Systematic study of the physiological and behavioral responses of neonates to specific examination, intervention, and care procedures in neonatal care units is critical for identifying and understanding stress patterns and potential risk, even for presumed benign procedures. The aim of this study was to explore physiological and behavioral tolerance and stress responses during "evaluative handling," the administration of a neurological assessment for preterm and full-term newborn infants in neonatal care units. This common procedure for infants at neurological and developmental risk may be conducted by neonatal team members (including neonatal physical therapists), neurologists, or developmental pediatricians to document neurological system integrity and provide baseline data for neurodevelopmental intervention and follow-up. As the primary mediators of infant stress during and after neonatal care procedures, neonatal nurses may also play a critical role in monitoring infant tolerance during the neurological assessment process. The purpose of the study was to investigate the effects of evaluative handling and gestational age on the physiological and behavioral stability of newborn infants.
BACKGROUND
Selected literature establishing the fragility of preterm infants is reviewed. Physiological and behavioral responses of neonates to caregiving and medical procedures in the neonatal intensive care unit (NICU) are described.
Anatomical and physiological vulnerability
Physiological homeostasis in preterm infants is challenged by anatomically and functionally immature organ systems, including the central nervous system, cardiovascular system, and respiratory system. Immaturity of the cardiovascular and central nervous systems, with immature development of cerebral vasculature control and cerebral autoregulation, contribute to the risk of intraventricular hemorrhage and white matter injury in preterm infants less than 34 weeks of gestation.1,2 Cerebral autoregulation is "the local control of brain blood flow that modifies resistance to compensate for changes in pressure, thus sustaining a constant, stable cerebral blood flow."3(p13) Cerebral autoregulation is present in the preterm infant; however, capabilities are limited and the range of autoregulation is narrower.1,4,5 Preterm infants also have a relatively low cerebral blood flow, which, when combined with limited cerebral autoregulation, results in a fine balance between cerebral ischemia and the risk of white matter injury and increased intracranial pressure with the potential for rupture of blood vessels and germinal matrix-intraventricular hemorrhage.2
Activities that lead to hypoxemia, hypercarbia, acidosis, or increased blood pressure can alter autoregulation, resulting in pressure-passive cerebral blood flow. Increases in systemic blood pressure can lead to a rise in cerebral blood flow and cerebral pressure.1,2,5 This condition increases the risk of capillary rupture in the fragile, thin-walled vessels in the periventricular region of the premature brain, where these vessels are poorly supported by the gelatinous tissue of the subependymal germinal matrix.1,6 Alterations in cerebral autoregulation can also reduce cerebral perfusion leading to development of ischemia and hypoxia.1,3 "Different areas of the brain are more sensitive to changes in blood flow due to the distribution of blood vessels and type of tissue. For example, the white matter of the immature brain, particularly in the periventricular area, and the germinal matrix are especially vulnerable to ischemic-hypoxia injury."3(p13) Changes in cerebral hemodynamics have been reported in conjunction with endotracheal tube repositioning and other complex caregiving procedures in critically ill preterm infants.7 Preterm infants are also predisposed to cerebral hemorrhage if cerebral blood pressure is suddenly increased as in resuscitation at birth for asphyxia. Vigorous changes in body position during evaluative handling for neurological assessment may cause sudden increase in cerebral blood flow, potentially contributing to hemorrhage risk in infants less than 34 weeks of gestation.
Structural and functional immaturity of the neonatal respiratory system contributes to inefficient gas exchange and predisposes preterm infants to respiratory distress. The configuration of the rib cage is circular with nearly horizontal alignment of the ribs to the sternum, creating biomechanically inefficient attachments for the diaphragm and intercostal musculature. The horizontal angle of insertion of the diaphragm combined with the horizontal rib cage promote distortion of the chest wall shape and inefficient ventilation.8 In addition, the bones of the rib cage are cartilaginous, leading to a more pliable chest wall, whereas the lungs have less elastic tissue leading to less compliant, stiffer lungs, the opposite from anatomical components found in adults.8 This anatomical combination increases the respiratory effort needed to expand the lungs.
