Nursing Medium1. What is dialysis?
Dialysis removes selected wastes and excess water and helps correct electrolyte and acid–base disturbances when the kidneys cannot do enough. It supports kidney function; it does not replace every kidney role, such as making erythropoietin. Treatment can be temporary in acute kidney injury or ongoing in kidney failure.
| Process | Easy meaning |
|---|---|
| Diffusion | Dissolved substances move down a concentration gradient across a membrane; important for small-solute clearance. |
| Ultrafiltration | Water is removed across a membrane. In haemodialysis, a pressure gradient drives this. |
| Convection | Solutes are carried with moving water; important in haemofiltration. |
| Osmosis in PD | An osmotic gradient, often created by glucose in dialysate, draws water into the peritoneal cavity. |
2. Dialysis types: compare the options
| Type | How it works | Useful distinction |
|---|---|---|
| Intermittent haemodialysis (IHD) | Blood passes through an external dialyser via vascular access. | Intermittent sessions; relatively rapid solute and fluid removal. Schedule and duration are individualised. |
| SLED / prolonged intermittent therapy | Slower treatment over a longer session than conventional IHD. | An ICU option where equipment, staffing and haemodynamic needs fit. |
| CRRT | Continuous extracorporeal kidney support, usually in ICU. | Often favoured for unstable patients needing gentler fluid management; not a guarantee of better survival for everyone. |
| Peritoneal dialysis (PD) | Dialysate fills the abdomen, dwells and drains; the peritoneum acts as the membrane. | CAPD uses manual exchanges; APD uses a cycler, commonly overnight. |
PD exchange cycle
- Fill: prescribed solution enters
- Dwell: exchange occurs
- Drain: used fluid leaves
| CRRT abbreviation | Main mechanism |
|---|---|
| CVVH: continuous veno-venous haemofiltration | Convection; requires replacement fluid. |
| CVVHD: continuous veno-venous haemodialysis | Predominantly diffusion using dialysate. |
| CVVHDF: continuous veno-venous haemodiafiltration | Diffusion plus convection. |
| SCUF: slow continuous ultrafiltration | Mainly fluid removal; limited solute clearance. |
3. Indications: remember AEIOU
| Trigger | Examples requiring urgent assessment |
|---|---|
| A — Acidosis | Severe metabolic acidosis not adequately responding to appropriate treatment. |
| E — Electrolytes | Dangerous hyperkalaemia, especially with ECG changes or persistence despite initial treatment. |
| I — Intoxication | Selected dialysable poisons; the substance and clinical condition determine treatment. |
| O — Overload | Pulmonary oedema/fluid overload not controlled by appropriate medical treatment. |
| U — Uraemia | Complications such as uraemic encephalopathy or pericarditis. |
In chronic kidney disease, the decision also considers symptoms, fluid control, nutrition, laboratory trends, kidney function and patient preferences. No single creatinine or urea value automatically decides when everyone must start dialysis.
[1] [2]4. Contraindications and modality-specific cautions
| Modality / issue | What the nurse should understand |
|---|---|
| IHD in severe haemodynamic instability | Rapid shifts may be poorly tolerated. CRRT or SLED may be selected; this is not a contraindication to all kidney replacement therapy. |
| Bleeding or suspected HIT | The usual anticoagulant may be unsuitable. The team may choose a different anticoagulant or an anticoagulant-free strategy. |
| PD with an unsafe or unusable peritoneal cavity | Major intra-abdominal pathology, severe adhesions, leaks or significant abdominal wall defects may prevent effective/safe PD. Surgical and nephrology assessment is needed. |
| Recent abdominal surgery or a hernia | Requires individual assessment and sometimes prescription changes or repair. Previous abdominal surgery alone is not always an absolute exclusion. |
| CRRT with regional citrate | Requires safe citrate metabolism and close calcium/acid–base monitoring. Severe shock or liver dysfunction warrants specialist assessment under the service protocol. |
5. Nursing care BEFORE treatment
| For every patient | Additional preparation |
|---|---|
| Verify identity, prescription, allergies, consent and treatment goals. Record weight where feasible, vital signs, respiratory status, oedema, fluid balance and relevant results. | Reconcile medicines and timing. Do not routinely withhold every antihypertensive, antibiotic or other drug; follow the individual plan. |
| For HD: inspect the access and assess fistula/graft patency. | Palpate the thrill and assess the bruit as trained. Avoid BP cuffs, venepuncture and tight clothing over the access arm. Report absent/changed flow before cannulation. |
