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

Water temperature during the cold pressor test: A scoping review

The cold pressor test (CPT) is a commonly used method to induce pain and stress in experimental settings. Previous research has found that the temperature of the water used in the test significantly affects outcome measures such as pain tolerance. Variations in CPT protocols, specifically regarding temperature, have been criticized. Hence, our objective is to investigate water temperature and associated methodological factors through a scoping review of the CPT in adults. Among 331 included trials, the most commonly reported temperature was 1°C (33.8°F). Reporting of the water temperature was adequate (93% of all trials), but a precise range within which the temperature was maintained was reported only in 27% of all trials. Pain measurement was the primary focus for most studies (90%), predominantly utilizing pain tolerance as the main outcome (78%). Water circulation was reported in 44% of studies, and 10% reported manually agitating the water. The most common maximum immersion time (i.e., ceiling time) was 180 s; notably, 64% of trials lacked information on participant awareness of this limit specification. The limb most immersed was the hand (76%). Overall, multiple methodological factors significantly impacting outcome measures were inconsistently implemented or reported. For future studies, we advocate for precise standardization of the water temperature used during the CPT. We suggest using 1°C (33.8°F), especially when assessing pain tolerance. A cooling apparatus allowing precise temperature control and continuous water circulation is advised. At the bare minimum, the temperature should be monitored continuously. While other decisions regarding the implementation of the CPT may differ depending on the specific aims of the respective study, it remains essential to standardize the water temperature and to provide a comprehensive report of the experimental protocol.

Feasibility and reliability of a quantitative sensory testing protocol in youth with acute musculoskeletal pain postsurgery or postinjury

ABSTRACT

Quantitative sensory testing (QST) is increasingly used in pediatric chronic pain; however, assessment in youth with acute musculoskeletal (MSK) pain is limited. This study evaluated the feasibility, reliability, and sources of variability of a brief QST protocol in 2 clinical samples of youth with acute MSK pain. Participants were 277 youth (M age = 14.5 years, SD = 2.0, range = 11-18 years, 59% female, 81% non-Hispanic) across 3 geographic study sites who completed a QST protocol assessing pressure and thermal pain sensitivity, temporal summation of pain, and conditioned pain modulation 8 weeks after MSK surgery (n = 100) or within 4 weeks after an acute MSK injury (n = 177). High feasibility was demonstrated by protocol completion rates ranging from 97.5% to 100% for each task, with 95.3% of youth completing all tasks. Reliability was high, with reliability coefficients of >0.97 for 7 out of 8 QST parameters and minimal influence of examiner or participating site effects. Younger youth had lower pressure and heat pain thresholds (11-12 vs 13-18 years, d = -0.80 to -0.56) and cold pain tolerance (d = -0.33). Hispanic youth had higher pressure and heat pain thresholds (d = 0.37-0.45) and pain ratings for cold pain tolerance (d = 0.54) compared with non-Hispanic youth. No significant differences were observed in QST values by sex or personal contextual factors at the time of assessment (momentary pain, menstrual period, use of pain medications). Overall findings demonstrate feasibility of a brief QST protocol with youth with diverse acute MSK pain and data provide initial support for the reliability of this QST protocol for multisite research studies.

Investigating sensory response to physical discomfort in children with autism spectrum disorder using near-infrared spectroscopy

Self-reporting of pain can be difficult in populations with communication challenges or atypical sensory processing, such as children with autism spectrum disorder (ASD). Consequently, pain can go untreated. An objective method to identify discomfort would be valuable to individuals unable to express or recognize their own bodily distress. Near-infrared spectroscopy (NIRS) is a brain-imaging modality that is suited for this application. We evaluated the potential of detecting a cortical response to discomfort in the ASD population using NIRS. Using a continuous-wave spectrometer, prefrontal and parietal measures were collected from 15 males with ASD and 7 typically developing (TD) males 10-15 years of age. Participants were exposed to a noxious cold stimulus by immersing their hands in cold water and tepid water as a baseline task. Across all participants, the magnitude and timing of the cold and tepid water-induced brain responses were significantly different (p < 0.001). The effect of the task on the brain response depended on the study group (group x task: p < 0.001), with the ASD group exhibiting a blunted response to the cold stimulus. Findings suggest that NIRS may serve as a tool for objective pain assessment and atypical sensory processing.

