The patient is likely experiencing supraventricular tachycardia that is causing him to become hemodynamically unstable. However, more information is needed and assessment is performed before interventions; therefore, the nurse first obtains a 12-lead electrocardiogram (ECG) to better determine the patient’s dysrhythmia. Then, a peripheral IV should be inserted into the patient’s right upper extremity to facilitate the administration of drugs such as adenosine to attempt to convert the patient’s rhythm or for resuscitation if necessary. Synchronized cardioversion will likely be required, but a 12-lead ECG must be performed first. Vagal maneuvers such as instigating the mammalian diving reflex through ice water to the face and eyes can be used to convert a patient in SVT to normal sinus rhythm if the SVT is not causing hemodynamic compromise; therefore, this is an inappropriate intervention for this patient.