Early this morning CALS and St-Leonard VFD units were dispatched for a reported cardiac arrest. CHF10 was already on the road enroute to CALS and was just minutes from the call and arrived on scene first. The patient had a very complex medical condition requiring a lot of complicated care. M104 (PMIC Middleton) arrived shortly after and worked with CHF10 and the units from St-Leonard for approximately 15 minutes at which point ROSC was achieved. As one paramedic took over focused resuscitative care the other quickly dual consulted with our local hospital and Children's National Medical Center. The patient was accepted at CNMC and was transported via MSP Trooper 7 with PMIC Middleton on board due to the complexity of the patient. MSP returned PMIC Middleton approximately an hour and a half later to CHMC so she could return to service in M104.