Objective Measures Of Pain Research Articles

An experimental study of objective pain measurement using pupillary response based on genetic algorithm and artificial neural network

An experimental study of objective pain measurement using pupillary response based on genetic algorithm and artificial neural network

Chronic pain-related cortical neural activity in patients with complex regional pain syndrome.

Quantitative objective measurement of chronic pain is important. We elucidated chronic pain-related cortical neural activity and neural connectivity among pain-related brain regions in complex regional pain syndrome (CRPS). Resting-state magnetoencephalography recordings were performed. Cortical current density and neural connectivity, revealed by amplitude envelope correlation (AEC), were estimated on standardized brain magnetic resonance imaging. Intra-experiment pain was assessed subjectively using a visual analogue scale (VAS). The correlation between current density and VAS scores was calculated for the occipital areas and pain-related cortices. Current density in the primary (SI) and secondary (SII) somatosensory cortex and precuneus in both hemispheres was negatively correlated with the pain VAS score. The AEC and VAS values were significantly correlated for the SII and the precuneus and for the SII and insular cortex in the alpha frequency band in the right hemisphere. In the theta frequency band, the AEC and VAS values correlated for the SII and posterior cingulate cortex in the right hemisphere. Our results suggested that disruption of pain processes and functions in the default mode network occurs in CRPS. Our method targeting the neural mechanism of pain has the potential to offer a clinically objective means of evaluating it.

Developmental cognitive neuroscience of pain: present and future

Past several decades have witnessed a booming research field of cognitive neuroscience of pain, yet the majority of such studies include young adult participants only, largely ignoring the age differences. The field needs to fill the gap and provide more comprehensive understanding on how pain is processed in the brain of the young and the elderly, and how pain can be successfully managed for different age groups. Importantly, the developmental perspective gives the invaluable insight that psychological and physiological characteristics of different age groups influence the validity of pain assessment and the efficacy of pain treatment, thus necessitating different pain measures and treatments for children, adolescents, adults, and the elderly. Future studies will exploit emerging innovative and advanced technologies, fully appreciate the multidimensional nature of pain, develop age-specific non-addictive pain treatment, and ensure transparency and openness in developmental pain research. Considering the current situation of the field in our country, we shall focus on four promising research projects in the future: (i) to develop reliable and valid objective pain measures; (ii) to establish a large-scale and comprehensive database on pain development; (iii) to untangle the role of age and psychological factors in the development and maintenance of chronic pain; (iv) to develop effective and safe pain management strategies for different age groups and promote clinical translation of basic research.

Comparison of remifentanil consumption in pupillometry-guided versus conventional administration in children: a randomized controlled trial.

Remifentanil is a commonly used opioid analgesic during anesthesia in children. Objective measurement of pain is required for adequate dosing of remifentanil. We investigated whether pupillometry-guided remifentanil administration can reduce intraoperative consumption of remifentanil in children. We performed a single-blinded, prospective, randomized controlled trial from December 2018 through June 2019. Children who were 3-12 years of age and classified as having an American Society of Anesthesiologists physical status I-II and undergoing elective surgery under general anesthesia were included. Fifty-six fulfilled the inclusion criteria, and fifty-four completed the study. Participants were randomly assigned to either a pupillometry or conventional group. Patients in both groups received target-controlled infusion of remifentanil. In the pupillometry group, the adjustment of the remifentanil effect site concentration was determined by the pupillary diameter, whereas in the conventional group, the adjustment was based on the anesthesiologist's experience. Primary outcome was intraoperative remifentanil consumption, divided by patient weight and infusion time (ng kg-1 min-1). Remifentanil consumption was reduced by 25% in the pupillometry group compared to the conventional group (116.7±56.0 ng kg-1 min-1 vs. 155.8±64.9 ng kg-1 min-1, respectively; P=0.02). There were no differences in intra- and postoperative blood pressure and heart rate. The incidences of postoperative desaturation or nausea/vomiting were not significantly different. Pupillometry-guided remifentanil administration in children undergoing general anesthesia can reduce the intraoperative remifentanil consumption.

Nerve Injury Decreases Hyperacute Resting-State Connectivity Between the Anterior Cingulate and Primary Somatosensory Cortex in Anesthetized Rats.