Respiratory muscle fatigue in preterm infants is influenced by incompletely developed type I and type II muscle fibers compared with infants born at term gestation.8,9 Type I fibers are high oxidative, slow twitch fibers found primarily in respiratory muscles but are also prominent in extremity, pelvic girdle, and shoulder girdle muscles. The lower percent of type I fibers in the diaphragm and intercostal muscles imply lower oxidative capacity in ventilator muscles of preterm infants. Type II are low oxidative, fast twitch fibers located in facial and hand musculature.
Decreased number and complexity of alveoli create less surface area for oxygen and carbon dioxide diffusion than in full-term infants. In addition, preterm infants less than 35 weeks of gestation have deficiency in synthesis, storage, and replacement of surfactant needed for maintaining alveolar wall stability and functional residual capacity. Anatomical and physiological immaturity of the respiratory system increase the work (oxygen cost; metabolic demand) of breathing.
Autonomic control of respiration is influenced by the sparse neuronal network linked to immature neurological development. Partial myelination of axons, incomplete dendritic and axonal branching, and small numbers of synapses contribute to neurologically based slow impulse transmission, prolonged conduction time, and inefficient temporal and spatial summation of impulses to respiratory neurons in the brain.8 These factors create a neuromaturational basis for inefficient respiration in preterm infants in addition to structural immaturity of the respiratory system.
Neonatal care procedures
Common caregiving activities in the NICU may contribute to physiological or behavioral stress in newborn infants. Preterm infants showed physiological stress responses during sponge bathing10-13 and unswaddled weighing procedures.14 Behavioral stress was linked to the clustering of routine care procedures15,16 and bolus tube feeding, compared with continuous feeding mode.17 Environmental stressors of noise,18-25 light,22,26,27 and handling for caregiving28,29 were found to increase behavioral and physiological reactivity and stress. In addition to potentially destabilizing routine caregiving activities, these NICU environmental factors may combine to magnify physiological and behavioral stress in preterm infants. For example, as noted earlier, changes in cerebral hemodynamics were reported in conjunction with complex caregiving procedures such as endotracheal tube repositioning in critically ill preterm infants.7
An increasing range of procedures designed to mediate stress in preterm neonates has been investigated and integrated into neonatal practice. These caregiving procedures with positive physiological or behavioral effects include facilitated tucking (flexed) position,30-37 skin-to-skin holding (kangaroo care),38-45 sucrose for procedural pain,36,46 nonnutritive sucking,45,47 and altered environmental (light, sound) conditions.48-52
Distinct patterns of physiological and behavioral stress have been established with neonatal care procedures and multiple supportive interventions implemented to mediate stress in newborn infants. Position changes, multisensory stimulation (tactile, kinesthetic, visual, auditory), and duration of neonatal neurological assessment create potential stressors that must be identified, analyzed, and carefully monitored in neonatal care units. The physiological and behavioral effects of evaluative handling are frequently unrecognized; therefore, this study will alert neonatal teams on potential risk and stress patterns of newborn infants to neurological assessment procedures. Infant response patterns from this study may also apply to handling tolerance during similar assessment and daily care routines.
METHODS
Design
The study involved 2 experiments in which heart rate and respiratory rate responses to evaluative handling were systematically replicated. In addition to the replication, the second experiment included investigation of circulatory-related skin color, mean arterial pressure, motor stress cues, and autonomic/visceral stress cues to expand the investigation of infant tolerance to neonatal neurological assessment procedures. A 2x2 factorial design was used for both experiments: factor l was gestational age, and factor 2 was evaluative handling. Three consecutive phases were designed for both experiments. Physiological (experiment 1) and physiological and behavioral (experiment 2) parameters were continuously monitored at 2-minute intervals during a baseline phase of 16 minutes, a physical handling phase of approximately 16 minutes for administration of the neonatal neurological assessment, and a second baseline (recovery) phase of 16 minutes.
