Conditional IF statement help

[Raisedwell]

How can I complete this formula?

Basically I want to say, only when cell H2 contains Item3, Item5, Item7 or Item9 then use the following formula:

=IF(I2="1-Critical",4,IF(I2="2-High",3,IF(I2="3-Medium",2,IF(I2="4-Low",1,"")))))

Summary:
If cell H2 contains Item3, Item5, Item7, or Item9, then it will populate the cell containing the formula with 4,3,2, or 1.