Cardiac Arrest During Pregnancy and Perimortem Cesarean Delivery

Cardiac Arrest During Pregnancy
and
Perimortem Cesarean Delivery
DR. Mahmoud Adel AL- Arnous ,MD
Professor Anesthesia and ICU
Zagazig Faculty of Medicine

Introduction
• During attempted resuscitation of a
pregnant woman, we have two potential
patients, the mother and the fetus.
• The best hope of fetal survival is maternal
survival.
• For the critically ill patient who is pregnant,
rescuers must provide appropriate
resuscitation, with consideration of the
physiologic changes due to pregnancy.

Key Points
1. The major causes of cardiopulmonary arrest
during pregnancy.
2. Maternal physiologic changes associated with
pregnancy.
3. The effects of physiologic changes from
pregnancy on maternal resuscitation.
4. Major differences in administering
cardiopulmonary resuscitation between pregnant
and non-pregnant patients.

5. The indications for a perimortem cesarean
delivery.
6. The beneficial effects of perimortem cesarean
delivery on maternal resuscitation.
.
7.Describe the 4 minute rule for perimortem
cesarean delivery.

Etiology
The major causes of cardiac arrest during pregnancy
include:
1. Venous thromboembolism.
2. Severe pregnancy induced hypertension (preeclampsia
and eclampsia).
3. Sepsis.
4. Amniotic fluid embolism.
5. Hemorrhage.
6. Trauma.
7. Iatrogenic causes (including complications of anesthesia,
drug errors, allergies).
8. Congenital and acquired heart disease.
9. An important contributor to cardiac arrest during
pregnancy is the increasing average age of pregnant
women, which increases the prevalence of comorbidities.

Obstetric and non-
obstetric causes of cardiac
arrest in pregnancy

Physiologic Changes During Pregnancy
and Effects on Maternal Resuscitation:
-Cardiovascular changes :
• Cardiac output increases by 30% to 50%, reaching its peak at about
32 weeks gestation.
• This increase is caused by increases in heart rate and
stroke volume, with a decrease in systemic vascular
resistance.
• Aortocaval compression by the gravid uterus occurs at
approximately 20 weeks of gestation and is responsible for
“supine hypotension syndrome,” reflecting a decrease in
cardiac output by as much as 25%.

Cont. C.V.S. changes
• The gravid uterus receives up to 30% of cardiac output as
the result of markedly increased uteroplacental blood flow,
compared with the non gravid uterus, which receives less
than 2% of cardiac output.
• Maternal blood volume increases as early as the seventh
week of gestation, reaching a plateau at 34 weeks.
• Red cell mass also increases, but relatively less than the
increase in plasma volume; this results in a decrease in
hematocrit and the physiologic anemia of pregnancy.
• During maternal cardiac arrest, anemia may have an
impact on oxygen delivery to vital organs such as the
heart, brain, and fetus.

Mean values for hemodynamic changes seen
throughout pregnancy

Laboratory values in pregnancy compared to
controls

-PULMONARY CHANGES:
• Resting oxygen consumption during
pregnancy.
• Functional residual capacity and residual
volume are reduced secondary to
diaphragmatic elevation by the gravid uterus
and enlarged breasts.
• The combination of these changes can lead to
a rapid decline in oxygen saturation during
apnea.

-G.I.T. changes:
• The pregnancy associated increase in
levels of progesterone relaxes sphincter
tone of the lower esophagus.
• Gastric emptying is delayed, increasing the
risk for aspiration during mask ventilation
and intubation.
-Airway problems:
• Edema of the upper airway, increased
breast size, and generalized weight gain can
interfere with adequate ventilation and
intubation during maternal resuscitation.

CPR During Maternal Cardiac Arrest
Maternal CPR may be impeded by the physiologic
changes of pregnancy as:
• -Cardiac compression in the pregnant woman is
inefficient because of the compression of the great vessels
by the gravid uterus and resultant decreases in venous
return and cardiac output.
• -Lateral tilting should be the first maneuver in the event
of maternal cardiac arrest.
• -Manual displacement of the uterus or placement of a
wedge under the right hip.

• - The Cardiff resuscitation wedge, a wooden
frame inclined at a 27 degree angle, is
specially designed for performing CPR
during pregnancy.
• -Alternatively, the “human wedge”
technique can be used to tilt the patient
on a rescuer’s knees to provide a
stable tilted position.

The Cardiff
wedge
Patient inclined laterally
by using Cardiff wedge
placement of a hard wooden board
beneath the patient

Treatment of Supine Hypotensive Syndrome (1)
(1) Milson I, Forssman L: Factors influencing aortocaval compressionin late pregnancy, Am J
Obtst Gynecol 148: 764-771, 1984

Primary ABCD Survey and
-Airway:
• No modifications.
-Breathing:
• No modifications .
modifications
-Circulation:
• Place the woman on her left side with her back angled 15° to 30° back
from the left lateral position. Then start chest compressions.
or
• Place a wedge under the woman’s right side (so that she tilts toward
her left side).
or
• Have one rescuer kneel next to the woman’s left side and pull the
gravid uterus laterally. This maneuver will relieve pressure on the
inferior vena cava.

