Severe sepsis and septic shock

SIRS Criteria (2 of the following are required)
Fever or hypothermia	<36°C (96.8°F) or >38°C (100.4°F)
Tachycardia	HR >90 bpm
Tachypnea	RR >20 or PaCO₂ <32 mmHg
Leukocytosis/leukopenia	<4000/microliter, >12 000/microliter, or >10% bands

Hypotension: systolic blood pressure <90 mmHg or mean arterial pressure <65 mmHg.
- Beware of relative hypotension in patients with chronic hypertension.
Encephalopathy and altered mental status.
Acute kidney injury presenting as oliguria or anuria.
Cardiogenic shock: decreased left ventricular ejection fraction on echocardiogram, troponin leak.
Lung injury or acute respiratory distress syndrome (ARDS).
Disseminated intravascular coagulation (DIC).

Step 1: Confirm the diagnosis and determine the severity of illness.

Basic metabolic panel: creatinine (acute kidney injury), glucose (increased insulin resistance).
CBC with differential: WBC <4000/microliter or >12 000/microliter (SIRS), platelets (DIC).
Coagulation profile: PT/INR/PTT (DIC).
Lactate: 4 mmol/L (evidence of cellular anaerobic respiration and threshold to initiate EGDT).
Arterial blood gas: pH (metabolic acidosis).
Liver function tests: AST, ALT, bilirubin (shock liver).
Cardiac markers: troponin (cardiac injury).

Step 2: Determine the etiology.

Chest radiograph to evaluate for pulmonary processes.
Urine analysis to rule out a urinary tract infection.
Lumbar puncture if symptoms are concerning for meningitis.
Cultures:
- Blood (two different sites + one from each chronically indwelling catheter).
- Urine.
- Sputum if there is a suspicion for pneumonia.
- Cerebrospinal fluid if clinically indicated.
Imaging as indicated by symptoms (computed tomography (CT) of the abdomen and pelvis, ultrasound, etc.).