2018.2 SAQ 5 – maternal CVS changes in pregnancy

SS_OB 1.1  Describe the physiological changes and their implications for anaesthesia that occur during pregnancy, labour and delivery, in particular the respiratory, cardiovascular, haematological and gastrointestinal changes
SS_OB 1.5  Describe the mechanism and consequences of aorto-caval compression in pregnancy

Answers to the following statements can be found in Kam & Power, and Miller.

T / F  there is no appreciable increase in HR during the first trimester

T / F  at term, the HR increases by at least 15%, and CO by about 50%

T / F  at term, utero-placental blood flow is about 750 mL/min – this increases the maternal SVR

T / F  maternal red cell volume increases by 20% at term – this increases maternal haemoglobin by a similar value

T / F  the risk of aortocaval compression is present from about 30 weeks gestation onwards

T / F  maternal CO and BP return to normal by about 2 weeks post delivery

SS_OB 1.4 Describe the utero-placental circulation and the principles of placental physiology as related to placental gas exchange and regulation of placental blood flow.

Uteroplacental blood flow at term is approximately 1125mL/min TRUE/FALSE

The utero-placental arteries have alpha-adrenergic receptors. TRUE/FALSE

The greatest driving force for diffusion of oxygen from maternal to foetal blood is the Bohr effect. TRUE/FALSE

The Haldane effect facilitates oxygen transfer from the mother to the foetus. TRUE/FALSE

The foetus has foetal haemoglobin which has a greater affinity for oxygen than adult haemoglobin. TRUE/FALSE

Aortocaval compression

SS_OB 1.5 Describe the mechanism and consequences of aorta-caval compression in pregnancy

In supine hypotensive syndrome, blood still returns to the right heart through the epidural, azygos and vertebral veins. TRUE/FALSE

Supine hypotension is compensated by an increase in peripheral sympathetic activity. TRUE/FALSE

The blood pressure measured in the arms, is a reliable predictor of uterine and placental blood flow, when the patient is supine. TRUE/FALSE

Aortocaval compression can reduce uterine perfusion due to reduced uterine venous pressure. TRUE/FALSE

General anaesthesia has no effect on supine hypotensive syndrome. TRUE/FALSE

 

Obs, Obs, Baby.

SS_OB 1.6 Describe the changes in the anatomy of the maternal airway and their impact on airway management during anaesthesia.

SS_OB 1.1 Describe the physiological changes and their implications for anaesthesia that occur during pregnancy, labour and delivery.

The increased risk of airway bleeding during manipulation is primarily due to platelet dysfunction in pregnancy. TRUE/FALSE

Lung compliance decreases in pregnancy. TRUE/FALSE

Closing capacity increases during pregnancy. TRUE/FALSE

Oxygen consumption is increased at term, regardless of whether the patient is in labour or not. TRUE/FALSE

Airway oedema can occur due to venous engorgement from labour. TRUE/FALSE

Neonatal circulation

SB_OB 1.3 Describe the transition from foetal to neonatal circulation and the establishment of ventilation.

At birth, the circulation changes from parallel to in series. TRUE/FALSE

Delivery of the neonate causes a reduction in flow through the IVC to the right atrium. TRUE/FALSE

The newborn’s ventricle is less compliant than an adult’s due to a lower proportion of non contractile proteins in the myocardial cells. TRUE/FALSE

Pulmonary vascular resistance falls at birth due to decreasing pH TRUE/FALSE

The neonatal circulation can revert back to the pattern of foetal circulation if there is pulmonary vasoconstriction. TRUE/FALSE

SS_OB 1.7

SS_OB 1.7 Describe the changes in the anatomy of the maternal vertebral column, the spinal cord and meninges relevant to the performance of a central neuraxial block including epidural, spinal and combined spinal-epidural, with appropriate surface markings

 

TRUE/FALSE  The risk of inadvertent venous puncture, with epidural placement in pregnant women, is the same as in the non-pregnant population

TRUE/FALSE  The line joining the iliac crests (Tuffier’s line) may transverse the body of L5 in late pregnancy

TRUE/FALSE  Epidural space pressure may be positive during labour

TRUE/FALSE  Epidural veins are engorged in late pregnancy

TRUE/FALSE   The ligamentum flavum softens during pregancy

Obstetrics and the primary exam

SS_OB 1.1

Describe the physiological changes and their implications for anaesthesia that occur during pregnancy, labour and delivery, in particular the respiratory, cardiovascular, haematological and gastrointestinal changes.

SB_

Normal physiological changes begin in the first trimester of pregnancy. TRUE/FALSE

The largest increase in cardiac output in a pregnant woman occurs immediately after delivery. TRUE/FALSE

The closing capacity in normal pregnancy does not change. TRUE/FALSE

Gastrin is secreted by the placenta TRUE/FALSE

Progesterone from the gestational sac may cause changes in the renin-angiotensin-aldosterone system in the first trimester, promoting sodium absorption and water retention. TRUE/FALSE

Hats off to those of you who sit this exam pregnant!

 

 

 

SS_OB 1.2

Keep the dream alive! Read “Primary LO of the Day”.

Outline the reference ranges for physiological and biochemical variables in pregnancy

Uterine blood flow is approximately 20% of maternal cardiac output at term gestation TRUE/FALSE

Maternal hyperventilation facilitates removal of CO2 from the foetus TRUE/FALSE

Antithrombin III and factor XIII are decreased in pregnancy TRUE/FALSE

Haemoglobin concentration and total red cell mass are decreased 15-20% in pregnancy TRUE/FALSE

The word “glidescope” is pronounced the same as “kaleidoscope” TRUE/FALSE