Methods
After IRB approval, imaging of children with neuroblastoma from the ages of 1 month to 10 years old was analyzed. Prior to the protocol change, we used an intravenous propofol infusion (150–250 mcg/kg/min) with nasal cannula. Following the protocol change, children’s airway was supported with a laryngeal mask airway (LMA) or an anesthesia mask with a strap connected to a Jackson-Rees circuit (Fig. 1). Air blender (FiO2 < 30%) was used to prevent absorption atelectasis [8]. Higher propofol infusion rate (250–300 mcg/kg/min) was used to allow children to tolerate in situ airway. Air flow and AP valve in the circuit were adjusted to maintain CPAP (5 to 10 cmH2O) [5]. We titrated infusion rate according to respiratory parameter (SpO2 > 95%) and hemodynamical parameter (mean arterial pressure above 40 mmHg).
A single, blinded pediatric radiologist graded the severity of atelectasis according to previously described scale [7] and determined whether there was significant atelectasis to confound image quality or not.
Statistics were calculated using Mcnemar’s test due to paired observations from children receiving imaging both pre- and post-protocol implementation.