Respiratory Failure in Children

Introduction to Pediatric Respiratory Failure

Definition

Respiratory failure occurs when the respiratory system fails in oxygenation and/or ventilation functions. In children, this represents a significant emergency requiring prompt recognition and intervention.

Key Concepts

Type I (Hypoxemic) Respiratory Failure:
- PaO2 < 60 mmHg on FiO2 > 0.6
- Normal or low PaCO2
- Primarily oxygenation failure
Type II (Hypercapnic) Respiratory Failure:
- PaCO2 > 50 mmHg
- May have associated hypoxemia
- Primarily ventilation failure

Epidemiology

Leading cause of cardiopulmonary arrest in children
Most common in children under 5 years
Higher incidence during respiratory virus seasons
Increased risk in children with chronic conditions

Risk Factors

Age-Related:
- Smaller airway diameter
- More compliant chest wall
- Immature immune system
- Higher metabolic demands
Anatomical:
- Chronic lung disease
- Airway anomalies
- Chest wall deformities
Medical Conditions:
- Neuromuscular disorders
- Immunodeficiency
- Cardiac disease
- Genetic syndromes

Pathophysiology and Types

Basic Respiratory Physiology

Ventilation Components:
- Neural drive
- Respiratory muscles
- Airways and alveoli
- Chest wall mechanics
Gas Exchange:
- Ventilation-perfusion matching
- Diffusion capacity
- Cardiac output

Pathophysiologic Mechanisms

Mechanism	Causes	Examples
Upper Airway Obstruction	Anatomic or functional obstruction	Croup, epiglottitis, foreign body
Lower Airway Disease	Bronchial obstruction or restriction	Asthma, bronchiolitis
Alveolar Disease	Inflammation or filling	Pneumonia, pulmonary edema
Chest Wall Dysfunction	Mechanical or neurological	Flail chest, muscular dystrophy
Control of Breathing	Central or peripheral	Brain injury, drug overdose

Types of Respiratory Failure

Type I (Hypoxemic):
- V/Q mismatch
- Right-to-left shunt
- Diffusion impairment
- Common in ARDS, pneumonia
Type II (Hypercapnic):
- Decreased minute ventilation
- Increased dead space
- Increased CO2 production
- Common in neuromuscular disease
Mixed:
- Combined oxygenation and ventilation failure
- Common in severe asthma
- Poor prognostic indicator

Clinical Presentation

Early Warning Signs

Respiratory:
- Tachypnea
- Increased work of breathing
- Nasal flaring
- Use of accessory muscles
- Retractions
Behavioral:
- Agitation
- Anxiety
- Poor feeding
- Decreased activity

Signs of Severe Respiratory Distress

Immediate Concerns:
- Lethargy or decreased consciousness
- Cyanosis
- Poor muscle tone
- Bradypnea or irregular breathing
- Grunting
Compensatory Mechanisms:
- Tachycardia
- Sweating
- Pallor
- Poor peripheral perfusion

Age-Specific Presentations

Age Group	Key Features	Common Causes
Neonates	Apnea, poor feeding, temperature instability	RDS, sepsis, CHD
Infants	Nasal flaring, head bobbing, poor feeding	Bronchiolitis, pneumonia
Toddlers	Tripod positioning, drooling, stridor	Croup, foreign body
School-age	Chest pain, anxiety, speak in phrases	Asthma, pneumonia
Adolescents	Fatigue, decreased exercise tolerance	Asthma, PE, pneumothorax

Assessment and Diagnosis

Initial Assessment

Vital Signs:

Age	Normal RR	Warning RR	Normal SpO2
0-3 months	30-60	>60 or <30	>95%
3-12 months	24-40	>50 or <24	>95%
1-4 years	20-30	>40 or <20	>95%
4-12 years	18-25	>30 or <18	>95%
>12 years	12-20	>25 or <12	>95%

Diagnostic Studies

Laboratory:
- Blood gas analysis (arterial preferred)
- Complete blood count
- Basic metabolic panel
- Inflammatory markers
- Blood cultures if indicated
Imaging:
- Chest X-ray (AP and lateral)
- Point-of-care ultrasound
- CT chest if indicated
Additional Studies:
- ECG
- Echocardiogram
- Viral studies
- Pulmonary function tests (if stable)

Management

Initial Stabilization

Airway:
- Position optimization
- Airway clearance
- Consider early intubation if indicated
Breathing:
- Oxygen supplementation
- Non-invasive ventilation when appropriate
- Mechanical ventilation parameters
Circulation:
- IV access
- Fluid management
- Cardiovascular support if needed

Respiratory Support

Support Type	Indications	Settings
High-Flow Nasal Cannula	Mild-moderate distress	1-2 L/kg/min up to 60 L/min
CPAP	Upper airway support	5-10 cmH2O
BiPAP	Type II failure	IPAP 10-20, EPAP 5-10
Mechanical Ventilation	Severe failure	Age/condition specific

Medication Therapy

Bronchodilators:
- Albuterol: 2.5-5 mg nebulized
- Epinephrine: 0.01 mg/kg IM
Anti-inflammatories:
- Steroids: 1-2 mg/kg/day
- Duration based on condition
Antibiotics:
- If bacterial infection suspected
- Choice based on likely pathogens

Monitoring and Complications

Continuous Monitoring

Clinical Parameters:
- Work of breathing
- Mental status
- Perfusion
- Urine output
Device Monitoring:
- Pulse oximetry
- Capnography
- Cardiac monitoring
- Blood pressure
Laboratory Monitoring:
- Serial blood gases
- Electrolytes
- Lactate
- Inflammatory markers

Complications

Respiratory:
- Atelectasis
- Ventilator-associated pneumonia
- Pneumothorax
- Post-extubation stridor
Cardiovascular:
- Right heart failure
- Shock
- Arrhythmias
- Pulmonary hypertension
Other Systems:
- Neurological deterioration
- Renal dysfunction
- GI complications
- Nosocomial infections

Prevention Strategies

Ventilator-Associated:
- Head elevation 30-45 degrees
- Oral care protocol
- Daily sedation interruption
- Ventilator bundle compliance
General Measures:
- Early mobilization when appropriate
- Stress ulcer prophylaxis
- DVT prophylaxis in adolescents
- Nutrition optimization

Specific Conditions

Status Asthmaticus

Assessment:
- Severe bronchospasm
- Poor response to initial therapy
- Air trapping
- Risk of respiratory failure
Management:
- Continuous albuterol nebulization
- IV magnesium sulfate
- Systemic corticosteroids
- Consider ketamine or heliox

ARDS

Diagnostic Criteria (PARDS):
- Acute onset
- Bilateral infiltrates
- PaO2/FiO2 ratio ≤ 300
- No evidence of left heart failure
Management Strategy:
- Lung-protective ventilation
- Permissive hypercapnia
- Conservative fluid management
- Prone positioning if severe

Bronchiolitis

Risk Factors:
- Age < 12 months
- Prematurity
- Chronic conditions
- Environmental exposure
Management Approach:
- Supportive care
- Oxygen supplementation
- Hydration maintenance
- HFNC if needed

Neuromuscular Weakness

Considerations:
- Progressive weakness
- Poor secretion clearance
- Sleep-disordered breathing
- Recurrent aspirations
Management:
- NIV support
- Airway clearance techniques
- Prevention of complications
- Early mobilization

Prognostic Factors

Factor	Good Prognosis	Poor Prognosis
Response to Therapy	Rapid improvement	Persistent deterioration
Underlying Condition	Reversible cause	Progressive disease
Organ Dysfunction	Single system	Multiple organ failure
Nutritional Status	Well-nourished	Malnourished