant risk factor, with risk rising sharply after several years. High cumulative glucose exposure, severe or recurrent peritonitis, fast or rapidly declining transport, and younger age all add to it. The hits are cumulative, which is why vintage matters so much.

Recognising and diagnosing EPS

• Suspect EPS when a long-duration PD or ex-PD patient develops bowel-obstruction symptoms, weight loss, malnutrition, bloody effluent, or unexplained ultrafiltration failure. The diagnosis rests on CT — peritoneal thickening, calcification, bowel tethering and cocoon formation, and loculated fluid — supported by inflammatory markers.

The prediction problem

• There is no single reliable predictor of EPS. The current best signal is long duration combined with a deteriorating membrane — falling ultrafiltration and rising transport over time — but it is neither sensitive nor specific. Predicting who will progress remains an unmet need, and risk is managed by stratification rather than by any one test.

Treating EPS

• Stop PD and support nutrition, often parenterally. Corticosteroids are used in the inflammatory phase and tamoxifen as an anti-fibrotic adjunct, though the evidence is uncontrolled. Bowel obstruction is referred for surgical enterolysis at an experienced centre, where outcomes are best.

Risk-stratified prevention

• Because cure is hard, prevention is the realistic goal: glucose-sparing throughout the PD life, minimising peritonitis, and, in long-duration high-risk patients, considering elective transfer off PD before a triggering event. Vigilance is heightened around the known triggers — stopping PD and transplantation.

Evidence base

• The metabolic cost of glucose absorption is well established. EPS evidence is observational: long duration as the dominant risk factor, CT as the diagnostic standard, and the consistent finding that no biomarker yet predicts it reliably. EPS treatments rest on case series rather than trials, which is why specialist referral and prevention dominate practice.

Five fully-built tables.

Table A — Metabolic consequences of the glucose load

Table B — Glucose-sparing strategies

Table C — EPS risk factors

Table D — Diagnosing EPS

Table E — Managing EPS

Visualise & Map

Causal chains, each ending in a named action.

Chain 1 — The daily metabolic cost

Dialysate glucose → large daily absorption → weight gain, high triglycerides, worse glycaemia → added cardiovascular risk → ACTION: glucose-sparing and metabolic management.

Chain 2 — Chronic membrane injury

Glucose, glucose-degradation products, low pH → mesothelial injury, neoangiogenesis, fibrosis → progressive sclerosis → ACTION: minimise glucose exposure; consider biocompatible solutions.

Chain 3 — The two hits

Chronic injury (first hit) primes the membrane → a second inflammatory trigger (severe peritonitis, stopping PD, transplant) → the encapsulating phase → bowel cocoon → ACTION: anticipate EPS around triggers in long-vintage patients.

Chain 4 — Cumulative risk

Long duration + rising transport + cumulative glucose → mounting EPS risk → ACTION: risk-stratify and consider elective transfer before a trigger.

Chain 5 — From sclerosis to obstruction

Fibrosis → bowel tethering and cocoon → obstruction and malnutrition → ACTION: stop PD, support nutrition, and refer obstruction for specialist surgery.

Numbered rules. These numbers are the cross-reference handle for the cases and flowcharts.

Clinical Reasoning

Four cases. Each stops you at a decision before it answers it.

Every mechanism from Level 3 earns a bedside consequence and an action.

Exhaustive. Every threshold and rule in the chapter is here.

Safety & Evidence

Panel A — Red flags

Panel B — NEVER DO

Anti-patterns clinicians fall into. Each becomes a Level 22 distractor.

The grade reflects strength of evidence, not importance.

Patient Decisions

Outcomes as natural frequencies. EPS is rare; figures are representative and the direction of effect is given where precise numbers are uncertain.

Apply & Test

Copy-paste chart notes that map to the real decisions in this chapter.

Template 1 — Metabolic review / glucose-sparing plan

• Glucose exposure: strengths used ___; estimated daily glucose load ___.
• Metabolic markers: weight/BMI ___; triglycerides ___; glycaemic control ___.
• Nutrition: appetite ___; protein intake ___; wasting? yes/no.
• Glucose-sparing plan: icodextrin ___; amino-acid dialysate ___; lower strength ___.
• Adjuncts: statin ___; glycaemic management ___; dietetic referral ___.

Template 2 — EPS risk / assessment note

• PD duration ___; transport trend ___; UF trend ___; peritonitis history ___.
• EPS risk: low / elevated / high (vintage + membrane decline).
• Symptoms: obstruction / weight loss / bloody effluent / UF failure — present? ___.
• CT (if suspected): findings ___.
• Plan: glucose-sparing / surveillance / discuss elective transfer / EPS treatment ___.

Pre-rounds compression. Numbers and rules only.

Active recall. At least one card per objective.

Micro-teaching for rounds. Two scenarios, five steps each.

Metacognition anchored to this chapter's tensions. No answers provided.

1. 1. With no test that predicts EPS, how do you talk about a rare but catastrophic risk without either frightening a well patient or falsely reassuring them?
2. 2. At what point does accumulating PD vintage tip the balance toward recommending transfer — and whose judgement should weigh most in that call?
3. 3. The daily glucose cost is invisible and the EPS risk is distant; how do you keep either from being discounted in routine reviews?
4. 4. Knowing that stopping PD and transplantation can trigger EPS, how should that shape the timing and counselling around a transplant in a long-vintage patient?
5. 5. If a reliable EPS predictor existed, what would you do differently tomorrow — and what does that reveal about how you manage the uncertainty today?

Nine items, each anchored in this chapter. At least one per objective.