A single institution experience of minimally invasive liver surgery: 12 years after the Louisville statement where do we stand?

Presenter: Patrick Salibi MD | Atrium Health Background: Despite significant improvements in perioperative outcomes, minimally invasive surgery (MIS) was broadly adopted relatively late in hepatic surgery. The Louisville Consensus Statement in 2008 recommended indications for MIS liver resection to solitary lesions < 5cm in segments 2 through 6. However, as MIS technology advanced and surgeon comfort increased, the indications for MIS liver resection have expanded. The aims of this study are to present an institutional experience of developing an MIS liver surgery program and to assess outcomes that define an institutional learning curve for these procedures. Methods: A prospectively maintained registry of all hepatic surgical cases performed at a single high-volume tertiary care center was queried from January 2008 to December of 2019. Retrospective record review was performed, collecting data including patient demographics, baseline laboratory values, surgical details, conversion to an open approach, estimated blood loss, blood transfusions, operative time, length of stay, complications, re-admissions and mortality. All data collection and record review were approved by the Institutional Review Board. Results: Our institution performed 1098 both open and MIS liver resection during the study period as well as an additional 842 microwave ablation procedures. Of these 501 patients underwent MIS liver resection and had complete data to perform accurate review. When assessing an institutional learning curve there was no significant difference noted over time for perioperative and postoperative outcomes including operative time, need for blood transfusions, length of stay, readmissions or morbidity/mortality. Consistent measures that improved overtime and remained stable for both laparoscopic and robotic MIS approaches, were conversion rate and estimated blood loss. When broken up by 4-year periods the conversion rate was noted to be 13.18% (2008-2011), 7.28% (2012-2015) and 4.64% (2016-2019). Estimated blood loss improved similarly during each epoch: 634ml (2008-2011), 483ml (2012-2015), and 348ml (2016-2019). A ceiling effect of percent MIS cases performed over time increased incrementally from 47.66% (2008-2011) to 67.98% (2012-2015) and plateaued at 75.85% (2016-2019). Conclusion: This study presents 12 years of data from a single institution and proposes that percent conversion rate and estimated blood loss appear to the be the best institutional predictors of learning curve given that over time introduction of junior faculty likely effects other perioperative and postoperative outcomes. Ceiling effect can be viewed as another measure of an institutions learning curve and again showed consistent increase overtime to a plateau of 75-80% which one would expect at a high-volume liver center were the need for maximally invasive surgery for major resections remains a necessity.