Pre-apneic capnography waveform abnormalities during procedural sedation and analgesia

Area of Science:

• Anesthesiology
• Respiratory Physiology
• Medical Technology

Background:

• Capnography monitoring is recommended during procedural sedation.
• Understanding capnography waveform abnormalities is crucial for patient safety.

Purpose of the Study:

• To examine the association between specific capnography waveform abnormalities and the onset of apnea during procedural sedation.
• To inform the development of targeted clinical alarms for capnography monitoring.

Main Methods:

• Analysis of capnography waveforms from 102 participants undergoing moderate procedural sedation.
• Use of a mixed-effects Cox model to assess the risk of apnea associated with hypopnea and bradypnea.
• Apnea defined as zero end-tidal carbon dioxide concentration, with sensitivity analyses for duration.

Main Results:

• Hypopnea (significant deviation from baseline end-tidal carbon dioxide) was associated with a 2.14-fold increased risk of apnea (95% CI 1.75 to 2.62).
• Bradypnea (respiratory rate < 8 breaths/min) was not associated with an increased risk of apnea (Hazard Ratio 0.64; 95% CI 0.33 to 1.25).
• Findings remained consistent when apnea duration was considered.

Conclusions:

• Hypopnea waveform abnormalities are significant predictors of apnea during procedural sedation.
• Bradypnea waveform abnormalities do not appear to increase apnea risk.
• Utilizing historical capnography waveform data may improve the prediction of apneic episodes and guide alarm strategies.