Novel method of measuring chronic stress for preterm infants: Skin cortisol

Abstract

Background and objectives-Infants who begin life in the medicalized environment of the neonatal intensive care unit (NICU) do so under stressful conditions. Environmental exposures are often abrasive to vulnerable infants, while invasive and noninvasive lifesaving interventions provide additional pain and/or stress. The most commonly selected biomarker to measure stress is cortisol. The skin is the barrier between the external environment and communicates with our neurological, endocrine and immune regulatory networks. To examine if skin cortisol may be a reliable biomarker of stress, NICU stress exposure and repeated measurements of skin cortisol in very preterm infants were examined prospectively during the first 6 weeks of life. The temporal relationship between skin cortisol and NICU stress exposure was also analyzed.Materials and methods-Participants included 82 preterm infants born weighing less than 1500 grams, admitted to a level III NICU, with a mean gestational age of 28.5 weeks. Infants were studied from birth through 6 weeks of life. NICU stress data was collected using the Neonatal Infant Stressor Scale. Skin samples were collected using D-squame tape as soon after birth as possible and every two weeks thereafter.Results-On average, infants experienced approximately 43 stressful events per day during the first 6 weeks of life in the NICU. Stress level and cortisol reactivity varied by gestation age. Higher stress resulted in higher cortisol for infant >28 weeks; lower stress scores were associated with higher stress for infants <28 weeks. Stress exposure during 7 days prior to cortisol sampling yielded the highest AUC for the 2 groups. A statistically significant interaction was identified between gestational age and stress exposure during the previous 7 days (p < 0.01).

Clinical validation of the Neonatal Infant Stressor Scale with preterm infant salivary cortisol

“…Support for this hypothesis can be found in the work of A.L. D'Agata et al (35) who found that the number of stressful events in the previous 7 days correlated with skin cortisol in hospitalized preterm infants. In that study, skin cortisol was not associated with stressful events over a shorter timeframe, i.e.…”

Associations Between Hormonal Biomarkers and Preterm Infant Health and Development During the First 2 Years After Birth

“…Having no differences in mean cortisol levels over time might make it more difficult to identify differences in infant’s outcomes. The other explanation is that cortisol levels were higher among neonates with smaller gestational age that altered HPA axis (D’Agata et al, 2019) and those levels were highest during the first week, then gradually decreased by the first month (Greaves et al, 2014). Altered HPA axis due to elevated cortisol levels might change with time as a negative association between cortisol levels and motor development was reported at 6 months in VLBW female infants (Cho et al, 2017) while no association was reported under 24 months in full-term infants (Macari et al, 2019).…”

“…VLBW infants who were exposed to multiple noxious stimuli in the NICU showed high cortisol levels, especially infants with gestational ages smaller than 28 weeks (D’Agata et al, 2019). Repeated noxious stimuli might increase allostatic load and cause problematic health and development.…”

Quality Improvement Initiative in the NICU for Improved Practice of Cuff Blood Pressure Measurements

“…Depending on the severity of illness or level of immaturity, many of the interventions performed are repeated over the course of the NICU stay 2. Although these procedures and interventions may be necessary for lifesaving measures, many of the everyday common nursing procedures are performed on a frequent, repetitive basis that can result in stressful and painful2 experiences that have cumulative and adverse effects on developmental outcomes. Studies have demonstrated that the frequency of medical and nursing procedures performed per infant includes the experience of 10 painful procedures per day and 38 handling interactions during a 24-hour period 3…”