What to check in a patient with Chronic Kidney Disease (CKD) who develops sepsis?

Evaluation of Sepsis in CKD Patients

In a CKD patient with sepsis, immediately check: lactate level, blood cultures (at least 2 sets), complete blood count, comprehensive metabolic panel including creatinine and electrolytes, urine output, vital signs with mean arterial pressure, and obtain prompt imaging to identify the infection source—while simultaneously initiating resuscitation and antimicrobials within the first hour. 1

Immediate Laboratory Assessment

Critical Initial Labs

• Serum lactate: Measure immediately to assess tissue hypoperfusion; elevated lactate (≥4 mmol/L) defines sepsis-induced tissue hypoperfusion requiring aggressive resuscitation 1
• Blood cultures: Obtain at least 2 sets (aerobic and anaerobic bottles) before antimicrobials if this causes no substantial delay (>45 minutes); draw at least one percutaneously and one through each vascular access device unless recently inserted (<48 hours) 1
• Complete blood count: Check for leukocytosis, left-shift, or neutropenia—all indicators for obtaining blood cultures 1
• Comprehensive metabolic panel: Essential to assess baseline renal function (creatinine, eGFR), electrolytes (particularly sodium), and albumin (hypoalbuminemia correlates with bacteremia) 1

Renal-Specific Monitoring

• Baseline creatinine and eGFR: Critical for determining antibiotic dosing adjustments and tracking acute-on-chronic kidney injury 2, 3
• Electrolytes: CKD patients are prone to hyperkalemia and acid-base disturbances that worsen with sepsis 4
• Urine output: Target ≥0.5 mL/kg/hr as a resuscitation goal 1

Hemodynamic Assessment

Vital Physiologic Parameters to Monitor

• Mean arterial pressure (MAP): Target ≥65 mmHg with vasopressors if needed 1
• Heart rate, respiratory rate, temperature, oxygen saturation: Reassess frequently during resuscitation 1
• Central venous oxygen saturation: Target ≥70% (superior vena cava) or ≥65% (mixed venous) if available 1

Fluid Responsiveness Assessment

• Dynamic variables preferred over static: Use dynamic measures to predict fluid responsiveness where available 1
• Serial lactate measurements: Recheck every 2-6 hours during acute resuscitation; target normalization as a marker of adequate tissue perfusion 1, 5

Critical caveat: CKD patients require careful fluid management—while the standard 30 mL/kg crystalloid bolus within 3 hours is recommended, frequent reassessment is essential to avoid volume overload, particularly in patients with coexistent heart failure 1, 4, 3

Infection Source Identification

Imaging Studies

• CT imaging with IV contrast: Perform promptly to confirm infection source; has 81.82% positive predictive value for identifying septic foci 1
  • Chest CT: Most common source (38.6% of cases show pneumonia) 1
  • Abdomen/pelvis CT: Second and third most common sources (22% abdominal, 20.5% genitourinary) 1
• Adjust contrast protocols: Consider non-contrast CT if acute kidney injury worsens, though contrast-enhanced studies have superior diagnostic yield 1

Clinical Examination Priorities

• Vascular access sites: Inspect for phlebitis or cellulitis 1
• Surgical/traumatic wounds: Examine for infection signs 1
• Pressure areas and injection sites: Check for soft tissue infection 1
• Sinusitis evaluation: Particularly in intubated patients 1
• Fundoscopy: Essential for detecting candidal endophthalmitis in systemic fungal sepsis 1
• Urine appearance: Frank purulence suggests urinary source 1
• Diarrhea: May indicate Clostridium difficile colitis 1

Additional Diagnostic Considerations

Biomarkers

• Procalcitonin (PCT): Levels ≥1.5 ng/mL have 100% sensitivity and 72% specificity for sepsis; useful for monitoring treatment response 1
• C-reactive protein (CRP): Levels ≥50 mg/L have 98.5% sensitivity and 75% specificity for sepsis 1
• Fungal markers: Consider 1,3-β-D-glucan assay and mannan/anti-mannan antibodies if invasive candidiasis is in the differential 1

Antimicrobial Timing

• Administer within 1 hour: Effective IV antimicrobials must be given within the first hour of recognizing septic shock 1
• Dose adjustment required: Reduce antibiotic doses based on creatinine clearance in CKD patients (e.g., piperacillin-tazobactam requires dosing adjustment when CrCl ≤40 mL/min) 2

Common Pitfalls in CKD Patients

Volume overload risk: CKD patients, especially those with coexistent heart failure, are at higher risk of pulmonary edema with aggressive fluid resuscitation—use dynamic assessment and consider early vasopressor support 4, 3

Delayed recognition of worsening AKI: Sepsis-associated AKI in CKD patients significantly increases long-term risks of CKD progression, end-stage renal disease, and mortality—close monitoring of creatinine trends is essential 6, 7, 8

Inadequate antibiotic dosing: Failure to adjust antimicrobial doses for renal function leads to toxicity or therapeutic failure 2

Conservative fluid resuscitation without evidence: Recent evidence suggests CKD/ESRD patients can tolerate standard 30 mL/kg initial bolus without increased complications when guided by fluid responsiveness 3