2.3. Respiratory management during the PVAI

Respiratory management during the RFCA was performed under an intravenous administration of propofol (bolus dose of 1 mg/kg and maintenance dose of 2 g/kg to 5 g/kg per hour) and dexmedetomidin (bolus dose of 1 μg/kg and maintenance dose of 0.2 μg/kg to 0.7 μg/kg per hour). In all patients, it was attempted to maintain the BIS index level between 40 and 60 [10] using a bispectral index monitor pasted on the front of the forehead (Fig. 2). If necessary, an intravenous bolus administration of pentazocine (15–30 mg) was used when patient movements resulting from an incidence of pain during the RFCA occurred. If pentazocine was not effective enough, or the BIS level was over 60, an intravenous bolus administration of propofol at a dose of 1 mg/kg was added. The peripheral oxygen saturation was monitored continuously, and supplemental oxygen was routinely used with a flow rate of 5–10 l per minute via a mask in the patients in Group A, or via an SGA in Group B with spontaneous breathing to maintain the peripheral oxygen saturation at more than 95%. When the peripheral oxygen saturation fell to less than 95%, even though supplemental oxygen with a flow rate of 10 l per minute via a mask or SGA during the procedures was used, an oropharyngeal airway was inserted into the mouth. To monitor the exhaling carbon dioxide concentration, a CO2 Sensor (TG-980P ^TM, NIHON KODEN, Tokyo, Japan) was attached to the SGA during the procedure. If it was still not adequate, mechanical respiratory support with non-invasive positive pressure ventilation (NIPPV) or endotracheal intubation was used. Hypotension was defined as a systolic blood pressure of 90 mmHg or less. If the hypotension did not improve with an intravenous administration of supplementary fluids, an intravenous administration of dopamine (maintenance dose of 5 μg/kg/min) was used.

Monitoring the bispectral index (full line) and peripheral oxygen saturation (dotted line) under deep sedation using a supraglottic airway (Group A) during radiofrequency catheter ablation (RFCA) of atrial fibrillation using EnSite^TM (St. Jude Medical, St. Paul, MN, USA). RFCA could be steadily performed by monitoring the BIS index without any hypoxia. PVAI=pulmonary vein antrum isolation.