Jejunal Free Flap



Jejunal Free Flap


J. J. COLEMAN III





The jejunal free flap or jejunal free autograft is a reliable, frequently used method of transferring a segment of bowel to replace an area lined with mucosa. Because of the length of the small bowel, its constant blood supply, and its more favorable bacterial content, the jejunum has been more popular than segments of the colon or stomach. The size of the jejunal branches of the mesenteric vessels allows revascularization at the site of reconstruction with microscope or loupe magnification.




ANATOMY

The jejunum is the second portion of the small intestine, beginning at the ligament of Treitz and extending approximately 8 feet distally. The blood supply includes the jejunal branches of the superior mesenteric artery and vein that pass through the mesentery and arborize to supply the gut. In the proximal mesentery, there is usually only one arcade of vessels distal to the segmental artery and vein, with the vasa recta extending directly off the arcade. This makes the relationship between the branch of the superior mesenteric artery and the segment of gut it supplies more direct than in the ileum, where there are two or three arcades of vessels between the superior mesenteric artery and vein and the vasa recta to the bowel (Fig. 226.2). When harvested, the diameter of the jejunal vessels from the superior mesenteric artery and vein range from 2 to 4 mm.


FLAP DESIGN AND DIMENSIONS

To some degree, the segment of jejunum available on a single pedicle depends on body habitus and the length of the mesentery. The selection of an appropriate branch and its subsequent blood supply can result in lengths of bowel from 10 to 30 cm. The mesentery of the small bowel varies with body habitus but generally ranges in length from 15 to 20 cm.

Selection of appropriate vessels in the neck before harvesting the jejunal free autograft is of paramount importance. The ischemia tolerance of jejunum is low, requiring revascularization in 2 hours or less. Because the ideal location for the bowel conduit is in the midline (the anatomic site of the pharynx and cervical esophagus), and because there is an obligate length of mesentery necessary before anastomosis can be done, vessels situated in the lateral neck are best for recipients.


OPERATIVE TECHNIQUE

The transverse cervical vessels can be found just lateral to the jugular vein deep to the omohyoid in the medial posterior triangle; these are ideal for anastomosis low in the neck. The facial and occipital branches of the external carotid, which lie just beneath the digastric muscle on the lateral neck and external jugular vein, may be dissected out and placed laterally in the superior neck (Fig. 226.3). Anastomosis to the main internal jugular or the proximal medial branches of the external carotid requires bowing of the jejunum off the midline or
folding of the mesentery. The former impairs subsequent transit of food through the conduit, and the latter increases the risk of venous thrombosis. Whatever vessels are chosen should be completely prepared for micosurgical anastomosis before division of the jejunal vessels.

Only gold members can continue reading. Log In or Register to continue

Jun 26, 2016 | Posted by in General Surgery | Comments Off on Jejunal Free Flap
Premium Wordpress Themes by UFO Themes