Sepsis

Life-threatening organ dysfunction caused by a dysregulated host response to infection (Sepsis-3 definition) a departure from earlier definitions requiring only SIRS criteria, reflecting recognition that the danger lies in organ dysfunction rather than infection alone.

Any source of infection can progress to sepsis, and early recognition and treatment are the primary determinants of outcome.

Classified by:

• Sepsis: infection plus organ dysfunction (qSOFA ≥2 at the bedside, or a SOFA score increase ≥2 in monitored settings)

• Septic shock: a subset with circulatory, cellular and metabolic abnormalities profound enough to substantially increase mortality: persistent hypotension requiring vasopressors to maintain MAP ≥65mmHg AND lactate >2mmol/L despite adequate fluid resuscitation

• Non-specific early features: fever or hypothermia, tachycardia, tachypnea, malaise, confusion (especially in the elderly, where it may be the only presenting sign)

• Source-specific symptoms: respiratory (cough, dyspnea), urinary (dysuria, flank pain), abdominal (pain, peritonism), skin/soft tissue (erythema, warmth, discharge), meningeal (headache, neck stiffness, photophobia)

• qSOFA ; bedside screening, ≥2 suggests high risk of poor outcome: respiratory rate ≥22/min, altered mentation (GCS <15), systolic BP ≤100mmHg

• Signs of organ dysfunction: altered mental status, reduced urine output, hypoxia, mottled or cool skin, prolonged capillary refill, jaundice, coagulopathy

• Red flag presentations warranting immediate escalation: responds only to voice or pain or unresponsive, systolic BP <90mmHg or a drop >40 from baseline, HR >130, RR ≥25, needing oxygen to maintain SpO2 ≥92%, non-blanching rash, mottled/ashen/cyanotic appearance, no urine passed in 18 hours (or <0.5mL/kg/hr if catheterized), lactate ≥2mmol/L, recent chemotherapy

• Clinical suspicion plus risk stratification (qSOFA, NEWS2, or local early warning score) — do not rely on a single score in isolation; clinical judgement matters

• Lactate: >2mmol/L indicates tissue hypoperfusion, is prognostic, and guides resuscitation response (the trend matters more than a single value)

• Blood cultures: ideally before antibiotics, but NEVER delay antibiotics beyond the first hour to obtain them

• FBC (leukocytosis or leukopenia : both can indicate sepsis; neutropenic sepsis is particularly high-risk), U&E/creatinine, LFTs, coagulation profile, CRP/procalcitonin (supportive, not diagnostic alone)

• Source identification: urinalysis and culture, CXR, imaging per suspected source, lumbar puncture if meningitis suspected ; do not delay antibiotics for LP

• Venous or arterial blood gas: acid-base status, lactate

Differentials: non-infective causes of SIRS or organ dysfunction (pancreatitis, trauma, burns, PE, adrenal crisis), other causes of shock (cardiogenic, hypovolemic, anaphylactic).

"Sepsis Six" administer within 1 hour of recognition.

Give three:

• Oxygen : titrate to target saturation (94-98%, or 88-92% if CO2 retention risk)

• IV fluids ; crystalloid bolus 30mL/kg within the first 3 hours for hypotension or lactate ≥4mmol/L, reassessing response; dynamic markers of fluid responsiveness are preferred over fixed volumes where expertise allows, and over-resuscitation should be avoided

• IV broad-spectrum antibiotics ; within 1 hour, empirical choice guided by likely source and local antimicrobial policy and resistance patterns (e.g. piperacillin-tazobactam, or ceftriaxone ± metronidazole for an intra-abdominal source, adding vancomycin if MRSA risk); de-escalate as soon as the organism is identified

Take three:

• Blood cultures and other relevant samples :before antibiotics if achievable without delay

• Lactate measurement : repeat to assess trend and response

• Urine output monitoring : catheterize if needed, target ≥0.5mL/kg/hr

Alongside the bundle:

• Source control is essential : drain abscess, remove infected line or device, debride necrotic tissue, relieve obstruction. Antibiotics alone are insufficient if the source is not controlled

• Escalation: senior review, ICU/HDU referral if not responding to initial fluid resuscitation, needing vasopressor support, or with significant organ dysfunction

• Ongoing monitoring: hourly vitals initially, repeat lactate targeting clearance, fluid balance, organ function trend, antibiotic de-escalation per cultures, and reassessment of continued IV fluid need to avoid overload once the initial resuscitation phase has passed

Special considerations: neutropenic sepsis :any fever in a patient on or recently completing chemotherapy is an emergency requiring empirical broad-spectrum antibiotics within 1 hour regardless of how well the patient appears.

Pregnancy-associated sepsis ; lower threshold for concern, as physiological changes mask severity; involve obstetrics early.

Pediatric sepsis ; age-specific vital sign thresholds, weight-based dosing, and recognition of non-specific presentation (poor feeding, lethargy, irritability).