VENTILATION STRATEGIES IN CHILDREN

VENTILATION STRATEGIES IN CHILDREN

Table of Contents

INTRODUCTION

Mechanical ventilation is one of the most commonly used organ-support therapies in paediatric intensive care and anaesthesia.

Children differ significantly from adults in respiratory anatomy, lung mechanics, chest wall compliance, airway calibre, oxygen consumption, and respiratory muscle function. Consequently, ventilation strategies derived from adult studies cannot be simply extrapolated to paediatric practice.

The modern approach to paediatric ventilation emphasises:

● Individualised ventilator settings

● Lung-protective ventilation

● Prevention of atelectasis

● Reduction of ventilator-induced lung injury (VILI)

● Preservation of diaphragmatic function

● Early liberation from mechanical ventilation

Recent evidence from PALICC-2, the NECTARINE study, and paediatric perioperative ventilation reviews has shifted practice toward protective ventilation, judicious oxygen therapy, and optimisation of patient–ventilator interaction.

UNIQUE RESPIRATORY PHYSIOLOGY OF CHILDREN

High Oxygen Consumption

Population Oxygen Consumption

Adult 3–4 mL/kg/min

Infant 6–8 mL/kg/min

Clinical Significance:

Rapid oxygen depletion
Short safe apnoea period
Faster desaturation during airway manipulation
Greater dependence on adequate minute ventilation

Reduced Functional Residual Capacity

FRC is proportionally lower in infants.

Consequences:

Less oxygen reserve
Early airway closure
Rapid atelectasis formation
Increased shunt fraction

Highly Compliant Chest Wall

The infant thorax is cartilaginous and highly compliant.

Effects:

Reduced outward recoil
Increased tendency for alveolar collapse
Greater susceptibility to respiratory failure

Immature Respiratory Musculature

Infants have:

Fewer type I fatigue-resistant fibres
Lower respiratory reserve
Earlier respiratory muscle fatigue

Small Airway Diameter

Resistance is inversely proportional to radius⁴.

Therefore:

Minimal oedema dramatically increases resistance
Secretions significantly impair ventilation
Airway obstruction develops rapidly

GOALS OF MECHANICAL VENTILATION

Gas Exchange

Maintain:

Adequate oxygenation
Adequate carbon dioxide elimination

Reduce Work of Breathing

Prevents:

Respiratory muscle fatigue
Oxygen debt
Progression to respiratory failure

Prevent Secondary Lung Injury

Minimise:

Barotrauma
Volutrauma
Atelectrauma
Biotrauma

VENTILATOR-INDUCED LUNG INJURY (VILI)

The concept of VILI forms the basis of modern ventilation.

Barotrauma: Damage from excessive pressure.

Manifestations:

Pneumothorax
Pneumomediastinum
Interstitial emphysema

Volutrauma: Overdistension caused by excessive tidal volume.

Results in:

Alveolar stretch
Endothelial injury
Cytokine release

Atelectrauma: Repeated opening and collapse of unstable alveoli.

Common during:

General anaesthesia
Low PEEP strategies
Obesity

Biotrauma: Mechanical injury triggers systemic inflammatory responses.

May contribute to:

Multiorgan dysfunction
Prolonged ICU stays

PRINCIPLES OF LUNG-PROTECTIVE VENTILATION

Paediatric practice increasingly adopts the same protective principles used in adults.

Low Tidal Volume Strategy

Normal Lungs: 6–8 mL/kg predicted body weight

PARDS: 4–6 mL/kg

Severe Restrictive Disease: 4–6 mL/kg

The goal is to avoid overdistension rather than achieve a specific number.

Limitation of Airway Pressure

Suggested targets:

Plateau Pressure < 28 cmH₂O

Driving Pressure: As low as feasible

Elevated driving pressure is increasingly recognised as a marker of lung stress.

Appropriate PEEP

PEEP prevents:

Alveolar collapse
Loss of FRC
Repetitive alveolar injury

PEEP should be individualised.

Excessive PEEP may cause:

Hyperinflation
Increased dead space
Reduced venous return

Permissive Hypercapnia

Accepting higher PaCO₂ to avoid injurious ventilator settings.

Often tolerated if: pH > 7.20

Benefits:

Reduced airway pressure
Reduced VILI

Contraindications:

Raised intracranial pressure
Severe pulmonary hypertension
Uncontrolled haemodynamic instability

OXYGEN THERAPY

Historically, children frequently received FiO₂ 1.0 throughout anaesthesia.
Recent evidence suggests excessive oxygen may contribute to:

Oxidative stress
Absorption atelectasis
Pulmonary injury

Modern Approach

Use:

Lowest FiO₂ required to maintain: SpO₂ 92–97%
Avoid prolonged hyperoxia whenever possible.

