Skin conductance variability between and within hospitalised infants at rest

Prematurity alters skin conductance and behavioural scoring after acute stress in term-equivalent age infants

AIM

The primary objective was to assess the effect of prematurity at term-equivalent age on skin conductance and behavioural responses to acute stress. The secondary objective was to explore the reliability of skin conductance in detecting neonatal discomfort in preterm and full-term populations.

METHODS

Very preterm infants at term-equivalent age and healthy full-term neonates, 34 infants in each group, underwent the hip dysplasia screening test. The acute pain in newborn infants (APN) scale was scored before and 15, 45 and 90 seconds after stimulus. Skin conductance was measured in the 30-second time-lap before and after stimulus.

RESULTS

The APN score was lower in preterm infants after intervention (term: 5.4 ± 2.8 vs. preterm: 3.9 ± 2.2; p = 0.03). Peaks-per-second, a skin conductance parameter, exhibited lower basal values in preterm infants than in term infants, with similar rise induced by stressful challenge. Peaks-per-second values were correlated to the 15-second APN score in both groups (term: r = 0.55, p < 0.001; preterm: r = 0.43, p = 0.01).

CONCLUSION

Preterm birth changed skin conductance signal and behavioural response to stress at term-equivalent age. The skin conductance device may be an objective tool for a continuous monitoring of acute neonatal stress.

Measuring pain-Physiological and self-rated measurements in relation to pain stimulation and anxiety

INTRODUCTION

The aim of the present study was to investigate how emotions influence pain, measured by one subjective self-rated measure, the numeric rating scale (NRS), and one objective physiological measure, the number of skin conductance responses (NSCR).

METHOD

Eighteen volunteers were exposed to conditions with pictorial emotional stimuli (neutral, positive, negative), authentic ICU-sound (noise, no-noise) and electrical stimulation (pain, no-pain) individually titrated to induce moderate pain. When using all combinations of picture inducing emotions, sound, and pain, each of these conditions (12 conditions lasting for 60 seconds each) were followed by pain ratings. Ratings of arousal (low to high) and valence (pleasant to unpleasant) were used as indicators of affective state for each condition. Mean NSCR was also measured throughout the experiment for each condition.

RESULTS

Even though NRS and NSCR increased during painful stimuli, they did not correlate during the trial. However, NSCR was positively correlated with the strength of the electrical stimulation, r = 0.48, P = 0.046, whereas NRS showed positive correlations with the anxiety level, assessed by affective ratings (arousal, r = 0.61, P < 0.001, and valence, r = 0.37, P < 0.001).

CONCLUSIONS

The NRS was strongly influenced by affective state, with higher pain ratings during more anxiety-like states, whereas NSCR correlated to the strength of electrical pain stimulation. That reported pain is moderated by anxiety, puts forward a discussion whether reduction of the anxiety level should be considered during analgesia treatment.

Prenatal opioid exposure heightens sympathetic arousal and facial expressions of pain/distress in term neonates at 24-48 hours post birth

Purpose: The rising issue of opioid use during pregnancy poses an increased risk of fetal exposure to opioids in-utero and the development of neonatal abstinence syndrome (NAS). The cessation of exposure to opioids upon birth causes elevated levels of norepinephrine in the circulation enhancing sympathetic arousal. Skin conductance (SC) detects sympathetic-mediated sweating while the Neonatal Facial Coding System (NFCS) depicts facial expressions of stress and pain. We hypothesize that there will be a direct correlation between SC and NFCS scores, such that neonates with prenatal opioid exposure will have higher SC and facial responses to pain/stress as compared with healthy neonates without prenatal opioid exposure.Objective: This study evaluates the utility of SC and the NFCS in the objective assessment of early postnatal pain response in opioid-exposed and non-opioid exposed neonates.Methods: This prospective, single-center, pilot study enrolled opioid-exposed term neonates (>37 weeks) and healthy controls. Subjects were observed within 24-48 hours post-birth (and prior to opioid withdrawal) for pain at baseline, during, and post-heel lance/squeeze (HLS) with simultaneously measured SC and videotaped facial expressions. SC data included electro-dermal responses over time (EDR/second) and the average amplitude of responses (mean of peaks [MP]). Video data were scored using the NFCS by two trained coders with inter-rater agreement >85%.Results: SC and NFCS scores were significantly associated with both groups. The opioid-exposed neonates had significantly higher skin conductance indices, EDR/sec for the HLS phase, and MP for HLS and post phases as compared with controls (p < .05). Opioid-exposed neonates demonstrated higher NFCS at baseline (p = .003).Conclusions: Prenatal opioid exposure was associated with heightened sympathetic arousal during both pain and recovery phases and higher facial expressions of pain/distress at baseline only. A multimodal system of assessment may be useful in understanding the complexity and severity of opioid withdrawal associated with NAS.

