Supporting sensory development in preterm infants
Hospital in Mumbai, India
About 15 million babies are born preterm world over every year. As per the World Health Organisation (WHO) in 2018,1 in 10 babies is born preterm. Due to recent advances in medical care and technology the mortality rates of preterm babies have drastically reduced in the two last decades. However, the morbidity rates and rates of disabilities in this population still seems to be high. These infants are at a higher risk for cerebral palsy, sensory deficits,learning disabilities and respiratory diseases as compared to theirterm counter parts. Oral sensory defensiveness, tactile defensiveness and general sensory processing disorders (SPDs) are also more prevalent in the preterm population(Kessenich, 2003).
The current literature suggests that preterm birth affects sensory processing, Due to their perinatal medical conditions, these infants spendsubstantial periods of time in the neonatal intensive care units. The sensory environment of the NICU can be very over stimulating and overwhelming for these fragile infants, who now need to complete their development outside of the mother’s womb. There are critical periods of sensory development in the fetus, during which exogenous and endogenous factors work harmoniously tofacilitate the development of the sensory systems. Out of phase sensory stimulation like that in the NICU, may interfere with the normal development of the sensory systems (White, 2014). Along with the sensory experiences of the NICU, the child also experiences interruption of the neurobiological intrauterine development which can alter the development and functioning of the sensory systems.
The intrauterine environment is very different to that of the NICU. The uterus can effectively limit and regulate the amount, type and the duration of the sensory stimulation that occurs in the prenatal period, thus supporting the optimal development of the sensory systems. The intrauterine environment is conducive to positive sensory input. It protects the developing fetus from the harsh external stimuli. The womb provides a variety of tactile, vestibular, chemical,hormonal, auditory and visual sensory stimuli. The intrauterine environment is characterized by limited light and noise exposure,normal sleep cycle development, andunrestricted access to the mother via somatosensory, chemosensory and auditory pathways.
The uterine wall provides aboundary for secured flexion and gentle containment. The vestibular and tactile input comes from the fetal and maternal movement and contact with the warm amniotic fluid, body parts and the wall ofthe uterus. Auditory input includes maternal voice, bowel sounds, blood flow through the placenta and umbilical cord and filtered sounds from the extra uterine environment,transmitted through liquid and solid media. This environment along with other endogenous factors contributes to normal sensory system development.
This process could be dramatically altered by the preterm birth. The sensory experience in the NICU is nothing like that of the womb. The sensory experiences in the NICU like reduced vestibular stimulation (movement in the mother’s womb) bright lights, high noise levels, excessive handling, and frequent painful interventions can have lasting effects on the developing brain and interfere in the natural development of the sensory systems.Other adverse sensory experience include quick and frequent handling,intubation and invasive ventilation,suctioning, heel lances, retinopathy of prematurity examination, pulling of adhesive tapes etc. Thus, this discrepency between the needs of the infant and the NICU environment may lead to stress, sensory overload and changes in the neurosensory development. (Als, 1986; Blackburn,1998; Lickliter, 2011). Implementations of adaptations in the environment and handling may help reduce the incidence of sensory processing difficulties seen in the preterm population. Developmental care is one such approach for these preterm infants to optimize and support their neurosensory development.
Developmental care uses strategies from neurodevelopment,environmental and human sciences to supplement and humanize hightech medical care. The generic ideas of providing appropriate and positive sensory experiences to promote optimal growth and developmentis one of the fundamental features of developmental care. It aims at reducing the sensory overload experienced by the infant in the NICU and allows for optimal neurobehavioral development. There are various models of developmental care. The most popular one is the NIDCAP or the Newborn Individualized Developmental Care Assessment and Program. It involves advanced skills in behavioral observation and analysis and cue based caregiving. NIDCAP’s goal is to prevent unexpected sensory overload and pain, and enhance strengths and competences (Heidelise Als, 2004).
