Raw Data for Unpublished Study "Physiologically Induced State Anxiety Reduces Perceived Heat Pain in Healthy Subjects"

Version hyper_v01_20231019
Authors: Alexandros Guekos, Madeleine Hau, Sabina Grob, Gil Sharvit, Petra Schweinhardt
The present data was collected from February 2022 to May 2023 for a study on the influence of hypercapnia on pain perception.
The results are to be published soon. A link to the manuscript will be provided.
Full details of the paradigm, the experimental setup, and the analysis will be given there. Therefore, the following description only summarizes the most important steps.
In total, 47 subjects (22 men and 25 women) participated in a single experimental session during which they inhaled two different air mixtures, one coresponding to regular room air (normocapnic air, 21% O2 and 0.04 CO2) and one with identical O2 concentration (21%) but 7.5% CO2 concentration (hypercapnic air) for about 13 minutes each. Starting condition, i.e. first mixture, was pseudorandomized across participants.
Each condition began with a task-free phase of 90s. Then, self-assessment manikin (SAM) ratings for valence and arousal had to be entered (10s) before the first heat stimulus. SAM ratings were prompted again in the middle of the condition, i.e. during the ninth interstimulus interval, and after rating the last, i.e. 18th stimulus. After the last stimulus, the body sensations questionnaire (BSQ) had to be filled in (60s). After a further 60s of task-free time the air mixture was switched and the entire procedure was repeated for the second condition.
Instructions for SAM were given before the start of the experiment (see SAM_instructions_final.pdf).
BSQ was obtained before the experiment as well (see paper version BSQ_new.pdf).
During inhalation participants received 18 painful heat stimuli of 6s each on three locations on the calf muscle. The stimuli were divided into low (6x), medium (6x), and high (6x). Stimulus temperature was determined based on the individual heat pain tolerance threshold (ToT), corresponding to roughly 95, 96.5, 98% ToT. ToT was determined as a mean of three method of limits beforehand.
Participants had to rate every stimulus on two scales, one for intensity and one for unpleasantness. The intensity scale ranged from 0 (no sensation) to 200 (maximum tolerable pain) with 100 being the individual pain threshold (HPT). The unpleasantness scale ranged from -100 (extremely unpleasant) to 100 (extremely pleasant) with 0 corresponding to neutral.
Both scales were presented as horizontal bars with anchors for the lowest, highest, quarter-, and mid-point values. Ratings had to be filled in using a mouse-controlled slider on the two scales displayed on the screen (see Ratings.png). The whole protocol was programmed and displayed with PsychoPy v3.2021.2.3 (Open Science Tools Ltd, Nottingham, UK). The total duration of each condition was approximately 13 minutes (778s).
During the whole experiment, physiological data was recorded. This included galvanic skin response from the toes (electrodes on biggest and middle toes, in muS), heart rate (three point measurement, in bpm), as well as exhaled O2 and C02 concentration (in %). Heart beat and end-tidal were directly calculated from the registered data during recording and saved with the data.
The study was funded by the Swiss National Science Foundation as part of a grant to PS (grant number 320030_179191/1).