| For catheter-based treatment: prepare aseptic access care. | Use prescribed hub disinfection and sterile handling. Confirm machine, dialysate, safety checks and access readiness through the local checklist. |
| For PD: inspect the exit site and the prescribed bag. | Check solution, concentration, volume, expiry and clarity. Use the approved warmer and exchange technique; explain the fill–dwell–drain process. |
| For CRRT: verify the complete prescription with the trained team. | Confirm modality, fluids, net fluid-removal goal, anticoagulation, line security and monitoring plan. |
6. Nursing care DURING treatment
| Modality | Key observations and response |
|---|---|
| HD / SLED | Monitor blood pressure, symptoms, rhythm when indicated, access and circuit. Watch for hypotension, cramps, bleeding, line disconnection and allergic reactions. A symptomatic BP fall needs assessment, prompt escalation and adjustment of ultrafiltration per protocol; prescribed fluid may be needed. |
| PD | Maintain aseptic connections. Record inflow, dwell, drainage, net fluid balance and effluent appearance. Assess pain, breathing and glucose when indicated. Cloudy effluent or abdominal pain needs urgent peritonitis assessment. |
| CRRT | Track actual net fluid balance, haemodynamics, temperature, circuit pressures and downtime. Check electrolytes, including calcium, magnesium and phosphate, as ordered. Investigate alarms safely; never bypass safety alarms to keep the machine running. |
7. Nursing care AFTER treatment
- Reassess vital signs, symptoms, weight where appropriate, fluid balance and whether the intended treatment was completed. Document actual fluid removed and any interruptions.
- After HD needle removal, apply the trained gentle pressure technique, confirm haemostasis and recheck access flow. Excessive pressure can obstruct the fistula. Escalate prolonged bleeding or loss of thrill.
- For a dialysis catheter, maintain the prescribed dressing and lock/closure procedure. Do not use it for unrelated access without authorisation.
- After a PD exchange, record drainage and net ultrafiltration, secure the system and reinforce aseptic self-care and red-flag reporting.
- After CRRT stops, continue surveillance for recurrent fluid overload, potassium/acid–base disturbance and inadequate urine output. Reconcile medicines for the change in clearance.
- Provide individual advice on medicines, access protection, fluid/diet plans and the next treatment. Review relevant repeat investigations rather than assuming one session has permanently corrected the problem.
8. Drugs and solutions: what may be needed?
These are examples, not a prescription bundle. Choice, dose and timing depend on the modality, renal function, current laboratory results and local orders.
| Drug / solution | Why used | Nursing point |
|---|---|---|
| Heparin for selected HD/CRRT prescriptions | Reduces extracorporeal circuit clotting. | Assess bleeding and platelets; confirm the prescribed strategy. Not every session requires systemic heparin. |
| Regional citrate ± calcium infusion in CRRT | Anticoagulates the circuit by binding calcium. | Use the specified protocol. Monitor systemic and post-filter ionised calcium as ordered and acid–base balance; citrate accumulation is a serious concern. |
| Dialysate and replacement solutions | Provide the prescribed electrolyte/buffer composition and clearance. | Check the exact bag, potassium/calcium content, route and expiry. Fluids are not interchangeable. |
| Prescribed isotonic fluid for symptomatic intradialytic hypotension | May support circulation after assessment. | Review ultrafiltration and patient status; do not give an automatic large bolus to every fluid-overloaded patient. |
| ESA and iron for selected chronic kidney-failure patients | Treat renal anaemia when indicated. | Monitor haemoglobin, iron status and blood pressure; these are not immediate substitutes for emergency treatment of bleeding. |
| Phosphate binders, e.g. sevelamer | Reduce phosphate absorption from food. | Take with meals/snacks as prescribed; they do not work by being given only after dialysis. |
| Antibiotics for infection; intraperitoneal treatment often used for PD peritonitis | Treat infection according to likely organisms and culture results. | Obtain ordered specimens promptly and start treatment without unnecessary delay. Systemic sepsis needs urgent systemic management. |
| Emergency hyperkalaemia medicines, if prescribed | IV calcium stabilises the myocardium; insulin with glucose shifts potassium into cells. | Neither removes potassium from the body. Monitor ECG and glucose; definitive removal may require dialysis. |
9. Investigations before and after
| Investigation | Before / baseline | During / after |
|---|---|---|
| Urea, creatinine, sodium, potassium, bicarbonate; calcium, magnesium and phosphate as indicated | Assess renal function, electrolyte risks and the prescription needed. | Recheck according to acuity and modality. Watch for recurrent hyperkalaemia and depletion during prolonged therapy. |