Participants and setting
Experiment 1
A sample of 32 neonates (16 preterm; 16 full-term) was selected from the available population in the neonatal intermediate care and newborn units at Madigan Army Medical Center, Tacoma, Washington. The medically stable infants were between 32 and 35 weeks of gestation (preterm) or between 39 and 41 weeks of gestation (full-term) on the day of neurological testing. The nonrandomized preterm and full-term participants were matched by race. The 2 groups were statistically homogeneous in race, gender, chronological age, and maternal age. A significant difference (P < .05) was found in delivery method. Preterm infants were more likely (61%) to have Caesarean section deliveries than infants born at term (31%). Infants were excluded if structural malformations or chromosomal abnormalities were documented or if they were less than 2 days of age at the time of testing.
Experiment 2
A nonrandomized, convenience sample of 40 additional neonates (20 preterm; 20 full-term) was recruited from the neonatal intermediate care and newborn units of 2 medical centers in Tacoma, Washington: (1) Madigan Army Medical Center: 29 infants (14 preterm; 15 full-term) and (2) Tacoma General Hospital: 11 infants (6 preterm; 5 full-term). The participant exclusion and inclusion criteria were replicated from experiment one except for an expanded range of 30 to 35 weeks of gestation for the preterm group. No significant differences in demographic characteristics were found between infants in the 2 medical centers. Neonates in the 2 gestational age groups were matched by race and gender.
Instrumentation
Heart rate (beat to beat) and respiratory rate (breaths per minute) were continuously measured through adhesive electrodes linked to a cardiorespirograph monitor. Mean arterial pressure was measured by a neonatal vital signs monitor at 2-minute intervals through a plastic cuff secured to the left thigh of each participant. The mean arterial pressure values were manually recorded from the digital display at 2-minute epochs. A stopwatch with an audible cue by earphone was used to measure the 2-minute intervals for manual recording of data by a research assistant from the digital displays of the 2 physiological monitors and from observation of each infant's behavioral responses.
An observational system of behavioral coding was modified from behavioral stress responses reported by Als and associates.53 Coding at 2-minute intervals occurred for behavioral state, circulatory-related skin color and selected behavioral stress cues (finger splay, arm salute posture, trunk arching, sneezes, hiccoughs, yawns, and regurgitation).
The Neurological Assessment of the Preterm and Full-Term Newborn Infant (NAPFNI) developed by Dubowitz and associates54 was selected as the neurological assessment protocol. Serving as a neurological and neurobehavioral assessment since 1980,55 the test has varying numbers of items distributed in the following categories: behavioral state (6), orientation and behavior (7), posture and tone (15), movement observation (3), and primitive reflexes (6). The items are scored on a 5-point scale and sequenced according to the intensity of response. When used clinically, the examination forms (illustrated with stick figures) can accommodate both baseline and repeat assessments, and an optimality score is available for interpreting patterns of responses for full-term infants. The assessment was designed for infants ranging from 30 weeks postmenstrual age to 4 months. A discriminative and predictive tool, the NAPFNI, was designed to document changes in the evolution of newborn behaviors in the preterm infant, compare preterm with full-term newborns, detect deviations in neurologic signs, and record patterns of resolution in neurological impairments.54,56,57
Procedure
Medical stability was confirmed by chart review and by physical examination from a neonatologist. In addition, participants were considered medically stable when mechanical ventilation and supplemental oxygen were discontinued and resolution of temperature instability and apnea/bradycardia episodes was confirmed. A neonatal physical therapist with 15 years of experience conducted the neurological assessment for all infants. Trained data collectors (pediatric physical therapists), blind to the hypotheses of the study, recorded all physiological and behavioral data. All evaluators achieved minimum reliability of 0.91 (point by point agreement) with each dependent variable for 5 pilot subjects.
The first baseline phase of 16 minutes was scheduled 90 minutes before feeding. Participants were given a 10-minute rest period after application of electrodes and blood pressure cuff to eliminate potential physiological reactions to physical handling before the baseline started.
The treatment phase of approximately 16-minute duration consisted of evaluative handling according to the procedures reported by Dubowitz and associates.55 The neurological assessment was consecutively administered in 3 subtests: habituation, neuromotor, and neurobehavioral. This sequence supported infant arousal from a sleep state into the awake states for neuromotor and neurobehavioral testing.
The second baseline of 16 minutes was a nonhandling rest period to document physiological and behavioral responses after the neurological assessment.
Statistical analysis
Two-way analysis of variance was used to analyze physiological differences between gestational age groups and among the evaluative handling phases. Similarities in physiological values among baseline and evaluative handling phases within gestational age groups were further analyzed in experiment 2 with Duncan's multiple range test. Demographic characteristics (nominal data) were compared by chi-square analysis or the Fisher exact test, depending on group size. Differences between mean physiological values among gestational age groups within each phase of the study were determined by t-test. A binomial test of differences between proportions was implemented to analyze differences between frequency data of behavioral states, color, and behavioral stress cues.
RESULTS
Compared with full-term infants, preterm neonates demonstrated significantly higher heart rate (P < .001), greater increase in mean arterial pressure (P < .01), and decreased peripheral oxygenation inferred from mottled skin color (P < .001) during the neurological assessment process. Respiratory rate was the least sensitive physiological measure with slightly higher (P < .05) respiratory rate found in preterm subjects only during the second experiment.
Significantly higher frequencies of behavioral (motor and autonomic) stress responses of finger splay (P < .001), arm salute (P < .01), hiccoughs (P < .001), and yawns (P < .001) were found in preterm than in full-term participants. Preterm neonates showed less frequent quiet sleep (P < .001), active alert (P < .01), and crying states (P < .001) than observed in full-term infants.
DISCUSSION
Differences in physiological and behavioral adaptation to neurological assessment procedures were found between preterm and full-term neonates. Both infant groups had greater change in physiological and behavioral responses during the neuromotor phase of the assessment, indicating a particular vulnerability during examination of tone and reflexes with related body position changes.
Physiological stress
Heart rate
In both experiments, preterm infants had higher resting heart rates in the first baseline phase than full-term neonates (see Figures 1A and 1B). This finding suggests that full-term infants were physiologically more stable, and before evaluative handling, preterm subjects had higher metabolic and cardiovascular demands and higher energy expenditure than full-term participants. Heart rates of both infant groups remained higher in the recovery baseline of experiment 2, compared with the initial baseline. Although heart rate was highest in the neuromotor phase for all infants, preterm infants continued to demonstrate higher heart rate in the neurobehavioral component, indicating longer duration of elevated heart rate than full-term subjects.
In response to neurological assessment, preterm infants showed a smaller relative change in heart rate than full-term subjects (see Figures 2A and 2B). With higher baseline heart rate values, the preterm group appeared unable to show the same proportionate, compensatory increase in cardiovascular response as the full-term group to the stress of evaluative handling. In experiment 2, the preterm participants' mean heart rates did not return to the initial baseline values. By a striking increase in cardiac output and an expedient return to initial baseline values, the full-term infants with intact neurological and cardiopulmonary systems demonstrated efficient cardiac compensation during evaluative handling. This response illustrated that relative percent change in heart rate does not alone reflect the degree of physiological stress with neonatal neurological assessment and infers that heart rate should not be used as the only parameter to determine if an infant is experiencing physiological stress.
