Paediatric shock

This occurs when the circulatory system fails to provide enough oxygen and essential nutrients to meet the energy needs of cells while also struggling to eliminate waste products (PERFUSION).

This situation is defined as a syndrome that occurs when there's a widespread disruption in the body's perfusion process. This disruption leads to cellular hypoxia (low oxygen), acidosis (imbalance in body's pH), and dysfunction of vital organs. The primary causes of this disruption include a failure in providing necessary nutrients and removing waste products.

The Main Factors at Play

Several critical factors contribute to this syndrome:

• The heart, which functions as the pumping mechanism
• The blood vessels, which serve as the pathways/conduit
• The blood itself, carrying vital components

Some Important Definitions

• Cardiac Output (CO): The amount of blood pumped by the heart per minute. It's calculated by multiplying Heart Rate (HR) by Stroke Volume (SV), where SV is influenced by factors like preload, afterload, and cardiac contractility.
• Blood Pressure: The force exerted by the blood against the walls of the blood vessels. It's determined by Cardiac Output (CO) and Systemic Vascular Resistance (SVR).
• Dissolved Oxygen (DO2): The volume of oxygen dissolved in the blood. It's calculated using Cardiac Output (CO), Content of Oxygen in arterial blood (CaO2), and a factor of 10.
• Content of Oxygen in arterial blood (CaO2): The total oxygen content in the blood. It's determined by the oxygen-carrying capacity of Hemoglobin (Hb), the percentage of saturated oxygen (SaO2), and the partial pressure of oxygen (PaO2).

Remember that under standard conditions, Hemoglobin (Hb) carries more than 99% of the oxygen in the blood.

• Occurs in approximately 2% of all hospitalized children and adults in the US, accounting for around 400,000 cases per year.
• Mortality rates range from 20% to 50%.
• Most patients do not succumb during the acute hypotensive phase, but rather due to complications like Multiple Organ Dysfunction Syndrome (MODS).
• About 25% of cases involve a single organ, while 60% affect two organs, and those with three or more organs impacted face a risk exceeding 85%.

Compensated vs Decompensated:

	Compensated	Decompensated
Pulse	Tachycardia	Marked tachycardia, weak or not recordable pulse
Skin	White, cool, moist	White, waxy cold, marked diaphoresis
Level of Consciousness	Unaltered	Altered (disoriented to coma)
Blood Pressure	Normotensive	Hypotensive

Classification

• Hypovolemic Shock: Caused by reduced blood volume.
• Cardiogenic Shock: Arises from heart dysfunction.
• Distributive Shock: Characterized by widespread vasodilation.
• Systemic Inflammatory Response Syndrome (SIRS)
• Anaphylactic Shock (Due to vasoactive compounds)
• Neurogenic Shock (Loss of vascular tone)
• Septic Shock (Vasodilatory Shock): Caused by severe infections.
• Obstructive: Resulting from physical obstruction to blood flow.

Hypovolemic Shock

Cause: Decreased preload due to internal or external losses of intravascular volume components.

This can result from:

• Blood Loss: Hemorrhage
• Plasma Loss: Burns, nephrotic syndrome
• Loss of Water & Electrolytes: Diarrhea, vomiting, diabetes
• Hypo-proteinemia: Resulting from liver injury or as a progressive complication of increased capillary permeability
• Third Spacing: Redistribution of fluid into non-functional spaces

Cardiogenic Shock

Cause: Cardiac pump failure, often resulting from poor myocardial contractility, backward flow from incompetent valves, or obstruction.

This can result from:

• Congenital Heart Disease: Structural heart issues from birth
• Cardiomyopathies: Diseases affecting the heart muscle
• Ischemia: Reduced blood supply to the heart
• Dysrhythmias: Abnormal heart rhythms
• Sepsis: Severe infection affecting the whole body
• Pericarditis, Myocarditis or Endocarditis: Inflammation of the heart layers

Septic Shock

Characteristics: Includes multiple forms of shock:

• Hypovolemic Shock: Caused by fluid redistribution into non-functional spaces (third spacing)
• Distributive Shock: Involves vasodilation, leading to decreased afterload and preload
• Cardiogenic Shock: Occurs due to depression of myocardial function by endotoxin

Caused By:

• Bacterial and Viral Infections
• Fungal Infections: Particularly in immunocompromised patients who are at increased risk

Distributive Shock

Involves a loss of vasomotor tone, leading to vasodilation.

