Assessment of gut perfusion is vital to prevent anastomotic disruption or strictures following bowel resection. If available during surgey, the risk of ischaemic problems would be reduced. We measured superficial tissue oxygenation and perfusion using a continuous, noninvasive localized visible light spectrophotometer in patients undergoing gastric bypass to assess it effectiveness.Study design:A prospective non-randomized feasibility study to measure jejunal, gastric pouch serosal and mucosal oxygenation with an FDA-approved visible light spectrophotometer (T-Stat®, Spectros, Portola Valley, CA) was done in patients undergoing Roux-Y gastric bypass. Sterile laparoscopic 2 mm probes were used. All patients were followed at 1, 6 weeks, 3 months post-surgery and checked for anastomotic leaks and strictures. Results22 patients were entered in the study. There were no intraoperative complication from using the device. No patients had leaks, or strictures (early or late) in the series. Two cases of jejunal ischaemia due to stapling of the jejunal mesenteric arteries too close to the bowel was successfully detected by the system. Resection of these segment prior reanastomosis was performed with an uneventful outcome in both cases. Capillary oxygen saturation greater than 40% seems to be a safe minimal level for serosal oxygenation. Oxygen saturation prior and after the anastomosis did not differ substantially in the series.ConclusionSuperficial tissue oxygenation measurement using visible light is an effective tool to assess tissue viability and ensure successful healing of gastro-intestinal anastomosis. The limited tissue penetration of visible light reflects capillary oxygenation at the healing site. Deeper spectroscopy measurement may result in an overestimate oxygen saturation as arterial saturation is included. A capillary oxygen saturation above 40% appears to be safe to prevent anastomotic disruption or ischemia. Intraoperative visual light spectroscopy measurements of tissue oxygenation may assist the surgeon to assess tissue viability on performing bowel anastomosis, helping to ensure successful healing.
Capillary Oxygen Saturation (N=22)

Operative Stage	Location	Average (% O2 sat.)	SD	Location	Average (% O2 sat.)	SD
Initial jejunal measure	Jejunal serosa	68.0	6.2	Distal Jejunum	57.1	16.9
Post jejunal division	Jejunal serosa	60.6	12.2
	Jejunal mucosa	42.4	15.6
Post jejuno-jejunostomy	Jejunal serosa	53.3	14.8
Stomach	serosa prior division	62.3	9.2	Distal Jejunum in upper abdo.	60.6	14.3
	serosa post division	48.1	16.3
	serosa post anastomosis	50.9	12.1	Jejunal limb post gastro-jejunostomy	55.7	11.9