Secondary objectives | Secondary end points |

To determine the feasibility of P_{EL} computation using the novel DPM | The time taken to perform the EDIT large volume aspiration, including measurement of ΔIPP using the DPM, recording of ΔV and computation of P_{EL} The failure rate of the procedure, defined as the proportion of patients in whom P _{EL} cannot be computed |

To determine the safety and tolerability of P_{EL} computation using the novel DPM | The occurrence of chest pain, cough or breathlessness during the procedure AEs) and SAEs associated with use of the DPM |

To assess the pleural fluid aspiration volume required to detect abnormal P_{EL} (where present) | The pleural fluid aspiration volume at which the rolling average pleural elastance over the preceding 250 mL (P_{EL250}) first exceeds the upper limit of normal (14.5 cm H_{2}O/L) |

To determine the proportion of patients allocated to EDIT management who require pneumothorax induction to facilitate safe ICD/IPC insertion following DPM | The proportion of patients in whom pneumothorax induction is required to facilitate safe ICD/IPC insertion in the EDIT arm |

To test the assumption that pleural cavity ΔV is equivalent to the volume of pleural fluid removed during aspiration | Pleural fluid aspiration volume (ΔV_{OUT}) Pleural cavity volume change, as measured directly using volumetric MRI (ΔV _{MRI}; defined as pre-aspiration minus post-aspiration pleural cavity volume) |

To test the accuracy of a predictive model of pleural effusion volume (V_{TUS}) based on TUS measurements, which is a proposed inclusion criterion for the EDIT study | TUS estimated total pleural effusion volume (V_{TUS}) Pre-pleural fluid aspiration pleural cavity volume (V _{MRI}) |

AE, adverse events; DPM, digital pleural manometer; EDIT, elastance-direct intrapleural catheter or talc pleurodesis; ICD, intercostal drain; IPC, indwelling pleural catheter; IPP, intrapleural pressure; P

_{EL}, pleural elastance; SAE, serious adverse event; TUS, thoracic ultrasound; V, pleural fluid volume.