Efeito agudo da técnica de compressão lenta na modulação autonômica cardíaca de recém nascidos prematuros: um estudo quase experimental

Abstract

The lung squeezing technique (LST) is recommended and widely used in the physiotherapeutic assistance of premature newborns (PNB). It consists of the compression of one of the hemithoraxes, aiding the expiration in a slow and rhythmic way. The effects of this technique on the PNB autonomic nervous system (ANS) have not been established yet. To evaluate the autonomic modulation can use a simple noninvasive method that is the verification of the Heart Rate Variability (HRV). Therefore, the objective of this study was to analyze the effects of LST on the HRV of PNB. The study was carried out in a Maternity School in the city of Fortaleza - Ceará. The sample consisted of 37 PNB, of both sexes, with fifth-minute Apgar score ≥ 7, gestational age between 23 and 36 weeks, and which had indication for the performance of respiratory physiotherapy. PNB who presented conditions that could influence the ANS were excluded from the study. To measure HRV before and after the intervention, the Polar RS800CX heart rate receiver was used (Polar Electro OY, Kempele, Finland). LST was performed for 10 minutes, with 5 minutes applied to the left hemithorax and 5 minutes applied to the right hemithorax. For comparison between the moments before and after the intervention, Analysis of Covariance (ANCOVA) was performed, adjusted for possible confounding factors, such as gender, chronological age, gestational age, birth weight and resting heart rate. The level of significance was set at 5%, using SPSS Statistics, a software used for statistical analysis. The results obtained in the present study show that the LST produced an increase in the parasympathetic modulation, expressed by the elevation of indicators such as SD1 (p=0,000), RMSSD (p=0,0001), pNN50 (p=0,0001), HF (ms2) (p=0,0001) and HF (un) (p=0,042). The TINN index (p = 0.018), which reflect the overall variability, showed increase after the intervention. LST also produced a significant reduction in resting heart rate (p = 0.0001) and increased peripheral oxygen saturation (SpO2) (p = 0.019). The LST performed with respect to signs of pain and discomfort caused, in an acute way, the increase in the parasympathetic modulation and the global variability, which translates into the improvement of the functioning of the ANS. In addition, we also observed a decrease in heart rate and increase in SpO2, after the intervention.