Bryski MG, et al. Techniques for intraoperative evaluation of bowel viability in mesenteric ischemia: A review. Am J Surg. 2020 Aug;220(2):309-315. Full-text for Emory users.
“Comparison studies in animal models and clinical experience featuring fluorescein flowmetry have consistently demonstrated the superiority of dye-based perfusion monitoring for intraoperative bowel assessment as compared to standard clinical criteria, DUS, and pulse oximetry/PPG. (45,46,47,53,54) However, these results are not universal, with some large animal models demonstrating no difference between fluorescein, DUS, and PPG, and an additional study showing that DUS actually outperforms fluorescein for intraoperative bowel assessment. (13,18,43)” (p. 312)
“An important drawback of qualitative, intraoperative assessments of bowel viability in AMI is the low detection threshold of each technique, which is especially true for fluorescein flowmetry. (60) In AMI, though blood flow to the bowel is often limited, it is rarely completely absent. Whitehill et al. demonstrate this case in which qualitative assessments are at risk of leaving soon-to-be necrotic bowel in situ due to inadequate blood flow. Although perfusion following ischemic insult may be sufficient for distributing fluorescein throughout the tissue, it belies imminent tissue necrosis because the impaired perfusion fails to meet physiological needs. Additionally, as with many visible light fluorophores, fluorescein flowmetry is confounded by endogenous fluorophores and tissue autofluorescence that emit in the same wavelength, creating background noise and false signal. Shorter excitation and emission wavelengths also mean greater susceptibility to scatter and consequent limits to depth of signal penetration.(61)” (p. 312)
Bornstein JE, et al. Assessment of Bowel End Perfusion After Mesenteric Division: Eye Versus SPY. J Surg Res. 2018 Dec;232:179-185. Full-text for Emory users.
Materials and methods: Forty-nine consecutive patients undergoing open or laparoscopic-assisted bowel resections were enrolled. After mesenteric division, the surgeon marked the site for bowel transection. Near-infrared fluorescence imaging was performed on the marked bowel ends. Imaging analysis identified theoretical transection sites based on the quantification of arterial and microvascular inflow (Perfusion) and venous outflow (Timing). The primary outcome was the measured disparity between the site marked by the surgeon using current standard of care parameters and the imaging-determined site. No clinical outcomes were assessed.
Results: Seventy-two bowel end segments from 46 patients were analyzed. Disparity was found in 11 of 72 (15%) bowel end segments. In five (7%), the disparity was due to either Perfusion or Timing (single), and in six (8%), due to both Perfusion and Timing (combined). In the single disparity group, the median disparity distance was 2.0 cm by Perfusion and 4.0 cm by Timing, and in the combined group, 3.8 cm by Perfusion and 3.5 cm by Timing. Disparity (either single or combined) was in 25% of colon and 11.5% of small bowel (P = NS). Combined and single disparity had equivalent lengths of disparity distance (P = NS).
Conclusions: Imaging coupled with this GI-specific analysis provides objective, real-time, and interpretable data of intramural blood supply. A 15% disparity rate from current clinical practice was observed.
More PubMed results on intraoperative perfusion assessment.