Effect of puff size instructions on puff volume.

In two experiments, the flexibility of puff volume was assessed using instructions and feedback to manipulate volume. Also, the effects of altered puff volume on puff duration, puff peak flow, and carbon monoxide (CO) boost were examined. In the first experiment, subjects were told to take small, medium, and large puffs. Subjects were able to accurately follow the puff size instructions; they took different-size puffs by altering their puff durations. In the second experiment, when puff duration was controlled, subjects were able to follow the puff size instructions by altering the intensity of their puffs. These two experiments demonstrated that a wide range of puff volumes can be generated by instructional control and that volume changes can result either from alterations of puff duration or of puff intensity.

RCT Entities:   Population Interventions Outcomes