Objective: Our aim was to evaluate a fluorescence-based enhanced-reality system to assess intestinal viability in a laparoscopic mesenteric ischemia model.
Materials and Methods: A small bowel loop was exposed, and 3 to 4 mesenteric vessels were clipped in 6 pigs. Indocyanine green (ICG) was administered intravenously 15 minutes later. The bowel was illuminated with an incoherent light source laparoscope (D-light-P, KarlStorz). The ICG fluorescence signal was analyzed with Ad Hoc imaging software (VR-RENDER), which provides a digital perfusion cartography that was superimposed to the intraoperative laparoscopic image [augmented reality (AR) synthesis]. Five regions of interest (ROIs) were marked under AR guidance (1, 2a-2b, 3a-3b corresponding to the ischemic, marginal, and vascularized zones, respectively). One hour later, capillary blood samples were obtained by puncturing the bowel serosa at the identified ROIs and lactates were measured using the EDGE analyzer. A surgical biopsy of each intestinal ROI was sent for mitochondrial respiratory rate assessment and for metabolites quantification.
Results: Mean capillary lactate levels were 3.98 (SD = 1.91) versus 1.05 (SD = 0.46) versus 0.74 (SD = 0.34) mmol/L at ROI 1 versus 2a-2b (P = 0.0001) versus 3a-3b (P = 0.0001), respectively. Mean maximal mitochondrial respiratory rate was 104.4 (±21.58) pmolO2/second/mg at the ROI 1 versus 191.1 ± 14.48 (2b, P = 0.03) versus 180.4 ± 16.71 (3a, P = 0.02) versus 199.2 ± 25.21 (3b, P = 0.02). Alanine, choline, ethanolamine, glucose, lactate, myoinositol, phosphocholine, sylloinositol, and valine showed statistically significant different concentrations between ischemic and nonischemic segments.
Conclusions: Fluorescence-based AR may effectively detect the boundary between the ischemic and the vascularized zones in this experimental model.
This experimental animal study introduces and validates the concept of functional augmented reality to assess intestinal perfusion. After injection of a fluorescent dye, the signal time-to-peak was used to construct a digital perfusion cartography, which was overlapped to the operative field to determine the extent of bowel resection.
†Department of Anesthesiology
‡Membrane Biophysics Laboratory and Nuclear Medicine Chemistry Institute
§Physiology Laboratory, Oxidative Stress, University of Strasbourg, France
¶CHUV, University Hospital of Lausanne, Switzerland.
Reprints: Michele Diana, MD, Department of Visceral Surgery, CHUV University Hospital of Lausanne, Rue du Bugnon 46, 1011 Lausanne, Switzerland; or IRCAD-EITS, University of Strasbourg, Place de l'Hôpital 1, 67091 Strasbourg, France. E-mail: email@example.com.
This work was presented at the annual meeting of the Swiss Society of Biomedical Engineering, August 27–28, 2012, at the Federal Polytechnic School of Lausanne (EPFL).
Disclosure: The authors declare no conflicts of interest.
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