Relationship between adaptation and cardiovascular response to tonic cold and heat pain Adaptability to tonic pain and cardiovascular responses.
BACKGROUND
The mechanisms of adaptation to tonic pain are not elucidated. We hypothesized that the adaptability to tonic pain is related to the cardiovascular system.


METHODS
Twenty-six subjects received over two sessions in a random order: tonic cold (7 ± 0.2 °C) and heat pain (47.5 ± 0.5 °C) on the hand for 5 min. Pain intensity, blood pressure (BP), and heart rate (HR) were continuously monitored.


RESULTS
Pain experience during the heat (HIT) and cold (CIT) immersion tests exhibited different average time courses, being approximated with a linear and cubic function, respectively. In each test, two groups of participants could be identified based on the time course of their tonic thermal pain: one-third of participants were pain adaptive and two-thirds non adaptive. The adaptive group exhibited higher initial pain, lower last pain, and shorter latency to peak pain than the non-adaptive one. Interestingly, some participants were adaptive to both pain stimuli, most were not. HIT as well as CIT produced a stable elevation of BP. However, BP was higher during CIT than HIT (p = 0.034). HR was also increased during CIT and HIT, but the two tests differed with respect to the time course of responses. Finally, the intensity and time course of pain rating to both HIT and CIT correlated with neither BP nor HR responses.


CONCLUSIONS
These results suggest that individual sensitivity and adaptability to tonic thermal pain is related to the intensity of initial pain rating and the latency to peak pain but not to cardiovascular responses.
Clermont Université, Université d'Auvergne, Neuro-Dol, France.|Clermont-Ferrand & Inserm U1107, France.|CHU Clermont-Ferrand, Service d'Odontologie, France.
L
L
Devoize
Université de Sherbrooke, Departement de Chirurgie, Canada.
P
P
Chalaye
Centre Hospitalier Universitaire de Sherbrooke, Département de Pédiatrie, Canada.
S
S
Lafrenaye
Université de Sherbrooke, Departement de Chirurgie, Canada.
S
S
Marchand
Clermont Université, Université d'Auvergne, Neuro-Dol, France.|Clermont-Ferrand & Inserm U1107, France.|CHU Clermont-Ferrand, Service d'Odontologie, France.
R
R
Dallel
D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D003080:Cold Temperature / Q000009:adverse effects*; D005260:Female; D006225:Hand; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008297:Male; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D010147:Pain Measurement; D011897:Random Allocation