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

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.

Safety of conscious sedation in electroanatomical mapping procedures and cryoballoon pulmonary vein isolation.

Immobilization of patients during electrophysiological procedures, to avoid complications by patients' unexpected bodily motion, is achieved by moderate to deep conscious sedation using benzodiazepines and propofol for sedation and opioids for analgesia. Our aim was to compare respiratory and hemodynamic safety endpoints of cryoballoon pulmonary vein isolation (PVI) and electroanatomical mapping (EAM) procedures. Included patients underwent either cryoballoon PVI or EAM procedures. Sedation monitoring included non-invasive blood pressure measurements, transcutaneous oxygen saturation (tSpO2) and transcutaneous carbon-dioxide (tpCO2) measurements. We enrolled 125 consecutive patients, 67 patients underwent cryoballoon atrial fibrillation ablation and 58 patients had an EAM and radiofrequency ablation procedure. Mean procedure duration of EAM procedures was significantly longer (p < 0.001) and propofol doses as well as morphine equivalent doses of administered opioids were significantly higher in EAM patients compared to cryoballoon patients (p < 0.001). Cryoballoon patients display higher tpCO2 levels compared to EAM patients at 30 min (cryoballoon: 51.1 ± 7.0 mmHg vs. EAM: 48.6 ± 6.2 mmHg, p = 0.009) and at 60 min (cryoballoon: 51.4 ± 7.3 mmHg vs. EAM: 48.9 ± 6.6 mmHg, p = 0.07) procedure duration. Mean arterial pressure was significantly higher after 60 min (cryoballoon: 84.7 ± 16.7 mmHg vs. EAM: 76.7 ± 13.3 mmHg, p = 0.017) in cryoballoon PVI compared to EAM procedures. Regarding respiratory and hemodynamic safety endpoints, no significant difference was detected regarding hypercapnia, hypoxia and episodes of hypotension. Despite longer procedure duration and deeper sedation requirement, conscious sedation in EAM procedures appears to be as safe as conscious sedation in cryoballoon ablation procedures regarding hemodynamic and respiratory safety endpoints.