The Integrative Developmental Care Model (Altimier & Phillips, 2016) delineates 7 core neuroprotective measures namely,partnering with families, positioningand handling, protection of the skin, optimizing nutrition, safe guarding sleep, minimizing stress and pain and optimizing the sensory environment. Neuroprotection has been defined as strategies capable of preventing neuronal cell death. Neuroprotective strategies are interventions used to support the developing brain or to facilitate the brain after a neuron injury in a way that decreases neuronal cell death and allows it to heal through developing new connections and pathways for functionality. Neuroprotective interventions that promote normal development and prevent disabilities include organizational, therapeutic,and environment-modifying measures such as family-centereddevelopmental care.
To support and enhance sensory system development, reducing negative experiences and enhancing positive sensory experiences is the mainstay of developmental care. To provide positive tactile experiences, tactile strategies for self-regulation like hand clasping, hands to face,sucking and foot bracing are facilitated for the infant. Slow gentle intentional handling, using the “Five Step Dialogue” by Cherry Bond helpsthe infant regulate to unexpected tactile stimuli. Gentle massage post 33 weeks of gestation has alsoshown to have positive effects on the infant’s tactile development. Skin to skin or Kangaroo MotherCare (KMC) reverses the stress responses to negative and painful tactile experiences and has other benefits for the infant and the parent as well as for infant mother bonding.Slow handling, containment and swaddling are other ways of providing support to the tactile system. Cold and light moving touch may be irritating for the infant, thus firm and warm hands should be used.
To prevent aversive responses to movement, the infants must be moved slowly and with containment and have single or two person transfers during KMC, avoiding any brisk rotations. Practices such as wrapped bathing and weighing prevent any quick jerky handling and prevent the infant from having any negative vestibular experiences. To enhance the chemosensory experiences, medication should be administered only through a orogastric or nasogastric tube. Early breast milk or bottled milk should be used for mouth care. The infant should be protected from noxiousodors e.g colognes or perfumes. Staff should wait for hand sanitising gel to dry before touching the infant on the face.
The auditory experiences of the NICU are predominantly noxious for the infant. The high-pitched sounds like alarms, beeps, slamming of doors and bins can cause painful reaction and destabilize the infant These high-pitched sounds mask the more positive sounds like the mother’s voice. To promote more positive auditory experiences,mothers are encouraged to sing, talk and even read to their infants. The effect of the environmental noise levels can be reduced with incubator covers, reducing the volume on alarms, closing bins quietly, padding cupboard doors and responding to alarms promptly. Staff behaviors like speaking in a soft voice, wearing soft soled shoes and even avoiding discussions by bedsides to protect sleep are recommended to enhance the auditory experience in the NICU.
The visual system is the last sensory system to develop. Bright chaotic light in the NICU is of a different spectrum to the uterine lighting and causes physiological instability, apneas and bradycardia.Post term insufficient lighting leadsto myopia. Protecting the eyes from direct light exposure (weak pupillary reflex till 33 weeks of gestation, thin eye lids cannot protect the eyes from direct light) by using eye shields or canopy covers and using spot lights for procedures is recommended.Cyclic lighting for building circadian rhythms after 32 weeks is imperative too.
Protecting the infants sleep is very important to promote normal neurosensory development. It is during the REM phase of the sleep cycle that the sensory development happens. To protect the infant’s sleep timing procedures, reducing environmental light and sound and other disturbances, swaddling, positioning for comfort and cyclic lighting are some strategies. In summary, through their knowledge of sensor system development and responses to sensory information, the SI therapist can develop strategies to enhance and support the development of the premature infant’s sensory systems.Generalized generic modification in the NICU environment can be made to facilitate sleep, growth and sensory system development. More specific responses to sensory input can be made through careful observations and individualized plans of care can be made to provide and enhance positive sensory experiences.
The premature infant’s susceptibility to sensory processing disorders has been strongly linked to the impact of the negative sensory experiences in the NICU. By using the principles of Ayres Sensory Integration, the therapist can innovate developmental care strategies and protocols. This will support the infant’s sensory system development and reduce the incidence of SPD in this vulnerable population. Mahek reports “The ISIC 2019 in Hong Kong was an exhilarating experience. It was amazing listening to our favorite authors and mentors.There were loads of seasonedspeakers and some very intriguing topics that were discussed. I look forward to ISIC 2020 in California. “Can’t wait! See you all there!”