Evaluation of Peak Expiratory Flow Rate in Pregnancy in a South Indian Tertiary Care Centre

Background: Pregnancy is a physiological state causing significant physical and functional changes in Cardiovascular and Respiratory system. It is important to recognize the adaptive changes during pregnancy in order to identify and manage Respiratory impairment. The Respiratory system undergoes structural and functional alterations affecting the thoracic cage, abdominal cavity and diaphragm. There is a decrease in Functional Residual Capacity (FRC), Expiratory Reserve Volume (ERV), Chest wall Compliance & increases in Tidal Volume (TV), Minute Ventilation (MV) during pregnancy. However, Airway function is postulated to largely remain unchanged during pregnancy with Peak Expiratory Flow Rate (PEFR), FVC and Forced Expiratory Rates like FEV1 showing little change. Hence, PEFR which is a simple, portable, cheap and reproducible parameter can be utilized to assess airway function during pregnancy. Due to conflicting reports of PEFR with advancing gestation in different ethnic groups and limited studies in the South Indian population, the present study was undertaken to evaluate the PEFR variation in different trimesters of normal pregnancy. Aim: To Evaluate the Peak Expiratory Flow Rate in Pregnancy in different trimesters. Materials and methods: Total of 165 pregnant women in the age group of 20-35 year with no respiratory illness or co morbidities (55 in each trimester) were included in our study. Control group consisted of 55 age and height matched non pregnant women. Informed consent was obtained and PEFR was performed using Mini Wright s Peak Flow Meter and best of three recordings noted. Data analyzed using SPSS package version 21.0. Association between PEFR with Age and BMI performed using Pearson correlation. The Bonferroni's Multiple Comparison Test executed to determine the significant variance of PEFR between control and study groups. Results: PEFR was significantly lower in all trimesters of pregnancy compared to controls. However, there was no significant difference in PEFR across trimesters. Age and BMI did not correlate with PEFR. Conclusions: PEFR was significantly lower in all trimesters compared to controls. Hence, prospective Indian studies with larger samples are needed to arrive at Normograms for PEFR in each trimester of normal pregnancy which would enable us to use PEFR as a simple tool to assess airway obstruction in pregnancy.