Dr A Hards, Dr S Davies, Dr A Salman, Dr M Balki Mount Sinai Hospital 2010

Aim

To enable you to competently manage a case of maternal cardiac arrest

Objectives

To review relevant maternal physiology

To review standard ACLS guidelines

To review ACLS modifications for pregnancy

Physiology of pregnancy

Respiratory System 1. 60% increase in oxygen consumption & decreased FRC

Implications – rapid desaturation & hypoxemia

2. increased minute ventilation and hypoxic ventilatory response

Implications - chronic respiratory alkalosis, difficult determining benign vs. sinister causes of dyspnea

3. increased capillary engorgement & mucosal edema

Implications – airway bleeding, nasal congestion, difficult airway, failed intubation

Physiology of pregnancy

Cardiovascular System1. cardiac output increases by 50% (due to increased HR & SV). Increased

contractility and LVEF.

2. SVR and PVR fall by up to 35%. SBP, DBP, MAP decrease during mid preganancy, return to baseline near term

3. Aorto-caval compression occurs from 13-16 weeks

Implications

- supine hypotension

- higher femoral/IVC pressures

Physiology of Pregnancy

Gastrointestinal System1. Anatomical changes

2. Reduced lower esophageal sphincter pressure

3. Increased intra-gastric pressure

4. Delayed gastric emptying in labour but probably normal at other times

Implications 

- High incidence of gastro-oesophageal reflux

- Increased risk of aspiration from ~ 16-20 weeks gestation

Physiology of Pregnancy

Hematological System

1. 50% increase in plasma volume

2. 30% increase in red cell volume

3. Increased platelet turnover, clotting and fibrinolysis

Implications

  - delayed presentation of hypovolaemia

- physiological anemia of pregnancy

- pro-coagulopathic state

ACLS in pregnancy

Essentially follows same guidelines as for non-pregnant patients

AHA recommend some modifications based on physiology

ACLS Cardiac Arrest Algorithm 2010

AHA Modifications for pregnancy

Ventilate with cricoid pressure (remove if impeding ventilation,

oxygenation or intubation)

Early intubation with a smaller diameter ETT (such as 6.5 cm)

Left Uterine Displacement

Position hands 1-2cm higher on sternum for chest compressions

Remove fetal monitoring for defibrillation

Do not use femoral or leg veins for IV access

Consider emergency cesarean section

Emergency cesarean sectionRationale for early CS

- Provides effective maternal resuscitation (improves venous return

& cardiac output)

- If fetus > 24-25 weeks may save the life of the baby

Management

Do not move patient to OR prior to CS

Continue maternal resuscitation during CS

Aim for skin incision by 4 minutes

Aim for delivery by 5 minutes

Cause of arrest

Always consider the “Hs and Ts”

Hypovolemia Tension PTX

Hypoxia Tamponade

Hydrogen ions Toxins

Hypo/erkalemia Thrombosis, cardiac

Hypothermia Thrombosis, coronary

Pregnancy-specific causes mnemonic “BEAU-CHOPS”

Maternal cardiac arrest algorithm

Vanden Hoek T L et al. Circulation 2010;122:S829-S861Copyright © American Heart Association

Any questions?

Summary

Reviewed relevant maternal physiology

Reviewed standard ACLS guidelines

Reviewed modifications for pregnancy