Comparison of a sidestream and mainstream capnometer in infants

Area of Science:

• Anesthesiology
• Pediatric Critical Care
• Respiratory Physiology

Background:

• Accurate monitoring of end-tidal carbon dioxide (EtCO2) is crucial in pediatric anesthesia.
• Capnography waveform analysis aids in assessing ventilation and patient status.
• Rapid mechanical ventilation can challenge the accuracy of CO2 monitoring devices.

Purpose of the Study:

• To compare the accuracy and waveform fidelity of sidestream and mainstream capnometers.
• To evaluate capnogram quality during rapid mechanical ventilation in infants.
• To determine the optimal capnometry technique for pediatric patients undergoing surgery.

Main Methods:

• Ten infants undergoing elective surgery were studied.
• Simultaneous capnograms were recorded using sidestream and mainstream capnometers.
• Arterial blood gases (PaCO2) were measured for comparison with end-tidal CO2 (PetCO2).

Main Results:

• The mean difference between arterial and end-tidal CO2 (PaCO2-PetCO2) was approximately 5 torr for both devices.
• Mainstream capnometry showed a slightly better correlation with PaCO2 (r2 = .895 vs. .654).
• Sidestream capnograms exhibited significant waveform distortion, including flattened ascending limbs and absent alveolar plateaus.

Conclusions:

• Mainstream capnometers provide a more accurate representation of the expired CO2 waveform in infants during rapid ventilation.
• The waveform distortions from sidestream devices can impede accurate interpretation of ventilation.
• Mainstream capnometry is recommended for improved accuracy in pediatric patients with rapid respiratory rates.