Guide — Critical Care
Sepsis & Septic Shock for RTs
Sepsis is a dysregulated host response to infection that injures organs — and the lungs are often first in line. This guide covers the Sepsis-3 definitions, the Surviving Sepsis Campaign bundle, and the respiratory therapist’s role in recognizing sepsis-induced respiratory failure, supporting oxygenation, and tracking the lactate trend.
9 min read · Critical Care
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Overview
Sepsis is a medical emergency: a dysregulated host response to infection that produces life-threatening organ dysfunction. The 2016 Sepsis-3 consensus reframed it around demonstrable organ failure rather than inflammation alone, defining sepsis as infection plus an acute rise in the SOFA score of 2 or more points. Septic shock is the most severe end of that spectrum — a circulatory and metabolic derangement carrying a markedly higher mortality.
For the respiratory therapist, sepsis matters because it is the leading driver of ARDS and a frequent path to mechanical ventilation. The RT supports oxygenation and ventilation as respiratory failure evolves, applies lung-protective settings if ARDS develops, and helps the team execute time-critical resuscitation — while watching the lactate trend as a marker of how that resuscitation is going.
Key Concepts
The Sepsis-3 framework distinguishes three things along a single continuum — infection, sepsis, and septic shock.
| Term | Definition |
|---|---|
| Infection | Invasion of normally sterile tissue by an organism — the precipitant, present without (yet) demonstrable organ dysfunction |
| Sepsis | Life-threatening organ dysfunction caused by a dysregulated host response to infection (acute rise in SOFA ≥ 2 points) |
| Septic shock | Sepsis with persisting hypotension needing vasopressors for MAP ≥ 65 mmHg AND lactate > 2 mmol/L despite adequate fluids |
- Septic shock is distributive shock. The dysregulated response causes widespread vasodilation and a low systemic vascular resistance. Cardiac output is often high or normal early, but oxygen extraction at the tissues is impaired — so the venous oxygen saturation (SvO₂) can be high even as cells starve. This is why pressors, not just fluids, are needed to restore perfusion pressure.
- qSOFA is a fast bedside screen. A positive qSOFA is 2 or more of: respiratory rate ≥ 22, altered mentation, and systolic BP ≤ 100 mmHg. The 2021 Surviving Sepsis Campaign no longer recommends qSOFA as the single screening tool, but it remains widely taught as a quick prompt to escalate assessment.
- Lactate is a resuscitation marker. An elevated lactate reflects tissue hypoperfusion. It is both a severity signal (a lactate ≥ 4 mmol/L triggers aggressive fluids) and a trend to follow — falling lactate, or lactate clearance, suggests resuscitation is working.
Assessment & Findings
- Temperature derangement. Fever is common, but hypothermia can occur and is an ominous sign — both reflect the dysregulated response, not a normal febrile reaction.
- Tachypnea and tachycardia. An elevated respiratory rate is one of the earliest and most sensitive signs, paired with a compensatory tachycardia.
- Hypotension and altered mentation. Falling blood pressure and new confusion or obtundation signal organ hypoperfusion and a slide toward shock.
- Rising lactate and falling urine output. A climbing lactate and decreasing urine output are markers of worsening tissue perfusion and renal dysfunction.
- Skin mottling, warm peripheries early. The distributive picture often shows warm, flushed extremities early; mottling appears as perfusion deteriorates.
RT Priorities / Interventions
Definitive sepsis management is a team effort built around the Surviving Sepsis Campaign “Hour-1” bundle — time-critical steps to start within the first hour of recognition.
| Element | Action |
|---|---|
| Measure lactate | Obtain a serum lactate; remeasure if the initial value is > 2 mmol/L to track clearance |
| Blood cultures | Draw cultures BEFORE giving antibiotics so the source organism can still be recovered |
| Broad-spectrum antibiotics | Administer broad-spectrum antibiotics — each hour of delay in septic shock raises mortality |
| Crystalloid | Begin rapid 30 mL/kg crystalloid for hypotension or a lactate ≥ 4 mmol/L |
| Vasopressors | Start vasopressors (norepinephrine first-line) if hypotensive during/after fluids to keep MAP ≥ 65 mmHg |
Within that effort, the respiratory therapist’s focus is the airway, oxygenation, and the lungs.
