Abdominal muscle electrical activity during labor expulsive stage: a cross-sectional study / Atividade elétrica muscular abdominal durante os esforços expulsivos do parto: um estudo transversal

BACKGROUND: During the second stage of labor, the progression of the fetal expulsion depends on many factors related to maternal and fetal parameters, including the voluntary abdominal pushing. OBJECTIVES: This study aimed to correlate the maternal and fetal parameters that may influence the voluntary maternal pushes during the second stage of labor by using surface electromyography. METHODS: The electromyographic activity of the rectus abdominis and external oblique muscles were measured during the second stage of labor in 24 Brazilian pregnant women. The diastasis of the rectus abdominis, the body mass index and the uterine fundal height were analyzed as maternal parameters and the fetal weight, cephalic circumference, APGAR scores and arterial pH and CO2 were analyzed as fetal parameters. The oxytocin usage and the expulsive phase duration were considered. RESULTS: A negative correlation between the rectus abdominis diastasis and the rectus abdomini muscle electromyographic parameters was found (r=-0.407 p=0.04). No statistically significant correlations were found among the rectus abdominis and external oblique muscles electromyography and the other maternal or fetal parameters, as well as among expulsive phase duration and the oxytocin usage. CONCLUSIONS: This study suggests that the rectus abdominis diastasis may be an influential parameter in generating voluntary pushes during the second stage of labor, however it cannot be considered the only necessary parameter for a successful labor.

CONTEXTUALIZAÇÃO: Durante o segundo estágio do parto, a progressão da expulsão fetal depende de vários fatores ligados a parâmetros maternos e fetais, dentre eles, o esforço abdominal voluntário. OBJETIVOS: Correlacionar os parâmetros maternos e fetais que podem influenciar os esforços voluntários durante a fase do segundo estágio do parto por meio da eletromiografia de superfície. MÉTODOS: As atividades eletromiográficas dos músculos retoabdominal e oblíquo externo foram medidas durante o segundo estágio do parto em 24 gestantes. A diástase do músculo retoabdominal, o índice de massa corpórea e a altura de fundo de útero foram analisados como parâmetros maternos, e o peso fetal, o perímetro cefálico, os índices de Apgar e o pH e pCO2 arterial foram analisados como parâmetros fetais. O uso de ocitocina e o tempo do período expulsivo foram considerados. RESULTADOS: Encontrou-se uma correlação negativa entre a diástase umbilical e os parâmetros eletromiográficos do músculo retoabdominal (p=0,04; r=-0,407). Não se encontrou correlação significativa entre a eletromiografia dos músculos retoabdominal e oblíquo externo e os demais parâmetros maternos e fetais, bem como entre o tempo do período expulsivo e o uso da ocitocina. CONCLUSÕES: O presente estudo sugere que a diástase umbilical pode ser um parâmetro influente na geração de esforços voluntários durante o período expulsivo do parto, porém não deve ser considerada de forma isolada para o sucesso do andamento do trabalho de parto.

Abdominal muscle electrical activity during labor expulsive stage: a cross-sectional study.

BACKGROUND: During the second stage of labor, the progression of the fetal expulsion depends on many factors related to maternal and fetal parameters, including the voluntary abdominal pushing. OBJECTIVES: This study aimed to correlate the maternal and fetal parameters that may influence the voluntary maternal pushes during the second stage of labor by using surface electromyography. METHODS: The electromyographic activity of the rectus abdominis and external oblique muscles were measured during the second stage of labor in 24 Brazilian pregnant women. The diastasis of the rectus abdominis, the body mass index and the uterine fundal height were analyzed as maternal parameters and the fetal weight, cephalic circumference, APGAR scores and arterial pH and CO2 were analyzed as fetal parameters. The oxytocin usage and the expulsive phase duration were considered. RESULTS: A negative correlation between the rectus abdominis diastasis and the rectus abdomini muscle electromyographic parameters was found (r=-0.407 p=0.04). No statistically significant correlations were found among the rectus abdominis and external oblique muscles electromyography and the other maternal or fetal parameters, as well as among expulsive phase duration and the oxytocin usage. CONCLUSIONS: This study suggests that the rectus abdominis diastasis may be an influential parameter in generating voluntary pushes during the second stage of labor, however it cannot be considered the only necessary parameter for a successful labor.

Inspiratory muscle endurance testing: pulmonary ventilation and electromyographic analysis.

This study analyzed regional pulmonary ventilation and electromyographic (EMG) activity of the respiratory muscles during an inspiratory muscle endurance (IME) test in 10 young women. Radioaerosol (99mTc-DTPA) was generated using a jet nebulizer connected to a linear inspiratory loading system. The lung scintigraphic analysis showed an increase in the radioaerosol deposition using loads of 20 and 30 cmH(2)O (p<0.01). The vertical gradient showed a larger radioaerosol deposition in the medium third of the lungs during the control period (p<0.001). There were larger amounts of radioaerosol deposition in the medium third when compared with the upper and lower third at 30 cmH(2)O (p<0.001). The horizontal gradient showed a larger deposition in the intermediate and central segments during all phases (p<0.00). Electromyographic activity from the muscles of the lower rib cage increased with loads of 20 and 30 cmH(2)O (p<0.03). There was an increase in deposition of radioaerosol when the load increased (r=0.584, p=0.000 for the left lung and r=0.609, p=0.000 for right lung). These findings suggest that during the IME test, EMG activity in the muscles of the lower rib cage increase during progressive respiratory workloads is associated with a greater radioaerosol deposition in the medium third and intermediate and central segments of the lungs.

Which pulmonary volume should be used in physiotherapy to obtain higher maximal inspiratory pressure in COPD patients?

BACKGROUND AND PURPOSE: Patients with chronic obstructive pulmonary disease (COPD) present pulmonary hyperinflation as the main cause of mechanical disadvantages in respiratory muscles. Measurement of the force generated by those muscles is converted into pressure changes. The aim of the present study was to evaluate the maximal inspiratory pressure (MIP) from the residual volume (RV) and from the functional residual capacity (FRC), in patients with COPD, and to determine which pulmonary volume should be used in physiotherapy so as to obtain higher MIP results. METHOD: An investigation of 18 male patients with stable COPD. Patients were examined using a manual vacuometer to measure the MIP of 20 daily manoeuvres. Ten measurements were taken from the RV and 10 from the FRC, taken alternately with an interval of 1 minute between each measurement, for five consecutive days. RESULTS: Increases in MIP were obtained from the RV measurements (mean +/- SE) from 59.7 (+/- 5.2) to 66.6 (+/- 5.3) cm H2O (F(4,64) = 3.34; p < 0.015) and from the FRC measurements, from 55.4 (+/- 4.9) to 64.4 (+/- 4,8) cm H2O (F(4,64) = 6.72; p < 0.001). Post hoc analysis showed an increase, over consecutive days, in both RV and FRC. For FRC, an increase was revealed on the second and third days, a fall was found on the fourth day and a new increase was found on the last day. MIP reached different levels, between RV and FRC, on the first (t = 2.888; p = 0.010) and fourth (t = 2.165; p = 0.045) days. CONCLUSION: In the present study, MIP reached higher levels at FRC during the five days of evaluation, and a learning effect occurred in the patients. Motor units from the respiratory muscles may have been recruited in order to perform the manoeuvres during the days of evaluation. The study suggests that there is good evidence for the use of the FRC as a parameter to find the major MIP value.