What is the recommended septic work‑up for an adult inpatient who meets criteria for suspected sepsis (e.g., fever, tachycardia, hypotension, altered mental status, or serum lactate ≥2 mmol/L)?

Hospital Septic Work-Up for Suspected Sepsis

For an adult inpatient meeting criteria for suspected sepsis, immediately obtain blood cultures within 1 hour of recognition, measure serum lactate, and initiate broad-spectrum IV antibiotics within 1 hour—these are the cornerstone diagnostic and therapeutic interventions that directly impact mortality. 1, 2

Immediate Diagnostic Work-Up (Within First Hour)

Blood Cultures

• Obtain at least two sets of blood cultures as soon as possible and within 1 hour of hospital arrival, but never delay antibiotics beyond 45-60 minutes waiting for cultures 1, 2
• Blood cultures should be drawn from separate sites before antibiotic administration whenever possible 1
• Even if antibiotics have been started, cultures retain diagnostic value if obtained within 4 hours of antibiotic initiation 1

Serum Lactate Measurement

• Measure serum lactate immediately upon recognition of suspected sepsis as a marker of tissue hypoperfusion 2, 3, 4
• Lactate ≥2 mmol/L indicates tissue hypoperfusion and warrants aggressive resuscitation 1
• Lactate ≥4 mmol/L defines severe tissue hypoperfusion and significantly increases mortality risk 1, 2, 4
• Repeat lactate measurement within 2-6 hours if initially elevated to guide resuscitation effectiveness 2, 4, 5

Clinical Assessment

• Document Glasgow Coma Scale score to assess mental status 1
• Measure vital signs including respiratory rate (≥22/min suggests organ dysfunction), systolic blood pressure (≤100 mmHg indicates hypotension), heart rate, and oxygen saturation 2, 3
• Assess tissue perfusion markers: capillary refill time (target <2 seconds), peripheral pulses, extremity temperature, skin mottling 1, 2

Additional Laboratory Work-Up

Essential Laboratory Tests

• Complete blood count with differential to assess for leukocytosis, leukopenia, or neutropenia 6
• Comprehensive metabolic panel including:
  • Serum sodium (hyponatremia predicts deterioration) 6
  • Serum bicarbonate and chloride (associated with lactate levels) 7
  • Blood urea nitrogen and creatinine (assess renal function and predict progression) 6
  • Liver function tests including AST (associated with high lactate) 7
• Arterial or venous blood gas if respiratory compromise or severe metabolic derangement suspected 1

Source Identification

• Perform detailed history and physical examination focusing on potential infection sources: respiratory (pneumonia), urinary, abdominal, skin/soft tissue, central nervous system 1, 2
• Obtain imaging as clinically indicated to identify infection source (chest X-ray for pneumonia, CT for abdominal source) 1
• Sample fluid or tissue from suspected infection site when feasible without delaying treatment (urine culture, sputum culture, wound cultures, cerebrospinal fluid if meningitis suspected) 1
• Gram stain and culture of sampled specimens 1

Hemodynamic Monitoring

Initial Assessment

• Continuous monitoring of blood pressure, heart rate, respiratory rate, temperature, oxygen saturation, and urine output 2
• Place urinary catheter to monitor urine output (target ≥0.5 mL/kg/hour) 1

Advanced Monitoring (If Available)

• Consider arterial catheter placement in patients requiring vasopressors for continuous blood pressure monitoring 1
• Central venous pressure monitoring may be considered but is not mandatory (target 8-12 mmHg if used) 1
• Central venous oxygen saturation (ScvO2) monitoring can guide resuscitation in select cases 5

Risk Stratification

High-Risk Features Predicting Deterioration

• Lactate ≥4 mmol/L has 97% specificity for subsequent deterioration but only 27% sensitivity 8
• Sequential Organ Failure Assessment (SOFA) score ≥5 predicts 39% progression to tissue hypoperfusion 6
• Presence of organ failures: respiratory, cardiovascular, central nervous system 6
• Hyperthermia, neutropenia, bandemia 6
• Elevated blood urea nitrogen 6

Important Caveats

• Normal lactate does NOT exclude sepsis or risk of deterioration—47% of critically ill sepsis patients have normal lactate levels despite comparable illness severity 7
• Low lactate has only 67% sensitivity for identifying patients at risk of deterioration 8
• Patients with intermediate lactate levels (2.0-4.0 mmol/L) have 23% risk of progression to shock and require close monitoring 6

Critical Pitfalls to Avoid

• Never delay antibiotic administration beyond 1 hour waiting for diagnostic tests—mortality increases 7.6% per hour of delay 2
• Do not assume adequate resuscitation based solely on normal lactate—assess multiple perfusion markers 2, 7
• Avoid continuing aggressive fluid resuscitation without assessing fluid responsiveness after initial 30 mL/kg bolus 4
• Do not attribute persistent lactate elevation to lactated Ringer's infusion—this delays recognition of serious pathology 4
• Serial lactate monitoring (not just initial measurement) is independently associated with reduced mortality and should be performed 5