• Loss of venous capacitance leads to decreased preload.
• Loss of arterial capacitance results in decreased afterload or systemic blood pressure.

Caused By:

• Anaphylaxis
• Neurologic Factors:
• Loss of sympathetic vascular tone secondary to spinal cord or brainstem injury
• Drugs:
• E.g. antihypertensive medications
• Sepsis

Obstructive Shock

Characteristics: Involves significant direct obstruction to right or left heart function, or restriction of all cardiac chambers.

Heat Stroke

Hypovolemia due to salt and water losses, along with decreased peripheral vascular resistance.

Caused By:

• Obstructive Shock: Resulting from:
• Large Pulmonary Embolism leading to right-sided heart failure
• Critical Coarctation of the Aorta leading to left-sided heart failure
• Other Causes:
• Pericardial Tamponade
• Tension Pneumothorax

Causes of Shock - The MISFITS

• Trauma: Both nonaccidental and accidental injuries
• Heart Disease and Hypovolemia: Conditions affecting the heart and reduced blood volume
• Endocrine: Examples include Congenital Adrenal Hyperplasia (CAH)
• Metabolic: Imbalances in electrolytes and other metabolic factors
• Inborn Errors of Metabolism
• Sepsis: Infections like meningitis, pneumonia, urinary tract infections (UTI)
• Formula Mishaps: Issues with formula preparation, such as underdilution or overdilution
• Intestinal Catastrophes: Conditions like volvulus, intussusception, necrotizing enterocolitis
• Toxins and Poisons
• Seizures

Shock Types

Type	Preload	Afterload	Contractility
Hypovolemic	↓	↓	↔
Cardiogenic	↑	↑	↓
Distributive	↓	↓	↑
Early Septic	↓	↓	↑
Late Septic	↑	↑	↓

• Baroreceptors:
• Located in the aortic arch and carotid sinus
• Stimulated by high MAP (mean arterial pressure)
• High Pressure Trigger (HPT) activates the cardioinhibitory center, leading to vasodilation, decreased blood pressure (BP), heart rate (HR), and cardiac output (CO)
• Hypotension reduces stimulation, causing vasoconstriction and increasing BP, HR, and CO
• Chemoreceptors:
• Respond to cellular acidosis, resulting in vasoconstriction and respiratory stimulation
• Renin-Angiotensin System (RAS):
• Reduced renal perfusion triggers renin secretion
• Angiotensin I is converted to angiotensin II, leading to vasoconstriction and aldosterone release
• Aldosterone promotes sodium and water retention
• Humoral Responses:
• Release of catecholamines increases cardiac contractility and peripheral vasoconstriction
• Autotransfusion:
• Interstitial fluid reabsorption results in decreased urine output

Pitfall

• Misconception: Shock is mistakenly thought to occur only when there's hypotension.
• Hypotension is a late presentation and carries a very high mortality rate.
• Patients might only exhibit tachycardia without rapid breathing (tachypnea).

Hypotension: A Late Sign of Shock (Pre-Arrest State)

