A mesenteric traction syndrome affects near-infrared spectroscopy evaluated cerebral oxygenation because skin blood flow increases

During abdominal surgery manipulation of internal organs may induce a “mesenteric traction syndrome” (MTS) including a triad of flushing, hypotension, and tachycardia that lasts for about 30 min. We evaluated whether MTS affects near-infrared spectroscopy (NIRS) assessed frontal lobe oxygenation (S_cO₂) by an increase in forehead skin blood flow (SkBF). The study intended to include 10 patients who developed MTS during pancreaticoduodenectomy and 22 patients were enrolled (age 61 ± 8 years; mean ± SD). NIRS determined ScO₂, laser Doppler flowmetry determined SkBF, cardiac output (CO) was evaluated by pulse-contour analysis (Modelflow), and transcranial Doppler assessed middle cerebral artery mean flow velocity (MCA V_mean). MTS was identified by flushing within 60 min after start of surgery. MTS developed 20 min (12–24; median with range) after the start of surgery and heart rate (78 ± 16 vs. 68 ± 17 bpm; P = 0.0032), CO (6.2 ± 1.4 vs. 5.3 ± 1.1 L min⁻¹; P = 0.0086), SkBF (98 ± 35 vs. 80 ± 23 PU; P = 0.0271), and S_cO₂ (71 ± 6 vs. 67 ± 8%; P < 0.0001), but not MCA V_mean (32 ± 8 vs. 32 ± 7; P = 0.1881) were largest in the patients who developed MTS. In some patients undergoing abdominal surgery NIRS-determined S_cO₂ is at least temporarily affected by an increase in extra-cranial perfusion independent of cerebral blood flow as indicated by MCA V_mean. Thus, NIRS evaluation of S_cO₂ may overestimate cerebral oxygenation if patients flush during surgery.