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Table 2 Summary of studies of oxygenation after thoracentesis in mechanically ventilated patients

From: Utility and safety of draining pleural effusions in mechanically ventilated patients: a systematic review and meta-analysis

Study N on MV a PEEP b (cm H 2 O) Volume Drained (mean ± SD) Time of Outcome Measurement Variable Outcome d
       Before After P-value
Ahmed 2004 22 Not reported 1,262 ± 762 mL (Initial drainage) <1 hour before and after drainage PaO2:FiO2 245 ± 103 270 ± 101 0.31c
      A-a Gradient 236 ± 170 211 ± 153 0.52c
      Shunt Fraction 26.6 ± 15.1 21.0 ± 7.8 0.03
De Waele 2003 24 Not reported 1,077 mL (SD not reported) (Over first 24 hours) Before and 24 hours after drainage PaO2:FiO2 190 ± 84 216 ± 74 0.16c
Doelken 2006 9 0 1,575 ± 450 mL (Initial drainage) Immediately before and after procedure PaO2:FiO2e 96 ± 29.7 102 ± 21.9 0.37
      A-a Gradient 226 ± 99.6 217 ± 85.2 0.34
Guinard 1997 36 12 ± 3 n/a 6 to 12 hours post-optimization procedure Predefined gas exchange response d   53% responded  
Roch 2005 44 6 ± 2 730 ± 440 mL (first three hours) Before and 12 hours after drainage PaO2:FiO2 (effusion <500 mL) (N = 20) 214 ± 83 232 ± 110 0.47c
      PaO2:FiO2 (effusion >500 mL) (N = 24) 206 ± 62 251 ± 91 <0.01
Talmor 1998 19 17 ± 1 863 ± 164 mL (first eight hours) Immediately before and 24 hours after drainage PaO2:FiO2 151.0 ± 66.7 244.5 ± 126.8 <0.0001
  1. aMV, mechanical ventilation.
  2. bPEEP, positive end-expiratory pressure.
  3. cP-value not provided in the original paper; we calculated the P-value based on the data provided, assuming a correlation between the before and after measurements of 0.4
  4. dPaO2 >100 mm Hg on FiO2 1.0 for at least six hours.
  5. aValues are reported as mean ± standard deviation.
  6. eOriginal paper reported PaO2 but all patients were on FiO2 1.0; we calculated PaO2:FiO2 from these data.