The apparent ceiling effect in preterm heart rate may be explained by the presence of limited cardiac reserve in preterm subjects. The smaller percent change in preterm heart rate during evaluative handling may relate to a physiological protective function associated with reaching maximum cardiac reserve.57 The smaller, proportionate compensatory increase in heart rate among preterm subjects, compared with full-term infants, presumably reflects a protective mechanism demanded by the high metabolic requirements and by mechanical contractile limitations of immature cardiac tissue.58
The highest mean heart rate for both age groups in both experiments occurred in the neuromotor phase of neurological assessment where the posture, tone, and reflex testing involved moving the infant's body through 5 positions (supine, sitting, standing, ventral suspension, and prone). Consistent increase in cardiac output occurred with neuromotor assessment, highlighting the need for particular caution with administering neuromotor items for newborn infants. Increased heart rate, color changes, and behavioral state transitions were observed with the following individual test items: (1) head lag during pull-to-sit with infant's arms; (2) head control: (a) activating posterior neck musculature for lifting the head to midline in supported sitting and (b) activating anterior neck musculature for lifting the head to midline in supported sitting; (3) Moro reflex; (4) walking reflex with chest support; (5) ventral suspension: activation of neck and trunk extension and extremity flexion when held in prone position against gravity. It would, therefore, be prudent to exclude these postural reaction items until infants reach 35 weeks of gestation to support maturation of hemodynamic stability including autoregulation of cerebral blood flow.1
Respiratory rate
The modestly higher (P < .05) respiratory rate in preterm infants than full-term participants during evaluative handling only in experiment 2 may be related to the slightly larger preterm sample (8 additional subjects) with decreased maturity (mean birth weight: 1641.5 g vs 1780 g) compared with experiment 1. Physiological tolerance to neurological assessment was more precisely determined by monitoring heart rate, blood pressure, and color.
Mean arterial pressure
The significantly higher (P < .001) mean arterial pressure demonstrated in full-term neonates compared with preterm infants was not an unexpected finding because higher pressure is required to perfuse a larger body mass. Full-term infants also have greater numbers of capillaries, which likely accounts for higher resistance to blood flow than in smaller preterm infants.
Among the phases of evaluative handling, mean arterial pressure increased significantly (P < .01) for preterm subjects only. The highest change in mean arterial pressure occurred in preterm participants during the neuromotor phase and slightly less for the neurobehavioral phase (see Figure 3), indicating that the cardiovascular demand for oxygen perfusion was likely higher for preterm than for full-term subjects. This increase in blood pressure for preterm subjects may indicate that a concomitant decrease in peripheral blood flow was required to maintain adequate internal perfusion of vital organs for cardiovascular homeostasis during the stress of neurological assessment. This assumption was supported by the findings of distinctly different changes among preterm and full-term subjects in circulatory-related skin color, a marker of peripheral perfusion.
Skin color
Full-term infants were more likely to begin with and retain normal color and to become red if stressed. Preterm subjects were more likely to be mottled in color during the initial baseline and to remain mottled during the other evaluative handling phases (see Figure 4).
The quality of peripheral oxygen perfusion can be inferred from observations of skin color. Redness in the skin occurs when capillaries are dilated, blood flow to the skin is increased, and oxygen saturation of peripheral tissues is high. Conversely, lower oxygen saturation of peripheral tissues is inferred when mottled skin color appears. In response to the stress of evaluative handling, preterm subjects appeared to have greater internal demands for oxygen and were not able to demonstrate the efficient peripheral perfusion of oxygen to the skin shown by many full-term subjects. Despite higher heart rates and greater change in blood pressure, the preterm subjects were not able to oxygenate the skin as efficiently as full-term participants. The physiological cost of neurological assessment procedures was therefore considered higher in the less mature, preterm subjects.
