Myoelectric assessment of bowel viability.

A device capable of quantitative measurement of intestinal ischemic damage has been designed. The device is called the electrical contractility meter and employs a clip-on strain gauge transducer that delivers a precisely controlled electrical stimulus to the bowel. Threshold stimulus level (TSL) is the stimulus current in milliamperes (mA) that is necessary to produce a clearly defined smooth-muscle contraction. In 30 dogs, TSL was used to establish viability boundaries in 40 cm ischemic bowel segments. Bowel viability was assessed with the use of TSL in comparison with gross features (color, peristalsis) and blood flow measured by means of Doppler ultrasound at 2 cm intervals in the ischemic small-bowel segments. The TSL scale ranges to 100 mA and varied from a low of 22 +/- 2 mA in normal bowel outside the ischemic segment to 97 +/- 4 mA in grossly gangrenous bowel. There was a consistent correlation between rising TSL and worsening bowel color, disappearance of visible peristalsis, and progressive disappearance of audible Doppler signals. Resection and anastomosis were performed in three groups of 10 dogs at TSL measurements of 30 mA, 40 mA, and 50 mA, respectively. Dogs were killed and anastomoses were inspected on the tenth postoperative day. There were no leaks at TSL = 30 mA, one leak at TSL = 40 mA, and four leaks at TSL = 50 mA. The number of leaks at TSL = 50 mA was significantly greater than at TSL = 30 mA (p less than 0.04, Fisher's exact test). These results show that the quantitative myoelectric parameters established by this device provide a reliable in vivo assessment of bowel viability. The electrical contractility meter is easy to use and may have clinical applicability.