Models for Nociception Stimulation and Memory Effects in Awake and Aware Healthy Individuals

OBJECTIVE

This paper introduces a primer in the health care practice, namely a mathematical model and methodology for detecting and analysing nociceptor stimulation followed by related tissue memory effects.

METHODS

Noninvasive nociceptor stimulus protocol and prototype device for measuring bioimpedance is provided. Various time instants, sensor location, and stimulus train have been analysed.

RESULTS

The method and model indicate that nociceptor stimulation perceived as pain in awake healthy volunteers is noninvasively detected. The existence of a memory effect is proven from data. Sensor location had minimal effect on detection level, while day-to-day variability was observed without being significant.

CONCLUSION

Following the experimental study, the model enables a comprehensive management of chronic pain patients, and possibly other analgesia, or pain related regulatory loops.

SIGNIFICANCE

A device and methodology for noninvasive for detecting nociception stimulation have been developed. The proposed method and models have been validated on healthy volunteers.

Comparative heel stick study showed that newborn infants who had undergone repeated painful procedures showed increased short-term pain responses

AIM

We evaluated the short-term effect of repeated pain exposure on the pain responses of newborn infants using different pain assessment methods, as this area had been under-researched.

METHODS

We compared 20 term, large for gestational age infants and 40 term, appropriate for gestational age controls. All had undergone a heel stick for a newborn screening test just before discharge, but the larger babies had also undergone at least other five painful stimuli prior to that. A pulse oximeter and a skin conductance algesimeter (SCA) were connected to the babies during the heel prick, and video recordings were made. Crying time, the Neonatal Infant Pain Scale (NIPS), heart rate, peripheral oxygen saturation (SpO₂ ) and SCA measurements were compared within and between the groups.

RESULTS

After the heel prick, the crying time (p = 0.021) and NIPS (p = 0.013) scores were significantly higher in the study group and the SpO₂ levels were significantly lower (p = 0.009), but the heart rate (p = 0.981) was not significantly different between the groups. SCA measurements did not differ significantly between the groups.

CONCLUSION

Babies who received more painful stimuli during the first few days of life showed greater pain responses during a subsequent heel prick.

Skin conductance in neonates suffering from abstinence syndrome and unexposed newborns

The aims of this study were to compare the skin conductance (SC) of newborns with opiate-induced neonatal abstinence syndrome (NAS) to that of unexposed newborns and to evaluate the potential of SC readings to detect distress in the context of NAS objectively. The SC of 12 newborns with NAS and 12 unexposed newborns was measured at nine specific times during their first 6 weeks of life. The number of SC fluctuations per second (NSCF/s), the amplitude of SC fluctuation, and the mean level of SC were recorded and analyzed. The SC of newborns treated for symptoms of NAS differed significantly from the SC of unexposed newborns with regard to the NSCF/s (p = 0.04). With the mean level of SC, we observed an interaction between groups over time (p value for interaction = 0.02). With increasing postnatal age, we observed higher values in all three SC parameters.

CONCLUSION

The NSCF/s and the mean level of SC appear to be suitable to reflect the distress of newborns suffering from NAS. As it is known that the sensitivity of SC increases with the level of stress experienced, its potential to indicate elevated stress levels in infants with NAS should be investigated in future studies evaluating different therapy regimens.

WHAT IS KNOWN

• Skin conductance is a result of the filling of palmar and plantar sweat glands innervated by the sympathetic nervous system • Skin conductance can be used as a measure of stress and pain in newborns What is New: • Skin conductance of newborns with neonatal abstinence syndrome (NAS) differs significantly from the SC of non-substance-exposed newborns during the first 6 weeks of life • Skin conductance appears to reflect the increased distress of infants with NAS.