A better understanding of neural pain processing and of the development of pain over time, is critical to identify objective measures of pain and to evaluate the effect of pain alleviation therapies. One issue is, that the brain areas known to be related to pain processing are not exclusively responding to painful stimuli, and the neuronal activity is also influenced by other brain areas. Functional connectivity reflects synchrony or covariation of activation between groups of neurons. Previous studies found changes in connectivity days or weeks after pain induction. However, less in known on the temporal development of pain. Our objective was therefore to investigate the interaction between the anterior cingulate cortex (ACC) and primary somatosensory cortex (SI) in the hyperacute (minute) and sustained (hours) response in an animal model of neuropathic pain. Intra-cortical local field potentials (LFP) were recorded in 18 rats. In 10 rats the spared nerve injury model was used as an intervention. The intra-cortical activity was recorded before, immediately after, and three hours after the intervention. The interaction was quantified as the calculated correlation and coherence. The results from the intervention group showed a decrease in correlation between ACC and SI activity, which was most pronounced in the hyperacute phase but a longer time frame may be required for plastic changes to occur. This indicated that both SI and ACC are involved in hyperacute pain processing.

Pain catastrophizing in athletes correlates with pain and cardiovascular changes during a painful cold pressor test.

Athletes are often exposed to pain due to injury and competition. There is preliminary evidence that cardiovascular measures could be an objective measure of pain, but the cardiovascular response can be influenced by psychological factors such as catastrophizing. The purpose of our study was to use a painful cold pressor test to measure the relationship between catastrophizing, pain, and cardiovascular variables in athletes. Pre-post test. We completed all measures in a laboratory setting. Thirty-six male rugby athletes participated in the study. We measured catastrophizing with the Pain Catastrophizing Scale and pain with a Numeric Pain Rating Scale. Cardiovascular measures included heart rate, systolic, and diastolic blood pressure, and heart rate variability. During the cold pressor test, participants experienced a significant increase in pain (0 to 4.1±2.2), systolic blood pressure (126.7±16.5mm Hg to 149.7±23.4mm Hg), diastolic blood pressure (76.9±8.3mm Hg to 91.9±11.5mm Hg) and heart rate variability (from 0.0164ms±0.0121 to 0.0400ms±0.0323) (all p<.001). In addition, there was a significant decrease in heart rate after the cold pressor test (p=0.04). There was a significant correlation between athlete's pain catastrophizing to both pain intensity and change in heart rate during the cold pressor test (p=.017 and p=.003 respectively). A significant linear regression indicated pain and catastrophizing explained 29% of the variance of the change in heart rate (p=.003). Athletes who have catastrophizing thoughts are more likely to experience higher levels of pain and a greater cardiovascular response during a painful stimulus. The change in cardiovascular variables may be a good alternative for an objective measure of pain in athletes in the future.

Association Between Pain Catastrophizing and Pain and Cardiovascular Changes During a Cold-Pressor Test in Athletes.

Athletes are often exposed to pain due to injury and competition. Using preliminary evidence, researchers have shown that cardiovascular measures could be an objective measure of pain, but the cardiovascular response can be influenced by psychological factors, such as catastrophizing. To use a painful cold-pressor test (CPT) to measure the relationship among catastrophizing, pain, and cardiovascular variables in athletes. Cohort study. Laboratory. A total of 36 male rugby athletes (age = 24.0 ± 4.6 years, height = 180.0 ± 6.1 cm, mass = 90.5 ± 13.8 kg). We measured catastrophizing using the Pain Catastrophizing Scale and pain using a numeric pain rating scale. Cardiovascular measures were heart rate, systolic and diastolic blood pressure, and heart rate variability. During the CPT, participants experienced increases in pain (from 0 to 4.1 ± 2.2), systolic blood pressure (from 126.7 ± 16.5 to 149.7 ± 23.4 mm Hg), diastolic blood pressure (from 76.9 ± 8.3 to 91.9 ± 11.5 mm Hg), and heart rate variability (from 0.0164 ± 0.0121 to 0.0400 ± 0.0323 milliseconds; all P values < .001). In addition, we observed a decrease in heart rate after the CPT (P = .04). We found a correlation between athletes' pain catastrophizing and both pain intensity and change in heart rate during the CPT (P = .02 and P = .003, respectively). Linear regression indicated that pain and catastrophizing explained 29% of the variance in the change in heart rate (P = .003). Athletes who had catastrophizing thoughts were more likely to experience higher levels of pain and a greater cardiovascular response during a painful stimulus. The change in cardiovascular variables may be a good objective measure of pain in athletes in the future.

