3. Dialysis Emergencies

Quick Recap

Renal System, Protocol 3/7. Acute complications occurring during or immediately after hemodialysis/RRT sessions — distinct from the general RRT indications/technique covered in the CRRT protocol.

1. Intradialytic Hypotension

Can occur with any modality but is MORE COMMON with IHD (rapid fluid/solute shifts) than CRRT (gentler, continuous shifts).

Mechanism beyond simple volume removal: rapid clearance of uremic solutes LOWERS serum osmolality -> fluid shifts toward the INTRACELLULAR space -> depletes intravascular volume independent of the ultrafiltration rate itself — an osmotic mechanism distinct from and additive to straightforward fluid removal.

High-risk patients: volume depletion, sepsis — use serial POCUS and invasive hemodynamic monitoring where indicated to confirm adequate volume status BEFORE initiating a session in these patients.

Management:

• 250mL normal saline bolus OR 25% albumin 100mL as initial steps
• Turn off ultrafiltration temporarily
• Decrease dialysate temperature to promote vasoconstriction
• Persistently hypotensive patients may need to switch to a CONTINUOUS modality (CRRT) rather than repeatedly fighting hypotension during IHD sessions

Differential diagnosis for intradialytic hypotension/hemodynamic instability (do not assume it's always simple volume-related): air embolism (rare but serious complication of dialysis itself), internal hemorrhage, pericardial tamponade, myocardial infarction — actively consider these, especially if the hypotension is disproportionate to the ultrafiltration rate or accompanied by other concerning findings.

2. Air Embolism During Dialysis/Line Placement

A rare but serious complication. Mechanism: gas enters the venous circulation via a negative pressure gradient with an open central/peripheral vein, or if the open vein is elevated above the right atrium. Even a seemingly small -5 cmH2O gradient can entrain gas at up to 100 mL/s through a 14G peripheral IV — illustrating how quickly this can become clinically significant. Estimated lethal venous dose ~200-300 mL (up to 500 mL if entrained slowly); as little as 50 mL entrained rapidly can cause hemodynamic compromise.

Prevention during line placement/dialysis catheter management:

• Position the patient FLAT (not head-up) if the head is not deliberately down while inserting the line
• NEVER leave a catheter lumen uncapped
• If suspected: position the patient right-side-up with head DOWN and aspirate blood mixed with air from the catheter

Management if air embolism occurs: left lateral decubitus positioning (elevates RV above its outflow tract, promoting air migration away from the RVOT), air aspiration via a central venous catheter positioned ~2cm below the SVC/RA junction can remove up to 50% of embolized gas with rapid hemodynamic improvement; emergency thoracotomy with direct RV aspiration as a last resort in refractory cardiopulmonary arrest. (See Obstructive Shock protocol, Cardiovascular System, for the full air embolism syndrome management detail — dialysis-associated air embolism follows the identical management principles.)

3. Arrhythmias

Mechanism: rapid electrolyte shifts during acute hemodialysis, and removal of certain antiarrhythmic drugs during the session itself (both direct clearance of the drug and the underlying electrolyte shift can precipitate arrhythmia).

Potassium dialysate concentration matters directly: chronic dialysis commonly uses a bath of 2-3 mEq/L potassium; when severe hyperkalemia necessitates a LOW-potassium dialysate (0-1 mEq/L), monitor HOURLY potassium levels, and do NOT use the low-potassium bath for more than 1 HOUR unless serum potassium remains critically elevated — overly aggressive/prolonged low-potassium dialysate use risks overshooting into dangerous hypokalemia.

Patients on digitalis are especially sensitive to hypokalemia — a specific, dangerous combination given digoxin toxicity risk rises sharply as potassium falls; extra caution warranted in this population during any potassium-lowering dialysis session.

Catheter-related arrhythmia triggers: during dialysis catheter placement itself, or from a malpositioned catheter, or occasionally during the dialysis session — if the arrhythmia causes hemodynamic compromise, discontinue dialysis immediately and proceed to cardioversion per the Arrhythmias protocol.

