Multi-modal pain assessment: are near-infrared spectroscopy, skin conductance, salivary cortisol, physiologic parameters, and Neonatal Facial Coding System interrelated during venepuncture in healthy, term neonates?

BACKGROUND: Improving pain and stress assessments in neonates remains important in preventing the short- and long-term consequences. We aimed to identify the relationships between different pain assessment parameters by simultaneously measuring changes in cortical, autonomic, hormonal, physiological, and behavioral evoked responses to venepuncture in healthy, full-term neonates. METHODS: This observational, prospective study (ancillary to the ACTISUCROSE trial) included 113 healthy, 3-day old, full-term neonates who underwent venepuncture for systematic neonatal screening, from July to October 2013, in a tertiary-level maternity ward of a university hospital. During venepuncture, we simultaneously measured the cortical single-channel near-infrared spectroscopy (NIRS) signals, foot skin conductance, salivary cortisol, physiological responses, and behavioral (Neonatal Facial Coding System [NFCS]) evoked responses. RESULTS: Regarding the NIRS analysis, the highest correlation was between the NFCS at venepuncture and the change in NIRS integrated values of total hemoglobin (r=0.41, P<0.001) or oxygenated hemoglobin (r=0.27, P<0.001). The NFCS at venepuncture was moderately positively correlated with changes in salivary cortisol (r=0.42, P<0.001) and skin conductance (r=0.29, P<0.001). Salivary cortisol and skin conductance changes were not correlated; the latter parameters were not correlated with heart rate, respiratory rate, or SpO2. CONCLUSION: During venepuncture, NFCS was mildly or moderately correlated with salivary cortisol, skin conductance, and cortical NIRS changes.