| CBC; iron studies for chronic anaemia; coagulation when indicated | Identify anaemia, infection clues and bleeding/anticoagulation issues. | Trend problems and treatment response; not all tests are needed after every session. |
| ECG and blood gas when clinically indicated | Evaluate suspected dangerous hyperkalaemia or major acid–base disturbance. | Reassess clinical/laboratory response; a normal ECG does not exclude hyperkalaemia. |
| Blood-borne virus screening and immunity status under the dialysis programme | Use the programme’s hepatitis B, hepatitis C and other screening plan. | Repeat according to exposure risk and programme policy; apply infection-control precautions consistently. |
| Properly timed pre- and post-HD urea | Paired samples support adequacy calculations such as URR/Kt/V. | Collect by the unit’s sampling protocol. A random post-treatment creatinine is not an adequacy calculation. |
| PD effluent cell count/differential and culture if peritonitis suspected | Cloudiness/pain triggers assessment rather than a routine culture of every clear bag. | Collect promptly, then follow the treatment and response-monitoring plan. |
| Ionised calcium and acid–base tests with citrate CRRT | Baseline values inform safe treatment. | Monitor systemic and post-filter values according to protocol, not total calcium alone. |
Investigate the cause of kidney injury as well—for example, renal ultrasound when obstruction is suspected. Laboratory trends must be interpreted alongside fluid balance, symptoms and the actual dialysis delivered.
[1]10. Scenario practice — 12 MCQs
These are original learning questions, not recalled examination questions. Choose one best answer, then open the explanation. Medicines and emergency actions follow supervised local protocols.
Q1. A patient has persistent severe hyperkalaemia despite initial treatment and develops ECG changes. What is the priority plan?
- Wait for a much higher creatinine
- Urgently escalate for definitive potassium removal, including dialysis assessment
- Give a phosphate binder only
- Restrict drinking and reassess next week
Show answer & rationale
Correct answer: B. Urgently escalate for definitive potassium removal, including dialysis assessment
Rationale: Dangerous refractory hyperkalaemia is an emergency indication for kidney replacement therapy. Treatment decisions are not based on creatinine alone. [1]
Q2. An ICU patient with AKI needs fluid removal but remains haemodynamically unstable. Which option may be better tolerated than standard IHD?
- CRRT under the critical-care prescription
- A rapid maximum-rate ultrafiltration session
- No kidney support is possible
- CAPD is mandatory for every unstable patient
Show answer & rationale
Correct answer: A. CRRT under the critical-care prescription
Rationale: CRRT allows slower continuous control of fluid and solutes. The team selects the modality according to clinical needs and resources. [1]
Q3. Before fistula cannulation, the nurse cannot feel the usual thrill. What should happen next?
- Cannulate repeatedly until blood appears
- Apply a BP cuff over the fistula
- Escalate possible access dysfunction before use
- Massage forcefully and ignore it
Show answer & rationale
Correct answer: C. Escalate possible access dysfunction before use
Rationale: A lost or changed thrill may signal impaired flow or thrombosis. The access needs assessment rather than blind cannulation. [7]
Q4. During HD, a patient becomes dizzy and hypotensive while fluid is being removed. What is the best first nursing response?
- Increase ultrafiltration
- Assess the patient, reduce/stop ultrafiltration under protocol and seek prompt review
- Give all scheduled antihypertensives immediately
- Ignore symptoms if the machine is running
Show answer & rationale
Correct answer: B. Assess the patient, reduce/stop ultrafiltration under protocol and seek prompt review
Rationale: Fluid removal may exceed circulatory tolerance. Assess the cause and follow the hypotension plan, including prescribed fluid when appropriate. [12]
Q5. A PD patient reports abdominal pain and the drained fluid is cloudy. What is the priority?
- Discard the fluid and wait a week
- Assume cloudy fluid is always normal
- Add unprescribed drugs to the bag
- Urgently assess for peritonitis and collect ordered effluent specimens
Show answer & rationale
Correct answer: D. Urgently assess for peritonitis and collect ordered effluent specimens
Rationale: Cloudy effluent with abdominal pain suggests peritonitis. Prompt assessment, cell count/culture and timely treatment protect the patient; do not unnecessarily delay antibiotics. [5]
Q6. A patient asks how CAPD differs from APD. Which explanation is correct?
