Table 5 presents the details of the three clinical studies52–54 that reported no change in outcomes after developmental interventions. Of these three studies, one study was rated level 1 and the remaining two studies were rated as level 2.
Much of the evidence supports the physical therapist’s role as a member of the interdisciplinary team that provides developmental intervention. Some of the evidence showed no significant effect on development after starting early physical therapy intervention in the NICU. It is important to note that none of the articles reviewed reported negative effects as a result of developmental intervention.
The following is a discussion of interventions that can be implemented by interdisciplinary team members including physical therapists. The effects of developmental intervention on the infants and the strength of the evidence for those interventions are also discussed.
Developmental Techniques Used in Promoting Infant Organization
Developmental intervention encompasses specific procedures used to minimize the infant’s stress and also techniques used to promote infant organization. The literature provides evidence of stimulation and handling techniques. Tables 3 through 5 show that most of the research studies reviewed used more than one intervention simultaneously. This makes it difficult to determine which treatment technique is the most effective.
One purpose of handling techniques is to provide proper positioning of the infant. Positioning procedures include promoting the prone position or using towel rolls to maintain flexion while the infant is side-lying. In addition to trunk flexion, authors suggest that the baby’s hands should be brought to midline to enable the hand to reach the mouth for self-consoling behavior.13,24 A study by Bozynski et al49compared transcutaneous oxygen and carbon dioxide levels in intubated infants when placed in right side lying, left side lying, and supine. No significant differences were found, but no detrimental effects were found either. Side lying was reported to provide more options for positioning in flexion. Benefits of prone positioning were reported to include improved oxygenation, increased quiet sleep, improved respiration and heart rates, and reduced incidence of reflux. All these are believed to be beneficial for promoting development.4,14 White-Traut et al44 showed that infants with neurologic injury may have delayed development of the autonomic system. They recommended that handling techniques be adjusted to avoid excessive increases in heart rate.
Additional techniques for promoting behavioral organization have been cited in the literature. These include providing swaddling and containment with blanket rolls to provide “nesting”;4,12–14,16,24 decreasing handling when the infant displays signs of stress;12,16 bundling care procedures together to provide longer periods of sleep;4,12,13,16 providing nonnutritive suckling with a pacifier, which helps to both progress the infant to bottle feed faster and to decrease energy expenditure through decreased crying;4,12–14 and promoting social interactions when the child is awake.4,16
Nurses typically provide most of the interventions mentioned thus far. Nurses, parents, or other interdisciplinary team members including occupational or physical therapists can employ additional interventions. These include sensory techniques such as auditory, kinesthetic, tactile, vestibular, and visual stimulation. Table 6 provides a summary of these techniques and presents the strength of the evidence for each sensory treatment or intervention. In general, sensory techniques were implemented similarly in each study. Subtle differences were noted in operational definitions of sensory technique as found in Appendix 2.
The evidence from the literature supported the importance of parental involvement and family education. Appendix 3 summarizes the content and method of family involvement.
Effects of Developmental Intervention on Infants in the NICU
The articles reviewed supported the effectiveness of developmental intervention. The benefits fall under three main categories: medical outcomes, cost-effectiveness, and infant growth and development.
Medical benefits of developmental intervention include improved oxygenation and faster weaning from supplemental oxygen.14,17,35–37 Infants were able to progress faster to bottle feeding14,17,35,37,42 and showed better outcomes in growth indicators such as weight gain, height and head circumference.17,35,39 They also had improved medical status with fewer complications.14,17,35,40
Treated infants had fewer complications, grew faster, and progressed quicker. Consequently, they could be discharged home sooner. Shorter length of hospitalization14,17,35,37,42 resulted in lower nursing cost and improved cost-effectiveness.14,17,35,37,40
One outcome measure reflective of progress in developmental milestones is state of arousal or the infant’s ability to regulate his/her sensory systems. Infants who received developmental intervention were able to show faster improvement in these measures.35,36,42,43 During hospitalization, and even after discharge, these infants demonstrated improved performance on developmental outcome indicators such as vital signs,36,39 growth measures35,39,41 and motor performance.14,17,33–37,39,47 They continued to show better performance on outcome indicators when they reached school age, as measured by IQ, social competence, and behavior5,7,41
The evidence supported many benefits from implementing a developmental approach in the NICU. However, other evidence provides room for discussion. Three studies showed no significant differences in infants who received developmental intervention. While they do not cite any harmful side effects in the infants, they raise questions as to the effectiveness of the intervention. Two of the three found that infants who started intervention early in the NICU had no difference in outcome measures compared to infants who started treatment when they were older52,54 (Table 5). Another study noted maternal socioeconomic factors as an obstacle to carrying over the techniques.53 The question remains, when is the most effective time for intervention to begin?
