In a professional or medical context, "portable suction" refers to devices used to clear airways (e.g., removing phlegm or obstructions). These devices, such as the Go to product viewer dialog for this item.
Using self-sucking portable devices is relatively straightforward. Here's a general guide: how to self suck portable
When individuals refer to "portable" methods, they generally mean techniques that can be practiced in any private space without specialized equipment: The Wall-Assisted Method: In a professional or medical context, "portable suction"