- Support oxygenation and ventilation. Deliver supplemental oxygen to support oxygen delivery (DO₂), watch for escalating work of breathing, and be ready to support ventilation — many septic patients progress to respiratory failure and intubation.
- Apply lung-protective ventilation if ARDS develops. Sepsis and pneumonia are the leading causes of ARDS; if it evolves, ventilate at 6 mL/kg of predicted body weight and keep the plateau pressure ≤ 30 cmH₂O per the lung-protective strategy.
- Monitor ABGs, lactate, and capnography. Trend arterial blood gases and the lactate as resuscitation markers, and use capnography to track ventilation and perfusion at the bedside.
- Grade evolving lung injury and assist resuscitation. Recalculate the P/F ratio to grade sepsis-induced ARDS as oxygenation changes, and assist the team with the fluid resuscitation and pressor support the bundle calls for.
Common Pitfalls
- Delaying antibiotics. In septic shock, each hour of delay to effective antibiotics increases mortality. Cultures should be drawn first, but they must not hold up timely therapy.
- Under-resuscitation. Failing to deliver the initial 30 mL/kg crystalloid for hypotension or a high lactate leaves the patient under-filled and the shock under-treated.
- Missing evolving ARDS. Bilateral infiltrates with worsening, refractory hypoxemia after a septic insult meet the ARDS definition — missing the label means missing the protective strategy that improves survival.
- Over-oxygenation. Liberal, untitrated oxygen carries its own harms; support DO₂ without leaving the patient hyperoxic.
- Ignoring the lactate trend. Lactate clearance is a key resuscitation marker; checking a single value and never trending it misses whether the patient is actually responding.
Board Exam Pearls
- Know the Sepsis-3 definitions: sepsis is infection plus organ dysfunction (acute SOFA rise ≥ 2), and septic shock adds a vasopressor requirement plus a lactate > 2 mmol/L despite adequate fluids.
- Norepinephrine is the first-line vasopressor, titrated to a MAP target of ≥ 65 mmHg.
- The initial crystalloid bolus is 30 mL/kg for hypotension or a lactate ≥ 4 mmol/L, and lactate clearance tracks the adequacy of resuscitation.
- Septic shock is a distributiveshock — low SVR, vasodilation, and impaired oxygen extraction — which is why pressors are required once fluids are optimized.
FAQ
What is the Sepsis-3 definition of sepsis?
Under the 2016 Sepsis-3 consensus, sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. Organ dysfunction is operationalized as an acute rise in the SOFA score of 2 or more points attributable to the infection. It is no longer defined by the older SIRS criteria — the emphasis shifted from inflammation alone to demonstrable organ dysfunction.
How is septic shock defined?
Septic shock is a subset of sepsis with profound circulatory and metabolic derangement and a higher mortality. Clinically it is defined as sepsis with persisting hypotension requiring vasopressors to maintain a mean arterial pressure of at least 65 mmHg AND a serum lactate greater than 2 mmol/L, both despite adequate fluid resuscitation. It is a distributive shock — widespread vasodilation, low systemic vascular resistance, and impaired oxygen extraction.
What is the first-line vasopressor in septic shock?
Norepinephrine is the first-line vasopressor in septic shock. It is started for hypotension that persists during or after adequate fluid resuscitation, titrated to keep the mean arterial pressure at or above 65 mmHg. Additional agents may be layered on per protocol, but norepinephrine is the recommended initial choice.
Why do septic patients so often end up on the ventilator?
Sepsis — and pneumonia in particular — is the leading cause of ARDS. The dysregulated inflammatory response injures the alveolar-capillary membrane, producing leaky, flooded lungs and refractory hypoxemia, while the metabolic demands of shock drive up work of breathing. Many septic patients therefore progress to acute respiratory failure and require mechanical ventilation, frequently with a lung-protective strategy once ARDS develops.
Put it to work
Sepsis-induced ARDS is graded by a single ratio. Run a PaO₂ and FiO₂ through the calculator to grade the lung injury and track how the oxygenation is trending as you resuscitate.
Open the P/F Ratio Calculator →Related Resources
Sources
- Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801-810.
- Evans L, Rhodes A, Alhazzani W, et al. Surviving Sepsis Campaign: international guidelines for management of sepsis and septic shock 2021. Crit Care Med. 2021;49(11):e1063-e1143.
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021.