Antireflux valves in patient‐controlled analgesia

Antireflux valves are widely used in conjunction with patient‐controlled analgesia devices. It is important to appreciate the limitations and dangers of these systems. They can achieve a potential ‘stored volume’ if occluded and they may, as part of the administration set, retard fluid administration. Seven antireflux systems currently available were tested in conjunction with three patient‐controlled analgesia pumps. The systems’ volume, time to occlusion alarm and flow rates were measured. Results showed that the sets with low stored volumes were less efficient as administration sets. A potentially dangerous bolus could result after release of occlusion if sets with large stored volumes were used in conjunction with pumps that utilised concentrated solutions of opioid. This study has identified the ideal antireflux valve system.