Transcutaneous carbon dioxide monitoring to avoid hypercapnia during complex catheter ablations: a feasibility study

The aim of this study was to determine if transcutaneous CO(2) monitoring (TCO(2)) is feasible to avoid hypercapnia during complex catheter ablation. Cumulative analgesic and anxiolytic effects during complex catheter ablation can rarely provoke hypoventilation and respiratory complications. End tidal CO(2) monitors have limitations in non-ventilated patients, and frequent arterial blood gas sampling is impractical.

Consecutive patients undergoing catheter ablation for atrial fibrillation (AF) or ventricular tachycardia (VT) received continuous TCO(2) monitoring. Procedural evaluation of TCO(2) was performed concomitantly with point-of-care arterial blood gas testing. Endpoints included PCO(2) protocol feasibility, TCO(2)/PCO(2) agreement, and avoidance of hypercapnia-related procedural complications.

Fifty patients [AF n = 36 (72 %), VT n = 14 (28 %)] underwent catheter ablation (mean 221.7 ± 57.0 min duration, median 41.4 ± 21.1 min fluoroscopy) in which 6.0 ± 2.6 mg midazolam and 449 ± 225.5 mcg of fentanyl were administered. Monitoring protocol implementation was feasible in 50/50 (100 %) cases. Protocol-driven anesthesia consultation avoided an unplanned intubation in 1 case (2 %) and there was only 1 unplanned intubation (2 %) for oxygen desaturation due to heart failure without hypercapnia during a VT ablation (TCO(2)/PCO(2) agreement <5 mmHg). There were no respiratory or pulseless electrical arrests (0 %) in the study. TCO(2) and PCO(2) correlated well (baseline: r = 0.75, p < 0.001; 1 h:r= 0.72, p < 0.001; 2 h: r = 0.55, p = 0.003; 3 h: r = 0.79, p = 0.02). However, desired agreement was lower than expected [baseline: 33/50 (66 %) < 5 mmHg, 48/50 (96 %) <10 mmHg; 1 h: 29/45 (64 %) < 5 mmHg, 39/45 (87 %) < 10 mmHg; 2 h: 14/26 (54 %) < 5 mmHg, 22/26 (85 %) < 10 mmHg; 3 h: 7/11 (64 %) < 5 mmHg, 10/11 (91 %) < 10 mmHg; >3 h: 1/3 (33 %) < 5 mmHg, 2/3 (66 %) < 10 mmHg].

Transcutaneous CO2 monitoring is feasible during complex catheter ablation and correlates with invasively obtained data. However, further development is needed to achieve the desired level of agreement.