- CAPD uses manual exchanges; APD uses a cycler
- CAPD always uses a blood dialyser
- APD has no catheter
- They are two types of ECMO
Show answer & rationale
Correct answer: A. CAPD uses manual exchanges; APD uses a cycler
Rationale: Both use the peritoneum. The difference is how the prescribed exchanges are performed: manually or with a machine. [4]
Q7. A patient on citrate-anticoagulated CRRT develops tingling and a low systemic ionised calcium result. What is the nursing priority?
- Stop calcium monitoring
- Give a phosphate binder and ignore it
- Urgently notify the team and follow the calcium/citrate protocol
- Increase citrate independently
Show answer & rationale
Correct answer: C. Urgently notify the team and follow the calcium/citrate protocol
Rationale: Citrate binds calcium. Systemic hypocalcaemia requires prompt assessment and prescribed correction; citrate accumulation and other causes must be considered. [10]
Q8. A patient takes a prescribed phosphate binder on an empty stomach several hours after eating. What teaching is best?
- Take it only on dialysis days regardless of food
- Take it with meals/snacks as prescribed so it can bind dietary phosphate
- Double every dose after HD
- It replaces all dialysis treatments
Show answer & rationale
Correct answer: B. Take it with meals/snacks as prescribed so it can bind dietary phosphate
Rationale: Binders act on phosphate in food within the gut. Timing with food matters; the exact schedule follows the prescription. [9]
Q9. After HD, the patient asks for a tight pressure dressing over the fistula to prevent bleeding. What should the nurse explain?
- The tighter the better
- The thrill should disappear after every treatment
- BP cuffs help preserve the fistula
- Use the trained gentle pressure technique and reassess flow and haemostasis
Show answer & rationale
Correct answer: D. Use the trained gentle pressure technique and reassess flow and haemostasis
Rationale: Excess pressure can obstruct access blood flow. Control bleeding while preserving patency, and escalate prolonged bleeding. [7]
Q10. Which samples help calculate a patient’s HD urea reduction ratio?
- Properly timed pre- and post-dialysis urea samples
- A single random sodium sample
- Post-dialysis creatinine alone
- Urine colour before treatment
Show answer & rationale
Correct answer: A. Properly timed pre- and post-dialysis urea samples
Rationale: URR compares urea before and after treatment. Sampling technique and timing matter because recirculation and rebound can distort interpretation. [8]
Q11. IV calcium is prescribed for severe hyperkalaemia with ECG changes while dialysis is arranged. Which statement is correct?
- Calcium removes all excess potassium
- Calcium makes dialysis unnecessary in every case
- Calcium helps stabilise the heart but does not remove potassium
- Calcium replaces ECG monitoring
Show answer & rationale
Correct answer: C. Calcium helps stabilise the heart but does not remove potassium
Rationale: Calcium addresses cardiac membrane instability. Potassium still needs to be shifted or removed with the appropriate treatment plan. [1]
Q12. After a dialysis session, the patient feels better and asks whether follow-up blood tests and fluid monitoring can stop. What is the best response?
- Yes, one session permanently corrects kidney failure
- Continue the individual monitoring plan because abnormalities can recur
- Only the machine needs monitoring
- Never repeat any laboratory test
Show answer & rationale
Correct answer: B. Continue the individual monitoring plan because abnormalities can recur
Rationale: Clinical improvement does not prove sustained electrolyte and fluid control. Ongoing assessment guides the next treatment and medicine plan. [2]
Sources and scope
- KDIGO: Acute kidney injury guideline (2012)
- KDIGO: CKD guideline (2024)
- NIDDK: Haemodialysis
- NIDDK: Peritoneal dialysis
- ISPD: Peritonitis guideline (2022)
- CDC: Dialysis bloodstream infection prevention
- National Kidney Foundation: Haemodialysis access
- NIDDK: Haemodialysis dose and adequacy
- National Kidney Foundation: Phosphorus and phosphate binders
- KDIGO guideline authors: Renal support summary
- National Kidney Foundation: Choosing treatment for kidney failure
- National Kidney Foundation: Ultrafiltration
- UK Kidney Association: Peritoneal access guidance
- National Kidney Foundation: Understanding kidney laboratory values
Sources checked 21 October 2026. Adult nursing revision; paediatric and neonatal prescriptions differ. Institutional ECMO protocols illustrate specialist practice and are not universal targets. Drug doses, monitoring intervals and treatment changes require the current patient-specific prescription and local protocol. These notes are educational; independent specialist review is not claimed.