Synopsis
Understand how haemodialysis removes solute and fluid, assess a routine treatment safely, and recognise prescription, access and haemodynamic problems requiring renal-team action.
- Haemodialysis circulates blood through a dialyser: diffusion clears small solutes down concentration gradients, while transmembrane pressure produces ultrafiltration of water.
- A functioning arteriovenous fistula is generally preferred for long-term access when appropriate; grafts and tunnelled central venous catheters have distinct advantages, maturation needs and infection risks.
- The prescription is individual: treatment time, frequency, blood and dialysate flows, dialyser, dialysate composition, temperature, anticoagulation and ultrafiltration target are renal-specialist decisions.
- Pre-dialysis weight minus target weight helps set fluid removal, but the target is a clinical estimate that must be revisited after illness, nutrition change or persistent hypertension and hypotension.
- Intradialytic hypotension demands immediate assessment: stop or reduce ultrafiltration, position safely, check the circuit and evaluate bleeding, sepsis, arrhythmia, myocardial ischaemia and excessive target-weight reduction.
- Fever or rigors during treatment is access infection or bloodstream infection until assessed; obtain cultures promptly and follow the local renal sepsis pathway without waiting for the session to end.
- Never take blood pressure, insert a cannula or compress unnecessarily over a fistula arm; inspect and palpate the access before every use and confirm its continuous thrill.
- Adequacy measures such as urea reduction ratio or Kt/V support quality review but cannot substitute for symptoms, nutrition, volume control, potassium and treatment attendance.
- Sudden chest pain, dyspnoea, neurological change, collapse, visible circuit blood loss or loss of access bruit is an emergency requiring treatment cessation and senior renal or resuscitation support.
Key red flags
Unresponsiveness, absent breathing or pulselessness during dialysis requires the resuscitation algorithm, immediate circuit management by trained staff and early defibrillator use when indicated.
Visible blood loss from a disconnected needle or line can be rapidly fatal because the blood pump may continue; stop the pump, clamp the circuit and call for emergency help.
Acute chest pain, arrhythmia, focal neurology or severe dyspnoea requires urgent medical assessment rather than routine completion of dialysis.
Port-wine or unexpectedly dark circuit blood, chest or back pain and dyspnoea may indicate haemolysis; stop dialysis and do not return potentially haemolysed circuit blood.
Abrupt cough, hypoxaemia, chest pain or neurological change after circuit air is suspected requires immediate line clamping, emergency support and the unit air-embolism protocol.
Investigation priorities
Evaluate fluid removal, haemodynamic tolerance and departure safety during each treatment.
Management branches
A patient arrives for a planned treatment and is clinically stable.
- Verify identity, prescription, allergies, interval events and medicines, then record weight, observations, symptoms and an access examination.
- Agree the ultrafiltration goal against current target weight and haemodynamic tolerance, escalating major weight or clinical discrepancies before connection.
- Cannulate or connect with aseptic technique, confirm circuit security and observe machine pressures, alarms, access sites and the patient throughout treatment.
- At completion, achieve haemostasis without occluding access flow, reassess weight and symptoms, and communicate prescription or follow-up changes.