Assessing parasympathetic measures of heart rate variability shortly after birth to predict motor repertoire at four months in low risk preterm infants born between 28 and 32 weeks of gestation.

In low risk preterm infants, the risk for mild to moderate neuro-motor impairment is extremely high. Additionally, the autonomic nervous system (ANS) function was also found to be impaired. ANS activity may predict neuro-motor development at four months corrected age. This study examines the predictive value of the ANS function in detecting neuro-motor impairments during the first 4 months of life among low risk preterm infants born between 28 and 32 weeks of gestation. 46 infants were recruited. For each infant, heart rate variability (HRV) measures were obtained at week born, 32- and 35-weeks postmenstrual age (PMA). The General Movement Assessment (GMA) and the Motor Optimality Score for 3- to 5- Month- Old Infants (MOS) were performed at 35 weeks PMA and at 4 months corrected age respectively. A significant correlation was found between the parasympathetic nervous system (PSNS) components of HRV and the MOS evaluation. Preterm infants with suboptimal MOS scores showed significantly lower HRV values in the components of the PSNS (0.01 < p-value <0.04). A weak correlation was found between the HRV and the GMA. A Receiver Operating Characteristic was designed and revealed the predictive validity of the PSNS in preterm infants with a suboptimal MOS score. The current study shows that among very preterm infants with no additional risk factors, the PSNS component of HRV can predict neuro-motor outcome at 4 months corrected age and may be used as an early sign for mild neuro-motor impairments in order to initiate an early intervention program.

Maturation of the cardiac autonomic regulation system, as function of gestational age in a cohort of low risk preterm infants born between 28 and 32 weeks of gestation.

OBJECTIVES: The maturation of the sympathetic nervous system (SNS) occurs steadily throughout gestation while the myelinated vagus has accelerated maturation periods, between 25 and 32 weeks of gestation and a further increase around 37-38 weeks of gestation. The aim was to quantify the cardiac autonomic regulation maturation, as a function of gestational age (GA) in a cohort of low risk preterm infants born between 28 and 32 weeks of gestation by assessing heart rate variability (HRV) at week 32, and at week 35 postmenstrual age (PMA). METHODS: Forty preterm infants were recruited, 24 h recordings of breathing rate and RR intervals were obtained at week 32 and week 35 PMA. RESULTS: A significant difference was noted between preterm infants born before 32 weeks GA and preterm infants born at week 32; the latter present higher HRV values throughout the follow-up period. No significant change over time was noted for the parasympathetic HRV measures while a significant increase was found in the sympathetic system. Moreover, a significant interaction effect of time and system was found, the increase in values of the sympathetic system over time was significantly larger than the change noted in the vagal HRV measures. CONCLUSIONS: Given the beneficial influence of vagal tone on health and developmental outcomes in preterm infants, the findings of the current study highlight the need for further studies on the impact of specifics gestational age on vagal development and later assessing interventions associate with its continue development and maturation at these specific periods.

Early cycling test as a predictor of walking performance in stroke patients.

BACKGROUND AND PURPOSE: To assess the relative contribution and the predictive value of an early cycling test to walking performance three months after stroke. METHOD: This follow-up study included subjects who were inpatients after afirst stroke (n=44). A cycling test was performed at the beginning of rehabilitation, followed by three-months' post-stroke evaluation of walking performance. The independent variables were the ability to cycle at constant rhythm of 50 rpm, without and with resistance, lower extremity motor strength and walking function, scored by the Scandinavian Stroke Scale. Dependent variables were gait velocity, distance and stair-climbing three months after stroke. RESULTS: Multiple linear regression analysis demonstrated that rhythmic, constant cycling is the best predictor of walking velocity (r2 = 0.4), gait distance (r2 = 0.2) and number of stairs climbed (r2 = 0.26). Lower extremity motor strength and walking function had no additional separate contribution to the prediction of study outcomes. CONCLUSIONS: The inability to cycle at a constant rhythm for one minute, two weeks after stroke is a more significant predictor than lower extremity motor strength or walking function of walking performance at three months post-stroke.