Peak flow measurement in the woman
This chapter overviews care in relation to taking a peak flow reading. The chapter explores principles of professional practice when supporting a woman to take a peak flow reading; it also provides a step by step approach to peak flow measurement.
Healthcare practitioners have an important role in promoting evidence-based practice and understanding the physiological basis of care is an essential professional accountability. As the result of hormonal, biochemical and skeletal adaptations in childbirth, the maternal respiratory system undergoes significant adaptations during pregnancy and childbirth. Progesterone is known to affect the biochemical function of the respiratory centre by regulating metabolic processes through detection of carbon dioxide and increasing arterial oxygen uptake. In addition, the effect of progesterone and relaxin on intercostal muscle elasticity enhances mechanical skeletal changes such as the displacement of the diaphragm and ribcage by the gravid uterus.
Usually, physiological changes to the respiratory system during childbirth do not cause any serious complications. However, in some cases midwives are supporting women who may experience an exacerbation or acute onset of respiratory pathology. National clinical guidance identifies the importance supporting those with asthma, a chronic long-term disease of the respiratory tract. Furthermore, the Confidential Enquiries into Maternal Mortality reports have noted the importance of detecting and treating asthma in childbirth as it is an attributable cause of maternal deaths (De Swiet 2011).
Clinical assessments to measure respiratory function include the following: