Influência do peso adicional e da prematuridade tardia no alcance de lactentes
Toledo, Aline Martins de
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Reaching behavior is an important motor skill because its emergence is one of the first phases of the voluntary motor development during childhood. However, few studies have shown how intrinsic (such as prematurity) and extrinsic factors (such as additional weight) influence this ability. Objectives: This study has as main objectives: 1) to analyze the development of categorical reach variables in preterm and full-term infants, 2) to verify the effect of additional weight attached on the wrists of preterm infants, 3) to verify the need for age correction in the reach of preterm infants. Methods: This study evaluated longitudinally 9 preterm infants aged 5-7 month with mean gestational age of 35.6 (± 0.5) weeks and 10 full-term infants with mean gestational age of 39 (± 0.73) weeks. Both groups had normal birthweight and Apgar score above 7 in the first and fifth minutes. Categorical and kinematic reach variables were analyzed. The categorical variables analyzed were: a) proximal adjustments: unimanual and bimanual b) distal adjustments: hand orientation (vertical, horizontal or oblique), hand classification (open, closed and semi-open), c) grasping: successful and unsuccessful grasping. The kinematic variables measured were: a) mean velocity (MV): ratio between distance traveled and time spent in movement b) movement unit (MU): phase of acceleration and deceleration of the movement during the trajectory; straightness index (SI): ratio between the distance traveled by the hand and the smallest distance that could be traveled on this path. To meet the objectives, three studies were developed for this PhD thesis. Results: Study I was aimed at investigating the development of proximal and distal adjustments of the reach of low-risk pre-term infants in the age group of 5-7 months. The categorical reach variables were analyzed. It was observed that the unimanual reach frequency was greater than the bimanual reach throughout the study period, with no difference between ages in both groups; the frequency of vertical orientation of the hand increased significantly from the 6th to the 7th month in the preterm group and from the 5th to the 7th month in the full-term group; the increased frequency of open hand and decreased frequency of semi-open hand were significant from the 5th to the 7th month in the preterm and full-term groups; the frequency of successful grasp increased from the 6th to the 7th month in preterm and full-term groups. A higher frequency of open hand was found in the preterm group at the 6th month compared to the full-term group between groups. Study II aimed to determine the influence of additional weight and its immediate removal on the reaching of low-risk preterm infants at the age group from 5 to 7 months. The kinematic variables and the grasping were analyzed. It was found that additional weight has reduced the straightness index at the age of five months, increased the mean velocity and decreased the movement units in all age groups and increased the frequency of reaches without grasp at 5 and 7 months. The post-weight reduced the straightness index at the age of 5 months and increased the movement units at 6 and 7 months. Finally, study III aimed to assess the reach of low-risk preterm infants at corrected and chronological ages in order to determine the need for age correction to evaluate the reaching behavior. Comparing the preterm group with chronological age with the full-term group, the former had lower speed, more movement units, hand more horizontal and higher frequency of unsuccessful grasp at 7 months of age. In the pre-corrected age, preterm infants showed lower speed than the full-term group, but with successful grasping. Conclusions: considering the intrinsic restriction imposed by prematurity (considering the corrected age of preterm infants), it seems that it was not enough to prevent the performance of the reaching task in the age group studied. When checking the extrinsic restriction caused by additional weight, it was found that it significantly influenced the reach parameters of preterm infants and these results could support future researches aimed at intervention techniques with the use of additional weight in infants at risk.