Airway:
Secondary ABCD Survey
• Insert an advanced airway early in resuscitation to reduce the risk of regurgitation
and aspiration.
• Airway edema and swelling may reduce the diameter of the trachea. Be prepared to
use a tracheal tube that is slightly smaller than the one you would use for a non pregnant
woman of similar size.
• Monitor for excessive bleeding following insertion of any tube into the oropharynx or
nasopharynx.
• No modifications to intubation techniques. A provider experienced in intubation
should insert the tracheal tube.
• Effective preoxygenation is critical because hypoxia can develop quickly.
• Rapid sequence intubation with continuous cricoid pressure is the preferred
technique.
• Agents for anesthesia or deep sedation should be selected to minimize hypotension.
Breathing:
• No modifications of confirmation of tube placement.

Modifications for Pregnant Women
• Airway and Breathing :
–Hormonal changes promote insufficiency of the gastroesophageal
sphincter, increasing the risk of regurgitation.
- Apply continuous cricoid pressure during positive-pressure
ventilation for any unconscious pregnant woman.
–Be prepared to use an endotracheal tube 0.5 to 1 mm smaller in
internal diameter than that used for a nonpregnant woman of similar
size because the airway may be narrowed from edema.
–Verify correct endotracheal tube placement using clinical assessment
and a device such as an exhaled CO2 detector.
–Ventilation volumes may need to be reduced because the mother’s
diaphragm is elevated.

• Circulation:
–Follow the ACLS guidelines for resuscitation
medications.
–Vasopressor agents such as epinephrine, vasopressin,
and dopamine will decrease blood flow to the uterus.
-There are no alternatives, however, to using all indicated
medications in recommended doses.
• Scant information is available regarding the potential
impact of resuscitation drugs on the fetus; however, the
vasoconstrictive effects of high doses of α-adrenergic
agents on uteroplacental circulation have been
demonstrated in animal studies.
• Use of these drugs in resuscitation is essential because
rapid restoration of maternal circulation offers the best
chance for survival for both mother and fetus.

Cont .Modifications for Pregnant Women
• Circulation:
–Perform chest compressions higher on the sternum, slightly above
the center of the sternum. This will adjust for the elevation of the
diaphragm and abdominal contents caused by the gravid uterus.
• Defibrillation :
–Defibrillate using standard ACLS defibrillation doses (Class IIa).
Review the ACLS Pulseless Arrest Algorithm ("Management of Cardiac
Arrest").
-There is no evidence that shocks from a direct current defibrillator
have adverse effects on the heart of the fetus.
– If fetal or uterine monitors are in place, remove them before
delivering shocks.

Sites of inseration of I.V. lines
• Because the enlarging uterus compresses
the pelvic veins, IV lines in the lower
extremities should be avoided, if possible.
• When IV access below the uterus is
unavoidable, medication administered by
that route has a limited return to the heart
and the arterial circulation of the mother.

• Differential Diagnosis and Decisions:
• Identify and treat reversible causes of the arrest.
-Consider causes related to pregnancy and causes considered
for all ACLS patients.
• 6 Hs and 6 Ts of Pulseless Electrical Activity
(PEA) and Asystole
• Hypovolemia
• Hypoxia
• Hydrogen ions
(acidosis)
• Hyper/hypokalemia
• Hypothermia
• Hypoglycemia
• Toxins (like drug OD)
• Tamponade
• Tension PTX
• Thrombosis (coronary)
• Thrombosis
(pulmonary)
• Trauma

Differential diagnoses.
• The same reversible causes of cardiac arrest
that occur in nonpregnant women can occur
during pregnancy. But providers should be
familiar with pregnancy-specific diseases and
procedural complications.
• Providers should try to identify these common
and reversible causes of cardiac arrest in
pregnancy during resuscitation attempts.
•

Differential diagnosis
Obviously depends upon presentation
• Anaphylaxis (Collapse)
• Pulmonary embolus
(Collapse)
• Aspiration (Hypoxaemia)
• Pre-eclampsia or eclampsia
(Fits, Coagulopathy)
• Haemorrhage (APH ; PPH)
• Septic shock
• Drug toxicity (MgSO4 , total
spinal, LA toxicity)
• Aortic dissection

Perimortem Cesarean Delivery
• Emergency Hysterotomy (Cesarean
Delivery) for the Pregnant Woman
in Cardiac Arrest.

Maternal Cardiac Arrest Not Immediately
Reversed by BLS and ACLS:
• The resuscitation team leader should consider the need
for an emergency hysterotomy (cesarean delivery) protocol
as soon as a pregnant woman develops cardiac arrest .
• The best survival rate for infants >24 to 25 weeks in
gestation occurs when the delivery of the infant occurs no
more than 5 minutes after the mother’s heart stops beating.
• This typically requires that the provider begin the
hysterotomy about 4 minutes after cardiac arrest.
• Emergency hysterotomy is an aggressive
procedure.
• Rescue of a potentially viable infant is
resuscitation of the mother .

