Effects of stress on the pre-term infant

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Chapter Two: Literature review

Introduction

As technology in the wider field of health sciences improves, the patient mortality rate decreases. Although this suggests positive advances across the board, pre-term infants still often experience short and long-term effects that are not as positive as we would like. These infants experience morbidity related to the immaturity of their organ systems and concurrent disease states (Symington & Pinelli, 2003: 1).
In spite of improved technology, pre-term infants tend to present with stress levels above their coping abilities. According to Symington and Pinelli (2003: 2), typical markers of stress are changes in physiological parameters like increased heart rate or decreased oxygen saturation. The growth of pre-term infants is negatively affected by the increased energy expenditure that occurs during routine care in the NICU. In a study done by Taquino and Lockridge (1999: 65), hypoxia occurs rapidly in pre-term infants when they are handled for routine procedures or exposed to loud noise and other stressors. These effects of stress contribute to the negative sequelae of the high-risk neonate.

Effects of stress on the pre-term infant

The Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing and Allied Health (1997: 1539-1540) defines stress as the sum of the biological reactions to any adverse stimulus, including physical, mental or emotional reactions and internal or external reactions, that tends to disturb the homeostasis of any organism. A stressor is further defined as “any factor that disturbs homeostasis, producing stress”. These would include the following: constant bright light, high noise levels, medical interventions, and routine handling during nursing care (Becker et al., 1991: 150).

Neurological development

One of the earliest systems to develop in the embryo is the neurological system, which only reaches maturity in adulthood. The pre-term infant is equipped with an immature and vulnerable neurological system that needs to manage stimuli from internal and external sources. Mounting organised responses to stimuli is a difficult task for the immature pre-term infant to complete. The extra-uterine environment can be overwhelming and disorientating even for adults equipped with mature neurological systems (Barb & Lemons, 1989: 8). Comparing the pre-term infant’s immature neurological system to the mature adult system reveals that significant challenges are presented when demands made by the NICU environment can influence the infant’s neuropsychological, psycho-emotional, and psychosocial development (Als, 1999: 19).
Brain development of the full-term infant occurs in the protected intrauterine environment where the infant has a constant supply of nutrition and optimal thermoregulation, waste removal and oxygenation. For the infant born too early, the chaotic environment of the NICU replaces this optimal environment.
The most crucial period of rapid brain growth and neuronal differentiation occurs between 28 and 40 weeks gestational age. From 28-32 weeks gestational age, the risk for neurological insults is increased as the germinal matrix is extremely vulnerable and the possibility of haemorrhage is high (Als, 1986: 6; Becker et al., 1991: 154; Als, 1999: 21; Glass, 1999: 91-92).
The central nervous system relies on sensory input in order to mature but brain development of the pre-term infant can be modified by abnormal experiences, such as either over-stimulation or deprivation of stimulation. Research has shown that sleep interruptions, supine positioning, routine and excessive handling, loud sounds, unattended crying, reduced sucking opportunities, and social and medical interactions have unfavourable developmental effects (Als, 1999: 30).
A randomised clinical trial conducted by Als and colleagues (2004: 846) investigated the effects of early experiences on brain function and structure. The experimental group consisted of 16 infants and the control group had 14 infants. The experimental group received the Newborn Individualised Developmental Care and Assessment Program (NIDCAP^®) within 72 hours of admission to the NICU. These infants were between 28 and 33 weeks gestational age and where assessed at two weeks, and nine months corrected age. The infants were assessed at two weeks corrected age with the following special investigations: electroencephalogram, magnetic resonance imaging and measurements of the transverse relaxation time. Other areas where the infants were assessed included: health status, growth and neurobehaviour. The results showed “consistently better function and more mature fibre structure for experimental infants compared with their control” (Als et al., 2004: 846).

Signs of stress

The neonate shows signs of stress using three main systems, namely the autonomic, motor and state organisation systems. The autonomic system’s stress signals include colour changes, hiccupping, sneezing, gagging, spitting up and changes in vital observations including increases or decreases in the following: heart rate, blood pressure, respiratory rate and temperature (Yeo, 1998: 279; Deacon & O’Neill, 1999: 525). Glass (1999: 91) notes additional effects of stress, including apnoea, bradycardia, vasoconstriction, decreased gastric motility and an increased secretion of cortisol, adrenaline and catecholamines. Increased levels of these hormones inhibits optimal repair of damaged tissue and normal growth. The infant also clearly shows stress through the motor system. Generalised hypotonia, flaccidity, hyperextension of extremities or body and splaying of fingers and toes are all due to some level of stress experienced by the pre-term infant. Variation in state organisation is also a good method of determining stress as this often presents in the NICU. When stressed infants exhibit irritable behaviour, sleep disturbances and inappropriate behaviour due to state disorganisation (Deacon & O’Neill, 1999: 525).
Becker et al. (1991: 150-151), and Als (1999: 35) discuss these signals as the pre-term infant’s attempts to express non-verbally both positive and negative responses, present in addition to the physiologically observable autonomic and visceral responses. From these methods of communication, one can assess the pre-term infant’s behaviour as well as the physiological parameters to determine whether medical, nursing or social interventions are beyond the infant’s coping mechanisms. The infant’s own behaviour supplies its care givers with the best information base in order to make the necessary alterations to care-giving techniques and environment, which can facilitate the reduction of the pre-term infant’s stress.

