Comparison of the effects of intercostal tube drainage of pleural fluid (drain group: solid bars) and no intervention (control group: open bars) on ventilation index (cm H2O/kPa/min=peak airway pressure×respiratory rate×arterial carbon dioxide tension (PaCO... Comparison of the effects of intercostal tube drainage of pleural fluid (drain group: solid bars) and no intervention (control group: open bars) on ventilation index (cm H2O/kPa/min=peak airway pressure×respiratory rate×arterial carbon dioxide tension (PaCO2)/1000) over 6 days in patients recovering from cardiac surgery. Data displayed as mean±SD. Fraser J H Brims et al. BMJ Open Resp Res 2015;2:e000080 ©2015 by British Thoracic Society