Mr. rogers is 2 days postoperative of a thoracotomy for removal of a malignant mass in his left chest. his pain is being managed via an epidural catheter with morphine (an opioid analgesic). as the nurse assumes care of mr. rogers, he is alert and fully oriented, and states that his current pain is 2 on a 1-to-10 scale. his vital signs are 37.8 – 92 – 12, 138/82. what are benefits of epidural versus systemic administration of opioids? the nurse monitors mr. rogers’ respiratory status and vital signs every 2 hours. what is the rationale for these frequent assessments?