Cont.
Perimortem CS
• No data suggest that perimortem cesarean
deliveries are associated with a lower rate of
maternal recovery.
• Most reports, suggest that evacuation of the fetus
helps restore maternal circulation.
• Indeed, a cesarean delivery is recommended by
the AHA for maternal reasons:
“Emptying the uterus for persistent cardiac
arrest in the mother offers the best hope for a
positive outcome for both the mother and the
fetus.”

It is likely that the beneficial effect of perimortem CS
is multifactorial:
• - Relief of compression on the inferior vena
cava increases cardiac output as the result of
greater venous return .
• - Autotransfusion from contraction of the
uterus.
• - Decreased shunting of blood to the utero
placental circulation further contributes to
increased cardiac output.
• -Functional residual capacity also is improved.
• -Maternal metabolic demand decreased, thus
increasing oxygenation.

• The mother cannot be resuscitated until
venous return and aortic output are restored.
• Delivery of the baby empties the uterus,
relieving both the venous obstruction and the
aortic compression.
• The hysterotomy also allows access to the
infant so that newborn resuscitation can begin.
• The critical point to remember is that you will
lose both mother and infant if you cannot
restore blood flow to the mother’s heart .

Perimortem Cesarean Section
• Technique:
-Delivery should be conducted in the mother's current
location; transportation to an operating room wastes
valuable time.
– Make sure it is indicated first and that
resuscitative team is ready.
– Vertical incision from xyphoid to pubis.
– Continue straight down through abdominal wall
and peritoneum.
– Cut through uterus and placenta (if anterior).
– Bluntly open uterus and remove fetus.
– Cut and clamp cord.

• 4 to 5 minutes is the maximum time rescuers will have
to determine if the arrest can be reversed by BLS and
ACLS interventions.
• The rescue team is not required to wait for this time to
elapse before initiating emergency hysterotomy
• 4 Minute Rule:
Maternal CPR for 4 minutes, Infant should be
delivered by the 5 th minute.

Decision Making for Emergency Hysterotomy
• The resuscitation team should consider several maternal
and fetal factors in determining the need for an emergency
hysterotomy.
1-Consider gestational age:
-Although the gravid uterus reaches a size that will begin
to compromise aortocaval blood flow at approximately 20
weeks of gestation, fetal viability begins at approximately
24 to 25 weeks.
-Portable ultrasonography, available in some emergency
departments, may aid in determination of gestational age
(in experienced hands) and positioning .

Neonatal Outcome following C-section
Time Interval
(min)
0 – 5
6 – 15
16-25
26-35
36+
Surviving
Infants
45
18
9
4
1
Intact neurologic
Status of Survivors
98%
83%
33%
25%
0%

• Consider features of the cardiac arrest:
The following features of the cardiac arrest can increase
the infant’s chance for survival:
–Short interval between the mother’s arrest and
the infant’s delivery.
–No sustained pre arrest hypoxia in the mother .
–Minimal or no signs of fetal distress before the
mother’s cardiac arrest.
–Aggressive and effective resuscitative efforts for
the mother .
–The hysterotomy is performed in a medical
center with a neonatal intensive care unit .
.

• Consider the professional setting:
–Are appropriate equipment and supplies
available?
–Is emergency hysterotomy within the
rescuer’s procedural range of experience and
skills?
–Are skilled neonatal/pediatric support
personnel available to care for the infant,
especially if the infant is not full term?
–Are obstetric personnel immediately
available to support the mother after delivery?

Advance Preparation
• - Experts and organizations have emphasized the
importance of advance preparation.
• -Medical centers must review whether
performance of an emergency hysterotomy is
feasible at their center, and if so, they must identify
the best means of rapidly accomplishing this
procedure.
• -The plans should be made in collaboration with
the obstetric and pediatric services.

Summary and Conclusion
• Successful resuscitation of a pregnant woman and survival of the
fetus require prompt and excellent CPR with some modifications in
basic and advanced cardiovascular life support techniques.
• By the 20th week of gestation, the gravid uterus can compress the
inferior vena cava and the aorta, obstructing venous return and arterial
blood flow. Rescuers can relieve this compression by positioning the
woman on her side or by pulling the gravid uterus to the side.
• Defibrillation and medication doses used for resuscitation of the
pregnant woman are the same as those used for other adults in
pulseless arrest.
• Rescuers should consider the need for emergency hysterotomy as
soon as the pregnant woman develops cardiac arrest because
rescuers should be prepared to proceed with the hysterotomy if the
resuscitation is not successful within minutes.
•
Immediate cesarean delivery not only improves survival of
the infant but also facilitates maternal resuscitation.