Investigating the effect of Eye Movement Desensitization and Reprocessing (EMDR) on postoperative pain intensity in adolescents undergoing surgery: a randomized controlled trial

AIM

To investigate the efficacy of Eye Movement Desensitization and Reprocessing for postoperative pain management in adolescents.

BACKGROUND

Eye Movement Desensitization and Reprocessing is an inexpensive, non-pharmacological intervention that has successfully been used to treat chronic pain. It holds promise in the treatment of acute, postsurgical pain based on its purported effects on the brain and nervous system.

DESIGN

A randomized controlled trial was used.

METHODS

Fifty-six adolescent surgical patients aged between 12-18 years were allocated to gender-balanced Eye Movement Desensitization and Reprocessing (treatment) or non-Eye Movement Desensitization and Reprocessing (control) groups. Pain was measured using the Wong-Baker FACES(®) Pain Rating Scale (WBFS) before and after the intervention (or non-intervention for the control group).

FINDINGS

A Wilcoxon signed-rank test demonstrated that the Eye Movement Desensitization and Reprocessing group experienced a significant reduction in pain intensity after treatment intervention, whereas the control group did not. Additionally, a Mann-Whitney U-test showed that, while there was no significant difference between the two groups at time 1, there was a significant difference in pain intensity between the two groups at time 2, with the Eye Movement Desensitization and Reprocessing group experiencing lower levels of pain.

CONCLUSION

These results suggest that Eye Movement Desensitization and Reprocessing may be an effective treatment modality for postoperative pain.

A pilot study: the role of the autonomic nervous system in cardiorespiratory regulation in infant feeding

AIM

The purpose of this pilot study was to examine the interplay between the parasympathetic (PNS) and sympathetic nervous systems' (SNS) contributions to prefeeding, feeding and satiation in young, healthy infants.

METHOD

This prospective study was completed on eleven full-term infants, less than 6 months old. Respiratory rate, heart rate, heart rate variability (HRV), electrodermal activity and low-frequency/high-frequency heart rate variability ratio were sampled from the infant during prefeeding, feeding and satiation periods.

RESULTS

A repeated-measures ANOVA revealed a significant difference in respiratory patterning during the three feeding phases (p = .049); however, none of the other physiological measures reached significance. An emerging trend across physiological measures suggests that the feeding phase was influenced by the SNS with increasing respiratory rate, heart rate, low-frequency HRV, electrodermal activity and decreasing high-frequency HRV compared to the prefeeding and satiation phases, which were influenced predominantly by the PNS.

CONCLUSION

Respiration rate increased significantly during the feeding phase compared to prefeeding and postfeeding phases. Emerging trends indicate a pattern of alternating relative tone in PNS versus SNS across feeding phases - with SNS predominating the feeding phase. More clinical research examining the SNS and PNS contributions to feeding should be completed across patient populations.

Skin conductance at baseline and postheel lance reflects sympathetic activation in neonatal opiate withdrawal

AIM

Skin conductance (SC) provides an objective measure of autonomic system regulation through sympathetic-mediated filling of sweat glands. This study aimed to test the utility of SC to detect sympathetic activation in neonatal abstinence syndrome (NAS).

METHODS

Fourteen term (mean, SE: 38.8 ± 0.35 weeks gestational age) neonates with chronic prenatal opiate exposure were enrolled. SC (peaks/seconds and mean of peaks) was measured at baseline, during heel lance/squeeze (HLS) and recovery from HLS at 24-48 (mean 38) hours of life prior to treatment for NAS. Blinded coders with established reliability assessed neonates using the Modified Finnegan Neonatal Scoring System (MFNSS). Nonparametric tests were used to determine group differences, phase differences from baseline to HLS and HLS to recovery, and associations between MFNSS and SC measures.

RESULTS

Neonates that would later require morphine treatment for NAS (n = 6) had higher baseline SC mean of peaks than those that did not require treatment (n = 8) (p < 0.05). Moreover, there were unique phase differences between groups and SC positively correlated with MFNSS (p < 0.05).

CONCLUSION

SC provides early identification of NAS severity. However, a larger sample is needed to determine sensitivity and specificity of SC for early identification of NAS and treatment effectiveness.

Preterm infants' behaviors and skin conductance responses to nurse handling in the NICU

Stress response patterns are indicative of the neonate's unique ability to cope with environmental demands and can be evaluated through autonomic and behavioral response parameters.

