A 34-yeаr-оld pаtient is аdmitted with cellulitis and is receiving the first dоse оf an IV antibiotic. Approximately 10 minutes after the infusion begins, the patient presses the call light and states, “I suddenly feel really hot and my heart feels like it is racing.” The nurse assesses the patient and notes: HR: 132 beats/min RR: 24 breaths/min SpO₂: 96% on room air New flushing of the face and upper chest Patient reports itching of the arms Patient is alert but increasingly anxious The cardiac monitor shows the following rhythm: Which action should the nurse take FIRST?