Give me a flowchart of pathophysiology of sepsis and septic shock based on Robbins Pathology and Bailey and Love Surgery
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Here is the flowchart, synthesized directly from Robbins, Cotran & Kumar - Pathologic Basis of Disease (Fig. 4.20 and surrounding text) and Bailey and Love's Short Practice of Surgery, 28th Ed. (Chapter 5). Below is the full textual breakdown of the pathway:
Pathophysiology of Sepsis and Septic Shock
1. Trigger: Infection / Microbial Products
- Gram-positive bacteria (most common trigger)
- Gram-negative bacteria (LPS/endotoxin from dying bacilli, e.g. E. coli)
- Fungi, viruses (e.g. SARS-CoV-2)
Bailey & Love: "Serious infection may lead to SIRS through the release of lipopolysaccharide endotoxin from the walls of dying Gram-negative bacilli."
2. Pattern Recognition: PAMPs + PRRs
Microbial PAMPs (and DAMPs from injured cells) engage:
- Toll-like receptors (TLRs) - on macrophages, neutrophils, dendritic cells, endothelium
- G-protein-coupled receptors - detect bacterial peptides
- C-type lectin receptors (Dectins) - detect fungal antigens
This triggers NF-kB nuclear translocation and gene upregulation.
3. Three Parallel Pathogenic Arms (Robbins)
A. Proinflammatory Cytokine Cascade
- TNF-α, IL-1, IL-6, IL-12, IL-18, IFN-γ, HMGB1
- ROS, prostaglandins, platelet-activating factor (PAF)
- Elevated CRP and procalcitonin (acute phase markers)
- Complement activation: C3a (mast cell activation), C5a (chemotaxis), C3b (opsonin)
Bailey & Love: "Cytokines IL-1 and TNF-α stimulate neutrophil adhesion to endothelial surfaces... a respiratory burst occurs releasing lysosomal enzymes, oxidants and free radicals."
B. Endothelial Activation and Injury
- Upregulation of adhesion molecules
- Loosening of tight junctions → vascular leakage, protein-rich edema
- Increased NO production → vascular smooth muscle relaxation → systemic hypotension
- Microvascular dysfunction: heterogeneous capillary flow, AV shunting, loss of autoregulation → O₂ supply/demand mismatch
C. Procoagulant State → DIC
- ↑ Tissue factor expression (monocytes, endothelium)
- ↓ Thrombomodulin, Protein C, TFPI (anticoagulant factors)
- ↑ PAI-1 → impaired fibrinolysis
- Neutrophil Extracellular Traps (NETs) promote both intrinsic and extrinsic coagulation
- Fibrin-rich thrombi in small vessels throughout the body
- In full-blown DIC: consumption of coagulation factors + platelets → paradoxical bleeding
4. Metabolic Derangements (Robbins)
- Insulin resistance + hyperglycemia
- ↑ Gluconeogenesis (driven by TNF, IL-1, glucagon, cortisol, catecholamines)
- Hyperglycemia suppresses neutrophil bactericidal function
- Cellular hypoxia + impaired mitochondrial oxidative phosphorylation → lactic acidosis
- Adrenal insufficiency (from DIC-induced adrenal necrosis - Waterhouse-Friderichsen syndrome)
5. Counter-regulatory Immunosuppression (Robbins)
The hyperinflammatory state triggers opposing mechanisms:
- Th1 → Th2 cytokine shift
- IL-10, soluble TNF receptor, IL-1 receptor antagonist
- Lymphocyte apoptosis and anergy
This creates oscillation between hyperinflammatory and immunosuppressed states.
6. SEPSIS
"Life-threatening organ dysfunction caused by a dysregulated host response to infection" - Robbins Cotran
SIRS criteria (Bailey & Love): ≥2 of: fever/hypothermia, tachycardia/tachypnoea, WBC >12 or <4 × 10⁹/L. Sepsis = SIRS + documented source of infection.
7. Organ Dysfunction (MODS)
| Organ | Effect |
|---|---|
| Lungs | ARDS |
| Kidneys | Acute tubular necrosis (ATN) |
| Heart | ↓ Contractility, myocardial depression |
| Liver | Hepatic dysfunction |
| Brain | Encephalopathy |
| Gut | Ileus, bacterial translocation |
Bailey & Love: "The more organs that fail, the more likely it becomes that death will follow despite all that a modern ICU can do for organ support."
8. Septic Shock
"A subset of sepsis in which profound circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality." - Robbins Cotran
Haemodynamic profile (Bailey & Love Table 2.1):
- High cardiac output (early/warm phase)
- Low systemic vascular resistance
- Low venous pressure
- High mixed venous saturation
Later phases: hypovolaemia from fluid extravasation + myocardial depression complicates the picture.
9. MSOF → Death
Vicious cycle: organ failure reduces host defences → further infection → further organ failure. Mortality remains 20-40% despite modern ICU support (Robbins).
Sources:
- Robbins, Cotran & Kumar - Pathologic Basis of Disease, Fig. 4.20 and pp. 134-137
- Robbins & Kumar - Basic Pathology, pp. 2782-2857
- Bailey and Love's Short Practice of Surgery, 28th Ed., Chapter 5 (pp. 779-800, 4451-4484)
Generate a presentation on the Surviving Sepsis Campaign bundles
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"Surviving Sepsis Campaign" bundles guidelines
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Surviving Sepsis Campaign 2021 guidelines 1-hour bundle elements update
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Your presentation is ready! Here's the download link:
Surviving Sepsis Campaign Bundles
Presentation · PPTX
What's Inside (14 Slides)
| # | Slide | Content |
|---|---|---|
| 1 | Title Slide | Dark navy theme with teal accents |
| 2 | Agenda | 10-topic overview with numbered cards |
| 3 | What is the SSC? | Timeline (2002–2021) + SSC mission & goals |
| 4 | Sepsis-3 Definitions | Infection → SIRS → Sepsis → Septic Shock with diagnostic criteria |
| 5 | Hour-1 Bundle | All 5 elements with colour-coded action panels |
| 6 | Fluid Resuscitation | 30 mL/kg crystalloid, balanced fluids (2021 update), dynamic assessment |
| 7 | Antimicrobials | Timing rules, empiric coverage, source control, stewardship |
| 8 | Vasopressors & Steroids | Full vasopressor table, peripheral IV use (2021 NEW), hydrocortisone, glycaemic control |
| 9 | Lactate & Monitoring | Lactate level tiers with actions, resuscitation targets, screening tools |
| 10 | Sepsis Six | Bailey & Love / UK Sepsis Trust — Give 3 vs Take 3 side-by-side layout |
| 11 | SSC 2021 Key Updates | Comparison table vs 2016 (7 new/changed recommendations) |
| 12 | Outcomes & Evidence | Mortality statistics + ANDROMEDA-SHOCK trial + bundle compliance data |
| 13 | Quick Reference Card | Bedside summary — colour-coded action steps with time targets |
| 14 | Key Takeaways | 8-point summary with references |
Sources used: Bailey & Love Surgery 28e, SSC 2021 International Guidelines (Evans et al., Crit Care Med 2021), SSC Hour-1 Bundle 2018, Robbins Pathology.
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