OBJECTIVE

To characterize stress responses during tactile stimulation to standard nurse handling in the NICU, and their association with severity of illness in preterm infants.

METHODS

Thirty preterm neonates were studied at postnatal day 4-5 during standard nurse caregiving. Heart rate (HR), respiratory rate (RR), skin conductance responses per second (SCR/s), and NIDCAP® stress behaviors were recorded before and during care. Non-parametric tests were used to assess differences from before to during care. Pearson's correlations were used to determine the association of biological and behavioral variables to the score for neonatal acute physiology (SNAP), a severity of illness index.

RESULTS

HR, RR, SCR/s and NIDCAP® behaviors (motor and attentional cues, and ability to self-console) increased from before to during the care (p < 0.01). NIDCAP® behaviors showed a significant negative association to the SNAP score (R = -0.45, p < 0.05).

CONCLUSIONS

HR, RR, SCR/s and NIDCAP® behaviors significantly increased during care. NIDCAP® stress behaviors were influenced by the severity of illness of the infant, while SCR/s was not influenced by severity of illness.

Assessing pain objectively: the use of physiological markers

Pain diagnosis and management would benefit from the development of objective markers of nociception and pain. Current research addressing this issue has focused on five main strategies, each with its own advantages and disadvantages. These encompass: (i) monitoring changes in the autonomic nervous system; (ii) biopotentials; (iii) neuroimaging; (iv) biological (bio-) markers; and (v) composite algorithms. Although each strategy has shown areas of promise, there are currently no validated objective markers of nociception or pain that can be recommended for clinical use. This article introduces the most important developments in the field and highlights shortcomings, with the aim of allowing the reader to make informed decisions about what trends to watch in the future.

Assessment of pain in critically ill children. Is cutaneous conductance a reliable tool?

PURPOSE

The purpose of this study is to assess the usefulness and accuracy of skin conductance (SC) as a tool to evaluate the level of sedation and pain in pediatric critical patients during painful procedures and to compare it with hemodynamic variables, clinical scales, and bispectral index (BIS).

MATERIALS AND METHODS

This is a prospective observational study in 61 critical children undergoing invasive procedures. Hemodynamic data (heart rate and arterial blood pressure), clinical scales punctuation (Ramsay, COMFORT, and numeric rating pain scales), BIS, and the number of fluctuations of SC per second were collected before, during, and at the end of the procedure.

RESULTS

The mean age of the patients was 42.9 (range, 1 month to 16 years). Seventy-two point six percent were postcardiac surgery patients. Nonmuscle-relaxed patients showed a moderate increase in heart rate (P = .02), numeric rating pain scales (P = .03), and Ramsay scale (P = .002). The number of fluctuations of SC per second increased significantly during the procedure (basal, 0.1; maneuver, 0.2; P = .015), but it never reached the level considered as pain or stress nor did it precede clinical scales or BIS. None of the variables studied showed a significant change during the procedure in muscle-relaxed patients.

CONCLUSIONS

Skin conductance was not found to be more sensitive or faster than clinical scales for the assessment of pain or stress in critical children undergoing painful procedures. Skin conductance was not useful in muscle-relaxed children.

Monitoring depth of anesthesia: from consciousness to nociception. A window on subcortical brain activity

Anesthesia results from several inhibitor processes, which interact to lead to loss of consciousness, amnesia, immobility, and analgesia. The anesthetic agents act on the whole brain, the cortical and subcortical areas according to their receptor targets. The conscious processes are rather integrated at the level of the cortical neuronal network, while the nonconscious processes such as the nociception or implicit memory require subcortical processing. A reliable and meaningful monitoring of depth of anesthesia should provide assessment of these different processes. Besides the EEG monitoring which gives mainly information on cortical anesthetic effects, it would be relevant to have also a subcortical feedback allowing an assessment of nociception. Several devices have been proposed in this last decade, to give us an idea of the analgesia/nociception balance. Up to now, most of them are based on the assessment of the autonomic response to noxious stimulation. Among the emerging clinical devices, we can mention those which assess vascular sympathetic response (skin conductance), cardiac and vascular sympathetic response (surgical pleth index), parasympathetic cardiac response (analgesia nociception index), and finally the pupillometry which is based on the assessment of the pupillary reflex dilatation induced by nociceptive stimulations. Basically, the skin conductance might be the most adapted to assess the stress in the awake or sedated neonate, while the performances of this method appear disappointing under anesthesia. The surgical pleth index is still poorly investigated in children. The analgesia nociception index showed promising results in adults, which have to be confirmed, especially in children and in infants, and lastly pupillometry, which can be considered as reliable and reactive in children as in adults, but which is still sometimes complicated in its use.

