HUMAN COLONIC SMOOTH-MUSCLE ELECTRICAL-ACTIVITY DURING AND AFTER RECOVERY FROM POSTOPERATIVE ILEUS

Colon smooth muscle electrical control (ECA) and response activities ( ERA) were recorded for up to 4 wk postoperatively for 48 patients afte r major abdominal operations. Bipolar electrodes were implanted into r ight and left colon circular muscle and exteriorized through the flank s, and signals were tape recorded for 2-24 h daily beginning on the 1s t postoperative day. A computer program was used for data reduction an d analysis. Recorded signals were digitized and filtered. The ECA freq uency components were identified by fast Fourier transformation, and t heir relative tenancy in low, mid, and high frequency ranges was deter mined. Short and long ERA burst duration and frequency and number and velocity of propagating long ERA bursts were determined. ECA was omnip resent and exhibited a downshift of the dominant frequency from the mi d to the low range as recovery from postoperative ileus progressed. Co ncurrently, first in the right and then in the left colon, the frequen cy of long ERA bursts increased, followed by the appearance of propaga ting long ERA. After the 6th postoperative day, no further significant changes in parameters of colon electrical activity occurred with time .