๐Ÿซ€ Chapter 42: Shock โ€” Initial Assessment and Management

Compensated vs Hypotensive Shock ยท Pathophysiology ยท Fluid Resuscitation ยท Inotropes & Vasoactive Agents ยท Lactate & ScvO2 ยท Phases of Management

๐Ÿ” Shock: Failure of Oxygen Delivery to Meet Metabolic Demands

๐Ÿ“Š Definition & Key Concepts
Shock = impaired systemic O2 delivery. BP defines stage: compensated (normal BP) vs hypotensive (low BP). Children compensate with tachycardia & increased SVR. Hypotension is a LATE sign in children.
๐Ÿฉธ Pathophysiology
Perfusion pressure = MAP - CVP = CO ร— SVR. Hypovolaemic: low preload. Distributive: low SVR. Cardiogenic: low contractility. Septic shock = combination of all three.
๐Ÿšจ Clinical Signs
Tachycardia, tachypnoea, delayed CRT, cool extremities, oliguria, altered sensorium. Compensated shock: normal BP. Hypotensive shock: BP <5th percentile.
๐Ÿงช Key Labs
Lactate >1.5 mmol/L = tissue hypoperfusion. ScvO2 65-75% normal; <65% = inadequate O2 delivery; >85-90% = poor prognostic sign (cellular O2 utilisation failure). Metabolic acidosis on ABG.
๐Ÿ’ง Fluid Resuscitation
20 mL/kg isotonic crystalloid rapid bolus (push-pull). Reassess after each bolus. IO if IV fails within 2 attempts/90 sec. Target CVP 8-10 (spontaneous) or 12-14 (ventilated). Stop if signs of fluid overload.
๐Ÿ’Š Vasoactive Agents
Noradrenaline (vasopressor) for warm shock. Adrenaline (inotrope) for cold shock. Milrinone/dobutamine for inodilator effects. Start after 40-60 mL/kg fluids if shock persists.
๐Ÿ“Œ Phases of Shock Management: Salvage (obtain minimal BP) โ†’ Optimisation (improve ScvO2, lactate) โ†’ Stabilisation (organ support) โ†’ De-escalation (wean vasoactives, negative fluid balance).

๐Ÿฉบ Step-by-Step: Shock Management Algorithm

1
Recognise shock clinically
Look for tachycardia, tachypnoea, delayed CRT (>2 sec), cool extremities, weak pulses, oliguria, altered sensorium. Do NOT wait for hypotension โ€” children compensate until late.
2
Assess for compensated vs hypotensive shock
Compensated: normal BP with signs of poor perfusion. Hypotensive: BP <5th percentile for age. Obtain IV/IO access immediately.
3
Administer oxygen & monitoring
100% O2 via NRM. Attach multichannel monitor (HR, BP, SpO2). Obtain ABG, lactate, blood culture.
4
Fluid resuscitation (20 mL/kg bolus)
Give isotonic crystalloid (NS or RL) rapid push over 5-10 min. Reassess after each bolus. Repeat up to 60 mL/kg. If no response after 40-60 mL/kg, start inotropes.
5
Insert invasive lines
Arterial line (continuous BP monitoring) and central venous line (CVP, ScvO2, vasoactive infusion). Urinary catheter for hourly UOP.
6
Choose vasoactive agent based on shock type
Cold shock (narrow pulse pressure, cool extremities, delayed CRT) โ†’ Adrenaline or dopamine. Warm shock (wide pulse pressure, bounding pulses, flash CRT) โ†’ Noradrenaline. Septic shock with myocardial dysfunction โ†’ Adrenaline + Milrinone.
7
Target therapeutic end points
HR normal for age, CRT <2 sec, warm extremities, UOP >1 mL/kg/h, lactate decreasing, ScvO2 >70%, MAP-CVP = age-appropriate perfusion pressure.