Mean OP measurements for each position and differences in measurements between positions

Mean OP ± SD (cm H2O)P Value
Prone flat15.3 ± 4.8
Prone tilt14.2 ± 5.9
LD12.6 ± 4.8
Difference between prone flat and prone tilt1.1 ± 0.80.20
Difference between LD and prone flat2.7 ± 0.69.001
Difference between LD and prone tilt1.6 ± 0.67.017