Treatment of Rigors
Rigors signal serious infection requiring immediate broad-spectrum intravenous antibiotics within 1 hour, aggressive fluid resuscitation with 30 mL/kg crystalloid, and vasopressor support if hypotension persists—this approach reduces mortality by approximately 7.6% for each hour gained. 1, 2
Immediate Recognition and Assessment (First 15 Minutes)
Rigors indicate systemic infection with high risk of sepsis or septic shock. Immediately assess for signs of tissue hypoperfusion: altered mental status, systolic blood pressure ≤100 mmHg, respiratory rate ≥22/min, mottled skin, delayed capillary refill (>3 seconds), oliguria, and elevated lactate 3, 1. These findings define septic shock when infection is confirmed, vasopressors are needed to maintain MAP ≥65 mmHg despite adequate fluid resuscitation, and lactate remains ≥2 mmol/L 3.
The Hour-1 Bundle: Five Critical Actions
1. Obtain Blood Cultures (Within 15 Minutes)
Draw at least two sets of blood cultures—one percutaneously and one from any vascular device in place >48 hours—before starting antibiotics, but never delay antibiotics beyond 45 minutes waiting for cultures 1, 2, 4. If culture acquisition causes significant delay, begin antibiotics immediately 1.
2. Measure and Monitor Lactate
Obtain serum lactate immediately and repeat within 2-4 hours if initial value is ≥2 mmol/L 1, 2. Target lactate normalization (<2 mmol/L) as a marker of adequate tissue perfusion 1, 2. Serial measurements every 2-6 hours guide resuscitation adequacy 2.
3. Administer Broad-Spectrum Antibiotics (Within 60 Minutes)
Start an extended-spectrum β-lactam (piperacillin-tazobactam 3.375-4.5g IV every 6-8 hours, cefepime, or meropenem) within 1 hour of recognizing sepsis 1, 2, 4. Each hour of delay increases mortality by 7.6-8% 1, 4.
For septic shock, neutropenia, or suspected multidrug-resistant organisms: Add an aminoglycoside (gentamicin 5-7 mg/kg IV once daily) or fluoroquinolone (ciprofloxacin or levofloxacin) for the first 3-5 days 1, 4. This combination improves outcomes by ensuring at least one agent is active against resistant pathogens 4.
For suspected pneumococcal bacteremia with shock: Add a macrolide (azithromycin) to the β-lactam 1, 2.
For β-lactam allergy: Use ciprofloxacin 400mg IV every 12 hours PLUS metronidazole 500mg IV every 8 hours 4.
Empiric therapy must cover all likely pathogens based on local resistance patterns, recent antimicrobial exposure (within 3 months), and suspected infection source 3.
4. Aggressive Fluid Resuscitation (First 3 Hours)
Administer 30 mL/kg of isotonic crystalloid (normal saline or balanced solution) rapidly over 5-10 minutes for hypotension or lactate ≥4 mmol/L 3, 1, 2. In children, give 20 mL/kg as a rapid bolus, up to 40-60 mL/kg in first aid 3.
After the initial 2 liters, guide further fluid administration with dynamic assessments (pulse-pressure variation, stroke-volume variation) or bedside echocardiography rather than static measurements alone 1, 2. Consider albumin when large volumes of crystalloids are required 1. Never use hydroxyethyl starches, hypotonic crystalloids, or gelatins—they increase acute kidney injury and mortality 1, 2.
5. Initiate Vasopressors for Persistent Hypotension
Start norepinephrine as the first-line vasopressor if MAP remains <65 mmHg after adequate fluid resuscitation 3, 1, 2. Target MAP ≥65 mmHg (consider 70-85 mmHg in chronic hypertension) 2. Do not delay vasopressor initiation while obtaining central access—peripheral IV administration is acceptable 1, 2.
Add vasopressin (0.03 U/min) when additional MAP support is needed or to reduce norepinephrine dose, but never use as the sole initial agent 1, 2. Add epinephrine if norepinephrine alone is insufficient 1, 2. Avoid dopamine—it increases arrhythmias and worsens outcomes 2.
Antipyretic and Supportive Measures
Antipyretics (acetaminophen or NSAIDs) may provide symptomatic relief from rigors but do not address the underlying infection 5. External warming with blankets can reduce shivering discomfort, but avoid aggressive warming that may mask fever as a clinical marker 3.
Provide intensive supportive care: Maintain hemoglobin 7-9 g/dL unless tissue hypoperfusion, active coronary ischemia, or acute hemorrhage is present 1, 2. Administer pharmacologic or mechanical deep vein thrombosis prophylaxis unless contraindicated 1, 2. Provide stress-ulcer prophylaxis (H₂-blocker or proton-pump inhibitor) in patients with bleeding risk factors 2. Control blood glucose and prevent stress-induced gastrointestinal bleeding 3.
Source Control (Within 12 Hours)
Identify and control the infection source within 12 hours when feasible 3, 1, 2. Perform thorough head-to-toe examination to locate the infection source 3. Use imaging (X-ray, ultrasound, CT) to answer specific diagnostic questions 3, 2. Drain abscesses or debride infected tissue using the least invasive effective intervention (percutaneous drainage preferred over open surgery) 1, 2. Remove intravascular devices promptly after establishing alternative access if they are a possible infection source 1, 2.
Daily Antimicrobial Reassessment and De-escalation
Reassess antimicrobial therapy daily once culture results and clinical response are available 3, 1, 4. Narrow to the most appropriate single agent based on susceptibility data within 3-5 days 3, 1, 4. Discontinue combination therapy within 3-5 days if clinical improvement is evident 1, 4.
Total antibiotic course: 7-10 days for most cases with adequate source control 1, 4. Extend beyond 10 days only for slow clinical response, persistent fever, undrainable infection focus, documented Staphylococcus aureus bacteremia, or immunocompromised/neutropenic state 1, 4.
Use procalcitonin levels to support discontinuing empiric antibiotics in patients with no subsequent evidence of infection 3, 1.
Common Pitfalls to Avoid
Do not delay antibiotics while awaiting culture results—obtain cultures quickly but initiate antimicrobials within 1 hour 1, 2, 4. Do not rely solely on MAP as a perfusion indicator—also monitor lactate, urine output (target >0.5 mL/kg/hour), mental status, and capillary refill 1, 2. Do not continue combination antibiotics beyond 3-5 days without clear indication—de-escalate based on culture data to reduce toxicity and resistance 1, 4. Do not use routine corticosteroids—reserve hydrocortisone 200 mg/day only for refractory septic shock unresponsive to adequate fluids and vasopressors 3, 2.
Special Consideration: Jarisch-Herxheimer Reaction
In patients with suspected spirochete infections (leptospirosis, syphilis, Lyme disease, relapsing fever), rigors with transient fever and hypotension occurring within 3-24 hours of antibiotic initiation may represent Jarisch-Herxheimer reaction rather than septic shock 6. Do not escalate antibiotics if JHR is strongly suspected—symptoms typically resolve within 15 hours of continued antibiotic therapy 6. However, this diagnosis requires detailed exposure history (land clearance, river water exposure, tick bites) and should not delay aggressive sepsis management when the diagnosis is uncertain 6.