Introduction: Assessing postoperative inefficiencies is vital to increase the feasibility of ambulatory lumbar fusion. This study aimed to identify patients who would have been eligible for same-day discharge following minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) and then analyze the limiting factors in their postoperative pathway that led to a delay in discharge.

Methods: Patients who would have met the eligibility criteria determined a priori for ambulatory lumbar fusion were included. Patient demographics, surgical data (start time, operative time, estimated blood loss [EBL], and complications) and postoperative in-hospital data (postoperative length of stay [LOS]; time in post-anesthesia recovery unit [PACU]; alertness check, neurological exam, and pain scores at 3 hours and 6 hours; type of analgesia; time to physical therapy [PT] visit; reasons for PT non-clearance; time to per-oral [PO] intake; time to 1^st and 2^nd voids; time to readiness for discharge; complications) were analyzed. Time taken to meet each discharge criterion was calculated. Time of discharge readiness was taken as the point when the patient had fulfilled all the criteria. The percentage of patients meeting each discharge criterion at 3 hours and 6 hours post-surgery was calculated. Correlation and regression analyses were performed to study the effect of postoperative variables on LOS. Multiple linear and logistic regression analyses were performed to study the effect of preoperative and operative variables on postoperative parameters influencing discharge.

Results: 71 patients were included of which only 4% were discharged on the same day. 69% of patients were discharged on postoperative day one. Physical therapy (PT) clearance was the last-met discharge criterion in 93% of patients. 66% of patients did not get a PT evaluation on the day of surgery. 76% of patients required intravenous (IV) opioids and <60% of patients had adequate pain control. 27% had orthostatic intolerance (OI). The median postoperative length of stay (LOS) was 26.9 hours, time in post-anesthesia care unit (PACU) was 4.2 hours, time to per-oral (PO) intake was 6.5 hours, time to 1^st void was 6.3 hours, time to 1^st PT visit was 17.7 hours, time to PT clearance was 21.8 hours, and time to discharge readiness was 21.9 hours. Regression analysis showed that time to PT clearance, time to PO intake, time to voiding, time in PACU, and pain score at 3 hours had a significant effect on LOS. There was no effect of preoperative and operative variables on postoperative parameters influencing discharge.

Conclusion: Unavailability of PT, orthostatic intolerance, inadequate pain control, prolonged PACU stay, and long feeding and voiding times were identified as modifiable factors preventing same-day discharge in patients eligible for ambulatory lumbar fusion. After the foremost step of appropriate patient selection, interventions like prehabilitation, recruitment and re-allocation of PT personnel and resources, scheduling of surgeries for the earlier part of the day, use of pre-emptive analgesia with paracetamol and NSAIDs or COX-2 inhibitors, reduction of peri-operative opioid use, PACU fast-tracking, and early postoperative feeding and voiding could increase the feasibility of ambulatory lumbar fusion.