End-Tidal CO₂ (ETCO₂) Monitoring
Overview
End-tidal CO₂ monitoring, or capnography, is a non-invasive method for measuring expired CO₂ levels, providing crucial information about ventilation, perfusion, and metabolism in pediatric patients.
Key Points
- Continuous real-time monitoring of respiratory status
- Early detection of respiratory compromise
- Normal ETCO₂ range: 35-45 mmHg
- Provides both numeric values and waveform analysis
- Essential for procedural sedation monitoring
Physiological Principles
CO₂ Transport
- Cellular production of CO₂
- Transport in blood (dissolved, bicarbonate, bound to proteins)
- Pulmonary circulation and gas exchange
- Alveolar ventilation
- V/Q matching principles
Respiratory Cycle Components
- Phase I: Dead space ventilation
- Phase II: Mixed dead space and alveolar gas
- Phase III: Alveolar plateau
- Phase IV: Beginning of inspiration
Monitoring Methods
Technology Types
- Mainstream capnography
- Sensor directly in airway
- Faster response time
- Better for neonates/small children
- Sidestream capnography
- Sample diverted to sensor
- More versatile applications
- Requires adequate sample flow
Equipment Setup
- Calibration requirements
- Sampling line connections
- Filter maintenance
- Zero baseline establishment
- Alarm setting configuration
Clinical Applications
Primary Indications
- Mechanical ventilation monitoring
- Procedural sedation
- Cardiopulmonary resuscitation
- Endotracheal tube placement verification
- Transport monitoring
- Respiratory disease management
Specific Clinical Scenarios
- Operating room monitoring
- Airway assessment
- Ventilation adequacy
- Metabolic status
- Critical care
- Ventilator weaning
- Respiratory deterioration
- CPR quality assessment
Waveform Analysis & Interpretation
Normal Capnogram Components
- Baseline (0 mmHg)
- Exponential rise
- Alveolar plateau
- Inspiratory descent
Abnormal Patterns
- Bronchospasm
- Shark fin appearance
- Prolonged Phase III
- Hyperventilation
- Decreased ETCO₂
- Increased respiratory rate
- Hypoventilation
- Elevated ETCO₂
- Decreased respiratory rate
- Rebreathing
- Elevated baseline
- Incomplete return to zero
Pediatric-Specific Considerations
Age-Related Factors
- Neonatal considerations
- Higher respiratory rates
- Smaller tidal volumes
- Equipment size selection
- Infants and toddlers
- Sampling method selection
- Movement artifacts
- Normal value variations
Technical Adaptations
- Equipment modifications
- Sampling flow rates
- Dead space considerations
- Interface selection
Monitoring Challenges
- Patient cooperation
- Mask fit issues
- Oral vs nasal breathing
- Activity level impact
