Aman B Ali, MD2, Toan B Nguyen1, Marc Garbey, PhD2, Brian J Dunkin, MD2. 1University of Houston, 2Methodist Institute for Technology, Innovation and Education – Houston Methodist Hospital
Introduction: Minimally invasive solid organ surgery, such as hepatectomy, are high-risk procedures that may be aided using image guidance. This mode of computer aided surgery can help a surgeon to avoid critical structures, achieve an adequate resection margin, and maximize organ preservation. The technique requires fusing a preoperative imaging set (CT or MRI) with the live intraoperative laparoscopic images, rendering the target organ to appear transparent. A significant challenge to achieving accurate image fusion is correcting for respiratory motion.
Hypothesis: High-frequency ventilation (HFV) will minimize the effect of respiratory motion on image guided surgery.
Method: We compared standard ventilation versus HFV on a cadaver during simulated minimally invasive liver surgery. Landmark points on the liver’s surface were created to allow tracking during different video frames (Figure A). The cadaver was then ventilated using varying modes of conventional ventilation (tidal volume, respiratory rate) versus varying frequencies of HFV. Novel tracking software was used to analyze the videos and record the trajectories of the liver markers throughout the respiratory cycle. The liver's motion was measured in millimeters (Figure B) and, in the case of HFV, plotted against respiratory rate (Figure C).
Results: Displacement of the liver markers from full inhalation to full exhalation was 15±2 mm using the lowest respiratory rate during standard ventilation (tV = 800 mL, rate = 10 b/min, PEEP = 10 cmH2O). When using HFV, the displacement decreased as rate increased with a clinical plateau at greater than 648 breaths/min or 10.8 Hz (Figure C). Above this frequency, the markers appeared stagnant on the laparoscopic view.
(A) Markers on the liver’s surface (B) Displacement (mm) of liver markers (C) Displacement versus respiratory rate
Conclusion: Many image-guided surgery techniques suffer from respiratory motion artifacts. Numerous researchers have attempted to correct for breathing motion using sophisticated computational methods. High-frequency ventilation (HFV) eliminates respiratory motion and can be maintained for many hours. It has the potential to revolutionize image guided surgery.
Presented at the SAGES 2017 Annual Meeting in Houston, TX.
Abstract ID: 80782
Program Number: P412
Presentation Session: Poster (Non CME)
Presentation Type: Poster
