Chest Drainage Therapy: What Comes out of Pandora's Box Can Affect Patient Outcomes.

Background: Over the last 100 years, the original three-bottle chest drainage system has been variously engineered into compact disposables and electronic units. Clinicians are now surrounded by a plethora of different types of systems, but little is known about the way that they work and perform. Thus, we sought to test the performance of the most commonly used chest drainage units under conditions that are relevant to clinical practice. Methods: A pleural space environment simulator was built. Thirty-two units were tested under four clinical scenarios: air leak interpretation during quiet breathing and after obstructed inspiration (-5 to -150 cmH 2 O), a buildup of negative pressure (-100 cmH 2 O), a bronchopleural fistula (10 L/min) and the need for effective external suction in the presence of air leakage. Twenty-five units were "traditional" thoracic drainages, five were "digital" low-flow/low-vacuum pumps and two were hybrids (a combination of the two). According to the design of the seal and of the suction control, the units were classified as wet-wet, wet-dry and dry-dry. Results: All wet units showed reverse air flow, with the potential to mimic an air leak when there was none. Ten wet units showed no automatic negative pressure relief features, while five dry-dry did but were slow to react. Ten wet and five dry-dry units showed no capability to handle a 10 L/min leak, as they were restrictive to flow (peak pressure up to 55 cmH 2 O). Only seven dry-suction units were able to maintain the set suction at high airflow rates (>20 L/min). Conclusions: Different chest drainage unit designs lead to different performances, some of which may negatively impact patient outcomes. This sounds the call to tailor our clinical practice for the individual patient. A paradigm shift to better understand all components of pleural physiology post-surgical intervention on this relatively neglected topic is needed to improve our daily practice.