Comprehensive Assessment of Hemodialysis Patients Pre and Post Dialysis
A thorough pre and post-dialysis assessment of hemodialysis patients should include monitoring of blood pressure, evaluation of fluid status, review of laboratory parameters, and assessment of dialysis adequacy through proper BUN sampling techniques to optimize patient outcomes and reduce mortality risk.
Pre-Dialysis Assessment
Clinical Evaluation
- Review patient's clinical status including vital signs, with special attention to blood pressure measurements, which should not rely solely on pre-dialysis readings as they are imprecise estimates of interdialytic blood pressure 1
- Assess for signs of volume overload (jugular venous distension, peripheral edema, pulmonary rales) or dehydration (dry mucous membranes, reduced skin turgor) 2
- Evaluate access site for patency and signs of infection or complications 1
- Review A/V needle placement, proximity, and orientation with patient care staff and patient 1
- Verify graft flow configuration to ensure proper needle placement 1
Technical Parameters Review
- Review previous dialysis session documentation when Kt/V or URR was measured 1
- Check hemodialyzer reuse log to evaluate total cell volume (TCV) 1
- Verify machine maintenance log for last calibration date and results 1
- Compare prescribed versus actual parameters from previous sessions, including blood flow rate (Qb), dialysate flow rate (Qd), and type of hemodialyzer 1
Laboratory Assessment
- Obtain predialysis BUN sample immediately prior to dialysis, using a technique that avoids dilution with saline or heparin 1
- For arteriovenous fistula/graft, obtain blood specimen from arterial needle before connecting arterial blood tubing 3
- For venous catheter, withdraw heparin/saline from arterial port following protocol 3
- Evaluate iron status in all patients before treatment and maintain iron repletion 4
Intra-Dialysis Monitoring
Hemodynamic Monitoring
- Monitor blood pressure throughout the session to assess for intradialytic hypotension 1
- Document extracorporeal pressures compared to previous sessions with prescribed Qb 1
- Check if prepump arterial pressures exceed 200 mmHg or if pressures are close to upper limits per dialysis unit policy 1
- Monitor for clinical events such as hypotension, muscle cramps, or chest pain that may necessitate changes in treatment parameters 1
Treatment Parameters
- Track effective hemodialysis treatment time (Td) to ensure delivery of prescribed treatment duration 1
- Document any interruptions or early terminations of treatment and their causes 1
- For patients with suspected access issues, perform hydraulic compression test during hemodialysis to identify stenotic lesions in grafts 1
Post-Dialysis Assessment
Clinical Evaluation
- Assess patient for symptoms of dialysis disequilibrium syndrome 3
- Evaluate for signs of excessive ultrafiltration (dizziness, cramping, hypotension) 1
- Document patient's post-dialysis weight and compare to target dry weight 1
Laboratory Assessment
- Obtain postdialysis BUN sample using the slow flow/stop pump technique to prevent sample dilution with recirculated blood 1
- Avoid drawing postdialysis BUN sample more than 5 minutes after dialysis ends to prevent urea rebound effects 1
- Ensure both predialysis and postdialysis BUN samples are analyzed at the same time to minimize interassay variability 1
Dialysis Adequacy Evaluation
- Calculate Kt/V or URR using properly collected pre and post-dialysis BUN samples 1
- Measure delivered dose of dialysis at least monthly to ensure adequate treatment 3
- If Kt/V or URR is below target, investigate potential causes including:
Common Pitfalls to Avoid
- Don't rely solely on pre and post-dialysis BP measurements for hypertension management, as they have either no association or a U/J-shaped association with mortality 1
- Avoid dilution of predialysis BUN sample with saline, which could artificially lower BUN values 3
- Don't draw predialysis BUN sample after dialysis has started 1
- Avoid drawing postdialysis BUN sample after blood reinfusion, which can lead to falsely high readings 1
- Don't overlook the importance of volume status assessment, as patients with fluid overload >2.5L before HD have poorer survival 5
Follow-up Actions Based on Assessment
- If delivered Kt/V is below target, implement a systematic approach to identify and correct the cause 1
- For patients with recurrent intradialytic hypotension, consider bioimpedance spectroscopy to optimize fluid management 6
- When evaluating nutritional status, remember that pre-HD albumin and creatinine levels are more accurate than post-HD levels in predicting mortality 7
- For patients receiving erythropoietin, monitor hemoglobin levels at least weekly until stable, then monthly 4