Impairment in locomotor activity as an objective measure of pain and analgesia in a rat model of osteoarthritis.

A major problem with current animal models of pain is their lack of face validity and their vulnerability for false positive results. The present study evaluated the efficacy of the open field locomotor system, as an objective measure of pain-related behavior and analgesic efficacy in rodents. Adult, male, Sprague-Dawley rats (180-250 g) received intra-articular injections of monoiodoacetate (MIA; 1 mg) in the left knee joint. Mechanical allodynia using von Frey filaments, the weight bearing difference test and the open field locomotor activity test were performed every other day for 21 days, following the MIA injection. The antinociceptive effects of ibuprofen (50 and 100 mg/kg) on the MIA-induced nociception were also evaluated. MIA induced a significant reduction in the paw withdrawal threshold (PWT) and a significant alteration in the weight bearing difference compared with control rats. Similarly, MIA induced a significant reduction in locomotor activity, with respect to X total counts, that represent the overall locomotor activity in the horizontal plane, and X ambulatory counts, which in turn represent small scale movements, such as scratching and grooming, and lastly, Z total counts, that represent rearing or standing. Both doses of ibuprofen resulted in a significant reversal of the MIA-induced alterations in PWT and weight bearing difference. Furthermore, the two doses of ibuprofen resulted in a significant reversal of the MIA-induced reduction in locomotor activity, with respect to X ambulatory counts, but not Z total counts. Only the higher dose of ibuprofen reversed the X total counts. The open field locomotor system may successfully be used to predict the analgesic efficacy of compounds in models of joint inflammation and osteoarthritis.

Differential Transcription of Selected Cytokine and Neuroactive Ligand-receptor Genes in Peripheral Leukocytes from Calves in Response to Cautery Disbudding.

Simple SummaryCalf disbudding is a painful husbandry practice on dairy and beef cattle farms. Continuing efforts to enhance the accuracy of pain assessment can aid in the application of effective anti-nociceptive (analgesic) agents in non-verbal animals. The aim of this study was to evaluate the changes in the expression of genes involved in inflammation and pain sensitisation in response to removal of horn buds in calves, using hot-iron cauterization. The efficacy of an analgesic, meloxicam, was also tested in attenuating the changes in expression of the studied genes post-disbudding. It was revealed that cautery disbudding induces significant changes in the expression of genes involved in inflammation. Meloxicam was able to blunt the increased expression of some of the genes at 4 h and 24 h after disbudding, while it could not attenuate the increased expression of a few other genes associated with inflammation.Calf disbudding is a painful husbandry practice on dairy and beef cattle farms. An objective measurement of pain is useful to reliably evaluate the pain intensity and anti-nociceptive (analgesic) efficacy of therapeutic agents. The aim of this study was to investigate the changes in peripheral leucocyte inflammatory cytokine gene expression in calves after disbudding, and to assess whether the changes in cytokine gene expression could be an indicator of the efficacy of analgesic drugs. In a randomised controlled study, 16 calves (aged 31 to 41 days and weighing 58 to 73 kg), undergoing routine disbudding, were randomly allocated into two groups (n = 8 in each group). Calves in the control group received no analgesic, while those in the treatment group received 0.5 mg kg−1 meloxicam subcutaneously prior to disbudding. Disbudding was performed using an electric debudder. Blood (10 mL) was sampled from the jugular vein just before and 4 and 24 h post-disbudding, RNA was extracted from leukocytes, and the transcription of 12 genes of interest was assessed using nCounter gene expression assay. The results showed significantly higher transcription (compared to baseline values) of the studied genes (except CRH, IFNγ, and IL10) in the control group calves at either 4 or 24 h post-disbudding. The administration of meloxicam one hour before disbudding significantly attenuated the upregulation of IL6, PGHS2, TAC1, NOS1, and CRH gene transcription post-disbudding, while it did not suppress the elevated transcription of acute and pro-inflammatory cytokines such as IL1β, IFNγ, IL8, and TNFα genes. In conclusion, nCounter gene expression assay seems to be a promising tool to study the expression of cytokine genes and thus could be used for the pre-clinical evaluation of novel analgesics.

