The objective of this study is to identify the opioid-sparing effects, and pain-reduction potential of low dose, sub-dissociative ketamine on patients undergoing thoracic endovascular aortic repair (TEVAR) procedures receiving naloxone continuous infusion (NCI).

Patients undergoing descending aortic repair often experience post-operative pain, and have high post operative opioid requirements. That pain is partially due to the use of naloxone continuous infusion (NCI). NCI is part of a bundled approach used in the first 48 hours post-operatively to prevent spinal cord ischemia, a devastating complication associated with surgical repair of the descending aortic. Data indicate that patients receiving NCI experience elevated post-operative pain scores and increased opioid requirements during the 48-hr post-operative NCI administration, compared to patients not receiving NCI.

Ketamine is an FDA-approved N-methyl D-aspartate (NMDA) antagonist that has been shown to provide adjunctive analgesia and opioid-sparing effects in post-operative surgical patients. At low doses, ketamine provides analgesic benefit without the anesthetic effects seen at higher doses. These doses are commonly referred to sub-dissociative. This study will evaluate whether use of sub dissociative ketamine (SDK) in patients undergoing aortic procedures with the use of NCI will lead to decreased post-operative opioid consumption, and produce improved pain scores in the first 48 hours.

Inclusion Criteria:

• willing to give informed consent
• scheduled for elective thoracic aorta repair or thoracoabdominal aortic repair
• requires naloxone continuous infusion for spinal prophylaxis

Exclusion Criteria:

• allergy to ketamine, acetaminophen, or fentanyl
• diagnosis of schizophrenia
• history of hydrocephalus or central nervous system mass
• incarcerated individuals
• pregnant or lactating individuals