• ABC + D: Airway, breathing, circulation, and dextrose (especially for neonates and infants)
• IV Access: Set up at least 2 large bore IV lines as soon as possible. If unsuccessful within 3 attempts, consider intraosseous insertion.
• Temperature: Keep the patient warm.
• Initial Fluid Bolus:
• In early shock, administer a rapid (5-10 min) initial fluid bolus of 20mL/kg of Normal Saline (NS) or Hartmann's solution, unless cardiogenic shock is suspected.
• Reassessment: Evaluate the adequacy of the fluid bolus and consider initiating other treatments (antibiotics, vasoactive agents, and colloids).
• Severe Shock: May require additional fluid boluses up to 60mL/kg within the first 1-2 hours.
• Fluid Management:
• Titrate fluid therapy until improvement is observed in heart rate (HR), blood pressure (BP), urine output, level of consciousness, and capillary refill time (CRT).
• If hypovolemia results from blood loss or protein-rich fluid, consider blood component transfusion (PRBC, whole blood, FFP, albumin).
• Replace ongoing losses after initial stabilization.
• If feasible, insert a Central Venous Pressure (CVP) line to guide fluid management.
• Crystalloid vs. Colloid: Controversial, consider patient factors.
• Refractory Shock: 3% saline may be beneficial.
• Hypocalcemia in Neonates: Correct aggressively.
• Goal of Treatment: Identify, evaluate, and manage shock in its earliest stage.
• Initial Priorities: Focus on ABC + D.
• Fluid Resuscitation:
• Begin with 20mL/kg of crystalloid and 10mL/kg of colloid.
• Subsequent treatment depends on the shock's cause and the patient's hemodynamic condition.
• Success Factors: Early and judicious intervention is crucial for successful resuscitation.

Corticosteroid in Treatment of Septic Shock

• Studies and Benefits:
• Some studies suggest potential benefits of corticosteroids in treating septic shock.
• Recommended Use:
• Currently, corticosteroids are recommended for patients who may have catecholamine-resistant septic shock or clear history/evidence of adrenal insufficiency.
• However, even in these scenarios, the use of steroids hasn't definitively shown a survival advantage.
• Dosage (from BNF 2010):
• Neonate: IV 2.5mg/kg every 6 hours for 48 hours or until BP recovers, then gradually reduce.
• Child (1 month – 18 years): 1mg/kg (max: 100mg) every 6 hours.

Anaphylactic Shock Management

• IM Adrenaline: 0.01mL/kg of 1:1000 concentration every 15-20 minutes (or IV if severe) – IV Adrenaline infusion may be considered for severe cases
• Supplemental Oxygen: Administer oxygen, place the patient in a recumbent position, and elevate the legs.
• H1 Blockade: Use IV Chlorpheniramine
• H2 Blockade: Administer IV Ranitidine 1mg/kg every 8 hours (useful in refractory cases)
• IV Normal Saline (NS) Bolus: Expand intravascular volume with a bolus of IV NS.
• Corticosteroids:
• Use IV Hydrocortisone 2-4mg/kg every 6 hours
• Alternatively, use IV Methylprednisolone 1mg/kg every 6 hours (useful for late reactions)
• Nebulized Salbutamol: Administer for bronchospasm.

Vasoactive/Cardiotonic Agents

Class	Action
Inotropes	Increase cardiac contractility and often heart rate (e.g., noradrenaline)
Vasopressors	Increase vascular resistance and blood pressure (e.g., dopamine, dobutamine)
Vasodilators	Decrease vascular resistance and cardiac afterload, promoting peripheral perfusion (e.g., sodium nitroprusside)
Inodilators	Increase cardiac contractility and reduce afterload (e.g., milrinone)

• Bacteremia: Presence of living bacteria in the body.
• Septicemia: Presence of rapidly dividing pathogenic bacteria in the body.
• Sepsis:
• Refers to the systemic inflammatory response syndrome (SIRS) associated with infection.
• Most common cause of mortality in children worldwide, especially infants, leading to Multiple Organ Dysfunction Syndrome (MODS).
• Infection:
• Suspected or proven infection caused by any pathogen, confirmed by positive culture, tissue stain, or PCR.
• Also includes clinical syndromes associated with a high probability of infection.

SIRS - Systemic Inflammatory Response Syndrome

• Criteria: Presence of at least 2 of the following 4 criteria (with abnormal temperature or leukocyte count being one of them):
• Core temperature > 38.5°C or < 36°C
• Tachycardia or bradycardia (for children < 1 year)
• Tachypnea
• Leukocytosis or leukopenia
• Source: Goldstein B, Giroir B, Randolph A, et al: International pediatric sepsis consensus conference: Definitions for sepsis & organ dysfunction in pediatrics. Pediatr Crit Care Med 2005

Severe Sepsis & Septic Shock

Severe Sepsis:

