10.2 Pediatric Sepsis, Septic Shock & Multiple Organ Dysfunction Syndrome

10.2 Pediatric Sepsis, Septic Shock & Multiple Organ Dysfunction Syndrome

Pediatric sepsis remains a leading cause of mortality in pediatric emergency departments globally. Sepsis occurs when an infectious pathogen triggers a dysregulated systemic host inflammatory response, resulting in widespread endothelial damage, microvascular thrombosis, tissue hypoperfusion, and cellular metabolic failure. Septic shock represents the severe end of the sepsis spectrum, defined as sepsis accompanied by persistent cardiovascular dysfunction (hypotension, reliance on vasoactive agents, or impaired microvascular perfusion) despite adequate volume resuscitation.

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Surviving Sepsis Campaign (SSC) International Guidelines

The International Surviving Sepsis Campaign (SSC) pediatric guidelines emphasize rapid, structured protocolized care. In pediatric emergency care, time-to-antimicrobial administration and rapid restoration of microvascular perfusion directly dictate survival.

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|                        SSC PEDIATRIC HOUR-1 SEPSIS BUNDLE                               |
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|  STEP 1: RECOGNIZE      | Identify sepsis-induced hypoperfusion & altered mental status |
|  STEP 2: DIAGNOSTICS    | Draw blood lactate & blood cultures (DO NOT DELAY ANTIBIOTICS)|
|  STEP 3: ANTIMICROBIALS | Administer empirical broad-spectrum IV/IO antibiotics < 60 min|
|  STEP 4: FLUIDS         | Give 10-20 mL/kg balanced crystalloids (max 40-60 mL/kg 1st hr)|
|                         | *Stop if hepatomegaly, crackles, or fluid overload appear*    |
|  STEP 5: VASOACTIVES    | Initiate Epinephrine (Cold Shock) or Norepinephrine (Warm)    |
|                         | if shock persists after 40-60 mL/kg fluid resuscitation         |
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Bundle Execution & Time-Critical Rules

1. Blood Lactate Measurement: Serum lactate $> 2.0 \text{ mmol/L}$ indicates cellular hypoperfusion. Repeat lactate monitoring tracks resuscitation efficacy.
2. Blood Cultures Prior to Antibiotics: Obtain blood cultures (and other sterile site cultures as indicated) before starting antibiotics, provided doing so does not delay antimicrobial administration beyond 60 minutes from recognition.
3. Empirical Antibiotic Timing: Administer broad-spectrum intravenous or intraosseous antibiotics within 1 hour of sepsis recognition. Every 60-minute delay beyond the first hour increases mortality significantly.
4. Controlled Fluid Resuscitation: Administer 10–20 mL/kg boluses of balanced crystalloids (e.g., Lactated Ringer's or Plasma-Lyte) over 10–20 minutes. Reassess for signs of fluid overload (hepatomegaly, rales/crackles, worsening oxygenation, gallop rhythm) after every bolus.
5. Vasoactive Initiation: If shock persists after 40–60 mL/kg of fluid resuscitation (or sooner if signs of fluid overload develop), initiate vasoactive drug infusions immediately through peripheral IV or IO while securing central venous access.

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Empirical Antimicrobial Selection

Antimicrobial coverage must target likely pediatric pathogens based on age, immune status, and clinical focus of infection:

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Fluid Selection: Balanced vs. Unbalanced Crystalloids

Historically, 0.9% Normal Saline ($154 \text{ mEq/L } Na^+, 154 \text{ mEq/L } Cl^-$) was the standard resuscitation fluid. Modern pediatric sepsis guidelines strongly prefer balanced crystalloids (Lactated Ringer's or Plasma-Lyte). Large volumes of 0.9% Normal Saline induce hyperchloremic metabolic acidosis, trigger renal vasoconstriction, worsen renal perfusion, and increase the risk of acute kidney injury (AKI).

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Vasoactive & Inotropic Selection: Warm vs. Cold Shock

Unlike adult septic shock (which is almost universally warm distributive shock with vasodilatation), pediatric septic shock presents as either cold shock or warm shock, and may transition between states during resuscitation.

