Following an out of hospital cardiac arrest, a 65-year-old patient has been receiving CPR for the past 10 minutes in the field. According to paramedics the initial rhythm was Ventricular Fibrillation (VF) with an ETCO2 upon intubation of 8. In the most recent pulse check a narrow-complex tachycardia was detected but a pulse was not palpable manually. The ETCO2 has jumped to 45. What is the best interpretation of the current situation?