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Table 2 Prone ventilation in relation to intra-abdominal pressure and obesity

From: Clinical review: Intra-abdominal hypertension: does it influence the physiology of prone ventilation?

     Intra-abdominal pressure   
Study Patients Abdominal unloading BMI (mean) Zero, primea Mean supine (mmHg) Mean prone (mmHg) ARDS typeb Comments or major conclusions
Pelosi and colleagues [37] 10c Yes 34.6 NA NR NR NA FRC increased 1 l, lung compliance increased 18 cmH2O
Pelosi and colleagues [36] 10d Yes NR Symph., 100 ml 11.4 14.8 (P = NS) 12% EP Decreased chest wall compliance. Oxygenation better
Hering and colleagues [38] 16 No NR Symph., 250 ml 12 15 (P < 0.05) 21% EP Renal function not impaired
Kiefer and colleagues [43] 25 Not described NR NRe 10 11 (P = NS) NR Gastric tonometry decrements common
Hering and colleagues [39] 12 No 26 Symph., 250 ml 10 13 (P < 0.05) 34% EP Splanchnic perfusion OK
Matejovic and colleagues [41] 11 No NR Axillary, 50 ml 10 11 (P = NS) 18% EP Splanchnic perfusion OK
Michelet and colleagues [40]f 20 No NR Symph., 100 ml Approx. 6 (foam) Approx. 12.5 (P < 0.01) 10% EP No BMI or IAP data reported
      Approx. 8 (air) Approx. 11 (P < 0.05)   
Chiumello and colleagues [44] 11 Random 23.1 Symph., 100 ml 12 14.5 (suspended) 27% EP Suspension not required
      14.5 (not)    
Fletcher [42] 10 No NR Axillary, 50 ml 14.5 8.4 to 11.4g (P = 0.0002) 100% DP Proning does not increase IAP
  1. ARDS, acute respiratory distress syndrome; axillary, mid-axillary line; BMI, body mass index; DP, direct pulmonary; EP, extrapulmonary; FRC, forced residual capacity; IAP, intra-abdominal pressure; NA, not applicable; NR, not reported; symph., pubic symphysis. aZero, reference point for IAP measurement; prime, priming volume for IAP measurement if intermittent bladder pressure measurement used. bAcute respiratory distress syndrome with best classification from reported data. cNo IAP measurements. dSixteen patients were in the main study but only 10 had IAP measured. eNo numerical IAP data reported only graphical results presented in this comparison of air-cushioned mattresses versus foam mattresses. fGastric pressure measurements. gTime series regression analysis of hourly IAP measurements.