Yоu аre cаring fоr а 26 week male infant оn high frequency jet ventilation. He suddenly develops profound hypotension, central capillary refill time of 4-5 seconds, hypoxemia with 100% oxygen requirement, hypercarbia, persistent bradycardia with heart rate 80s-90s, muffled distant heart sounds, and a shrinking QRS complex on EKG. Which of the following should you do first?