No abstract

Introduction: When a standard water-seal pleural drain unit (PDU) is used under hyperbaric conditions there are scenarios where excessive negative intrapleural pressure (IPP) and/or fluid reflux can be induced, risking significant morbidity. We developed and tested a pleural vacuum relief (PVR) device which automatically manages these risks, whilst allowing more rapid hyperbaric pressure change rates. Methods: The custom-made PVR device consists of a one-way pressure relief valve connected in line with a sterile micro filter selected for its specific flow capacity. The PVR device is designed for connection to the patient side sampling port of a PDU system, allowing inflow of ambient air whenever negative pressure is present, creating a small, controlled air leak which prevents excessive negative pressure. The hyperbaric performance of a Pleur-Evac A-6000 intercostal drain was assessed with and without this added device by measuring simulated IPP with an electronic pressure monitor connected at the patient end of the PDU. IPP readings were taken at 10, 15, 20 and 30 cmH 2 O of suction (set on the drain unit) at compression rates of 10, 30, 60, 80, 90 and 180 kPa•min -1 to a pressure of 280 kPa. Results: At any compression rate of > 10 kPa•min -1 , the negative IPP generated by the Pleur-Evac A-6000 alone was excessive and resulted in back flow through the PDU water seal. By adding the PVR device, the generated negative IPP remains within a clinically acceptable range, allowing compression rates of at least 30 kPa•min -1 with suction settings up to -20 cmH 2 O during all phases of hyperbaric treatment. Conclusions:The PDU PVR device we have developed works well, minimising attendant workload and automatically avoiding the excessive negative IPPs that can otherwise occur. This device should only be used with suction.

In elderly patients with polyarthritis, the differential diagnosis must include autoimmune diseases, crystal deposition diseases or an infection associated conditions. A clinical suspicion of gout should be confirmed by uric acid crystals detection in the synovial fluid or in the tophus. However, it is sometimes for different reasons not possible to proceed with an arthrocentesis. In such cases, non-invasive tests, as high-resolution musculoskeletal ultrasound or DECT investigation could be useful to the clinician.