• Sepsis + 1 of the following:
• Cardiovascular organ dysfunction
• Acute Respiratory Distress Syndrome (ARDS)
• 2 or more other organ dysfunctions

Septic Shock:

• Sepsis + Cardiovascular organ dysfunction

Definition of Hypotension by Age - Children

Age	Systolic BP (mmHg)
<1 month	≤60
1 month – 1 year	≤70
1 year – 10 years	≤70 + (2 × age in years)
>10 years	≤90

Definitions of Variables by Age

Age	Heart Rate		Respiratory Rate	Leukocyte Count
	Tachycardia	Bradycardia
0 – 1 week	>180	<100	>50	>34
1 wk – 1 mon	>180	<100	>40	>19.5 or <5
1 mon – 1 yr	>180	<90	>34	>17.5 or <5
2 – 5 years	>140	NA	>22	>15.5 or <6
6 – 12 years	>130	NA	>18	>13.5 or <4.5
13 – 18 years	>110	NA	>14	>11 or <4.5

Organ Dysfunction Criteria

Cardiovascular

• Despite administration of isotonic IV fluid bolus ≥ 40mL/kg in 1 hour:
• Decrease in BP < 5th percentile for age
• Need for vasoactive drug to maintain BP in normal range
• Two of the following:
• Unexplained metabolic acidosis: Base Excess (BE) > 5
• Increased arterial lactate > 2x upper limit of normal
• Oliguria: Urine output < 0.5mL/kg/h
• Prolonged Capillary Refill Time (CRT) > 5 seconds
• Core to peripheral temperature gap > 3°C

Respiratory

• PaO2/FiO2 < 300 in absence of cyanotic heart disease or pre-existing lung disease OR
• PaCO2 > 65mmHg or 20mmHg over baseline PaCO2 OR
• Proven need or >50% FiO2 to maintain SpO2 ≥ 92% OR
• Need for nonselective invasive or noninvasive mechanical ventilation

Neurologic

• Glasgow Coma Scale (GCS) ≤ 11 OR
• Acute change in mental status with decrease in GCS ≥ 3 points from abnormal baseline

Hematologic

• Platelet count < 80,000 or a decline of 50% in the platelet count from highest value recorded over the last 3 days (for patients with chronic hematologic or oncologic disorders) OR
• International Normalized Ratio (INR) > 2

Renal

• Serum creatinine ≥ 2x upper limit of normal for age or 2-fold increase in baseline creatinine

Hepatic

• Total bilirubin ≥ 4mg/dL (68) – not applicable for newborn
• ALT level 2x upper limit of normal for age

• Unusual form of shock typically observed in children < 3 years old.
• Characterized by:
• Encephalopathy
• Fever
• Shock
• Watery diarrhea
• Severe Disseminated Intravascular Coagulation (DIC)
• Renal and hepatic dysfunction
• May also present with:
• Seizures
• Other severe neurologic findings due to cerebral edema
• Possible complications: myoglobinuria from rhabdomyolysis
• Treatment involves:
• Fluid resuscitation
• Maintaining adequate cardiac output
• Supporting renal and hepatic function
• Ameliorating acute neurologic abnormalities
• Associated with a high mortality rate; survivors often experience a high incidence of neurologic problems.

• The goal of treatment is to identify, evaluate, and manage shock in its earliest stage.
• Initial priorities include airway, breathing, circulation, and addressing any deficits (ABC + D).
• Fluid resuscitation starts with 20mL/kg of crystalloid and 10mL/kg of colloid.
• Subsequent treatment depends on the type and cause of shock and the patient's hemodynamic status.
• Successful resuscitation hinges on early and well-judged intervention.

QUESTIONS

1. What is the likely type of shock for an 8-year-old who, following a head-first fall into an unfilled swimming pool, presents to the ED with a normal heart rate of 90 bpm, is hypotensive (50/30 mmHg) despite excessive fluid resuscitation, and has multiple CT scans that reveal only a small cerebral contusion?

Answer: Neurogenic Shock

2. What is the difference between warm and cold shock?

Warm shock involves peripheral vasodilation and warm extremities, while cold shock is characterized by peripheral vasoconstriction and cold extremities.