RECRUITMENT MANOEUVRES

Definition: Transient increase in transpulmonary pressure aimed at reopening collapsed alveoli.
Benefits

Improved oxygenation
Improved compliance
Reduction in atelectasis

Risks

Hypotension
Overdistension
Barotrauma

Therefore, recruitment should not be routine; use it selectively.

VENTILATION MODES IN CHILDREN

PRESSURE-CONTROLLED VENTILATION (PCV)

Most commonly employed PICU mode.
Clinician sets:

Inspiratory pressure
Respiratory rate
Inspiratory time
PEEP

Tidal volume varies according to compliance.
Advantages:

Pressure limitation
Better tolerance in infants
Useful in poor compliance states

Disadvantages:

Variable tidal volume
Risk of hypoventilation when compliance worsens

VOLUME-CONTROLLED VENTILATION (VCV)

A preset tidal volume is delivered.
Advantages:

Stable minute ventilation
Predictable CO₂ elimination

Disadvantages:

Potential for high airway pressures

PRESSURE REGULATED VOLUME CONTROL (PRVC)

Hybrid mode.
Ventilator automatically adjusts inspiratory pressure to achieve target tidal volume.
Benefits:

Consistent tidal volume
Lower peak pressure
Reduced risk of volutrauma

PRESSURE SUPPORT VENTILATION (PSV)

Patient initiates breaths.
Ventilator supplies:

Pressure assistance
PEEP

Benefits:

Reduced work of breathing
Improved comfort
Useful during weaning

SYNCHRONISED INTERMITTENT MANDATORY VENTILATION (SIMV)

Combines:

Mandatory breaths
Spontaneous breathing

Useful for:

Transition to spontaneous ventilation
Weaning

NON-INVASIVE RESPIRATORY SUPPORT

HIGH-FLOW NASAL CANNULA (HFNC)

Provides:

Heated humidified gas
High flow rates
Dead-space washout
Mild distending pressure

Typical Flow–Infants: 1–2 L/kg/min, Older children: Up to 50–60 L/min

Indications-Bronchiolitis,Pneumonia,Post-extubation support,Mild respiratory failure

CPAP

Provides continuous positive airway pressure.
Benefits:

Improved FRC
Reduced atelectasis
Reduced work of breathing

BiPAP

Provides:

Inspiratory pressure support
Expiratory pressure support

Useful in:

Neuromuscular disorders
Hypercapnic respiratory failure

DISEASE-SPECIFIC VENTILATION

PAEDIATRIC ARDS (PARDS)

The PALICC-2 guidelines guide current management.
Ventilatory Goals

Avoid overdistension
Prevent cyclic alveolar collapse
Maintain adequate oxygen delivery

Recommended Strategy

Tidal volume: 4–8 mL/kg
Depending on compliance
Lower values used when compliance is poor.
PEEP: Moderate-to-high, Individualised
Plateau pressure: Generally <28 cmH₂O

Adjunctive Therapies

Prone Positioning

Improves:

V/Q matching
Recruitment
Oxygenation

Neuromuscular Blockade: May improve synchrony in severe disease.
HFOV: Rescue therapy for refractory hypoxaemia.
ECMO: Considered in severe refractory PARDS.

STATUS ASTHMATICUS

Major Problem: Dynamic hyperinflation.
Ventilation Strategy

Low Respiratory Rate: 10–16/min
Prolonged Expiratory Time: I:E 1:3–1:5
Avoid Excessive PEEP
Accept Hypercapnia
Permissive hypercapnia frequently required.

Goal

Prevent:

Breath stacking
Auto-PEEP
Haemodynamic compromise

BRONCHIOLITIS

Ventilation should address:

Small-airway obstruction
Air trapping
Increased work of breathing

Preferred Escalation

HFNC

↓

CPAP

↓

Mechanical ventilation

Ventilator Strategy

Moderate PEEP
Longer expiratory time
Avoid excessive pressures

NEUROMUSCULAR DISEASE

Examples:

SMA
Duchenne muscular dystrophy
Guillain–Barré syndrome

Goals:

Support ventilation
Prevent atelectasis
Facilitate secretion clearance

Often managed successfully using:

NIV
Mechanical insufflation–exsufflation

PERIOPERATIVE VENTILATION

Recent paediatric anaesthesia literature has focused on prevention of postoperative pulmonary complications.

