Cardiac Arrest in Pregnancy

Question 1

What are the causes of cardiac arrest in pregnancy?

Answer 1

The Resuscitation Council UK list the reversible causes of adult cardiac arrest as the 4 Ts and 4 Hs:

4 Ts:

• Thrombosis (i.e. PE or MI)
• Tension pneumothorax
• Toxins
• Tamponade (cardiac)

4 Hs:

• Hypoxia
• Hypovolaemia
• Hypothermia
• Hyperkalaemia, hypoglycaemia, and other metabolic abnormalities

The RCOG guideline advises adding to the list:

• Eclampsia
• Intracranial haemorrhage

Question 2

What are the three major causes of cardiac arrest in pregnancy?

Answer 2

The three major causes of cardiac arrest in pregnancy to remember are:

• Obstetric haemorrhage
• Pulmonary embolism
• Sepsis leading to metabolic acidosis and septic shock

Question 3

Give examples of causes of obstetric haemorrhage

Answer 3

Obstetric haemorrhage is a major cause of severe hypovolaemia and cardiac arrest. Remember the causes of massive obstetric haemorrhage:

• Ectopic pregnancy (early pregnancy)
• Placental abruption (including concealed haemorrhage)
• Placenta praevia
• Placenta accreta
• Uterine rupture

Question 4

Briefly describe the significance of aortocaval compression in cardiac arrest

Answer 4

After 20 weeks gestation, the uterus is a significant size. When a pregnant woman lies on her back (supine), the mass of the uterus can compress the inferior vena cava and aorta. The compression on the vena cava is most significant, as it reduces the blood returning to the heart (venous return). This reduces the cardiac output, leading to hypotension. In some instances, this can be enough to lead to the loss of cardiac output and cardiac arrest.

The vena cava is slightly to the right side of the body. The solution to aortocaval compression is to place the woman in the left lateral position, lying on her left side, with the pregnant uterus positioned away from the inferior vena cava. This should relieve the compression on the inferior vena cava and improve venous return and cardiac output.

Question 5

What factors make cardiac resuscitation more complicated in pregnancy?

Answer 5

Several factors make resuscitation more complicated in pregnancy:

• Aortocaval compression
• Increased oxygen requirements
• Splinting of the diaphragm by the pregnant abdomen
• Difficulty with intubation
• Increased risk of aspiration
• Ongoing obstetric haemorrhage

Question 6

In addition to the standard adult life support, what extra steps need to be taken in cardiac arrest of a pregnant patient?

Answer 6

Resuscitation in pregnancy follows the same principles as standard adult life support, except for:

• A 15 degree tilt to the left side for CPR, to relieve compression of the inferior vena cava and aorta
• Early intubation to protect the airway
• Early supplementary oxygen
• Aggressive fluid resuscitation (caution in pre-eclampsia)
• Delivery of the baby after 4 minutes, and within 5 minutes of starting CPR

Question 7

When is an immediate caesarean indicated in a pregnant woman?

Answer 7

Immediate caesarean section is performed in a pregnant woman when:

• There is no response after 4 minutes to CPR performed correctly
• CPR continues for more than 4 minutes in a woman more than 20 weeks gestation

The aim is to deliver the baby and placenta within 5 minutes of CPR commencing. The operation is performed at the site of the arrest, for example, in A&E resus or on the ward.

Question 8

What is the role of immediate delivery in cardiac arrest during pregnancy?

Answer 8

The primary reason for the immediate delivery is to improve the survival of the mother. Delivery improves the venous return to the heart, improves cardiac output and reduces oxygen consumption. It also helps with ventilation and chest compressions. Delivery increases the chances of the baby surviving, although this is secondary to the survival of the mother.