Quantitative myoelectric determination of bowel viability.

A new device designed to quantitatively measure viability in ischemic bowel was studied in 20 dogs. This strain gauge device is clipped on the serosal surface and can rapidly deliver an electrical stimulus. The threshold stimulus level (TSL) was the stimulus necessary to produce a clearly defined smooth muscle contraction. TSL was compared with blood flow measured by Doppler ultrasound at 2-cm intervals in 30-cm ischemic segments as a determinant of bowel viability. Doppler readings were taken from the bowel wall (BW), peripheral arteriolar branches of the marginal artery (PA), and marginal artery (MA), itself, at each 2-cm interval. Bowel color and peristalsis were correlated with Doppler and TSL data. TSL scale ranged from 0 to 100 mA and varied from 21 +/- 2 mA in normal bowel to 98 +/- 2 mA in gangrenous bowel. At the locus of the last audible Doppler signal in the BW, PA, and MA, mean TSL readings were 27 +/- 5, 34 +/- 6, and 48 +/- 16 mA, respectively. These readings were each significantly greater than the TSL of normal bowel at P less than or equal to 0.0001 level. Portions of each ischemic segment were resected and reanastomosed. Absence of Doppler signals in the BW and PA did not preclude healing of ischemic bowel. These data suggest that TSL measurement is more sensitive than either Doppler ultrasound or gross visual evaluation in assessment of bowel viability.