What are the immediate laboratory tests and interventions for a patient with concern for sepsis?

Immediate Laboratory Tests and Interventions for Suspected Sepsis

For patients with concern for sepsis, immediate laboratory tests should include blood cultures (at least two sets), serum lactate, complete blood count, comprehensive metabolic panel, and coagulation studies, followed by prompt administration of broad-spectrum antibiotics within one hour of recognition and aggressive fluid resuscitation targeting a mean arterial pressure of 65 mmHg. 1

Initial Laboratory Evaluation

• Blood cultures: Obtain at least two sets (aerobic and anaerobic bottles) before starting antimicrobial therapy, with at least one drawn percutaneously and one through each vascular access device (if present for <48 hours), provided this does not significantly delay (<45 minutes) antibiotic administration 1
• Serum lactate: Essential for risk stratification and as a marker of tissue hypoperfusion; elevated levels (>2 mmol/L) indicate more severe disease and need for more aggressive resuscitation 1
• Complete blood count: To assess for leukocytosis, leukopenia, or bandemia 1
• Comprehensive metabolic panel: To evaluate organ function (renal, hepatic) and electrolyte abnormalities 1
• Coagulation studies: To assess for coagulopathy which may indicate more severe disease 1
• Procalcitonin: Consider as an adjunctive test to assist in determining likelihood of bacterial infection and potentially guide antibiotic discontinuation 1

Immediate Interventions

Antimicrobial Therapy

• Administer broad-spectrum IV antibiotics within one hour of recognition of sepsis or septic shock 1
• Choose empiric antibiotics that cover all likely pathogens (bacterial, fungal, viral as appropriate) and that penetrate adequately into the presumed source of infection 1
• Combination therapy is recommended for neutropenic patients, suspected multidrug-resistant pathogens (Pseudomonas, Acinetobacter), or patients with respiratory failure and septic shock 1
• Reassess antimicrobial regimen daily for potential de-escalation based on clinical improvement and culture results 1

Hemodynamic Support and Resuscitation

• Administer IV crystalloid fluids rapidly for patients with hypotension or elevated lactate (≥4 mmol/L) 1
• Initial fluid resuscitation with 30 mL/kg of crystalloid solution 1
• Target a mean arterial pressure (MAP) of 65 mmHg in patients requiring vasopressors 1
• Norepinephrine is the first-line vasopressor for septic shock 1
• Guide resuscitation to normalize lactate levels in patients with elevated lactate as a marker of tissue hypoperfusion 1
• Avoid fluid overload which may lead to pulmonary edema and increased intra-abdominal pressure 1

Source Control

• Obtain prompt imaging studies to identify potential sources of infection requiring drainage or surgical intervention 1
• Implement source control measures (e.g., drainage of abscesses, removal of infected devices) as soon as possible after initial resuscitation 1

Ongoing Monitoring

• Serial lactate measurements to guide resuscitation and assess response to therapy 1
• Monitor vital signs including heart rate, blood pressure, respiratory rate, temperature, and oxygen saturation 1
• Assess organ function using tools such as the Sequential Organ Failure Assessment (SOFA) score 1
• Monitor urine output targeting ≥0.5 mL/kg/hr as a marker of adequate renal perfusion 1

Common Pitfalls and Caveats

• Do not delay antibiotics for culture collection if it would result in significant delays (>45 minutes) in antimicrobial administration 1
• Blood culture contamination can lead to unnecessary antibiotic use and prolonged hospitalization; ensure proper sterile technique during collection 2
• Avoid undertreating suspected multidrug-resistant infections in high-risk patients (healthcare-associated infections, recent antibiotic exposure) 1
• Recognize that not all septic patients will present with fever or elevated white blood cell count; altered mental status or hypotension may be the only presenting signs 3
• Avoid excessive fluid administration in patients with signs of volume overload or cardiac dysfunction 1
• Do not rely solely on a single parameter (such as blood pressure) to guide resuscitation; use multiple clinical indicators including lactate clearance, urine output, and mental status 1