Devices, systems, and methods for inflation are provided. Inflation devices include a housing, a compressed gas canister disposed therein, a syringe disposed within the housing, a plunger slidably disposed in the syringe having an unloaded position and a loaded position relative to the syringe, a puncture mechanism disposed within the housing and configured to open a fluid path between the compressed gas canister and the syringe, and a positive pressure mechanism disposed within the housing and operably coupled to the syringe. Engagement of the puncture mechanism puts the syringe into fluid communication with the compressed gas canister such that gas contained therein loads into the syringe and the plunger moves from the unloaded position and the loaded position. The positive pressure mechanism is configured to maintain the gas within the syringe at a positive pressure relative to ambient pressure in order to prevent air from entering the syringe after loading.