A Multi-Method Approach to Understand Parent Behaviors During Child Acute Pain

Abstract. Parent behaviors strongly predict child responses to acute pain; less studied are the factors shaping parent behaviors. Heart rate variability (HRV) is considered a physiological correlate of emotional responding. Resting or “trait” HRV is indicative of the capacity for emotion regulation, while momentary changes or “state” HRV is reflective of current emotion regulatory efforts. This study aimed to examine: (1) parent state HRV as a contributor to parent verbal behaviors before and during child pain and (2) parent trait HRV as a moderator between parent emotional states (anxiety, catastrophizing) and parent behaviors. Children 7–12 years of age completed the cold pressor task (CPT) in the presence of a primary caregiver. Parents rated their state anxiety and catastrophizing about child pain. Parent HRV was examined at 30-second epochs at rest (“trait HRV”), before (“state HRV-warm”), and during their child’s CPT (“state HRV-cold”). Parent behaviors were video recorded and coded as coping-promoting or distress-promoting. Thirty-one parents had complete cardiac, observational, and self-report data. A small to moderate negative correlation emerged between state HRV-cold and CP behaviors during CPT. Trait HRV moderated the association between parent state catastrophizing and distress-promoting behaviors. Parents experiencing state catastrophizing were more likely to engage in distress-promoting behavior if they had low trait HRV. This novel work suggests parents who generally have a low (vs. high) HRV, reflective of low capacity for emotion regulation, may be at risk of engaging in behaviors that increase child distress when catastrophizing about their child’s pain.

The effectiveness of parental distraction during children's acute pain: The moderating effect of socioeconomic status

BACKGROUND

Parental responses to children's pain shape how children interpret and cope with pain symptoms through parental modelling and operant conditioning. Evidence suggests that parental distraction is effective in reducing children's acute pain responses, but findings are inconsistent across pain tolerance, intensity and unpleasantness, and are limited to samples of primarily middle and upper-middle class families. Although socioeconomically disadvantaged families may have fewer psychological resources to cope with pain, no studies have examined whether the utility of parent distraction varies by family socioeconomic status (SES). The current study tested the hypothesis that relations between parental distraction and acute pain responses in children vary by family SES, with children from higher versus lower SES families experiencing more substantial benefits.

METHODS

Children's pain symptoms and parents' use of verbal distraction during a cold pressor task were examined in a community sample of 530 twin children aged 7-12 years old and their primary caregivers.

RESULTS

Parental distraction was positively associated with children's pain tolerance and unrelated to intensity and unpleasantness, but these associations are qualified by significant moderation. In families with higher SES, parental distraction was an effective technique in children's pain management, associated with more pain tolerance and less pain intensity and unpleasantness. However, for families with lower SES, these same benefits were not present.

CONCLUSIONS

Findings suggest that the effectiveness of parental distraction for children's acute pain may depend on family SES.

SIGNIFICANCE

Study findings suggest that the effects of parental distraction on children's responses to an acute pain task vary by family SES. Although parental distraction may be effective for higher SES children, further research is needed to identify whether and why distraction may not be beneficial for lower SES families.

Learning to fear pain after observing another's pain: An experimental study in schoolchildren

BACKGROUND

Children of individuals with chronic pain have an increased vulnerability to experience pain problems, possibly through observation of pain in their parents. As pain-related fear (PRF) is a critical factor in the development and maintenance of chronic pain, the current experimental study examined the acquisition of PRF through observational learning and subsequent extinction after first-hand experience of the feared stimulus.

METHODS

Healthy children (8-16 years) observed either their mother or a stranger performing two cold pressor tasks (CPT) filled with coloured water. In a differential conditioning procedure, one colour (CS+) was combined with genuine painful facial expressions and the other colour (CS-) with neutral facial expressions. Following this observation phase, children performed both CPTs (10°C) themselves.

RESULTS

Children expected the CS+ to be more painful than the CS- and they reported being more afraid and hesitant to immerse in the CS+ compared to the CS-. Moreover, this fear was reflected in children's level of arousal in anticipation of CPT performance. This learned association extinguished after performing both CPTs. Effects were not moderated by whether the child observed their mother or a stranger, by the child's pain catastrophizing, trait PRF or trait anxiety. Remarkably, learning effects increased when the child perceived a larger difference between the model's painful and neutral facial expressions.

CONCLUSIONS

This study provides evidence for observational learning of PRF and subsequent extinction in schoolchildren. This acquisition of PRF by observing parental pain may contribute to vulnerabilities in children of parents with chronic pain.

SIGNIFICANCE

Children may acquire pain-related fear by observing pain in others and this learned fear can diminish after first-hand experience. Remarkably, observational learning did not depend on the children's relationship with the model, but it did depend on the intensity of pain that is perceived. A better understanding of the impact of observing (parental) pain may help clarify the intergenerational transmission of risk for pain and inform the development of preventive programs.

Activación emocional en sujetos humanos: procedimientos para la inducción experimental de estrés

Resumen El estudio de los efectos del estrés sobre la cognición y el comportamiento es un área de especial interés y desarrollo científico, tanto para la Psicología como para las Neurociencias. La inducción de estrés constituye un elemento fundamental en estos estudios, pues permite la manipulación de esta forma de activación emocional, como variable independiente, para observar su efecto sobre la conducta; no obstante, esta inducción debe ser suficiente para generar incrementos significativos en los niveles de cortisol y cumplir los estándares éticos establecidos para la experimentación con humanos. El presente artículo tiene como propósito aportar una revisión general sobre la activación emocional, para profundizar en el conocimiento acerca de los procedimientos utilizados en la inducción experimental de estrés en sujetos humanos. Se concluye que se requiere el diseño de protocolos más eficaces, para lo cual, el uso de las simulaciones y otras herramientas tecnológicas puede ser de gran utilidad.

