Date of Award

1-1-1999

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

Nursing and Public Health

Faculty

Faculty of Communications, Health and Science

First Advisor

Prof. Linda Kristjanson

Second Advisor

Dr. Sharon Evans

Third Advisor

Prof. Joan Cole

Abstract

The prone position is used routinely in neonatal intensive care units worldwide in the nursing of preterm infants because of reported beneficial psychological effects This position can, however, lead to development of flattened posture very low birthweight (VLBW) infants and contributes to both short and longer term implications for functional motor development of upper and lower extremities. To date limited research has been undertaken to investigate methods of reducing flattened posture and its related negative outcomes temperature instability is also a problem for VLBW infants and no nappy exists that meets postural size and thermoregulation requirements. The purpose of this study was to demonstrate the effect of a nursing care model designed for the primary prevention of neuromotor problems and temperature instability in VLBW infants. The theoretical framework was based on two bodies of knowledge thermoregulation and neuromotor development. A two phase study was used to test two hypotheses: (1) use of a cloth postural support nappy (N) with an inner absorbent nappy liner would improve temperature stability in VLBW infants nursed in incubators on infant servo control (ISC): and (2) use of a postural support roll (R) with or without a N would improve neuromotor development in the short and longer term. In Phase1 a sample of 23 infants < 31 weeks gestation nursed in incubators on ISC was recruited over two months to a randomised, observer blind, crossover trial infants were randomised to commence wearing either a N with or without an inner absorbent liner and alternated wearing each nappy for a 24 hour period over four days. Eight hourly per axilla (PA) temperatures and hourly measurements of infant handling, skin and incubator temperatures were recorded. lnfants in both groups were well matched for birth and postnatal variables. Findings showed that nursing infants in a N with an inner absorbent liner experienced clinically and statistically significant higher skin and lower incubator temperatures. In addition, a prediction model for PA temperature was developed that showed it was possible to predict PA temperatures from skin temperatures. In Phase 2. a sample of 123 infants < 31 weeks gestation was recruited to a randomised, observer blind, controlled trial. Infants were randomised to one of three treatment groups (i.e., N only, N and R, or R only). Measurements of neuromotor development were performed at three assessment periods (i.e., from birth to term conceptional age, then at four and eight months conceptional age). Randomisation was effective. Findings confirmed previous study findings that use of a N improves hip posture up to term conceptional age. The major finding was that use of a R while VLBW infants are nursed in the prone position in a NICU improved hip and shoulder posture up to eight months conceptional age. In addition, an Infant Posture Evaluation Tool (IPAT) was developed that will enhance the clinical skills of health Professionals involved in the care of these infants. The findings contribute to neonatal nursing theory development in thermoregulation and neuromotor development and function in VLBW infants. Practice implications focus on promoting temperature stability and normal neuromotor function in VLBW infants up until eight months conceptional age. Longer term research will determine the effect of postural interventions on gait and foot progression angles. Testing and validation of the IPAT will facilitate future research related to infant posture.

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