V1.i · Obstetric Physiology

This viva will explore your knowledge of maternofoetal physiology. This is a normal blood gas of a pregnant woman at term breathing room air. Outline the changes and explain their physiological basis. pH 7.45 pO2 105 mmHg pCO2 30 mmHg HCO3- 20 mmol/L BE -2

This viva will examine respiratory changes in pregnancy. The figure below depicts the expected changes in oxygen saturation when individuals are pre- oxygenated prior to intubation. Explain why pregnant patients desaturate so quickly. (Image removed from report.)

This Viva tested knowledge on obstetric and neonatal physiology. It explored the cardiovascular changes in pregnancy, factors that influence gas exchange across the placenta, the changes with the first breath and went on to aspects of humidity.

This Viva will examine maternal physiology and pharmacology. Write down the expected values in an Arterial Blood Gas for a pregnant woman at term. Subsequent discussion involved respiratory changes with pregnancy, including spirometry, pharmacology of drug transfer across the placenta, pharmacology of syntocinon and ergotamine.

This Viva relates to the respiratory changes of pregnancy at term, hypoxaemia and the foetal circulation. Q 1. Describe the respiratory changes in pregnancy at term. Subsequent questions sought a description of ABG at term pregnancy, physiological mechanism to explain an increased A-a gradient, causes of a low PaO2 in a patient with a normal A-a gradient, the response of hypoxemia to supplemental O2 when the A – a gradient is normal and when abnormal, and a description of the foetal circulation and the changes that occur at birth.