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

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.

Recent advances in respiratory monitory in nonoperating room anesthesia

PURPOSE OF REVIEW

Sedation for nonoperating room procedures is experiencing a considerable increase in demand. Respiratory compromise is one of the most common adverse events seen in sedation. Capnography is a modality that has been widely adopted in this area, but may not be well suited to the special demands of nonoperating room sedation. This review is an assessment of new technologies that may improve outcomes beyond those achievable with capnography.

RECENT FINDINGS

New devices for detecting the onset of apnea and for assessing respiratory depression have emerged which have advantages over conventional capnography for detecting apnea without excessive false positive and false negative rates. In addition, monitors that assess respiratory drive have become available, and these may prove useful in regulating depth of sedation.

SUMMARY

No single monitor is ideal for all settings. During brief endoscopic sedation, detection of apnea is paramount, while during longer procedures, avoiding excessive respiratory depression is more critical. The clinician must choose the appropriate monitor based on an understanding of the challenges of the particular environment.