Short and long-term sequelae of stress

Aversive procedures, excessive handling, interrupted sleep, noxious oral medication high noise levels and bright light are some of the negative stimuli the pre-term infant experiences while in the NICU. These stimuli are direct causes of stress that result in disorganised stimulation of the developing sensory systems, which may influence morbidity (Glass, 1999: 91). According to Taquino and Lockrigde (1999: 64), the compromised pre-term infant does not have the ability to tolerate such stressors.
The short-term sequelae of increased stress levels, such as disturbed heart rate, respiration rate, colour changes, blood pressure and saturation levels, are specifically related to physiological instability. When observed in an infant, they reflect changes in respiration patterns and temperature instability, and the infant may present with gagging, hiccupping, disturbed motor behaviour, postural tone and facial expressions, and alterations in behavioural states (Becker et al., 1991: 151).
Sick and pre-term infants who survive the NICU period have a higher prevalence of cognitive, sensory, motor and developmental problems than infants who do not spend time in the NICU. The healthy pre-term infant is also faced with developmental problems, which manifest during school-going years. Als (1999: 19) and Taquino and Lockrigde (1999: 64) mention the following developmental problems: learning disabilities, lower intelligence proportion, attention deficit disorders, impulsiveness, concentration difficulties, language comprehension and speech difficulties, visual motor impairments, space orientation disturbances, affective vulnerability and altered self-esteem.
Long-term problems related to prematurity identified by Bohin, Draper and Field (1999: include: cerebral palsy, developmental delays, visual impairment, hearing impairment, impaired growth, epilepsy, chronic lung disease and hydrocephalus. Als (1999: 19, 1986: 4) adds the following complications: bronchopulmonary dysplasia, intraventricular haemorrhage, retinopathy of prematurity and necrotising enterocolitis. These complications are reiterated by Bellefeuille-Reid and Jakubek (1989: 93), who also include susceptibility to disease and poor resistance to infection. In addition, insecure attachment relationships, hyperactivity disorders and information processing abnormalities are seen (Pressler, Turnage-Carrier & Kenner, 2004: 14).
It is common for these children to experience frequent re-admissions to hospital for health problems, such as those mentioned above, that relate to a pre-term birth. These infants often require long-term developmental and functional habilitation, including treatment by speech therapists, audiologists, occupational therapists and physiotherapists. Birth weight, gestational age, clinical course and related complications play a large role in the determination of outcomes for these infants (Taquino & Lockrigde, 1999: 64).

Developmental care (DC)

The negative sequelae just mentioned can be reduced through developmental care (DC). DC provides a simple and effective method of reducing these complications by modifying the environment to which the high-risk neonate is exposed. DC, which is described by Symington and Pinelli (2003: 2) as a broad category of interventions designed to minimise the impact of the NICU environment, is a relatively new concept in the care of high-risk neonates. These interventions may include control of one or more elements of the external environment influencing the vestibular, auditory, visual, tactile, olfactory and gustatory systems. Different interventions have been used to modify the extrauterine environment so as to decrease a variety of stressors. These interventions contributed to an increased rest periods to the benefit of the infant.
Taquino and Lockrigde (1999: 64) refer to DC as the provision of social interactions and necessary nursing interventions in a manner that facilitates and supports the neurodevelopmental and physiological stability of the newborn infant. DC is an individualised care approach that attempts to manipulate the pre-term infant’s environment to reduce external stressors, and to use the infant’s unique behavioural and physiological cues as a foundation for interactions and interventions.
The principles of DC include individualised infant care, family-centred care, appropriate handling and touching of the pre-term infant, initiation of cluster care for nursing activities, developmental positioning and swaddling, kangaroo mother care (KMC), non-nutritive sucking, manipulation of the external environment to reduce negative stimuli (noise, light and negative smell stimuli) and introduce positive smell stimuli, and pain management. For the purposes of this study, all of these principles of DC will be investigated. These interventions result in reduced stress levels and increased rest periods, which are beneficial to the pre-term infant (Taquino & Lockrigde, 1999: 64-79; Jorgensen, 2000: 3; Byers, 2003: 174-179; Hennessy, 2003: 1-52).
Making stress alleviation a priority in the NICU enhances the pre-term infant’s potential development and improves interpersonal relationships between family and infant (Yeo, 1998: 278). By using information gleaned from stress signals, the care giver can modify the pre-term infant’s environment to promote neurodevelopment and stress reduction.

