Relevance of Water Temperature, Apparatus, and Age to Children's Pain during the Cold Pressor Task.

Background: Effective use of experimental pain in research depends on a thorough understanding of factors influencing their use. Although studies using the cold pressor task (CPT) have critically advanced our knowledge of pain mechanisms, assessment, and management in adults and children, the impact of identified methodological variability in its use is not known (ie, water temperature and apparatus); furthermore, whether methodological variations differentially impact children across development.

Methods: Pain outcomes were examined in 113 healthy children from three age groups (8- to 9-, 10- to 11-, and 12- to 14-year-olds) who completed three CPTs at different water temperatures (5, 7, 10°C) in counterbalanced order. Children were randomly assigned to one of two apparatus (ice- vs. electric-cooled) for all CPTs. Children's hand was warmed to its baseline temperature between CPTs.

Results: Colder water (2 to 3°C decreases) was associated with significantly higher pain intensity and unpleasantness, and lower pain tolerance and threshold. Older children (12 to 14 years) reported significantly worse pain intensity and unpleasantness as compared to 8- to 9-year-olds, likely due to longer pain tolerance. Pain outcomes in 10- to 11-year-olds fell between the other age groups, with significant differences for pain unpleasantness and pain tolerance (at 10°C). Higher pain-related fear and pain unpleasantness occurred with the electric-cooled apparatus. Girls had higher pain tolerance and threshold at all temperatures.

Conclusions: These results provide critically important information about water temperature, apparatus, and child age on CPT pain responding. It informs design of future CPT studies and directs consideration of methodological variability and child age when interpreting study findings.