Strength of the Evidence for Implementing Developmental Intervention
The impact of evidence is lost if findings are not integrated into treatment. The rating scale used in this paper determined which studies offered stronger evidence of practice. The scale primarily addressed study design, subject assignment, and sample size. However, other issues of internal and external validity were also considered.
Issues of internal validity pertinent to the reviewed articles included the individual’s medical-surgical history or hospital course and control of the interventions. Infants who are born prematurely have a variable medical course. The history of each subject in a longitudinal study is a difficult variable to control. Hence, interventions lose their strength because the improvements may have occurred with the passing of time alone. In some studies, nurses who were trained to execute developmental intervention techniques were also responsible for treating infants in a control group. Environmental modifications appropriate for the intervention group may have also been unintentionally applied to control infants, thus biasing the results. Attempts were made to avoid these threats to internal validity by putting the treatment group in a different room or having interventions begin after the control group was discharged from the hospital.
Issues of external validity include the ability to generalize the outcome to the population, selection of the population, exposure of subject to multiple simultaneous treatments, and the description of the experimental intervention. Many of the studies had comparable inclusion criteria for the gestational age of subjects. But birth weight criteria varied from study to study, making it difficult to compare results between studies. In addition, publication bias is an important factor to consider. Authors may choose not to submit a paper for publication if their study results do not support the initial hypothesis.
Two articles by White-Traut et al42,43 showed good internal validity by controlling the variables of the study design. However, their gain in internal validity further compromised the external validity of these studies. In addition, these studies were weakened by the small sample sizes (N = 25 and 42, respectively).
These two articles provide important evidence that techniques can be offered simultaneously and with great effect. For example, after comparing auditory, tactile, visual, and vestibular stimulation, White-Traut et al42 found vestibular stimulation is a potential moderator of the rapid heart rate response found with tactile stimulation. In clinical practice, physical therapists frequently use multisystem stimulation. Time spent simply rocking the infant during the treatment session can provide vestibular stimulation while potentially minimizing heart rate elevation. Another finding was that the infants who had vestibular stimulation added to the treatment had increased state of arousal after the end of the session. The conclusion was that vestibular stimulation may offer the benefit of increased infant organization.
The second article by White-Traut et al43 also supported the importance of multimodal stimulation. Providing nonnutritive sucking (ie, pacifier) can be beneficial for increasing and organizing the infant’s state of arousal. The infant then may be able to focus on other forms of stimulation (ie, visual) more effectively.
The degree of detail given in the description of the interventions was variable among the studies reviewed. Some of the articles gave details of the intervention, enabling practitioners to reproduce the intervention. The study by Kelly et al10 monitored physiologic responses of infants born prematurely to tactile stimulation in side-lying and supported sitting positions. Specific information is given on therapist hand placement and degrees of movement for each position. Other authors gave no description of the intervention such as the report by Brown et al.53
Of the 26 articles reviewed, only three studies demonstrated a high level of scientific rigor (level 1). Two of the level 1 studies found statistically significant differences between those infants receiving developmental intervention compared to those without intervention. The third study by Piper et al52 found no statistically significant difference between the infant groups at their 12-month follow-up assessment. Thus, it is apparent that there is very little literature available that provides evidence of the effectiveness of developmental intervention in the NICU. This includes the lack of evidence regarding specific physical therapy interventions. In addition, significant differences in inclusion/exclusion criteria, operational definitions of terms, and training levels of caregivers/researchers limit general comparisons of results and weaken possible recommendations for clinical application.
