Intermittent capnography during high-frequency jet ventilation for prolonged rigid bronchoscopy

Area of Science:

• Anesthesiology
• Pulmonology
• Critical Care Medicine

Background:

• Arterial blood gas analysis is the standard for monitoring gas exchange during high-frequency jet ventilation (HFJV) for prolonged rigid bronchoscopy (RBS).
• Capnography offers a potentially reliable and noninvasive method for assessing gas exchange by analyzing expired gases during brief HFJV interruptions.

Purpose of the Study:

• To demonstrate the reliability of capnography during short HFJV discontinuations as a measure of PaCO2 during prolonged RBS.
• To compare the accuracy of single-breath capnography versus capnography with a reduced respiratory rate (RR=10 x min(-1)).

Main Methods:

• 100 patients undergoing HFJV for RBS were prospectively studied.
• Capnography (PetCO2) was assessed at 5-minute intervals and compared with simultaneously drawn arterial blood samples (PaCO2).
• The study compared single-breath CO2 sampling with sampling at RR=10 x min(-1).

Main Results:

• A significant correlation was found between capnography (PetCO2) and PaCO2 (r=0.90 for RR=10 x min(-1), r=0.91 for single breath).
• The mean difference between PaCO2 and PetCO2 was minimal (0.37+/-0.2 kPa).
• No significant differences in accuracy were observed between single-breath sampling and sampling at RR=10 x min(-1).

Conclusions:

• Capnography during brief HFJV pauses reliably and noninvasively reflects PaCO2 during prolonged RBS.
• This method can potentially decrease the need for frequent arterial blood gas sampling, shorten unmonitored intervals, and reduce healthcare costs.