Effects of Somatostatin Prophylaxis after Pylorus-preserving Pancreaticoduodenectomy: Increased Delayed Gastric Emptying and Reduced Plasma Motilin

Somatostatin inhibits gastroenteropancreatic exocrine secretion and is often used after pancreaticoduodenectomy to reduce pancreatic secretion to minimize tissue damage and pancreatic stump complications. Because our earlier clinical work saw a major increase in delayed gastric emptying (DGE) with somatostatin prophylaxis after pylorus-preserving pancreaticoduodenectomy (PPPD), this small-group study was designed to confirm or disprove that observation. From August 1997 to December 2000, a total of 23 post-PPPD patients were randomized to receive somatostatin prophylaxis [somatostain (+)] (n = 11) or not [somatostatin] (−) (n = 12). The incidence of DGE, scintographic solid-phase emptying results on day 14 postoperatively, and sequential fasting plasma motilin levels were compared, as motilin levels are related to both gastric motility and somatostatin levels. The somatostatin(+) group exhibited greatly increased patient complaints of DGE: 9 of 11 (82%) versus 3 of 12 (25%) in the somatostatin(−) group. Radiologic scintography showed somatostatin prophylaxis prolonged the half-time (T_1/2) of solid-phase emptying: 144.5 ± 51.4 minutes for somatostatin(+) versus 89.0 ± 59.9 minutes for somatostatin(−) (p < 0.001). Comparing pre-PPPD and post-PPPD plasma motilin levels prior to somatostatin infusion, motilin decreased 80% in reaction to the surgery. For somatostatin(−) patients, motilin levels oscillated, or “rang,” postoperatively, reaching a higher level on day 3, declined to a new record minimum on day 7, and by day 21 were 50% of the original and the slope of the recovery curve was increasing well. In somatostatin(+) patients the same ringing pattern was observed but decreased with motilin levels 30% to 70% lower than in the somatostatin(−) patients. By day 21 somatostatin(+) motilin levels were recovering but still only 20% original levels, and the slope of the recovery curve was not optimistic. On postoperative day 14 the plasma motilin levels (below approximately 6 bg/ml) correlated strongly with DGE for both groups. Despite the small sample size, the results indicated that (1) somatostatin prophylaxis significantly decreases fasting plasma motilin; (2) somatostatin prophylaxis produces lingering suppression of plasma motilin; (3) PPPD surgery itself significantly reduces fasting motilin levels with recovery to 50% normal at day 21; (4) the mechanism of somatostatin-induced DGE seems related to reduced fasting plasma motilin levels.