Evaluation of in vitro performance of suction drains

To assess the in vitro performance of suction drains.

11 drainage systems (3 rigid drains and 8 compressible drains [2 grenade type, 5 concertina type, and 1 pancake type]).

A pressure transducer was connected to the patient end of each drainage system. Serial pressure measurements were obtained during incremental addition and removal of air into the reservoir of each system, followed by incremental addition of water. The volume of air removed to restore the initial suction was recorded. Maximum filling volume was compared with the stated reservoir volume. For compressible drains, the suction generated following 3 compression methods was compared.

The initial suction generated by the drainage systems ranged from -633.4 +/- 14.7 mm Hg to -90.1 +/- 19.5 mm Hg. Rigid drains had greater initial suction than compressible drains. For all compressible drains, compression with 2 hands, rather than 1, produced greater suction, apart from the pancake-type (200-mL reservoir) drains for which the reverse occurred. For grenade-type drains, rolling the reservoir from apex to base generated greater suction than 1-hand compression. Maximum filling volume was lower than stated for the concertina-type drains with 50-mL, 25-mL, and 400-mL reservoirs and the rigid-type drain with a 200-mL reservoir. As increments of air or water were added, compressible drains lost suction rapidly up to a fill of 20% to 30% and then more gradually. Rigid drains lost suction more slowly.

Drainage systems varied widely in their initial suction and rate of loss of suction during filling.