Behavioral stress
Motor stress cues
With the multisensory stimulation inherent in the neurological assessment process, preterm infants became overloaded by the stimuli and demonstrated upper extremity motor stress signals more frequently than full-term infants (see Figures 5A and 5B). The pattern of finger splay and arm salute postures for both age groups was highest in the neuromotor phase but remained elevated in the neurobehavioral phase and recovery baseline, indicating a disorganizing effect on the motor system with concomitant increased heart rate and expected increased metabolic demands and increased energy expenditure. Harrison and colleagues59 reported motor activity cues as critical indicators of physiological stress and linked to low oxygen saturation levels. In fact, motor activity was reported to be a more frequent determinant of physiological stress than behavioral distress cues.
Autonomic stress cues
Hiccoughs, yawns, sneezes, and regurgitation are signs of automatic stress used by neonates to communicate autonomic system overload and the need for disengagement from sensory stimulation.53,60 During evaluative handling, preterm infants demonstrated more than double the total frequency of hiccoughs (P < .001) and yawns (P < .001) than full-term neonates (see Figures 6A and 6B). Preterm subjects also had higher baseline frequencies of hiccoughs and yawns than full-term participants, indicating more autonomic stress before the neurological assessment procedures began. The vulnerability of preterm infants to autonomic stress from neurological and organ system immaturity is further magnified by continuous exposure to the intermittently overstimulating neonatal intensive care environment.
State organization
Full-term subjects exhibited a wide range of behavioral states with more frequent quiet sleep (P < .001) and crying (P < .001) than observed in preterm infants. Conversely, preterm subjects appeared to cluster state behaviors toward the mid-range with more frequent active sleep (P < .001), drowsy (P < .001), and quiet alert (P < .001) states than full-term participants. These findings confirmed previous reports of lower alertness levels in preterm infants61-63 The infrequent crying of preterm participants may, according to Als60 synactive theory, be interpreted as a self-regulatory strategy for energy conservation. Rather than crying, the vigorous preterm infants appeared to respond to evaluative handling by assuming the active alert state with excessive extremity movement while the more fragile preterm subjects became drowsy.
Clinical implications
Although this study focused on infant responses to a specific neurological assessment, the findings have implications for handling of infants during daily nursing care in the neonatal intensive care unit and during other types of assessments. Continual and careful assessment of an infant's behavioral cues and physiologic stress signals is imperative with any caregiving procedure or assessment. Recognition of these responses to environmental stressors will allow the nurse to intervene early and thus reduce the risk of escalating responses that can lead to pathological changes. All neonatal nurses, as well as other care providers including parents, should be able to recognize stress behaviors in both preterm and term infants and respond appropriately to protect the infant from further stress. Assessment before, during, and after all caregiving and procedures is critical for establishing the infant's baseline, determining if the infant can tolerate a procedure at that time (if the procedure is a nonemergency), monitoring the infant during the procedure or caregiving activity, and assessing recovery afterward. Nurses should also understand techniques to reduce stress and collaborate with families and other care providers to identify which strategies are most effective for that infant at that stage of an infant's development.
Monitoring of behavioral and physiological cues during assessments by other care providers is best accomplished by collaboration of the neonatal nurse and the examiner to determine the following parameters of a neurological or other assessment:
Timing: schedule after a rest period, not after imaging, medical, or clustered care procedures; 30 minutes before feeding
Duration: depending on infant stress and responsiveness, separate the assessment into shorter sessions on consecutive days
Infant state and color: interpret drowsy behavior in preterm infants as probable withdrawal from an overstimulating encounter; identify mottled skin color as an early sign of decreased peripheral perfusion
Infant motor disorganization: recognize finger splay and arm salute postures as signs of emerging physiological stress
Infant physiological values: monitor heart rate and mean arterial pressure as more sensitive physiological measures than respiratory rate during evaluative handing
Infant autonomic signs: note hiccoughs and yawns as indicators of stress and as signals for a short break or rescheduling of the assessment.
Inclusion in the discharge evaluation process may be the optimal time to conduct neonatal neurological assessment when infant stability and maturation contribute to reliability of findings. The interpretation of neurological assessment results from a discharge examination may guide decisions for frequency of interdisciplinary outpatient follow-up and timing for developmental intervention referrals.
