Paeds · acute-care-resuscitation-and-toxicology
Shock in children: physiology and classification
Also known as Paediatric shock · Childhood circulatory failure · Compensated and decompensated shock in children · Classification of shock in children · Paediatric shock physiology
A fellowship approach to the physiology and classification of shock in children. Shock is inadequate delivery or use of oxygen and substrate at the mitochondrion, not a blood pressure number. Children compensate with tachycardia and vasoconstriction and maintain blood pressure until late, so recognise compensated shock from the whole child, watch the trend, and never wait for hypotension. Classify by haemodynamic phenotype as hypovolaemic, distributive, cardiogenic or obstructive, and grade severity as compensated, decompensated or irreversibly failing.
On this page
Study tools
Your progress
Saved on this device.
Practise this topic
Target exams
Red flags
- Tachycardia out of keeping with fever or distress, with cool mottled skin and prolonged capillary refill: compensated shock until proven otherwise
- A falling or abnormally low heart rate in a deteriorating child is decompensation, not recovery
- Weak or absent central pulses, cold pale or mottled skin, or altered consciousness with poor perfusion: decompensated shock
- Hypotension for age is a late and dangerous sign; do not wait for it to diagnose shock
- A wide pulse pressure with warm peripheries and flash capillary refill suggests distributive shock, not a well child
- Poor response to a fluid aliquot, or a child needing repeated aliquots, demands early vasoactive support and critical care
- Bradycardia, irregular breathing or falling consciousness herald imminent arrest: move to the paediatric arrest algorithm
Life stages
Care settings
Clinical exam formats
Board mappings
- Acute Care
- Current 2026 PREP curriculum — Learning Objective 2.2.1: Recognise, prioritise and manage an acutely ill infant, child or young person
- Current 2026 PREP curriculum — Learning Objective 2.4.4: Assess and manage infants, children and young people with potential cardiac, respiratory or neurological emergencies or acute sepsis
- Renewed curriculum for first-year trainees from 2027 — Learning goal 11: Acute care and procedures
- Renewed curriculum for first-year trainees from 2027 — Learning goal 17: Acute care
- Clinical Applications
- Medical Sciences
- Long Cases
- Short Cases
- 4. Professional skills and knowledge: Patient management
- 6. Leadership and team working
- 7. Patient safety, including safe prescribing
- General Paediatrics: Resuscitates, stabilises and treats extremely unwell babies, children and young people, liaising with specialist teams, as necessary
- Foundation of Practice (FOP)
- Theory and Science (TAS)
- Applied Knowledge in Practice (AKP)
- Clinical
- History
- Video
- General Pediatrics Content Outline — Domain 7: Emergency and Critical Care
- General Pediatrics Content Outline — Universal Task 1: Physiology and Pathophysiology
- General Pediatrics Content Outline — Universal Task 3: Diagnosis
- Patient Care 4: Clinical Reasoning
- Patient Care 5: Patient Management
- Medical Knowledge 1: Core knowledge
- Medical Expert
- Pediatrics: Foundations EPA #1 — Recognizing deteriorating and/or critically ill patients and initiating stabilization and management
Overview & Definition
Shock is not low blood pressure. It is the state in which the delivery of oxygen and metabolic substrate to the tissues, or the cell's ability to use them, falls below demand, so cells shift to anaerobic metabolism and ATP production fails. Blood pressure is only one of several perfusion signs, and in children it is the last to fall. If you wait for hypotension to recognise shock you have already missed the child. [1] [9]
The clinical task is to spot the failing circulation from the whole child before blood pressure collapses, and to act on the trend. A child who is tachycardic with cool peripheries, prolonged capillary refill and altered interaction is in shock even when the blood pressure reads normal. A child whose perfusion improves after one action but then drifts back is still in shock and needs the next decision, not a pause. Shock is dynamic, and its management is reassessment. [1] [6]
[1] [9]Shock grades through a recognisable trajectory as reserve is spent. Compensated shock keeps blood pressure in the normal range for age through tachycardia and vasoconstriction, even though perfusion is already failing at the tissue. Decompensated shock adds hypotension for age with falling consciousness and weak or absent pulses. Irreversible shock is the late phase in which organ failure and cell death can no longer be reversed even by restoring perfusion; the practical point is to act long before the child reaches it. Each grade changes the tempo and the first action. [1] [6]
This topic is the physiology and classification hub. It tells you what shock is, how to grade it, and how to name the type. The complete fluid, vasoactive and sepsis algorithms live in the dedicated septic shock resuscitation and paediatric life support pages; this hub gives the principles, the phenotypes and the thresholds that connect them. [5] [9]
References11ShowHide
- [1]Bjorklund A, Resch J, Slusher T Pediatric Shock Review Pediatrics in review, 2023.PMID 37777656
- [2]Fleming S, Thompson M, Stevens R, et al. Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies Lancet (London, England), 2011.PMID 21411136
- [3]Fleming S, Gill P, Jones C, et al. The Diagnostic Value of Capillary Refill Time for Detecting Serious Illness in Children: A Systematic Review and Meta-Analysis PloS one, 2015.PMID 26375953
- [4]Maitland K, Kiguli S, Opoka RO, et al. Mortality after fluid bolus in African children with severe infection The New England journal of medicine, 2011.PMID 21615299
- [5]Weiss, Scott L Surviving Sepsis Campaign International Guidelines for the Management of Sepsis and Septic Shock in Children 2026 Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies, 2026.PMID 41869844
- [6]Topjian AA, Raymond TT, Atkins D, et al. Part 4: Pediatric Basic and Advanced Life Support 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Pediatrics, 2021.PMID 33087552
- [7]Maconochie IK, Aickin R, Hazinski MF, et al. Pediatric Life Support: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations Circulation, 2020.PMID 33084393
- [8]Schlapbach LJ, Watson RS, Sorce LR, et al. International Consensus Criteria for Pediatric Sepsis and Septic Shock JAMA, 2024.PMID 38245889
- [9]Davis AL, Carcillo JA, Aneja RK, et al. The American College of Critical Care Medicine Clinical Practice Parameters for Hemodynamic Support of Pediatric and Neonatal Septic Shock: Executive Summary Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies, 2017.PMID 28723883
- [10]Paul R, Niedner M, Riggs R, et al. Bundled Care to Reduce Sepsis Mortality: The Improving Pediatric Sepsis Outcomes (IPSO) Collaborative Pediatrics, 2023.PMID 37435672
- [11]Carlton EF, Gebremariam A, Maddux AB, et al. New and Progressive Medical Conditions After Pediatric Sepsis Hospitalization Requiring Critical Care JAMA pediatrics, 2022.PMID 36215045