Does skin-to-skin contact reduce stress during diaper change in preterm infants?

BACKGROUND

Skin-to-skin contact reduces pain response in preterm infants subjected to minor painful procedures, such as heel lance. Diaper change is a procedure performed several times daily in hospitalized preterm infants. Routine care giving tasks such as diaper change may be stressful for the infant.

AIMS

The purpose of this study was to investigate whether diaper change induces stress and if skin-to-skin contact could reduce such stress, measured by changes in skin conductance.

STUDY DESIGN

This was a randomized crossover pilot study in 19 preterm infants with gestational age between 28 and 34 weeks. The diaper change procedure was done twice in each infant, once during skin-to-skin contact, and once in incubator or bed with the mother present.

OUTCOME MEASURES

During diaper change heart rate (HR), peripheral oxygen saturation (SpO2), and changes in skin conductance (SC) peaks per sec, using the Skin Conductance Algesimeter (SCA), were registered.

RESULTS

The mean SC peaks/sec increased/decreased significantly under/after change of diapers which thereby underpins that this is a stressful procedure for the preterm infant. Skin-to-skin contact (SSC) entails significantly lower stress levels (p<0.05) compared to diaper changed in an incubator/bed measured by the SCA.

CONCLUSIONS

Diaper change is a stressful procedure for preterm infants and may be ameliorated by skin-to-skin contact.

Intubation in the delivery room: experience with nasal midazolam

BACKGROUND

Neonates are often intubated in the delivery room (DR) without anesthesia because vascular access is impossible.

AIMS

To assess neonatal comfort and adverse events after use of nasal midazolam (nMDZ) for intubation in the DR.

STUDY DESIGN

Prospective data collection over 6months on the intubation of neonates with respiratory distress requiring tracheal instillation of surfactant.

SUBJECTS

Twenty-seven neonates with median (Q25-75) gestational age and birthweight of, respectively, 29 (27-33)weeks and 1270 (817-1942)g received a 0.1mg/kg dose of nMDZ, and intubation was performed at the onset of tonus resolution or apnea.

OUTCOME MEASURES

Comfort was assessed with a scale of hetero-pain assessment and electrical skin conductance monitoring. Continuous pulse oximetry was recorded in the first postnatal hour, with oscillometric blood pressure measurement every 10min.

RESULTS

Seventy percent of the patients required a single dose, with intubation performed 4.8 (3-9)min after administration. Combined electro-clinical assessment found adequate comfort during the procedure in 68% of neonates. Mean blood pressure decreased from 39 (34-44)mmHg before to 31 (25-33)mmHg 1h following nMDZ (p=0.011).

CONCLUSION

nMDZ provided rapid and effective sedation to intubate neonates in the DR but potentially exposed them to hypotension, thus requiring close hemodynamic monitoring.

Comparison of skin conductance measurements and subjective pain scores in children with minor injuries

AIM

Objective measures of perceived pain may aid clinicians in decision-making regarding analgesia. This study aimed to assess the effectiveness of an algesimeter to assess the pain response of children to minor injury when compared with self-report.

METHODS

A commercially available skin conductance algesimeter was used to record pain in children presenting with a minor injury to a district general hospital. The recordings were compared with self-reported pain scores using the Wong-Baker FACES(®) Pain Rating Scale.

RESULTS

Sixty-seven children below 16 years of age (36 females, 53.7%, mean age 11.9 years, standard deviation 3.1 years) were assessed. There was a significant correlation between self-reported pain and number of fluctuations in skin conductance per second for girls (r = 0.325, p = 0.027), but not for boys (r = 0.160, p = 0.194). There was no significant association between self-reported pain and number of fluctuation in skin conductance per second and patient age.

CONCLUSION

There was a significant correlation between self-reported pain and the number of fluctuations in skin conductance in girls, but not boys. There may be a number of reasons for this gender variation, including difficulty in rating pain and lack of sensitivity in the pain rating scale.