Atelectasis During Anaesthesia

Occurs rapidly after induction.

Contributors:

Muscle paralysis
High FiO₂
Supine position
Reduced FRC

Current recommendations for protective Intraoperative Ventilation favour:

Moderate PEEP
Recruitment when indicated
Avoidance of unnecessarily high FiO₂
Age-appropriate tidal volumes
Early spontaneous breathing when feasible

NEONATAL VENTILATION

The NECTARINE study highlighted the vulnerability of neonates and young infants.
These patients exhibit:

Minimal respiratory reserve
High oxygen consumption
Greater perioperative respiratory risk

Key Principles

Gentle ventilation
Avoid excessive tidal volumes
Careful monitoring of ETCO₂
Avoid prolonged hyperoxia
Vigilant postoperative observation

NOVEL VENTILATION TECHNIQUES

NAVA

Neurally Adjusted Ventilatory Assist
Ventilation is triggered by electrical activity of the diaphragm.
Advantages:

Superior synchrony
Reduced sedation
Improved comfort
Potential diaphragm protection

ADAPTIVE SUPPORT VENTILATION

Closed-loop mode.
Ventilator automatically adjusts:

Respiratory rate
Pressure support
Minute ventilation

based on patient physiology.

VARIABLE VENTILATION

Mimics natural variability of breathing.
Potential benefits:

Improved recruitment
Reduced repetitive stress injury

FLOW-CONTROLLED VENTILATION

Maintains constant inspiratory and expiratory flow.
Potential advantages:

Improved gas distribution
Reduced airway stress

Currently an emerging technology.

VENTILATOR-INDUCED DIAPHRAGMATIC DYSFUNCTION

Recent literature emphasises diaphragm injury from excessive ventilatory support.

Consequences:

Muscle atrophy
Difficult weaning
Prolonged ventilation

Strategies to prevent VIDD:

Early spontaneous breathing
Appropriate support levels
Avoid over-assistance

WEANING AND EXTUBATION

Readiness Criteria:

Improving disease process
Adequate oxygenation
Stable haemodynamics
Effective cough
Manageable secretions

Spontaneous Breathing Trial

Methods:

CPAP
PSV

Duration: 30–120 minutes

Extubation Failure Risk Factors

Young age
Neuromuscular disease
Airway oedema
Excessive secretions
Diaphragm dysfunction

RECENT ADVANCES

PALICC-2 emphasis on individualised ventilation
NAVA-guided ventilation
Electrical impedance tomography (EIT)
Closed-loop ventilatory modes
Lung ultrasound-guided PEEP optimisation
Diaphragm-protective ventilation
Precision ventilation using respiratory mechanics

KEY EXAM PEARLS

✓ Infants desaturate rapidly because of high oxygen consumption and low FRC.

✓ Lung-protective ventilation aims to prevent volutrauma, barotrauma, atelectrauma and biotrauma.

✓ PARDS management is based on PALICC-2 recommendations.

✓ PEEP should be individualised rather than fixed.

✓ Hyperoxia is increasingly recognised as potentially harmful.

✓ HFNC is first-line support for many infants with bronchiolitis.

✓ NAVA improves patient–ventilator synchrony.

✓ Ventilator-induced diaphragmatic dysfunction is an important emerging concept.

✓ The goal is not merely oxygenation and ventilation, but preservation of lung and diaphragm function.

REFERENCES

1. Pediatric Acute Lung Injury Consensus Conference (PALICC-2) International Guidelines, 2023.

2. Rocha G, Habre W, Albu G. Novel Ventilation Techniques in Children. Front Pediatr. 2022.

3. Janszen L, van Meenen DMP, Polderman KH. Perioperative Ventilation Practices in Children. BJA Education. 2025.

4. Fuchs J et al. Perioperative Ventilation and Pulmonary Outcomes in Neonates and Infants (NECTARINE Secondary Analysis). Br J Anaesth. 2025.

5. Egbuta C, Mason KP. Risk Factors and Prevention of Perioperative Respiratory Adverse Events in Children. J Clin Med. 2020.

6. Understanding Paediatric Anaesthesia. 4th Edition.

7. Smith’s Anesthesia for Infants and Children. 10th Edition.

8. Barash, Cullen and Stoelting’s Clinical Anesthesia. 9th Edition.

9. Fuhrman & Zimmerman’s Pediatric Critical Care.

10. Rogers’ Textbook of Pediatric Intensive Care.