Which dressing is least effective for creating an airtight seal?

The least effective dressing for creating an airtight seal is gauze pads. Unlike other options, gauze pads are porous and designed to absorb exudate rather than act as a barrier to air and contaminants. Their structure allows air to pass through, which makes them inadequate for situations requiring an airtight seal, such as treating specific types of wounds like open chest injuries.

In contrast, options like plastic and aluminum foil can be used to create a more effective barrier by covering the wound completely and preventing air from entering. Vaseline gauze, while it provides some level of moisture control, is still more effective than gauze pads for sealing since it can reduce the risk of air exposure to some extent. Thus, gauze pads are not suitable for applications where an airtight environment is critical.