Therapeutic Suggestion in Postoperative Pain Control: A Randomized Controlled Trial.

There is conflicting research on the effect of therapeutic suggestion in the perioperative period. This study systematically compared subjective and objective measures of postoperative pain, nausea and vomiting, urinary and bowel function, and global perception of symptomatic improvement between participants receiving perioperative therapeutic suggestion versus routine perioperative care during minimally invasive pelvic reconstructive surgery. This was a single-blinded, randomized controlled trial of participants undergoing vaginal hysterectomy with minimally invasive sacrocolpopexy and concomitant prolapse repairs. The intervention group received perioperative therapeutic suggestion, whereas the control group did not. Primary outcomes included postoperative pain scores and analgesic use. Secondary outcomes included a postoperative nausea and vomiting scale, the Pelvic Floor Distress Inventory Questionnaire-Short Form 20, the Patient Global Impression of Improvement scale, and time to return of bowel and bladder function. Sixteen participants were randomized to each group. Final analysis included 15 intervention and 14 control participants. Overall measures of postoperative pain and analgesic use were low across all participants without a significant difference between intervention and control groups (opioid: 52.5; interquartile range [IQR], 25.5-58.9 vs 66 IQR, 7.3-125.8; morphine milligram equivalents; P = 0.64; acetaminophen: 2225 mg; IQR, 500-2600 mg vs 2800 mg; IQR, 650-4775 mg; P = 0.38). There were no statistically significant differences in secondary outcomes of urinary symptoms, bowel function, and subjective improvement of prolapse symptoms. No differences in postoperative pain, analgesic use, return of bowel and bladder function, or pelvic organ prolapse symptoms were noted in participants receiving perioperative therapeutic suggestion versus routine perioperative care.

Advances in Understanding the Causes and Consequences of Health Disparities in Aging Minorities.

The purpose was to discuss appropriate methods for advancing our understanding of health disparities or minority aging including life-course perspectives, biological measures, pain measurement, and generational approaches. Life course perspectives provide an orientation for studying older minorities that concomitantly captures exposures and stressors that may lead to earlier onset of disease and premature mortality. The use of biological markers to study health disparities in older minorities is necessary in order to identify pathways between psychosocial factors and health outcomes. Work focusing on pain disparities should include explorations of relationships between psychosocial factors, and subjective and objective measures of pain. Studying families can provide insight into genetic associations and coping styles in older minorities. Methodological approaches that take life course, biology, and social factors into account may help identify causal pathways between social determinants of health and health outcomes among older minorities. Once these causal pathways have been identified, more strategies and interventions that strive toward health equity across older adults of all race/ethnic groups can be developed.

Biomarkers Can't Bypass the Mouth of a Wound.

This article critiques the idealization of a biomarker-based "objective pain scale" in order to argue for increased investment in communication-centric approaches to chronic pain diagnosis and treatment. Although new technological advances and the rise of big data have revived old fantasies of objective pain measures, scholars have long affirmed the dangers of converting human experience into numbers, as well as the fundamental impossibility of reducing pain to physiology. Biomarkers can certainly be useful tools, but investments must also be made in fostering the "strong objectivity" that feminist scholars have advocated for and that the incorporation of narrative-driven initiatives can provide. Because expressing pain is notoriously difficult, doing this creative, communication-driven work well requires substantial effort, time, and training. Engaging with chronic pain from a feminist standpoint-one that affirms individuals' situated experiences as valuable data and that attends to the rich multi-modal vocabularies emerging on social media-can pave the way to a more equitable, ethical, and effective future of pain care.

Pain in individuals with RASopathies: Prevalence and clinical characterization in a sample of 80 affected patients.

