A preserved pancreatic exocrine function after pancreatectomy may be a crucial cause of pancreatic fistula: paradoxical results of the ¹³C-trioctanoin breath test in the perioperative period

Purpose: The aim of this study was to elucidate the association between pancreatic fistula (PF) and the sequential changes in the perioperative exocrine function after pancreatectomy. Methods: The subjects were 96 patients who underwent a ¹³C-trioctanoin breath test before and 1 month after pancreatectomy, between 2006 and 2018. We retrospectively compared the pre- and postoperative fat absorption levels between patients with PF (PF group; n = 17) and without PF (non-PF group; n = 79) using the breath test. Results: The preoperative level of ¹³C-trioctanoin absorption (%dose/h) was comparable between the non-PF and PF groups (36.5 vs. 36.9). In the non-PF group, ¹³C-trioctanoin absorption was significantly decreased after surgery in comparison to the preoperative setting (post-operative 28.5; pre-operative 36.5; p < 0.0001), whereas these values were comparable (post-operative 36.9; pre-operative 34.5; p = 0.129) in the PF group. Moreover, postoperative absorption in the PF group was significantly better than that in the non-PF group (34.5 vs. 28.5%, p = 0.0003). The maximum drain amylase level was significantly higher in patients with a ¹³C-trioctanoin absorption level (%dose/h) of ≥ 30 in comparison to patients with levels of < 30 (2502 vs. 398 U/L, p = 0.001). Conclusion: PF did not exacerbate the pancreatic exocrine function in the early postoperative period, and the acceleration or preservation of the exocrine function after surgery may be an important cause of PF.