The Inova Heart and Vascular Institute (IHVI) perform over 300 coronary artery bypass graft (CABG) surgeries per year. While opioid medications are the institutional standard of care for post-operative pain therapy little is known about the variation in pain scores, incidence of post- operative complications, and cost of hospitalization when an alternative multimodal pain regimen consisting of oral Gabapentin and intravenous Acetaminophen (IV APAP) is utilized.

The objective is to determine whether there is a substantial difference in pain scores, incidence of post-operative complications, and costs associated with hospitalization when a non-opioid multimodal pain regimen is utilized A single- center, open label, prospective, randomized, controlled clinical trial comprised of 20 total patients who have undergone isolated CABG at the IHVI will be conducted. Separate cohorts will include patients receiving opioid medications post-operatively (Group 1) and patients receiving the non-opioid regimen of oral Gabapentin and IV APAP (Group 2) to be followed for 72 hours post CABG surgery.

Main outcome measures include pain scores in both study groups, requests for breakthrough pain medication in both groups, gastrointestinal and respiratory complications of ileus and reduction in tidal volumes or forced vital capacity (FVC) at baseline and at 72 hours,increase in serum AST/ALT, and comparison of cost of hospitalization between groups.

The objective of this pilot study is to provide evidence that multimodal pain therapy utilizing IV APAP and PO Gabapentin will provide more effective pain relief than standard of care opioids as evidenced by pain scores <2. And the reduced consumption of opioids will lead to a reduction in ileus, no increase in AST/ALT, post-operative tidal volumes as assessed by incentive spirometry comparable to pre- surgical values, while also showing a positive effect on the cost of hospitalization.

The Cardiovascular Intensive Care Unit (CVICU) of the Inova Heart and Vascular Institute (IHVI) will be the setting of this clinical trial involving two groups of subjects and comparing the opiate based standard of care regimen currently adopted (Group 1) at the IHVI with a treatment group (Group 2). Group 2 will receive a scheduled multimodal pain regimen consisting of PO (pro ora [oral]) Gabapentin paired with intravenous Acetaminophen. Opioids will be available for breakthrough pain in the treatment group for pain scores greater than 4. The outcomes of total opioid consumption and minimum/ maximum pain scores will be assessed at the 24 hours, 48 hours, 72 hours, and PRN (pro re nata [as the situation demands]) timepoints. Assessment will include amount of opioids consumed in both groups as well as number of requests for breakthrough pain medication in Group 2.

Minimum and maximum pain scores in all study groups will be assessed via Numeric Rating Scale (0-10) as per Inova Health System (IHS) policy; 'Pain Management for the Adult Population', at 24 hours, 48 hours, 72 hours, and PRN with opioid requests in all groups and opioid administration follow up within one hour as per IHS inpatient medication administration policy. Follow up medication administration scores will not be recorded as part of study results.

Secondary assessments will include the incidence of ileus both during hospitalization, increase in aspartate aminotransferase (AST)/ alanine aminotransferase (ALT), post-operative tidal volumes as assessed by incentive spirometry as compared to pre- surgical values, time from Cardiovascular Intensive Care Unit (CVICU) arrival to extubation in both groups, and the effects of an opioid based regimen versus an opioid sparing regimen on cost of medication and hospitalization.

The investigators hypothesize that a scheduled opioid- sparing pain regimen consisting of intravenous Acetaminophen IV APAP and PO Gabapentin for 48 hours post- operatively will reduce opioid consumption while maintaining adequate pain relief as evidenced by pain scores less than two (2), and a reduction in opioid consumption, and that reduced opioid consumption will lead to a reduction in the incidence of ileus, an opioid related side effect, no increase in AST/ALT, post-operative tidal volumes as assessed by incentive spirometry comparable to pre- surgical values, and demonstrate a positive effect on the cost of medication and hospitalization.

Inclusion Criteria:

1. Patient between 18 and 85 years old.
2. Elective or urgent surgery requiring sternotomy approach
3. Subject is able to read and has signed and dated the informed consent document including authorization permitting release of personal health information (PHI) approved by the Inova Institutional Review Board (IRB).

Exclusion Criteria:

1. Patients lacking enteral access on post-operative day 0
2. Inability to communicate
3. Active chronic pain with opioid therapy
4. Active chronic use of gabapentin or pregabalin
5. Active substance abuse
6. Current self- report of alcoholism
7. End stage renal disease
8. Active renal dialysis therapy

randomization through 72 hours after randomization