While you are waiting for the SIMV ventilator to be connected,the oxygen saturation falls to 70%.With bag-endotracheal ventilation,it rises to 86%,but the infant is now requiring 100%inspired oxygen. What has happened? What is your next step? While you are waiting for the SIMV ventilator to be connected, the oxygen saturation falls to 70%. With bag-endotracheal ventilation, it rises to 86%, but the infant is now requiring 100% inspired oxygen. What is your next step? What has happened?