It has been demonstrated that infants and children experience pain in a similar manner to adults, however it used to be undertreated when compared to adult.

Perfusion Index (PI) derived from pulse plethysmography waveform, represents a ratio of pulsatile signal (during arterial inflow) to non-pulsatile signal. PI can represent the peripheral perfusion dynamics due to change of peripheral vasomotor tone. Low PI values suggest peripheral vasoconstriction and high PI values suggest peripheral vasodilation.

The sympathetic nervous system is inherently involved in the pathophysiological responses evoked by painful stimulation.

In the current study, investigators hypothesise that the PI could be a good objective tool for assessment of postoperative pain in children undergoing adenotonsillectomy.

Inclusion Criteria:

1. ASA physical status I-II
2. Age 3 to 7 years
3. Children undergoing adenotonsillectomy.

Exclusion Criteria:

1. Parents' refusal.
2. Children with behavioral changes
3. Children with physical developmental delay
4. Children on treatment with sedative or anticonvulsant.

Children 3-7 years, ASA physical status I or II, undergoing Adenotonsillectomy will be included