What investigations should the duty doctor of a dialysis unit prioritize for patients?

Investigations Required by Duty Doctor in Dialysis Unit

The duty doctor in a dialysis unit must prioritize monthly adequacy monitoring (Kt/V or URR with pre/post-dialysis BUN), monthly hemoglobin and iron studies (ferritin, transferrin saturation), monthly electrolytes (including sodium, potassium, calcium, phosphorus, magnesium, bicarbonate), and quarterly albumin measurements, while maintaining vigilant infection surveillance through monthly hepatitis B surface antigen screening in susceptible patients and semi-annual hepatitis C testing. 1, 2

Core Monthly Laboratory Investigations

Dialysis Adequacy Assessment

• Measure Kt/V or urea reduction ratio (URR) monthly to ensure adequate solute clearance, targeting Kt/V ≥1.2 for hemodialysis patients 1
• Obtain predialysis BUN sample immediately before dialysis using technique that avoids dilution with saline or heparin 3
• Obtain postdialysis BUN sample using the slow flow/stop pump technique to prevent sample dilution with recirculated blood 3
• For hemodialysis patients, draw blood samples before the midweek dialysis session to minimize variability 1
• If Kt/V or URR falls below target, investigate: clearance (K) less than assumed, effective treatment time (Td) less than prescribed, or errors in blood sampling/processing 3

Anemia Management Panel

• Measure hemoglobin monthly using predialysis samples (more stable and accurate than hematocrit) 1
• Initiate anemia workup when Hgb falls below 11 g/dL in premenopausal females/prepubertal patients or below 12 g/dL in adult males/postmenopausal females 1
• Check serum ferritin and transferrin saturation monthly to guide iron therapy 1
• Target transferrin saturation ≥20% and serum ferritin >100 ng/mL to ensure adequate iron availability for erythropoiesis 1

Electrolyte and Mineral Panel

• Measure sodium, potassium, calcium, phosphorus, magnesium, and bicarbonate monthly 1
• Check magnesium levels routinely, as hypomagnesemia occurs in 60-65% of dialysis patients and causes refractory hypokalemia/hypocalcemia 1

Quarterly Laboratory Investigations

• Measure serum albumin every 3 months as a marker of nutritional status and predictor of mortality 1

Infection Surveillance Testing

Hepatitis B Screening

• Screen all incident hemodialysis patients for HBsAg, anti-HBs, and anti-HBc before admission to outpatient dialysis facility 2
• Patients susceptible to HBV (negative HBsAg and anti-HBs) should be screened monthly for HBsAg to identify seroconversion early 2
• Patients immune to HBV (positive anti-HBs) should have anti-HBs levels screened annually and be revaccinated if levels decrease to <10 IU/L 2

Hepatitis C Screening

• Screen patients using ALT level monthly and HCV immunoassay or NAT every 6 months 2
• If newly acquired HCV infection is detected, test all patients in the hemodialysis center and increase frequency of subsequent testing 2

HIV Screening

• All incident hemodialysis patients should be screened for HIV infection 2

Vascular Access Monitoring

Physical Examination at Each Session

• Check access for patency, thrombosis, aneurysm/pseudoaneurysm, and signs of infection at each dialysis session 2, 3
• Examine exit site for signs of infection after hand hygiene 2
• Review A/V needle placement, proximity, and orientation with patient care staff and patient 3

Cultures When Indicated

• Obtain cultures and sensitivities of blood and any available infected access material, surrounding tissue, or drainage prior to initiating antibiotic therapy when infection is suspected 2

Cardiac Risk Stratification Investigations

Baseline Cardiac Evaluation

• Obtain baseline 12-lead ECG on all dialysis patients regardless of age 4
• Obtain echocardiography within 1-3 months after achieving dry weight to assess for left ventricular hypertrophy, systolic dysfunction, and diastolic dysfunction 4
• Approximately 75% of dialysis patients have systolic dysfunction, diastolic dysfunction, or overt left ventricular hypertrophy at dialysis initiation 4

Ongoing Cardiac Surveillance

• Perform annual ECGs after dialysis initiation 4
• Repeat echocardiography every 3 years in stable patients or when clinical status changes 4, 1
• Measure serum troponin T for risk stratification, as elevated troponin T independently predicts all-cause and cardiovascular mortality 4
• Measure high-sensitivity C-reactive protein (hs-CRP) as it predicts all-cause and cardiovascular mortality 4

Water Quality Monitoring

• Perform cultures and endotoxin analysis of water and dialysate monthly as a proactive strategy 2
• Results should be reviewed by the medical director to ensure disinfection schedule and process successfully control bacteria and endotoxin 2
• If bacterial or endotoxin levels exceed typical action level, notify medical director immediately to determine if it is safe to continue dialyzing patients 2

Intradialytic Monitoring

Vital Signs and Clinical Parameters

• Review patient's clinical status including vital signs, with special attention to blood pressure measurements 3
• Monitor blood pressure throughout the session to assess for intradialytic hypotension 3
• Document extracorporeal pressures compared to previous sessions with prescribed Qb 3
• Check if prepump arterial pressures exceed 200 mmHg or approach upper limits per dialysis unit policy 3
• Track effective hemodialysis treatment time (Td) to ensure delivery of prescribed treatment duration 3

Post-Dialysis Assessment

• Assess patient for symptoms of dialysis disequilibrium syndrome 3
• Evaluate for signs of excessive ultrafiltration 3
• Document patient's post-dialysis weight and compare to target dry weight 3

Common Pitfalls to Avoid

• Do not rely solely on pre-dialysis blood pressure readings as they are imprecise estimates of interdialytic blood pressure 3
• Avoid diluting BUN samples with saline or heparin when obtaining predialysis samples 3
• Do not use the slow flow/stop pump technique for predialysis BUN samples (only for postdialysis samples) 3
• Do not isolate HCV-infected patients during hemodialysis sessions or use dedicated dialysis machines, as there is no evidence of HCV transmission through internal pathways of single-pass dialysis machines 2