Preliminary Validation of Transcutaneous CO<sub>2</sub> Monitoring in Patients Undergoing Cardiac Ablation Using Jet Ventilation

Abstract

Objectives: There is no data in the current medical literature on efficacy or accuracy of transcutaneous (tcPCO 2 ) monitoring during jet ventilation for cardiac ablation. The use of tcPCO 2 during cardiac ablation procedures offers the opportunity to compare end-tidal and transcutaneous methods of CO 2 measurement before and after the use of the jet ventilation. Comparison of these measurements with arterial blood gas CO 2 levels allows evaluation of the accuracy of the tcPCO 2 technique for use during jet ventilation. Design: Observational study; patients served as their own controls. Setting: Cardiac electrophysiology laboratory. Participants: 15 adult patients (9 M), ASA III-IV, aged 26 to 82 years (median 66 years) undergoing radiofrequency ablation for atrial fibrillation. Interventions: Jet ventilation (JV) versus conventional ventilation. Measurements and Main Results: Paired measurements of end-tidal CO 2 (EtCO 2 ) and transcutaneous CO 2 (tcPCO 2 ) were recorded during periods of conventional ventilation. Paired measurements of arterial blood CO 2 (Pa-CO 2 ) levels and tcPCO 2 were recorded during JV. ABG samples were drawn at the anesthesiologist's discretion to assess the patient's respiratory status. The level of agreement between the three methods was compared using the Bland Altman plot. We found that tcPCO 2 values consistently provided a close approximation to PaCO 2 levels. The mean difference between tcPCO 2 and EtCO 2 values in baseline and post-JV was on the order of 3 -5 mmHg, with standard deviation of 4 -6 mmHg. This is well within the range of variability that is accepted in clinical practice. Conclusions: These preliminary results suggest that tcPCO 2 provides an acceptable estimate of CO 2 concentration in arterial blood during JV, as well as prior to and following JV.