The paucity of well-designed pediatric outcomes research including the NICU setting has been addressed elsewhere. In a recent review, Forrest et al55 conclude that outcomes research in pediatric settings is lacking “depth in any single content area.” Their review of 39 articles published between 1994 and 1999 in peer-reviewed journals revealed that more research is needed to evaluate the effectiveness of management and services for the pediatric population.
Any research done with this population has inherent challenges. There is the ethical limitation of needing a control group that has treatment withheld. Also, the physical therapist must have the cooperation of the interdisciplinary team. This is difficult as interventions may be perceived as an interruption to routine care. If nurses are recruited for assistance, there is a risk of contaminating the control group with treatments depending on staffing assignments.
The sample size was a limiting factor in many articles. A multicenter trial that focuses on functional outcome indicators of infants born prematurely would provide results that may be more easily generalized to the population.. Studies should focus on unimodal treatments to determine which one is more effective than another. Finally, the skill level of the physical therapist providing the intervention should be standardized. Following the criteria set forth in the Practice Guidelines for the Physical Therapist in the NICU is one way of providing a more consistent level of proficient intervention.56
The Guide to Physical Therapy Practice11 under the neuromuscular practice pattern defines what is within the scope of the physical therapist’s practice. Many of the techniques addressed in the Guide are cited in the studies reviewed in this paper. Consequently, these aspects of physical therapy practice fall under the umbrella of developmental intervention.
Although rigorous study of specific techniques used in a program of developmental intervention is still warranted, there is good evidence that infants progress toward matching the development of their full-term counterparts earlier if they receive appropriate intervention. Physical therapists who practice in the NICU setting should feel empowered that what they do contributes to supporting the development of the premature infant. Several studies have been reported in the literature, yet larger, randomized controlled studies are still needed to contribute to the body of evidence related to the individual interventions.
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APPENDIX 2: Description of Sensory Techniques
Nurses sang or talked to the infant while they were bottle feeding or the researcher spoke to the infant during treatment.38, 42, 43
Playing cassette recordings of human heartbeat, classical music, or the parent’s voice.34
One article listed auditory stimulation as an intervention but gave no specifics on the method of delivery.53
Kinesthetic stimulation was specifically defined in this article as having nurses hold the infant while sitting in a rocking chair and attempting to promote eye-to-eye contact during feeding and play time.38 Passive range of motion exercises.34
“Baby massage” defined as tactile-kinesthetic stimulation.39
Specific intervention activities to facilitate midline orientation and facilitation of trunk flexion in side-lying and supported sitting positions.10
Nurses provided “soothing and rubbing” during feeding.38
Researcher or nurse provided massage for 10 minutes or other methods, which did not specify time limits.34,42,43
No specific technique given except that nurses patted the babies during feeding.41
“Baby massage” defined as tactile-kinesthetic stimulation.39
Specific intervention activities to facilitate midline orientation and facilitation of trunk flexion in side-lying and supported sitting positions.10
Observer sat next to the isolette and recorded the tactile experience of the baby, both self-generated by reaching and externally generated by family, nursing care procedures, etc.
No specifics except that tactile (including oral) stimulation were provided.53
Researcher provided five minutes of rocking.42,43
Nurses held the infant while sitting in a rocking chair during feeding and play time defined in another article as part of kinesthetic stimulation.38
Use of an insulated water mattress.34
No specifics for vestibular stimulation given.53
Attempting to make eye contact with the infant.42,43 Note: This was also defined in another article38 as part of kinesthetic stimulation.
Placing pictures of faces, mobiles, and color patterns in the warmer or isolette.34,38
Provided visual stimulation by taking birds from a mobile and placing them about nine inches away from the baby.41
Assessment of the baby’s facial behavior, visual fixation, and rating of measures of attention while they focused on a pattern.50,51
No specifics for visual stimulation given.53
Parents were educated in and expected to carry out the developmental intervention home program.33,54
Education in the Infant Development Program.34
Parents educated infant behavioral organization and how to modify interaction to decrease stress levels.5,34,41
Promoting parental involvement in the care of the infant.35, 37, 47
Education of the parent in specific handling, positioning, and stimulation techniques.52,53
Keywords:© 2005 Lippincott Williams & Wilkins, Inc.
infant; premature; infant care; treatment outcome; developmental disabilities/prevention and control; physical therapy/methods; review