Pain in individuals with RASopathies is a neglected topic in literature. In this article, we assessed prevalence and profile of pain in a sample of 80 individuals affected by RASopathies. The study sample included individuals with Noonan syndrome (N = 42), Costello syndrome (N = 17), and cardio-facio-cutaneous syndrome (N = 21). A set of standardized questionnaires and scales were administered (VAS/numeric scale, r-FLACC, Wang-Baker scale, NPSI, BPI, NCCPC-R) to detect and characterize acute and chronic pain and to study the influence of pain on quality of life (PEDs-QL, SF-36) and sleeping patterns (SDSC); revision of past medical history and multisystemic evaluation was provided. Available clinical data were correlated to the presence of pain. High prevalence of acute (44%) and chronic (61%) pain was documented in the examined sample. Due to age and intellectual disability, acute pain was localized in 18/35 individuals and chronic pain in 33/49. Muscle-skeletal and abdominal pain was more frequently reported. The intensity of acute and chronic pain interfered with daily activities in 1/3 of the sample. Pain negatively impacted on QoL and sleeping patterns. This work documents that pain is highly prevalent in RASopathies. Future studies including subjective and objective measures of pain are required to discriminate a somatosensory abnormality from an abnormal elaboration of painful stimuli at a central level.

A Systematic Review of Devices and Techniques that Objectively Measure Patients’ Pain

Background: Assessment of pain is important in daily clinical practice and as an endpoint in clinical studies. Because pain perception is highly subjective, pain measurement is complex. Selfrating pain scales are currently of great importance but have limitations. They depend on many more factors than pain, which could lead to an incorrect assessment of therapies or clinical studies. Therefore, there is need for valid, reliable, safe, and low-cost methods to determine and quantify patients’ pain more objectively. Objective: To provide an overview of devices and techniques that can be used to administer a pain stimulus with similar intensity as the endogenous pain experienced by the patient, in order to quantify and subsequently follow patients’ pain more objectively. Study Design: In this systematic review, articles from PubMed, EMBASE, Cochrane library and Scopus were reviewed for eligibility. Methods: Studies that described a device or technique that could be used to induce a variable, controlled, and measurable pain stimulus were included. Studies that made correlations with established pain scales or those who compared outcomes in multiple tests were selected to assess validity and reliability. Results: A total of 1,308 manuscripts were initially retrieved. After independent screening by a team of 4 reviewers, 19 studies were eventually included describing 15 different devices or techniques. These devices could be divided into groups based on stimulus administration: electrical, external pressure (probe) and miscellaneous pain stimulators. Electrical stimulators were found to be tested extensively and proven to be both valid and reliable. Limitations: To correlate new techniques with older methods such as the Numeric Rating Scale (NRS) and Visual Analogue Scale (VAS) for which an improvement is desired, is debatable. To (partially) address this problem, the reliability is added as an additional primary outcome to assess which device works best. Further limitations include the heterogeneity of studies found in both the types of pain measured as in outcome measures presented. In addition, it is important to note that part of the devices described cannot directly be used for clinical practice due to products that have cease to exist or the description of solely techniques rather than testing ready-to-use devices. Conclusion: Several devices and techniques compared pain intensity experienced by patients with an external pain stimulus that potentially could be used as a new objective pain measurement tool. Given the results of our review, electrical stimulators that have been tested extensively with high validity, reliability, and feasibility would be recommended for use for clinical and research purposes. Moreover, normalization of pain intensity scores for current perception is important. Pain intensity normalization leads to higher correlations with established pain scales and possibly to increased inter-patient reliability. Registration number: Registered in the PROSPERO database (PROSPERO 2016:CRD42016041974) Key words: Systematic review, objective pain measurement, pain scales; devices, techniques, validity, reliability, safety, feasibility

Sample Size Determination for Evaluation of Time Domain Heart Rate Variability Indices in Canine Lameness.