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                    |     PEDIATRIC SEPTIC SHOCK STAGES        |
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                                         |
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           v                                                           v
      COLD SHOCK                                                  WARM SHOCK
- Low Cardiac Output, High SVR                              - High Cardiac Output, Low SVR
- CRT > 3-4 seconds                                         - Flash CRT (< 1 second)
- Cool, pale, mottled extremities                           - Warm, flushed extremities
- Weak, thready peripheral pulses                           - Bounding peripheral pulses
- Narrow pulse pressure                                     - Wide pulse pressure
           |                                                           |
           v                                                           v
FIRST-LINE VASOACTIVE:                                      FIRST-LINE VASOACTIVE:
  EPINEPHRINE                                                 NOREPINEPHRINE
  (0.05 - 0.3 mcg/kg/min)                                     (0.05 - 0.3 mcg/kg/min)

Vasoactive Pharmacology Breakdown

• Epinephrine (First-Line for Cold Shock): Low-dose Epinephrine ($0.02 - 0.08 \text{ mcg/kg/min}$) acts primarily on cardiac $\beta_1$ and $\beta_2$ receptors, enhancing myocardial contractility (inotropy) and heart rate (chronotropy) while reducing SVR. Higher doses ($> 0.1 \text{ mcg/kg/min}$) recruit $\alpha_1$ receptors to increase SVR.
• Norepinephrine (First-Line for Warm Shock): Potent $\alpha_1$-agonist with modest $\beta_1$-inotropic effects. Increases SVR and diastolic blood pressure, restoring vascular tone in warm distributive shock.
• Dobutamine: Pure $\beta_1/\beta_2$-agonist used for persistent myocardial dysfunction with adequate blood pressure. Reduces SVR while improving cardiac output.
• Vasopressin (Second-Line Agent): Used as an adjunct in refractory warm shock with severe catecholamine-resistant vasodilation ($0.0002 - 0.002 \text{ units/kg/min}$).
• Hydrocortisone Therapy: Indicated ONLY for fluid-refractory, catecholamine-resistant septic shock in children with suspected or proven absolute adrenal insufficiency or septic shock with history of chronic steroid use ($2 \text{ mg/kg/dose IV}$, max $100 \text{ mg}$). Routine steroid administration in pediatric sepsis without shock is not recommended.

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Multiple Organ Dysfunction Syndrome (MODS) & DIC

Multiple Organ Dysfunction Syndrome (MODS) is defined as progressive, reversible dysfunction of two or more organ systems secondary to acute systemic insult (sepsis, severe trauma, or burns).

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|                         PEDIATRIC MODS ORGAN SYSTEM CRITERIA                            |
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| SYSTEM          | CLINICAL CRITERIA / LABORATORY MARKERS                                |
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| Cardiovascular  | Hypotension, requirement for vasoactive infusion, serum lactate > 4   |
| Respiratory     | PaO2/FiO2 ratio < 300, need for mechanical ventilation, ARDS          |
| Hematologic     | Platelet count < 100,000/mcL, INR > 1.5, severe anemia                |
| Renal           | Serum creatinine >= 2x upper limit of normal for age, oliguria        |
| Hepatic         | Total bilirubin >= 4.0 mg/dL, ALT/AST >= 2x normal upper limit        |
| Neurologic      | Glasgow Coma Scale (GCS) <= 11, acute change in mental status         |
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Disseminated Intravascular Coagulation (DIC)

Septic endothelial injury triggers widespread consumption of clotting factors and platelets alongside impaired fibrinolysis. Microvascular fibrin thrombi cause ischemic tissue necrosis, while factor consumption leads to severe hemorrhage.

• Diagnostic Findings: Thrombocytopenia ($< 100,000 /\mu L$), prolonged PT/INR and aPTT, decreased fibrinogen ($< 150 \text{ mg/dL}$), and elevated D-dimer / FDPs.
• Emergency Interventions: Treat underlying sepsis. Administer Fresh Frozen Plasma (FFP) (10–15 mL/kg) for prolonged PT/aPTT with active bleeding, Platelets (10 mL/kg) for severe thrombocytopenia ($< 20,000/\mu L$ or $< 50,000/\mu L$ with active bleeding), and Cryoprecipitate (1 unit per 5–10 kg) for severe hypofibrinogenemia ($< 100 \text{ mg/dL}$).