Increases in total respiratory resistance during forehead temperature stimulation

We investigated the effects of forehead temperature stimulation on total re spiratory resistance in healthy individuals. In two experiments involving a total of 38 participants we studied the time course and stability of the r esponse at moderate temperature (20-23 degreesC). Small plastic bags filled with water were positioned on the forehead for a duration of 60 s. Oscilla tory resistance (R-os), heart period (HP), respiratory sinus arrhythmia (RS A), and ventilatory parameters were measured continuously. Experiment 1 sho wed similar phasic increases in R-os during the first 20 s of stimulation w ith moderate (20-23 degreesC) as compared to cold (8-11 degreesC) temperatu re. Phasic increases by moderate temperature were replicated in Experiment 2 over five successive stimulation trials. Within-session stability of indi vidual differences in response was only modest. Ventilatory adjustments did not facilitate the phasic R-os increases. As increases were mainly due to the inspiratory component of R-os. a substantial contribution of upper airw ay artifacts was less likely. Increases in HP were the most pronounced resp onses to all stimulation conditions. while RSA did not increase significant ly. (C) 2000 Elsevier Science B.V. All rights reserved.