Heart rate variability (HRV) is a physiologic phenomenon that occurs due to changing autonomic tone resulting in variable RR intervals. A reduction in HRV is used as an index of pain in neonatal human patients. Objective measures of pain would be valuable in the evaluation of canine patients and assessment of response to pain management strategies. We hypothesized that dogs with diseases associated with discomfort (osteoarthritis and bone neoplasia) would have reduced HRV compared with normal, healthy dogs. The aim of the study was to calculate the sample size necessary to investigate this hypothesis. Seventeen dogs from the Ryan Veterinary Hospital of the University of Pennsylvania patient population or owned by Ryan Veterinary Hospital of the University of Pennsylvania staff were enrolled in this single-blind, prospective pilot study. A 30 min electrocardiogram (ECG) was obtained from each dog using an ambulatory electrocardiographic monitor. All ECGs were obtained between 10 a.m. and 2 p.m. ECGs were analyzed and time-domain HRV indices computed. Sample size calculations suggest that 207 dogs would be necessary to ascertain if HRV is reduced in dogs experiencing discomfort or pain (50 in the arthritis group, 79 in the bone cancer group, and 78 in the control group).

Objectifying the Assessment of Pain

Category: Other Introduction/Purpose: Pain is a pervasive problem that accounts for a high percentage of referrals to health care providers including foot and ankle surgeons and is an important factor in narcotic addictions and their related deaths. Unfortunately, the analogue pain scores are determined by subjective (SUB) responses of the patient and fail to utilize objective criteria for making the assessments. In an attempt to resolve the subjectivity/objectivity concerns, we developed a scoring system that uses objective (OBJ) criteria based on three 0-to-10 scales. The measurements include the patients’ requirements for analgesics, how the pain affects their levels of activity and how it affects their thought processes. Methods: Over an 18 month period and as part of a physician pain management group’s initial assessment of their patients, the study group was asked to rate their pain using the three SUB scales (Numerical Rating Scale, Visual Analogue Scale and Verbal Rating Scale) as well as our three OBJ scales. Each of our three OBJ (analgesics, activities and thought processes) scales used precise terms to quantify the numerical value for the scale. For example, the analgesics requirement ranged from no drug (0-points) to requirement for hospitalization for pain management (10-points). The activity scale ranged from no limitations (0-points) to pain noticed only with activity (4-points) to total limitation of activities (10-points). Analogous objective criteria were used for the third scale, how pain affects thought processes. Data analysis included patients’ responses to the objective pain measurements as well as correlations between OBJ and SUB evaluation scoring systems. Results: Data was collected prospectively on 109 patients. The mean scores (summation of the3 SUB pain scales divided by 3 and doing likewise for the OBJ pain scales was significantly higher for the SUB scores (6.4 vs. 4.2, p &lt; 0.001). The lowest correlations between the SUB scores and each OBJ scale was with analgesic use (r = .36 vs. r’s = .53 for the other 2 OBJ scales). In general patients who scored highest on the SUB scores, preferred them to the OBJ measurements. Differences between the scores on the OBJ activity scale versus the OBJ thought processes scale helped distinguish pain of central versus peripheral origins. Ninety percent of patients completed the SUB plus OBJ scoring in less than 3 minutes. Conclusion: Our OBJ Pain Score helped differentiate those patients who magnified their pain symptom from those who did not. Patients with higher scores on the thought processes scale would appear to be best managed by central nervous system acting drugs. Conversely those with higher OBJ activity scores would likely respond to peripheral acting agents such as non-steroidal analgesics, local injections or analgesic patches. In summary, our scoring system moves the evaluation of pain from subjective to objective. This has important ramifications for pain management, analgesic selection and avoidance of narcotic dependency.

Objective clinical pain analysis using serum cyclooxygenase-2 and inducible nitric oxide synthase in American patients

