Background and Goal of Study: Ketamine is commonly used as an opioid sparing adjuvant in the "Enhanced Recovery After Surgery" pathways. However postoperative sedation and confusion may occur, especially in th elderly. Dexmedetomidine has analgesic properties but it is known to cause sedation, hypotension and bradycardia which may prolong PACU stay. The goal of this study was to examine the effects of these medications on analgesia and sedation in patients undergoing minimally invasive thoracic surgery (MITS).
 Materials and Methods: With IRB approval, 130 records of patients undergoing MITS were retrospectively reviewed. Ketamine (Ket=67) or Dexmedetomidine (Dex = 63) were administered intraoperatively at the discretion of the primary anesthesia team and stopped at the end of the case. Postoperative analgesia consisted of an intravenous opioid PCA and adjuvants. Cases receiving neuraxial analgesia were excluded. Intra- and postoperative opioid totals (in iv morphine equivalents), non-opioid anti-inflammatory drugs requirements, sedation [using the Richmond Agitation Sedation Scale] and pain scores were compared between the two groups at PACU arrival and after 4 hours. Fisher’s exact test was used for categorical variables, and Wilcoxon rank sum test for continuous one. 
Results and Discussion: Patient characteristics and comorbidities were comparable between the two groups. Intraoperative morphine equivalents were similar between the two groups as well as multimodal analgesia with acetaminophen and ketorolac, and the use of dexamethasone. Ket patients had lower RASS (figure 1) and higher pain scores (figure 2) on PACU arrival with an improvement at 4 hours.  Surgical times, intraoperative fluids, estimated blood loss and pressor requirement were similar between the two groups. There was no difference in PACU as well as hospital stay. 
Conclusion(s): This retrospective study showed that the intraoperative use of Dex or Ket as part of multimodal analgesia in patients undergoing MITS is associated with similar effects on intraoperative analgesia and hemodynamic parameters. Patients seem to be more sedated and with higher pain scores when arriving in PACU after the use of ketamine, but this effect does not persist and does not affect PACU stay. The use of intraoperative Dexmedetomidine can be considered as an alternative to Ketamine for MITS and enhanced recovery pathways.

11 / Opioid Sparing Effects of Intraoperative Dexmedetomidine or Ketamine in Patients Undergoing Minimally Invasive Thoracic Surgery_x000D_