Sedation protocol
In our center all AF ablation procedures are usually performed under conscious sedation; GA is not routinely used. During the first part of the year, AF ablation procedures were performed using propofol, which was administered and monitored by an anesthesiologist in the operating room (group 1). Induction of sedation was performed with a bolus of 2 ml of 1% propofol followed by an infusion starting at 1 mg/Kg/h and then titrated to the clinical response.
After the unexpected COVID-19 pandemic arrival, due to organizational challenges and given the shortage of available anesthesiologists, sedation was performed by the electrophysiology (EP) team (consisting of two operating electrophysiologists for each procedure, at least two dedicated nurses and a radiology technician) using dexmedetomidine (group 2) without anesthesiologist supervision, according to a shared protocol approved in advance. The EP medical and nursing staff were trained and certified in advanced life support. An on-call anesthesiologist was available from within the hospital in case of emergency.
In both groups, patient’s monitoring started in the EP laboratory waiting room: non-invasive blood pressure, heart rate and rhythm and oxygen saturation were continuously recorded. End-tidal carbon dioxide (etCO2) monitoring was used to detect early respiratory dysfunction. In the EP laboratory, a 12-lead electrocardiogram (ECG) was continuously recorded for every patient; respiratory rate was also assessed. Continuous infusion of dexmedetomidine was started at a rate of 0.7 mcg/Kg/h before venipuncture and titrated to clinical response during the procedure (maximum dosage 1.4 mcg/Kg/h) in order to obtain patient’s sedation with cessation of body movements. In case of adverse events, dexmedetomidine infusion rate was reduced if deemed necessary. Oxygen supplementation was administered by nasal cannulas at 2 l/min at baseline in both groups.
At the beginning of the procedure every patient (either in the propofol or in the dexmedetomidine group) received 1 mcg/Kg of midazolam as a single bolus. Moreover, a 0.05 mg single bolus of fentanyl was administered for analgesia prior to radiofrequency application on the left pulmonary veins (PVs), and the bolus was repeated before starting ablation on the right PVs. If the patient was in AF when entering the EP laboratory, electrical cardioversion (EC) was performed at the beginning of the procedure with an additional bolus of propofol 1 mg/Kg in both groups. In case of EC, the starting infusion rate in group 1 was reduced to 0.8 mg/Kg/h without any other bolus.
Vital signs were monitored throughout the procedure: peripheral oxygen saturation, respiratory rate, heart rate and rhythm were monitored continuously, while blood pressure was monitored with a brachial cuff at 3-minute intervals.
Adverse events such as oxygen desaturation (< 90%), bradycardia (heart rate < 45 bpm) and hypotension (systolic blood pressure < 90 mmHg) were recorded. In case of airway compromise, the head tilt-chin lift maneuver was performed; in case of desaturation oxygen delivery was increased and/or the nasal cannula was changed to a facial mask with increased oxygen delivery capability with/without insertion of an oropharyngeal airway; in case of bradycardia, cardiac stimulation was performed via the catheters placed in the heart or by atropine administration; in case of significant hypotension, saline loading was performed with simultaneous check for mechanical complications by means of intracardiac echocardiography (ICE), routinely used during AF ablation procedures at our Institution.