13.1 Sepsis & Septic Shock
Key Takeaways
- Sepsis-3 defines sepsis as suspected or documented infection plus an acute rise in the SOFA score of at least 2 points; the term severe sepsis is retired.
- Septic shock requires BOTH a vasopressor to maintain MAP at least 65 mmHg AND lactate above 2 mmol/L after adequate fluid resuscitation, with mortality over 40 percent.
- The Surviving Sepsis Campaign Hour-1 bundle is: measure lactate, obtain blood cultures before antibiotics, give broad-spectrum antibiotics, give 30 mL/kg crystalloid, and start vasopressors for persistent hypotension.
- Norepinephrine is the first-line vasopressor; vasopressin 0.03 units/min is the second agent, and hydrocortisone 200 mg/day is added for ongoing vasopressor requirement.
- qSOFA (RR at least 22, altered mentation, SBP at most 100) is a bedside screen, not a diagnostic tool; SSC 2021 advises against using it alone.
Sepsis-3 Definitions
Sepsis (Sepsis-3, 2016) is life-threatening organ dysfunction caused by a dysregulated host response to infection. It is operationalized at the bedside as a suspected or documented infection plus an acute increase in the Sequential Organ Failure Assessment (SOFA) score of at least 2 points (baseline SOFA is assumed to be 0 in a previously healthy patient). The older concept of severe sepsis — sepsis plus organ dysfunction — has been retired because, under Sepsis-3, organ dysfunction is already built into the definition of sepsis itself. The CCRN expects you to recognize that infection without new organ dysfunction is uncomplicated infection, not sepsis.
Septic shock is a subset of sepsis in which underlying circulatory, cellular, and metabolic abnormalities are profound enough to substantially increase mortality. The clinical criteria require BOTH of the following after adequate fluid resuscitation: (1) a vasopressor requirement to maintain a mean arterial pressure (MAP) of at least 65 mmHg, AND (2) a serum lactate greater than 2 mmol/L. In-hospital mortality of septic shock exceeds 40 percent, versus roughly 10 percent for sepsis without shock. A common exam trap is calling a hypotensive septic patient "septic shock" before a fluid challenge — the vasopressor and lactate criteria apply after fluids.
SOFA and qSOFA
SOFA scores six organ systems from 0 to 4 (respiration, coagulation, liver, cardiovascular, central nervous system, renal). qSOFA (quick SOFA) is a rapid bedside screen using three variables — respiratory rate at least 22/min, altered mentation (Glasgow Coma Scale below 15), and systolic BP at most 100 mmHg. Two or more points flags a patient at higher risk of a poor outcome. Crucially, qSOFA is a screening and prognostic tool, not a diagnostic criterion; the Surviving Sepsis Campaign (SSC) 2021 guidelines recommend against using qSOFA as the single screening tool because it is specific but insensitive, and advise pairing it with Systemic Inflammatory Response Syndrome (SIRS), the National Early Warning Score (NEWS), or the Modified Early Warning Score (MEWS).
The Surviving Sepsis Hour-1 Bundle
The SSC Hour-1 bundle compresses initial resuscitation into interventions begun within the first hour of recognition. Memorize the five elements — they are heavily tested:
| Element | Action | Key detail |
|---|---|---|
| Lactate | Measure serum lactate | Remeasure within 2-4 h if initial value is above 2 mmol/L |
| Cultures | Obtain blood cultures | Before antibiotics, if it does not delay them past 45 min |
| Antibiotics | Broad-spectrum antimicrobials | Within 1 h for shock; a leading driver of mortality per hour of delay |
| Fluids | 30 mL/kg IV crystalloid | For hypotension or lactate at least 4 mmol/L; balanced crystalloid preferred |
| Vasopressors | Start if hypotensive during/after fluids | Titrate to MAP at least 65 mmHg |
The sequencing logic matters: cultures precede antibiotics so the pathogen is not masked, but antibiotics are never delayed for the sake of cultures in a patient with shock. The 30 mL/kg bolus is given rapidly; SSC 2021 favors balanced crystalloids (such as lactated Ringer's) over 0.9 percent saline and advises against starches.
Vasopressor Sequencing
Norepinephrine is the first-line vasopressor in septic shock — it raises systemic vascular resistance and MAP with less tachyarrhythmia than dopamine, which is no longer recommended. When escalating norepinephrine fails to reach MAP 65, add vasopressin at a fixed dose of 0.03 units/min to reduce catecholamine requirements; epinephrine is the next add-on. Dobutamine is reserved for persistent hypoperfusion (low cardiac output, high lactate) despite adequate volume and MAP — it is an inotrope, not a first-line pressor. For ongoing vasopressor requirement, add IV hydrocortisone 200 mg/day (commonly 50 mg every 6 h or a continuous infusion).
Source Control
Definitive source control — draining an abscess, removing an infected line or device, debriding necrotic tissue, or relieving an obstructed viscus — should be pursued as soon as the diagnosis is made, ideally within 6 to 12 hours. Antibiotics and hemodynamic support will not reverse sepsis if an undrained anatomic focus keeps seeding the bloodstream. On the CCRN, when a septic patient fails to improve despite a correct Hour-1 bundle, the best next step is frequently identifying and controlling the source, not simply escalating pressors.
Lactate-Guided Resuscitation
Lactate is both a diagnostic and a resuscitation target. An elevated lactate reflects tissue hypoperfusion and anaerobic metabolism; SSC recommends guiding resuscitation to normalize (decrease) lactate in patients with an elevated initial value, remeasuring every 2 to 4 hours. A falling lactate signals improving perfusion, while a rising lactate on adequate MAP is an ominous sign of ongoing shock. After the initial 30 mL/kg, further fluid is given based on dynamic measures of fluid responsiveness — passive leg raise, stroke-volume or pulse-pressure variation, or the response to a small bolus — rather than static central venous pressure alone, so you avoid the fluid overload that worsens outcomes.
Worked Scenario and Common Traps
Consider a patient with urosepsis: temperature 39.2 C, BP 82/44, HR 122, lactate 4.6 mmol/L. The correct order is to draw cultures and lactate, start broad-spectrum antibiotics, and infuse 30 mL/kg crystalloid; if the MAP remains below 65 after fluids, start norepinephrine. Two frequent traps: (1) delaying antibiotics to wait for a CT or complete cultures — antibiotics must not be delayed in shock; and (2) reaching for dopamine or a fluid bolus larger than needed instead of norepinephrine once the patient is fluid-refractory. A third trap is treating a MAP of 65 as "good enough" when the lactate is still climbing — that combination means perfusion is inadequate and demands reassessment of source control and cardiac output.
A patient with pneumonia has a suspected infection, a new lactate of 3.2 mmol/L, and a SOFA score that has risen from 0 to 3. After 30 mL/kg crystalloid the MAP is 70 mmHg on no vasopressors. How is this patient BEST classified?
A septic shock patient has cardiac index 5.5 L/min/m2, SVR 450 dynes/sec/cm-5, and MAP 55 mmHg despite 30 mL/kg crystalloid. Per the Surviving Sepsis Campaign, which vasopressor should be started FIRST?
Which action is required by the Surviving Sepsis Campaign Hour-1 bundle BEFORE administering broad-spectrum antibiotics, provided it does not cause significant delay?