OLP at the intracuff pressure of 60cm H2 O was significantly higher than that of 40cm H2 O ( 17.93.9 vs 16.94.2 cm H2 O , P = 0.004 ) and was comparable with that of 80cm H2 O ( 17.93.9 vs 17.84.6 cm H2 O , P = 0.938 ) .