Add to ORKGA wearable infusion delivery device with an IV bag holding chamber for holding an IV bag for feeding an intravenous solution, a pressing member bounding a pressure chamber, a pressurizer for generating a pressure in the pressure chamber higher than the ambient pressure. The pressure chamber has a flexible pressure chamber wall arranged for, in response to an increasing pressure in the pressure chamber, displacing towards one of the largest sides of the bag holding chamber on a side of the bag opposite of a side of the bag where the pressing member is located. While solution is delivered from the bag, causing first and second walls of the bag contact each other, first in an initial contact area remote from an outlet port and subsequently cau...