Comparison of the Caldwell needle/cannula with Angiocath needle in large volume paracentesis

To evaluate the efficacy and safety of a newly designed paracentesis needle, the Caldwell needle/ cannula (CNC), and to compare it with the Angiocath needle for large volume paracentesis (LVP).

Forty patients (ages, 18-75 yr) with symptomatic non-malignant ascites and serum creatinines < 1.6 were randomized to undergo LVP with either the 15-gauge CNC or the 14-gauge Angiocath needle. LVP was considered complete when the ascitic fluid was believed to have been completely removed, a goal of 6 L was attained, or fluid return was poor despite clinically obvious ascites. Outcome parameters measured included time necessary for the LVP, amount of ascitic fluid removed, number of peritoneal punctures, and the reason for termination of LVP. Ascitic fluid from eight patients was used to measure in vitro flow rates for both needles at -80, -120, and -200 mm Hg.

Twenty patients underwent LVP with the CNC and 20 with the Angiocath. Patients in whom the CNC was used had significantly faster paracenteses (17.0 +/- 0.8 vs. 34.1 +/- 1.5 min) and required fewer second peritoneal punctures (1 vs. 6, p = 0.046). Fewer LVPs in the CNC group were terminated secondary to poor fluid return (8 vs. 1, p = 0.022). The volume of fluid removed was greater with the CNC than with the Angiocath, but this difference did not reach statistical significance (5205 +/- 209 vs. 4683 +/- 269 ml, p = 0.079). There were no complications in either group. In vitro flow rates were 2.2-3.8 times faster through the CNC than through the Angiocath at all pressures tested (p < 0.05 for all groups).

The CNC provides a faster, more complete paracentesis requiring fewer peritoneal punctures than a single-bore needle.