Morphine Fentanyl Significance Pre-induction (Tbaseline) 9.6 ± 2.5 9.1 ± 2.7 N.S 30 min post-induction (T1) 8.9 ± 1.5 8.8 ± 2.1  30 min post-bypass (T2) 9.9 ± 1.9 8.8 ± 2.1 1 hour post-bypass (T3) 7.3 ± 2.7 *** 6.5 ± 1.4 *** 2 hours post-bypass (T4) 8.1 ± 1.9 * 7.7 ± 1.1 ** On ICU admission (T5) 8.6 ± 1.9 8.3 ± 1.2 3 hours after ICU admission (T6) 8.8 ± 2.8 7.9 ± 2.2 * 6 hours after ICU admission (T7) 8.3 ± 0.7 8.4 ± 0.9 Data presented as median (interquartile range). P value by Kruskall-Wallis. Intergroup differences (p<0.05) by Tukey’s test after log transformation: N.S=Non Significant **P<0.01 compared to Tbaseline *P<0.05 compared to Tbaseline ***P<0.001 compared to Tbaseline

Table 5: Central venous pressure changes (cm H2O) in the two studied groups.