Electrical cardioversion of atrial fibrillation: evaluation of sedation safety with midazolam by means of EtCO₂ and IPI algorithm analysis.

BACKGROUND: For several years, the electrical external cardioversion (ECV) has entered into clinical practice without assistance of anesthesiology team. The aim of this study was to evaluate the efficacy and safety of sedation with midazolam in patients undergoing electrical cardioversion of atrial fibrillation (AF) by means of the evaluation of capnometry and pulmonary integrated index (IPI) using the Oridion Capnostream 20.

METHODS: We studied 45 consecutive patients (pts) who underwent ECV of AF sedated with midazolam at mean dose of 5mg bolus followed by another 5mg in 2 minutes (min). Maximum dosage was 11 mg (average 8 ± 2 mg). After cardioversion we infused Anexate 0.5mg bolus followed by 0.5mg in 30 min. All pts were monitored with blood pressure, O2 saturation, cardiac frequency and capnometers.

RESULTS: EtCO2 value at baseline was 37.14 ± 2.7, 35.02 ± 1.7 after induction of sedation and 36.59 ± 1.2 after awaking (p<0.05 baseline to induction). IPI index was 9.58 ± 0.5 at basal 8.09 ± 0.63 at induction time and 9.02 ± 0.5 after awaking (p<0.05 basal to induction, induction to awaking and basal to awaking but all data were in normal range). No pts had apnea or hypoxia but there was only one case of hypotension after shock, which lasted 2 min.

CONCLUSIONS: Conscious sedation with midazolam for electrical cardioversion of AF appears to be safe and effective because it does not affect adversely the respiratory parameters of pts as demonstrated by the analysis of EtCO2 and IPI index.