[RESULTS] Dermatomes of hypoalgesia was 5.1 1.0 segments in group P. VAS scores of rest pain ( 2.4 0.4 , 2.6 0.5 , 2.4 0.4 , 2.2 0.3 vs 3.7 0.7 , 3.6 0.8 , 3.4 0.6 , 3.1 0.6 , all P < 0.01 ) , cough pain ( 3.7 0.8 , 3.9 1.0 , 3.8 1.1 , 3.8 0.9 vs 4.4 1.1 , 4.9 1.3 , 4.8 1.3 , 4.3 1.2 , P < 0.05 , < 0.01 ) and sedation scores ( 2.2 0.4 , 2.0 0.4 , 1.9 0.3 , 1.8 0.3 , 2.6 0.5 , 2.5 0.4 , 2.4 0.5 , 2.2 0.4 , P < 0.05 ) in group P were significantly lower than in group I at the four points .