Physiological studies using laser Doppler flowmetry to compare blood flow to the zones of the free TRAM flap.

Physiological studies of in vivo blood flow within the various types of lower transverse rectus abdominis musculocutaneous (TRAM) flaps have been limited. Therefore, to supplement our knowledge, intraoperative measurements of flow to the cutaneous paddle as derived from laser Doppler flowmetry were recorded in 13 free TRAM flaps in 10 patients (3 bilateral). The relative contributions from both the deep inferior epigastric artery (DIEA) and the superior epigastric artery (SEA) to each zone were assessed jointly and then independently. Mean flow via the DIEA contribution alone was equal to or greater than twice that of the SEA in all zones, although this was not significant (p = 0.079). Flow from either the DIEA or the SEA diminished the farther the zone was from the source pedicle. Contralateral skin territories had significantly decreased flow when compared with all ipsilateral territories (p = 0.005), so that a relative ischemia exists even in free TRAM flaps, which could be the source of unexpected partial flap loss and/or fat necrosis in these zones. These findings were consistent with anatomic descriptions of the lower TRAM flap that imply that the DIEA is the dominant source vessel to the skin of this region.