4. Dialyzer Reactions

Type A (anaphylactic) reactions: rare (~4 per 100,000 sessions), present within the FIRST FEW MINUTES once circuit blood returns to the patient. Symptoms: urticaria, flushing, chest pain, back pain, dyspnea, vomiting, chills; severe cases progress to hypotension, cardiac arrest, death. Believed related to residual ETHYLENE OXIDE used to sterilize dialyzers. Management: IMMEDIATELY DISCONTINUE the session and DISCARD the circuit blood (do NOT return it to the patient, unlike routine session completion) — further therapy with epinephrine/bronchodilators per severity, following standard anaphylaxis management principles.

Type B reactions: more common (3-4% of sessions), LESS SEVERE, present LATER (usually after the first 15 minutes). Thought related to unsubstituted cellulose dialyzer membranes and complement activation. Symptoms overlap with Type A (chest pain, back pain, dyspnea, GI symptoms) but milder. If not severe, dialysis can be CONTINUED and symptoms resolve slowly — a key distinguishing management point from Type A (which mandates immediate discontinuation). Treatment is supportive: IV saline, analgesics, antihistamines.

Timing is the key discriminator between Type A and Type B (first few minutes vs after 15 minutes), and this timing should directly inform whether to stop immediately (Type A pattern) or continue with supportive care (Type B pattern).

5. Dialysis Catheter-Related Problems

Nontunneled catheters: placed at bedside for acute need. Infection/bacteremia generally warrants prompt catheter removal, unless vascular access is especially difficult (in which case salvage attempts may be reasonable with close infectious disease input).

Thrombus/fibrin sheath formation: impairs adequate blood flow for dialysis; hub-instilled heparin post-session does not reliably prevent this. Alteplase lock technique: instill 1-2mg into each catheter lumen, cap 2-3 hours, then aspirate before resuming dialysis — NEVER give alteplase systemically for this indication. If malfunction persists despite this, replace the catheter completely (not over a guidewire) — exchanging over a guidewire in the setting of a thrombosed/infected catheter risks seeding the new catheter or failing to resolve the underlying obstruction.

Subclavian vein AVOIDANCE in CKD patients: high risk of subclavian venous stenosis, which can preclude future AV fistula/graft placement in that extremity — preserve upper extremity venous access options in any patient who may eventually need permanent dialysis access.

Tunneled catheter indications: multiple malfunctioning temporary catheters, poor chance of early renal recovery, or transfer to a different facility. No infection-rate or dialysis-adequacy superiority has been demonstrated for tunneled over temporary catheters in ICU AKI patients specifically — tunneling is a practical/logistic decision, not an evidence-based infection-prevention strategy in this population. Clotted tunneled catheters require interventional radiology consultation for endoluminal brushing.

6. Central Venous Access Complications (Broader, Line-Placement-Related)

Bleeding/hematoma: compress until bleeding stops; correct coagulopathy if present.

Hemothorax: correct coagulopathy; may need drainage if massive.

Cardiac tamponade/perforation: surgical intervention if perforation confirmed (see Cardiac Tamponade protocol, Cardiovascular System, for pericardiocentesis management if tamponade physiology develops).

Pneumothorax: always place an intercostal (chest) tube if the patient is on positive-pressure ventilation; if TENSION pneumothorax, immediate needle decompression followed by tube drainage (see Pneumothorax protocol, Respiratory System); small pneumothorax in a spontaneously breathing patient can be observed closely without immediate intervention.

Nerve injury: generally conservative management.

Tracheal/laryngeal injury: may require intubation.

Catheter malposition causing arrhythmia: withdraw the catheter until positioned in the SVC (not advanced into the RA/RV, which triggers ectopy/arrhythmia).

