Exploration of optimal paracentesis volume for terminally ill patients with malignant ascites.
Authors: Ito Tetsuya , Yokomichi Naosuke , Ishiki Hiroto , Kawaguchi Takashi , Masuda Ken , Tsukuura Hiroaki , Funaki Hiromi , Suzuki Kozue , Oya Kiyofumi , Nakagawa Jun , Mori Masanori , Yamaguchi Takuhiro 
Published: June 2021

12089 Background: Malignant ascites (MA) often causes distressing symptoms especially for terminally ill cancer patients. Control of such symptoms is generally difficult when it becomes refractory to standard antitumor therapies. Paracentesis is the most common treatment modality which provides rapid and temporary symptom relief, while it requires frequently repeated treatment to maintain symptom control. The optimal procedure is often a balance between the potential for symptom improvement and the known risks of adverse events such as hypotension and renal impairment. However, there are limited data regarding the optimal amount of fluid to be removed. The aim of this study was to explore the efficacy (paracentesis interval and symptom relief) and safety (adverse events) of paracentesis by the drainage volume. Methods: This is part of a multicenter prospective observational study (EASED study). Consecutive adult patients with advanced cancer admitted to 23 participating palliative care units were eligible. We analyzed patients with MA who received paracentesis. We compared paracentesis-free survival (PFS) using Cox regression among 3 groups with different paracentesis volumes: minimum: < = 1500 mL, small: 1500-2500 mL, and moderate: > 2500 mL, with adjustment for potential confounders: age, sex, the Karnofsky Performance Status, and variables of which P-values were < 0.1 in univariate analysis. Trend of the difference in abdominal distention numerical rating scale (NRS) before and after paracentesis and adverse events were compared among 3 groups. Under missing at random assumption, missing values were imputed using multiple imputation. Results: A total of 1926 patients were enrolled and 673 patients developed MA at admission. Of these, 586 patients never received paracentesis during their PCU stay. Thus, the population for analysis consisted of 87 patients. Median PFS was 7 days. Compared with a moderate volume, small-volume paracentesis was not a significant risk for shorter PFS (HR: 1.14, 95%CI: 0.69-1.93), while a minimum volume was a significant risk for shorter PFS (HR: 2.34, 95%CI: 1.25-4.39). The spline-based hazard ratio curve indicated that a dose-response of the ascites drainage volume to PFS was not likely when more than 2,000 mL of ascites was removed. Abdominal distension NRS significantly decreased after paracentesis (median: 7.5 to 4.0, p < 0.0001), while the difference did not significantly increase as the volume of paracentesis rose (p = 0.61). No severe adverse event was observed. Conclusions: Even small-volume paracentesis could alleviate abdominal distension of terminally ill cancer patients with MA without shortening the paracentesis interval compared with moderate-volume paracentesis. Small-volume paracentesis was an effective and safe treatment for such patients. Our findings may help physicians estimate an optimal volume of paracentesis for each patient with MA.