Approximately 12%, or 500,000 infants, are born preterm each year in the United States alone. Although survival rates of preterm infants have increased with advances in medical care, the risk of developmental delay and disability has remained constant. Very preterm infants (\<32 weeks gestation) necessitate care in the neonatal intensive care unit (NICU) for an average of three months after birth, which is a significant period of time coinciding with a critical window of brain development. While medical factors, such as brain injury, can heighten the risk of adverse neurodevelopmental outcome, the NICU environment may also have deleterious effects on early brain structure and function.
The Influence of Early Environment: Maternal deprivation and isolation from positive sensory experiences are prominent features of orphan studies. Consequences of language and human deprivation include emotional disturbances, delayed cognitive and language skills, and abnormalities evident on magnetic resonance imaging (MRI). Although the preterm infant differs from a child who has been institutionalized or deprived of caregiving attention after full term birth, there are similarities, such as the altered temporal lobe structures, and the pattern of developmental impairments. There is growing evidence supporting the importance of parents in the NICU. Low frequency visits between parents and their hospitalized preterm infants have been associated with suboptimal outcomes, like child abuse and abandonment and adverse emotional functioning. NICU's in Sweden have been successful with engaging parents in care from admission to discharge and have reported shorter hospitalizations. There is also a growing body of evidence supporting positive sensory exposures for preterm infants, including maternal voice recordings, massage, skin-to-skin holding, and vestibular and kinesthetic interventions. In addition, my team has made important research findings pointing to the potential need for developmentally-appropriate sensory exposures in the NICU.
Outcomes Associated with Preterm Birth: While advances in medical technologies have improved the rates of survival among preterm infants, the risk of long-term morbidities remains high, with 50-70% of very preterm infants exhibiting developmental problems. In addition to motor problems, language and communication problems are common in former preterm infants when studied at school age, and recent evidence suggests that language deficits persist through childhood. Language difficulties have also been shown to affect a broad range of factors important for social prowess and academic achievement. In addition, preterm infants have a heightened risk of attachment disorders and other social-emotional problems.
Outcomes Associated with Parenting a Preterm Infant: Many negative psychological sequelae are associated with parenting a preterm infant, including depression, anxiety, and post-traumatic stress. Such negative parental mental health outcomes proceed to influence the parent-child relationship, leading to a parent's inability to recognize infant cues as well as increased negativity and intrusiveness. Negative maternal-child interactions continue into the first several months of life if stress remains high. Forming such a foundation may then lead to negative child outcomes associated with social-emotional development, including attachment insecurity, and mental health issues.
Sensory Stimuli and Current Practice in the NICU: High-risk infants who receive care in the NICU are exposed to significant stressors that include painful procedures, disruption of normal sensory experiences, and stress related to parent-infant separation. In addition to the loss of parental nurturing, there is growing concern that stress during a period of extensive brain development may result in permanent and deleterious developmental outcomes.
Developmental care, which includes sensory minimization, has been the predominant model of care in the NICU since the 1980s, because the bright and noisy environment, which exceeds sensory standards set by the American Academy of Pediatrics, is understood to adversely affect growth and development of the preterm infant. In support of developmental care principles, NICU staff makes efforts to reduce modifiable stimuli to the high-risk infant in the NICU. However, there is emerging research on the positive effects of sensory stimulation for preterm infants in the NICU.
Positive sensory exposures in the NICU are critical, as they can have life-long implications on learning, memory, emotions, and developmental progression. In an environment where stimuli are primarily negative, it is especially important to define and implement positive sensory exposures in the NICU. Further, it is well understood that multi-dimensional sensory exposures are present in utero in the final months and weeks of pregnancy, but the preterm infant misses potentially important, timed exposures that may be absent or altered in the NICU environment. Positive forms of sensory exposure during periods of infant readiness may be important to facilitate appropriate neural pathways and enable positive experiences.
Results from a rigorous systematic review, benchmarking, and expert opinion were used to develop a clinical practice guideline for sensory-based interventions for hospitalized, very preterm infants using the Appraisal of Guidelines for Research and Evaluation II instrument. The manualized intervention (from the integrative review and development of the implementation plan) includes evidenced-based interventions that can be conducted by parents with their preterm infants across postmenstrual age while hospitalized. The sensory-based intervention includes the provision of specific amounts of auditory, tactile, vestibular, kinesthetic, olfactory, and visual exposure to be conducted daily through hospitalization. The intervention plan is intended to be implemented by parents (when available) and by surrogates when the parents are unable to be present in the hospital. Surveys, focus groups of a multidisciplinary team of health care professionals and parents of preterm infants in the NICU, and a pilot/feasibility study were conducted to assess acceptability, appropriateness and feasibility of the sensory-based intervention plan. The investigators enrolled 30 very preterm infants within the first week of life and implemented the sensory-based program. Logging sheets were placed at the infant's bedside to document the execution of sensory-based interventions, who conducted the intervention (parent, member of research team or other caregiver), and infant responses and consequences of the intervention. Physiological (such as heart rate and oxygen saturation fluctuations), state (levels of arousal) and behavioral (such as crying, changes in motoric tone) responses were recorded by caregivers during interventions on the bedside logs. Negative sequelae of the intervention resulted in stopping the intervention and modifying the criteria for sensory-based interventions accordingly. A licensed therapist provided guidance as to when infants can and cannot tolerate sensory exposures. From clinical documentation and bedside logging, implementation factors were assessed. Adaptations to the sensory-based program were made until it was deemed appropriate by the investigative team. This occurred after the model for an enhanced sensory environment could be documented 75% of the time on at least 3 consecutive participants.
The aim of this randomized clinical trial was to assess the effect of a sensory-based intervention in the NICU on outcomes of preterm infants and their families.
After obtaining informed consent, 70 preterm infants were randomized to 2 levels of sensory exposure: the sensory-based intervention or traditional care group. The parents of infants in the sensory-based intervention group were educated and supported to conduct sensory interventions with their infants using the systematized protocol. The traditional care group had therapists and nurses provide and educate parents about sensory exposures as standard of care. For both care groups, infant neurobehavior, sensory processing, mother-infant interaction, and parent mental health were assessed at term age prior to hospital discharge. Child development, sensory processing, and parent mental health were measured again at age one year corrected using standardized measures. Differences between groups were explored.
