Ketamine in Patients Undergoing TEVAR Procedures Receiving 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.

• Saline (Drug): Saline infusion
• Ketamine (Drug): Continuous ketamine infusion at a dose of 0.2 mg/kg/hr, initiated at the induction of anesthesia and continued for 48 hours postoperatively.

Primary outcomes

• Cumulative Opioid Dose [48 hours]: Total morphine milligram equivalents (MME) will be assessed every 6 hours for 48 hours.

Secondary outcomes

• Change in Pain [48 hours]: Pain will be assessed using a 10-Point Numerical Pain Scale (as part of standard of care) every hour for the first 24 hours and every two hours for the next 24 hours. Scores range from 0-10; higher scores indicated higher levels of pain.
• Number of Patients with Ketamine-Induced Delirium [48 hours]: Ketamine-induced delirium will be monitored via the Confusion Assessment Method (CAM-ICU) survey every 8 hours for 48 hours. The CAM-ICU assesses four diagnostic features of delirium and the result is a binary (yes or no) determination.
• Number of Patients with Uncontrolled Hypertension [48 hours]: Uncontrolled hypertension is defined as a systolic pressure of 160 mmHg despite 3 intravenous antihypertensive agents.

Sex: All, ages: 18 Years to 90 Years

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

• Anna Rockich, Pharm D, Study director, University of Kentucky
• Samuel Tyagi, MD, Principal investigator, University of Kentucky