BackgroundPain is a multidimensional condition of multiple origins. Determining both intensity and underlying cause are critical for effective management. Utilization of painkillers does not follow any guidelines relying on biomarkers, which effectively eliminates objective treatment. The aim of this study was to evaluate the use of serum cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) as pain biomarkers. This work could significantly advance the diagnosis and treatment of pain. MethodsWe assessed the potential utility of serum COX-2 and iNOS as objective measures of pain in a sample of American patients. Pain was scaled between level 0–5 in accordance with the level reported by the patients. Blood samples were collected from 102 patients in the emergency room. Sandwich ELISA was used to determine the COX-2 and iNOS levels in the blood serum while statistical analysis was performed using Pearson product-moment correlation coefficients, Regression and Receiver Operating Characteristics (ROC) analyses. The biomarker results were also compared with self-reports of pain by the patients using conventional pain ratings and patients were asked to report the cause of the pain. Pain levels were clustered into four groups as 0 [self-reported 0], 1 [self-reported as 1], 2 [self-reported as 2 and 3] and 3 [self-reported as 4 and 5]. Co-expression of COX-2 and iNOS could significantly alter pain development and its sensitization. Therefore, iNOS dependent COX-2 levels were employed as categorized level. ResultsSelf-reported pain levels did not show a correlation with the serum level of COX-2 and iNOS. The lack of correlation is attributed to multiple reasons including patients' intake of painkillers prior to participation, painkiller intake habit, chronic diseases, and subjectivity of self-reported pain. Increased serum COX-2 levels were reported in relation to the subtypes of these health issues. Further, 83% of the patients who reported pain also showed the presence of COX-2 in serum, while only 53% of the patients showed the presence of iNOS in serum. Moderate relation was found between the clustered pain level and categorized COX-2 and iNOS- levels. ConclusionsThe findings support the requirement of further studies to use COX-2 and iNOS as prognostic biomarkers for objective quantification of pain at the clinical level.

Objective Pain Measurement based on Physiological Signals

In an attempt to understand human physiological signals when an individual is subjected to pain, we set up a tonic pain experiment in a laboratory setting. The subjects’ physiological signals were recorded, timestamped, and compared to an initial 30 second baseline measurement. Subjects were also asked to verbally state their level of pain based on a visual analog scale in order to compare reported pain levels with physiological signals. The physiological signals measured were: Electroencephalography (EEG), Pupillary Unrest Under Ambient Light (PUAL), Skin Conductance (SC), Electromyography (EMG), Respiration Rate (RR), Blood Volume Pulse (BVP), Skin Temperature (ST), Blood Pressure (BP), and Facial Expression (FE). ANOVA and frequency domain analyses were conducted on the data in order to determine whether there was a significant difference between the ‘pain’ and ‘no pain’ (baseline) states of an individual. Based on our results, skin conductance, PUAL, facial expression, and EEG signals were theorized to be good signals for the classification of tonic pain, or any pain applied directly to an individual.

Objectively measuring pain using facial expression: is the technology finally ready?

Currently, clinicians observe pain-related behaviors and use patient self-report measures in order to determine pain severity. This paper reviews the evidence when facial expression is used as a measure of pain. We review the literature reporting the relevance of facial expression as a diagnostic measure, which facial movements are indicative of pain, and whether such movements can be reliably used to measure pain. We conclude that although the technology for objective pain measurement is not yet ready for use in clinical settings, the potential benefits to patients in improved pain management, combined with the advances being made in sensor technology and artificial intelligence, provide opportunities for research and innovation.

Salivary Cortisol and Pain Scoring to Compare the Efficacy of Oral Dextrose and Pacifier for Neonatal Pain Control

Objective: Pain assessment usually involves the use of subjective pain scales; as their use may be associated with inter-/intra-observer bias, objective pain measurements, such as assessment of cortisol response to pain, are needed. This study aimed to compare the efficacy of oral dextrose and a pacifier in neonatal pain control using an objective measurement of salivary cortisol level and subjective pain scoring. Methods: This prospective, randomized, partially blinded clinical trial included healthy newborns from a nursery (n=142). Blood was sampled using a lancet and newborns were randomly assigned to four groups by drawing lots: control (n=33), sterile water (n=35), 25% dextrose (n=35), and pacifier group (n=39). For all groups, neonatal infant pain scale, neonatal facial coding system, and premature infant pain profile scores were evaluated before, during, and 2 minutes after newborn screening test by two independent observers who watched recorded videos. Moreover, samples of saliva were collected before and 30 minutes after the pain procedure, and salivary cortisol level was measured using an enzyme-linked immunosorbent assay. Results: Subjective pain scores were not statistically different among the four groups before, during, and after blood sampling using a lancet. However, the salivary cortisol level in the 25% dextrose group was significantly lower than that in the other groups (P=0.045). Conclusion: Oral administration of 25% dextrose solution for pain control during the newborn screening test led to a significantly lower salivary cortisol level than the use of sterile water or a pacifier. However, no difference in pain scores was found among groups.