Limitations
Generalization of the data to other neonatal populations is limited because stratification of subjects according to national census statistics did not occur, and the available population was selected rather than randomized within each gestational age group. While consistency in evaluative handling was maintained for all subjects in both experiments, an examiner with less than or more than 15 years experience might elicit different physiological and behavioral responses from newborn subjects. The generalizability of the findings to practitioners with minimal neonatal examination experience is questionable.
Although the small number of African American infants (8 in experiment 1; 8 in experiment 2) were evenly divided between preterm and full-term groups, the assessment of skin-related color changes was difficult in African American participants. Higher proportionate percent of normal color was observed in African American than in Caucasian subjects. The reported color changes during evaluative handling might have been more frequent if African American infants were excluded from the study or if the data collectors had additional, in-depth training on the observation of subtle color changes in African American infants.
Unfortunately, the unreliability of pulse oximetry related to motion artifacts occurred consistently when the newborn subjects moved spontaneously or were being moved by the examiner during the neurological assessment protocol in the pilot phase. The measurement of oxygen saturation was therefore excluded from the methods for both experiments.
Future research
In future investigations, design changes may be explored to expand this study. Physiological and behavioral analyses of infant tolerance to specific neuromotor and neurobehavioral items are needed to target, quantify, and exclude highly stressful examination items for fragile infants. Random order of neuromotor and neurobehavioral subtests could be implemented to further evaluate the pattern of stress in newborn subjects during neurological testing and provide data to examiners on the least stressful sequencing of the subtests. Inclusion of brief intervals for measurement of oxygen saturation are recommended before and after each phase and neurological assessment subtest. A third group of matched preterm infants at 40 weeks postconception could be recruited to explore physiological and behavioral maturation-related resiliency or ongoing vulnerability during neurological assessment procedures. Similarly, the vulnerability of neonates with a late preterm birth (gestational age of 34 weeks, 0 days to 36 weeks, 6 days) could be investigated and compared to physiological and behavioral response patterns of the participants in this study.
Further understanding of how infants at varying gestational ages respond behaviorally and physiologically to caregiving and other procedures is critical to guide neonatal teams. Further delineation of the order in which infants express stress cues is needed to expand evidence reported by Peters64 that infants expressed motor cues (extremity extension movements) before negative physiological events (>2 standard deviation changes in heart rate or oxygen saturation levels) during a routine bathing procedure. This line of expanded study is needed on the sequencing of both physiological and behavioral cues of newborn infants before, during, and after caregiving and medical procedures.
Clinical research on effects of presumed benign handling and neonatal caregiving procedures is critical. The use of single-subject research designs with replication across subjects and across neonatal care units may be more practical and expedient for clinical researchers than group designs. Comparisons of neonatal stress responses between neonatal neurological assessment and routine nursing caregiving episodes have not been conducted. Investigation of the potential risks and presumed benefits of neonatal examinations, care procedures, and developmental interventions must be continued to protect vulnerable neonates and to guide neonatal teams.
CONCLUSIONS
An inverse relationship between gestational age and tolerance to evaluative handling indicated that the physiological and behavioral cost of neurological assessment was greater for preterm than for full-term infants. These data represent a pattern of physiological and behavioral vulnerability in medically stable, preterm infants less than 34 weeks of gestation from evaluative handling during a neurological assessment. Behavioral responses and heart rate or blood pressure were more sensitive indicators of physiological stress than respiratory rate. Withdrawing to less alert states, rather than crying, was a marker of preterm infant stress during evaluative handling.
The relative benefit and safety of neurological assessment must be questioned for medically unstable or borderline-stable neonates. Neonatal nurses and other team members must scrutinize the presumed diagnostic benefit of neurological assessment, given the expected physiological and behavioral changes, particularly during the assessment of tone, posture, and reflexes.
References