Historical perspective of neonatal care

The care of high-risk neonates is recorded as early as 1880 in France, where the first primitive incubator was developed. At this time and for many years afterwards, pre-term infants were termed ‘weaklings’, and so described in the first textbook on neonatal care, written in 1900. The initial care approach was to maintain thermoregulation, promote nutritional status through oral and digestive tube feeding, control infection and minimise handling. Pre-term and sick infants were also put on exhibition to public viewing and profit was made from this practice (Pressler et al., 2004: 1).
This approach of minimal handling by medical staff and parents resulted in an environment of sensory deprivation for these pre-term infants, since many important factors were neglected. Problems included incorrect positioning, inappropriate touch and handling, rapid vestibular disturbances as well as a lack of environmental manipulation of sound, light and smell.
Between 1960 and 1970, much technological advancement occurred that improved medical care delivered to the pre-term neonatal population. This included improved thermoregulatory ability facilitated by the radiant warmer, refined ventilatory setting for infants of smaller birth weights, the introduction of total parenteral nutrition and the use of central infusion lines. Specific ground and air transportation teams were also initiated (Pressler et al., 2004: 3).
Early intervention programmes in the NICU grew from a realisation of sensory deprivation, and were first implemented in the 1970’s. Early intervention programmes concentrated on providing structured auditory, visual and vestibular stimulation. The theoretical foundation for this approach was the concept of brain elasticity, which suggested that the brain could respond positively to proper stimulation and regulate in abnormal conditions. Much in these programmes were based on interaction with healthy infants. Although this approach was implemented with good intentions, this type of stimulation was not appropriate for the compromised and stressed pre-term infant (Taquino & Lockrigde, 1999: 65).

Chapter One: Introduction 
1.1 Introduction
1.2 Background and rationale for the study
1.3 Problem statement
1.4 Research question
1.5 Purpose.
1.6 Objectives
1.6.1 Objective 1
1.6.2 Objective 2
1.6.3 Objective 3
1.6.4 Objective 4
1.6.5 Objective 5 .
1.7 Conceptual definitions
1.8 Methods and procedures.
1.8.1 Research design
1.8.2.1 Phase One: problem analysis and project planning
1.8.2.1.a Population and sampling
1.8.2.1.b Method of data collection
1.8.2.1.c Data analysis
1.8.2.2 Phase Two: information gathering and synthesis
1.8.2.2.a Population and sampling
1.8.2.2.b Method of data collection
1.8.2.2.c Data analysis
1.8.2.3 Phase Three: design of the intervention plan
1.8.2.3.a Population and sampling
1.8.2.3.b Method of data collection
1.8.2.3.c Data synthesis
1.8.2.4 Phase Four: implementation
1.8.2.4.a Population and sampling
1.8.2.4.b Method of data collection
1.8.2.4.c Data synthesis
1.8.2.5 Phase Five: evaluation and advanced development
1.8.2.5.a Population and sampling
1.8.2.5.b Method of data collection
1.8.2.5.c Data analysis
1.9 Expected limitations
1.10 Ethical considerations
1.11 Strategies to ensure trustworthines
1.12 Outline of chapters
2 Chapter Two: Literature review 
2.1 Introduction
2.2 Effects of stress on the pre-term infant
2.2.1 Neurological development
2.2.2 Signs of stress
2.2.3 Short and long-term sequelae of stress
2.3 Developmental care (DC)
2.3.1 Historical perspective of neonatal care
2.3.2 Theoretical perspective on developmental care
2.3.3 Principles of developmental care
2.3.3.1 Individualised care
2.3.3.3 Environmental manipulation
2.3.3.3.a Light reduction
2.3.3.3.b Noise reduction
2.3.3.3.c Smell.
2.3.3.4 Developmental positioning
2.3.3.5 Handling, positive touch and vestibular care.
2.3.3.6 Non-nutritive sucking
2.3.3.7 Pain management
2.3.4 Outcomes of developmental care
2.4 Developmental care implementation
2.5 Conclusion
3 Chapter Three: Methodology – intervention research
3.1 Introduction
3.2 Historical aspects of intervention research
3.3 Intervention design and development
3.4 Conclusion
4 Chapter Four: Phase One – problem analysis and project planning.
4.1 Introduction
4.2 Aim of Phase One
4.3 Identifying and involving clients.
4.4 Gaining entry and cooperation from the setting
4.5 Identifying concerns of the population
4.6 Environmental audits
4.7 Postulation of additional problems: a personal reflection
4.8 Analysing identified problems
4.9 Project planning
4.10 Setting goals and objectives
4.11 Conclusion
5 Chapter Five: Phase Two – information gathering and synthesis
5.1 Introduction
5.2 Aim of Phase Two
5.3 Review of existing information sources
5.4 Natural examples
5.5 Functional elements of successful models
5.6 Conclusion
6 Chapter Six: Phases Three and Four – design and implementation of the intervention plan
6.1 Introduction
6.2 Designing an intervention plan
6.3 Procedural elements and implementation of the intervention plan
6.4 Refinement of the intervention plan
6.5 Conclusion
7 Chapter Seven: Phase Five – evaluation and advanced development
7.1 Introduction
7.2 Evaluation methods
7.3 Validation of implementation guidelines for developmental care
7.4 Conclusion.
8 Chapter Eight: Conclusion and recommendations .
8.1 Introduction
8.2 Summary of the research methodology
8.3 Realisation of strategies to ensure trustworthiness
8.4 Ethical considerations
8.5 Limitations of the study
8.6 Recommendations for dissemination of this research
8.7 Conclusion
9 References
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