If preterm baby already given caffeine loading and on maintenance, after 4-5 days want to extubate him , is it enough for him that he already on caffeine maintenance or shall we give him extra dose of caffeine 1-2 hours before extubation to prevent failure of extubation

Routinely not needed to give extra loading dose. But, there is a variation of practice in maintenance dose between 5-10mg/kg/dose of caffeine citrate. And some units go higher than 10mg/kg/dose. 

Caffeine in preterm.pdf

In my experience an extra loading dose isn’t given but as @kishoreyv17 says there is variation in dosing. Sometimes a dose of 7.5mg/kg twice a day is used! 

There could be an argument for checking caffeine levels to ensure they are in a therapeutic range before giving additional doses but I don’t think I’ve ever seen a caffeine level checked!!!! 
 

 

Already on caffeine we don’t give an extra dose before extubation.

 

If you're actually worried about extubation failure, there are evidence based things you can do to improve chances of successful extubation such as extubating to NIPPV and having the non-invasive interface setup (or even part way on the baby) at time of extubation to minimize loss of FRC. There is no evidence that I am aware of to support re-loading caffeine.