Cold Pressor Pain Response in Children With Cancer

OBJECTIVE

The goal of this study was to examine pain responses in pediatric patients with cancer.

METHOD

Children (ages 6 to 18) undergoing treatment for cancer (N=68) completed the cold pressor task.

RESULTS

Average pain tolerance was 118.22 seconds (SD=101.18) and 40% of the children kept their hand in the water the entire 4-minute ceiling. On a 0 to 10 numeric rating scale, children reported a pain severity of 5.07 (SD=3.47) at their first report of pain, a pain severity of 5.94 (SD=3.54) at their maximum report of pain, and a pain severity of 5.33 (SD=3.72) at the time they reached pain tolerance. Children receiving chemotherapy agents (N=56) with possible neuropathic effects exhibited higher pain tolerance compared with children not receiving such treatments (N=10), β=0.84, SE=0.38, Wald χ1=4.88, P=0.027, hazard ratio=2.33, 95% confidence interval (1.10-4.92).

CONCLUSIONS

This study provides data on experimental pain responses in a sample of children undergoing cancer treatment and suggests that pain experience may be moderated by cancer treatment type.

Can Interoception Improve the Pragmatic Search for Biomarkers in Psychiatry?

Disrupted interoception is a prominent feature of the diagnostic classification of several psychiatric disorders. However, progress in understanding the interoceptive basis of these disorders has been incremental, and the application of interoception in clinical treatment is currently limited to panic disorder. To examine the degree to which the scientific community has recognized interoception as a construct of interest, we identified and individually screened all articles published in the English language on interoception and associated root terms in Pubmed, Psychinfo, and ISI Web of Knowledge. This search revealed that interoception is a multifaceted process that is being increasingly studied within the fields of psychiatry, psychology, neuroscience, and biomedical science. To illustrate the multifaceted nature of interoception, we provide a focused review of one of the most commonly studied interoceptive channels, the cardiovascular system, and give a detailed comparison of the most popular methods used to study cardiac interoception. We subsequently review evidence of interoceptive dysfunction in panic disorder, depression, somatic symptom disorders, anorexia nervosa, and bulimia nervosa. For each disorder, we suggest how interoceptive predictions constructed by the brain may erroneously bias individuals to express key symptoms and behaviors, and outline questions that are suitable for the development of neuroscience-based mental health interventions. We conclude that interoception represents a viable avenue for clinical and translational research in psychiatry, with a well-established conceptual framework, a neural basis, measurable biomarkers, interdisciplinary appeal, and transdiagnostic targets for understanding and improving mental health outcomes.

Impact of Threat Level, Task Instruction, and Individual Characteristics on Cold Pressor Pain and Fear among Children and Their Parents

The cold pressor task (CPT) is increasingly used to induce experimental pain in children, but the specific methodology of the CPT is quite variable across pediatric studies. This study examined how subtle variations in CPT methodology (eg. provision of low- or high-threat information regarding the task; provision or omission of maximum immersion time) may influence children's and parents' perceptions of the pain experience. Forty-eight children (8 to 14 years) and their parents were randomly assigned to receive information about the CPT that varied on 2 dimensions, prior to completing the task: (i) threat level: high-threat (task described as very painful, high pain expressions depicted) or low-threat (standard CPT instructions provided, low pain expressions depicted); (ii) ceiling: informed (provided maximum immersion time) or uninformed (information about maximum immersion time omitted). Parents and children in the high-threat condition expected greater child pain, and these children reported higher perceived threat of pain and state pain catastrophizing. For children in the low-threat condition, an informed ceiling was associated with less state pain catastrophizing during the CPT. Pain intensity, tolerance, and fear during the CPT did not differ by experimental group, but were predicted by child characteristics. Findings suggest that provision of threatening information may impact anticipatory outcomes, but experienced pain was better explained by individual child variables.

Responses of the hands and feet to cold exposure

An initial response to whole-body or local exposure of the extremities to cold is a strong vasoconstriction, leading to a rapid decrease in hand and foot temperature. This impairs tactile sensitivity, manual dexterity, and muscle contractile characteristics while increasing pain and sympathetic drive, decreasing gross motor function, occupational performance, and survival. A paradoxical and cyclical vasodilatation often occurs in the fingers, toes, and face, and this has been termed the hunting response or cold-induced vasodilatation (CIVD). Despite being described almost a century ago, the mechanisms of CIVD are still disputed; research in this area has remained largely descriptive in nature. Recent research into CIVD has brought increased standardization of methodology along with new knowledge about the impact of mediating factors such as hypoxia and physical fitness. Increasing mechanistic analysis of CIVD has also emerged along with improved modeling and prediction of CIVD responses. The present review will survey work conducted during this century on CIVD, its potential mechanisms and modeling, and also the broader context of manual function in cold conditions.