Study of Minute Ventilation, Maximum Voluntary Ventilation and Dyspneic Index During Pregnancy: An Observational, Prospective and Comparative Study

Abstract

Introduction This study was designed to evaluate the Minute ventilation (MV). Maximum Voluntary Ventilation (MVV) & Dyspneic Index (DI) in different trimesters of pregnancy and compare the results with non pregnant control group. Materials and Method This study was carried out in 80 healthy women in the age range of 20–40 years with 20 subjects each in 1st, 2nd, 3rd trimesters of pregnancy and non-pregnant control group. The respiratory parameters were recorded in study and control groups. Statistical analysis was done by SPSS Software Package. Results It was observed that there was a significant decrease in MVV and dyspneic index (DI) in all trimesters of pregnancy and an insignificant variation in MV when compared to the control group. These changes are due to pressure of enlarging gravid uterus, elevating the diaphragm and restricting the movements of lungs thus hampering forceful expiration. The decrease seen in MVV in 1st trimester might be due to the effect of bronchoconstriction due to decreased alveolar Pco2. Conclusions Decrease in respiratory parameters was seen particularly in first trimester of pregnancy compared to 2nd & 3rd. The normal Minute Ventilation tries to maintain the respiratory need of pregnancy at rest. At increased physiological needs of respiration or during exercise the decreased Maximum Voluntary Ventilation makes pregnant female dyspneic.