Continuous transcutaneous carbon-dioxide monitoring to avoid hypercapnia in complex catheter ablations under conscious sedation

Abstract

Background: Ablation of complex cardiac arrhythmias requires an immobilized patient. For a successful and safe intervention and for patient comfort, this can be achieved by conscious sedation. Administered sedatives and analgesics have respiratory depressant side effects and require close monitoring. We investigated the feasibility and accuracy of additional, continuous transcutaneous carbon-dioxide partial pressure (tpCO₂) measurement during conscious sedation in complex electrophysiological catheter ablation procedures.

Method: We evaluated the accuracy and additional value of continuous tpCO₂ detection by application of a Severinghaus electrode in comparison to arterial and venous blood gas analyses.

Results: We included 110 patients in this prospective observational study. Arterial pCO₂ (paCO₂) and tpCO₂ showed good correlation throughout the procedures (r = 0.60-0.87, p < 0.005). Venous pCO₂ (pvCO₂) were also well correlated to transcutaneous values (r = 0.65-0.85, p < 0.0001). Analyses of the difference of pvCO₂ and tpCO₂ measurements showed a tolerance within <10 mmHg in up to 96-98% of patients. Hypercapnia (pCO₂ < 70 mmHg) was detected more likely and earlier by continuous tpCO₂ monitoring compared to half-hourly pvCO₂ measurements.

Conclusion: Continuous tpCO₂ monitoring is feasible and precise with good correlation to arterial and venous blood gas carbon-dioxide analysis during complex catheter ablations under conscious sedation and may contribute to additional safety.

Keywords: Complex catheter ablations; Conscious sedation; Electrophysiology; Hypercapnia; Transcutaneous carbon-dioxide monitoring.