Delay revision petition.

1) Husband may pray anything to avoid or reduce maintenance.

2) Maintenance is granted based on the financial income of the husband and the comforts allowed to the wife at the time of seperation and parental home.

3) Hence any attempt to reduce may be contested.

You can file application for review u/s 127 before lower court  and than revision on it to higher court.

But you make a solid case for reduction. Medical expanses is no excuse.