Exit-Site and Tunnel

The contract between this chapter and the reader.

1. 1. Diagnose exit-site infection and distinguish it from simple inflammation.
2. 2. Apply an exit-site score to grade severity and track response.
3. 3. Diagnose tunnel infection, including the role of ultrasound.
4. 4. Identify the key organisms and culture the drainage to direct therapy.
5. 5. Prescribe empiric and organism-directed therapy with the correct duration.
6. 6. Manage Staphylococcus aureus and Pseudomonas exit-site infections specifically.
7. 7. Decide when salvage fails and catheter removal or replacement is needed.
8. 8. Recognise when exit-site or tunnel infection threatens the peritoneum.
9. 9. Construct an exit-site infection prevention programme.

A sixty-second reading. Each bullet stands alone.

• Purulent drainage at the exit site is an exit-site infection by definition; erythema alone may be early or simple inflammation.
• An exit-site score — redness, swelling, crust, pain, drainage — grades severity and tracks the response to treatment.
• Tunnel infection is erythema, swelling, and tenderness along the catheter tract; it is often occult, and ultrasound detects a peri-catheter collection.
• Staphylococcus aureus is the commonest and most dangerous exit-site organism; Pseudomonas is the most aggressive.
• Culture the drainage to direct therapy.
• Most exit-site infections respond to oral antibiotics plus intensified local care.
• Treat S. aureus with an anti-staphylococcal agent; treat Pseudomonas with a fluoroquinolone, often with a second agent and a longer course.
• Continue antibiotics until the exit site looks normal — at least two weeks, and three for Pseudomonas.
• Tunnel infection involving the deep cuff, or refractory exit-site infection, often needs catheter removal or replacement.
• Exit-site or tunnel infection sharing an organism with a peritonitis episode is a strong indication for catheter removal.
• Topical exit-site antibiotic — mupirocin or gentamicin — reduces exit-site infection and peritonitis; gentamicin also covers Pseudomonas.
• Daily exit-site care and catheter immobilization are the foundation of prevention.

The medical core. An expert should agree exit-site and tunnel infection are fully covered here.

Why it matters at the bedside

An exit-site infection is rarely dangerous in itself, but it is the doorway to the two things that end PD — tunnel infection and peritonitis. Treat the exit promptly, watch the tunnel, and know when the catheter has become the problem, and most of that progression is prevented.

What an exit-site infection is

• Purulent drainage at the exit is an exit-site infection, with or without redness. Erythema alone, without pus, may be early infection or simple mechanical irritation, and is watched and treated locally before committing to antibiotics.
• An exit-site score grades swelling, crust, redness, pain, and drainage; a score above the threshold, or any purulent drainage, marks infection, and the same score tracks the response to treatment.

Tunnel infection — the hidden extension

• Tunnel infection is inflammation along the subcutaneous catheter tract — erythema, swelling, and tenderness over the cuffs. It is frequently occult, with a near-normal exit, so a tender tract prompts ultrasound, which shows a peri-catheter fluid collection.
• Tunnel infection involving the deep cuff is serious: it rarely clears with antibiotics alone and readily seeds the peritoneum.

The organisms that matter

• Staphylococcus aureus is the most common and most consequential organism, with a real risk of tunnel involvement and peritonitis. Pseudomonas aeruginosa is the most aggressive, often demanding two agents, a longer course, and frequently the catheter. Culture every infected exit to direct therapy.

Which tests change management

• Culture of the drainage selects the antibiotic; the exit-site score grades and tracks; and tunnel ultrasound confirms occult tunnel involvement and helps decide salvage versus removal.

Treatment — empiric and directed

• Start empiric anti-staphylococcal therapy, covering MRSA where it is prevalent, then narrow to the cultured organism. Pseudomonas needs a fluoroquinolone, usually with a second agent, for a prolonged course.
• Continue until the exit looks normal — a minimum of two weeks, and three for Pseudomonas — alongside intensified local care; stopping when redness merely fades invites relapse.

When to salvage and when to remove

• An exit-site infection alone is usually salvageable with antibiotics and local care. Refractory infection may respond to cuff shaving or unroofing, but a deep-cuff tunnel infection, or one that will not clear, calls for catheter removal and replacement — often simultaneously when there is no peritonitis.

When the peritoneum is threatened

• If the organism in the exit or tunnel is the same as one causing peritonitis, the catheter is the source and is removed (Chapter 5). S. aureus and Pseudomonas exit infections carry the highest risk of this progression and are watched closely.

Prevention

• Daily exit-site care, catheter immobilization to avoid trauma, and a topical exit-site antibiotic are the core. Mupirocin covers gram-positives; gentamicin cream adds gram-negative and Pseudomonas cover. Treating S. aureus nasal carriage and a downward exit direction (set at insertion) complete the programme.

Five fully-built tables.

Table A — Exit-site appearance

Table B — Exit-site score (graded 0–2 per component)

A total score at or above the threshold, or any purulent drainage, indicates infection.

Table C — Organisms and therapy

Table D — Salvage versus removal

Table E — Prevention bundle

Visualise & Map

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.

Exhaustive. Every 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. Figures are representative; 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 — Exit-site assessment note

• Appearance: drainage ___; redness ___; swelling ___; crust ___; pain ___.
• Exit-site score: ___ (infection if at/above threshold or purulent).
• Tract: soft / tender / swollen — tunnel suspected? yes/no.
• Culture sent: yes/no; organism (when back): ___.
• Assessment: not infected / exit-site infection / tunnel infection.

Template 2 — Treatment and follow-up note

• Empiric therapy started: agent ___; MRSA cover? yes/no.
• Directed therapy after culture: agent ___; planned duration ___ (≥ 2 wks; 3 for Pseudomonas).
• Local care intensified: yes/no. Ultrasound (if tender tract): ___.
• Salvage vs removal decision: ___ ; effluent checked for peritonitis: ___.
• Review date and resolution criterion (exit normal): ___.

Pre-rounds compression. Rules only.

Active recall. At least one card per objective.

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

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