7. Infectious Complications Prevention (CVC/Dialysis Catheter Care Bundle)

• Use the line only when necessary; remove as soon as not required
• Prefer subclavian vein for general CVC placement (avoiding femoral/internal jugular) for infection-prevention purposes — note this is DISTINCT from the dialysis-specific recommendation to AVOID subclavian for dialysis catheters in CKD patients (Section 5) — the two recommendations serve different priorities (general infection prevention vs preserving future dialysis access) and should not be confused
• Minimum necessary number of ports/lumens
• Chlorhexidine skin antisepsis (back-and-forth rubbing >=30 seconds, air-dry >=2 minutes, do not wipe/blot) — preferred over povidone-iodine
• Sterile gauze/dressing; gauze dressings changed every 2 days, transparent dressings every 7 days (or immediately if diaphoresis/bleeding/oozing present)
• Chlorhexidine-impregnated sponge dressing if infection rates remain elevated despite basic measures
• Daily 2% chlorhexidine patient skin cleansing (not the insertion site specifically)
• Daily insertion site evaluation for infection signs
• Sutureless securement devices
• Antimicrobial-impregnated CVC (chlorhexidine/silver sulfadiazine or minocycline/rifampin) for anticipated dwell >5 days or high infection-rate settings
• Povidone-iodine or bacitracin/polymyxin B ointment at the HEMODIALYSIS catheter exit site specifically, after insertion and at the end of each dialysis session

8. Organ Support

Standard ICU supportive care during and after management of any dialysis emergency; hemodynamic support as needed for intradialytic hypotension refractory to initial measures; modality switch (IHD to CRRT) for persistently hypotension-prone patients.

9. Consultation Matrix

10. Monitoring Framework

Continuous hemodynamic monitoring during dialysis sessions, hourly potassium if using low-potassium dialysate, temperature/reaction symptom monitoring in the first 15+ minutes of each new dialyzer exposure, catheter site daily inspection, post-procedural imaging (CXR) after any new line placement to confirm position and exclude pneumothorax.

11. Complications

See sections above — hypotension, air embolism, arrhythmia, dialyzer reactions (Type A/B), catheter thrombosis/infection, line-placement mechanical complications (pneumothorax, hemothorax, tamponade, nerve injury). Prevention: appropriate pre-session volume assessment, careful catheter capping/handling technique, timing-based dialyzer reaction recognition, CVC care bundle adherence. Rescue: modality switch for refractory hypotension, immediate discontinuation for Type A reactions, alteplase lock for catheter thrombosis, standard line-complication management per site-specific protocols.

12. Escalation & De-escalation

Escalate: hemodynamic instability not resolving with standard measures, suspected air embolism, Type A dialyzer reaction, arrhythmia with hemodynamic compromise -> immediate session discontinuation and targeted rescue therapy.

De-escalate: stable session tolerance re-established (fluid bolus response, ultrafiltration resumed cautiously, Type B reaction resolving) -> continue/complete the session with ongoing close monitoring.

13. Documentation & Medicolegal Checklist

14. Key Guidelines

Cummings J, Vijayan A. Renal Replacement Therapy (complications section). Washington Manual of Critical Care, 4th ed, 2025 (Ch. 48). O'Grady NP, Alexander M, Burns LA, et al. Guidelines for the prevention of intravascular catheter-related infections. Clin Infect Dis. 2011;52(9):e162-e193.

15. Controversies

Optimal pre-session volume assessment methodology (clinical exam alone vs POCUS vs invasive monitoring) varies by institution and patient risk profile without a single mandated approach. The precise mechanism and best management of Type B dialyzer reactions remains less well-characterized than Type A given their generally self-limited course, and practice varies in how aggressively to investigate mild recurrent reactions.

16. References

1. Cummings J, Vijayan A. Renal Replacement Therapy. Washington Manual of Critical Care, 4th ed, 2025 (Ch. 48).
2. O'Grady NP, Alexander M, Burns LA, et al. Guidelines for the prevention of intravascular catheter-related infections. Clin Infect Dis. 2011;52(9):e162-e193.
3. Chawla R, Todi S, eds. Central Line Placement (complications table). ICU Protocols: A Step-wise Approach, 2nd ed. Springer; 2020 (Ch. 39).
4. Mirski MA, Lele AV, Fitzsimmons L, et al. Diagnosis and treatment of vascular air embolism. Anesthesiology. 2007;106(1):164-177.

See also: CRRT Indications and Acute Kidney Injury (Renal System); Obstructive Shock (air embolism full detail), Arrhythmias, Cardiac Tamponade, Pneumothorax (site-specific complication management) across other systems.