Skin conductance as a marker of pain in infants of different gestational age

AIMS

To assess the use of skin conductance as an objective measure of pain in infants of different gestational age. A second aim was to investigate the relationship between skin conductivity and selected physiological and behavioural variables (oxygen saturation, heart rate and behavioural state).

METHODS

Infants were divided according to gestational age into the following 3 groups; group A: 25+0-31+6 weeks (13 infants), group B: 32+0-35+6 weeks (25 infants), group C: 36+0-41+6 weeks (19 infants). The pain stimulus was blood sampling.

RESULTS

The most sensitive parameter for describing changes in skin conductance related to pain was peak per second. No other parameter correlated with the physiological variables chosen. The results showed that the inability to determine basal skin conductance is a crucial disadvantage to practical application. The lack of correlation between conductance parameters and gestational age is surprising.

CONCLUSION

We conclude that the Peak per Second is the best parameter for evaluating skin conductance in infants and it is not influenced by gestational age. Peaks per Second correlate only with Prechtl's Scale of behavioural state and not with the physiological parameters chosen.

Pain assessment in children undergoing venipuncture: the Wong-Baker faces scale versus skin conductance fluctuations

The aim of this study was to evaluate the efficacy of the subjective Wong–Baker faces pain rating scale (WBFS) and of the objective skin conductance fluctuation (SCF) test in assessing pain in children undergoing venipuncture. One-hundred and fifty children (aged 5–16 years) entered the study. All underwent venipuncture at the antecubital fossa to collect blood specimens for routine testing in the same environmental conditions. After venipuncture, the children indicated their pain intensity using the WBFS, whereas the number of SCFs was recorded before, during and after venipuncture. So, pain level was measured in each child with WBFS and SCF. We found that the level of WBFS-assessed pain was lower in all children, particularly those above 8 years of age, than SCF-assessed pain (p < 0.0001). Moreover, the number of SCFs was significantly higher during venipuncture than before or after venipuncture (p < 0.0001). At multivariate regression analysis, age and previous experience of venipuncture influenced the WBFS (β = −1.81, p < 0.001, and β = −0.86, p < 0.001, respectively) but not SCFs. In conclusion, although both procedures can be useful for research and clinical practice, our findings show that WBFS was affected by age and previous venipuncture, whereas SCF produced uniform data. If verified in other studies, our results should be taken into account when using these tools to evaluate pain in children.

Pain monitoring in anesthetized children: first assessment of skin conductance and analgesia-nociception index at different infusion rates of remifentanil

BACKGROUND

Analgesia and nociception can not be specifically monitored during general anesthesia. Movement of the patient or hemodynamic variations are usually considered as symptoms of insufficient analgesia. The measure of skin conductance (SC) allows an assessment of peripheral sympathetic activity. The analgesia-nociception index (ANI) provides an evaluation of the parasympathetic activity based on heart rate variability. These two non-invasive monitors might allow a better assessment of perioperative nociception.

OBJECTIVES

Describe the profiles of SC and ANI after a standardized nociceptive stimulation, in anesthetized children, at different infusion rates of remifentanil.

MATERIALS/METHODS

For this pilot study, 12 children (8.4 ± 5 years) scheduled for middle-ear surgery were anesthetized with desflurane to maintain a bispectral index at 50. Remifentanil was used for analgesia, at an initial infusion rate of 0.2 μg·kg(-1) ·min(-1) . Remifentanil infusion rate was then decreased: Five steady-state periods of 10 min were obtained at 0.2, 0.16, 0.12, 0.08, and 0.04 μg·kg(-1) ·min(-1) . At the end of each period, a standardized tetanic stimulation was applied to the patient. Variations in heart rate, blood pressure, SC, and ANI were recorded before and after each stimulation.

RESULTS

After the stimulation, ANI was significantly decreased compared with prestimulation values for all remifentanil infusion rates. This decrease was greater at 0.04 μg·kg(-1) ·min(-1) than at the other infusion rates. SC, heart rate, and blood pressure were not modified by the stimulations, whatever the dose of remifentanil.

CONCLUSION

ANI might provide a more sensitive assessment of nociception in anesthetized children than hemodynamic parameters or skin conductance.