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Improving the care of sleep apnoea
P124 Effusion Size on the Chest Radiograph at Day 7 Post-Pleural Drainage is a Good Predictor of Size at 3 Months, Regardless of Initial Intrapleural Therapy
  1. RJ Hallifax1,
  2. M Nagendran1,
  3. M Maruthappu1,
  4. A Manuel1,
  5. JM Wrightson1,
  6. NA Maskell1,
  7. HE Davies2,
  8. NM Rahman1
  1. 1Oxford Centre for Respiratory Medicine, Oxford, England
  2. 2Department of Respiratory Medicine, Cardiff, Wales


Introduction Drainage of infection pleural fluid is essential in improving patient outcomes. The MIST-2 Trial (NEJM 2011) demonstrated intrapleural tissue plasminogen activator (t-PA) and DNase therapy improves drainage in patients with pleural infection from Day 1 to 7 compared to placebo. However, there is no evidence assessing whether this difference is sustained at 3 months. Methodology used in the MIST-2 trial demonstrated that a digital chest radiograph measurement strategy was an effective measurement of pleural fluid volume and correlated closely with computed tomography scanning in estimating effusion size.


  1. To determine whether intrapleural treatment with t-PA, DNase, or both, showed a sustained significant difference in effusion size at 3 months.

  2. To assess predictors of residual pleural shadowing 3 months post treatment.

Methods 132/193 (68%) patients in the MIST-2 trial had assessable chest radiographs at 3 months (remaining patients were lost to follow-up or died). Effusion size was measured as a percentage of the hemithorax occupied on digital radiograph image (JPEG format). Each image was analysed independently by a medical student and respiratory specialist. Where the difference in estimates exceeded 2%, the radiographs were reassessed together to generate consensus. Analysis was blind to treatment arm.

Results There was no significant difference between placebo and any treatment group in the 3 month radiology outcome. The 3 month effusion size was positively correlated with that at Day 7 (Pearsons 0.27, p=0.003). Neither Day 1 effusion size, nor the difference between Day 1 to 7 was significantly correlated with 3 month outcome. Linear regression analysis demonstrated significant correlation for Day 7 effusion size with 3 months size (p=0.004), but non-significance by treatment arm (p=0.071).

Conclusions In those that survive and have a chest radiograph at 3 months, there is no difference in the radiological outcome at 3 months between treatment groups on the basis of treatments given, including surgical intervention. However, the appearance at day 7 is significantly correlated with the 3 month chest radiograph. Further statistical modelling of this data is now required to assess the relative contributions of intrapleural interventions and surgery in those that survive to 3 months.

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