Medication Overview: Drugs, Doses, and Maternal-Fetal Considerations

Drug Drug Class PRF Lactation

Typical Doses Indications Receptor

Activity

Potential Maternal-Fetal Effects

Atropine

Parasympatholytic PRF: C

Lact: Compatible

0.5 mg IV*-up to 3 doses

1mg IV or IO-up to 3 doses Symptomatic bradycardia

Asystole/slow PEA Muscarinic

blocker Rapidly crosses placenta, brief (<10 mins) decreased fetal breathing movements, no fetal hypoxia or effect on FHT variability, unclear if first trimester use is associated with minor fetal anomalies

Epinephrine

Sympathomimetic PRF: C Lact: ND

2-10 mcg/min 1mg IV or IO**

2-2.5mg ET

Infusion for symptomatic bradycardia or if refractory to pacing

VF/VT/PEA/Asystole

β2, β1, α1, α2

agonists Theoretical decreased uterine perfusion, easily crosses placenta, historic reports of 1st trimester exposure associated with fetal malformations, large study showed no major anomalies, if used for maternal hypotension ephedrine may be a better option

Dopamine

Sympathomimetic PRF: C Lact: ND/PC

2-10 mcg/min*** Infusion for symptomatic

bradycardia, refractory to pacing or for post-

DA1, DA2, β1, β2, α1, α2 agonists

Dose dependent decreased uterine perfusion, no harmful subsequent neonatal effects

Lact: ND/PC pacing or for post

resuscitation hypotension agonists

Vasopressin¥

Vasopressor PRF: B Lact: Compatible

40 U IV or IO

-may be used to replace the 1st or 2nd dose of epinephrine in PEA treatment

VF/VT/Asystole AVPR-1A, 1B, 2

agonists Stimulates uterine contractions, no adverse fetal or neonatal effects

Amiodarone

Class III antiarrhythmic

PRF D 150mg IV over 10 mins

10 i PRN WPW

Wid l h di Affects Na+,

K C Placental transfer of 10-30% of maternal serum levels (up to 60% reported),

l QT i l i h & f b d di l h i f l &

PRF: D Lact: CI

-can repeat q 10 mins PRN -infusion of 1mg/min x6 h, then 0.5 mg/min x18 h initial load -max dose: 2.2g/day

300mg IV/IO push or 5mg/kg IV/IO push

-can follow with 150mg IV/IO x1 dose if needed after 10 mins

Wide complex tachycardia VF/pulseless VT

K+, Ca+

channels -α & β adrenergic blocker

prolongs QT interval in mother & fetus, bradycardia, maternal hypotension, fetal &

neonatal hypothyroidism or hyperthyroidism, fetal or neonatal goiter, IUGR, potential proarryhthmic

Of note: also used therapeutically in pregnancy to treat fetal tachyarrymias but not as a first-line agent

Lidocaine

Class IB antiarrythmic PRF: B

Lact: LHD/PC

1-1.5mg/kg IV push

-if refractory, 0.5-0.75 mg/kg IV push q5-10 mins PRN

-max dose of 3mg/kg

VF/pulseless VT Na+ channel

blocker

Rapid placental transfer of 50-70% of maternal serum levels, potential CNS depression in newborns with high serum levels, not associated with major or minor fetal anomalies

Magnesium

Antiarrhythmic PRF: B Lact: Compatible

1-2g IV or IO

-load over 5-20 mins if VF/VT associated with Torsades

Torsades de Pointes Unclear mechanism of activity

Non-teratogenic, rapid placental transfer of 70-100% of maternal serum levels, transient newborn neurologic & respiratory depression may occur, neonatal hypocalcemia

Lact: Compatible associated with Torsades -can load over 30-60 mins if the patient has a pulse

activity hypocalcemia

Adenosine

Class V antiarrhythmic PRF: C

Lact: ND/PC

6 mg IV x1

12 mg IV -up to 2 doses SVT w/wo abberancy (not

used in WPW) Nodal blocker

Unclear mechanism

Non-teratogenic, short half life, crosses the placenta with variable transfer, fetal arrhythmia can occur, of note: also used to treat fetal SVT via the mother

Diltiazem

Class IV Antiarrhythmic

PRF C 0.25 mg/kg load IV over 2 mins

l d ith 0 35 /k ft 15 SVT (not used in WPW)

AFib/Fl tt Ca+ channel

bl k Maternal hypotension could result in decreased uterine blood flow PRF: C

Lact: Compatible -can re-load with 0.35 mg/kg after 15 mins if 1st load ineffective -drip: 5-20 mg/hr with sinus rhythm conversion

AFib/Flutter

Junctional Tachycardia blocker

Esmolol

Class II antiarrhythmic PRF: C (both) Lact: ND/PC

Esmolol: 500 mcg/kg load IV over 1 min

-drip: 5-200 mcg/kg/min

SVT (not WPW) β1 selective

blocker

Non-teratogenic, short half life, crosses the placenta with variable transfer, fetal bradycardia, maternal hypotension could result in decreased uterine blood flow

Table 1: Medications used in ACLS protocols and effects on the mother and fetus. The benefit of giving these medications to pregnant patients in extremis outweighs the fetal risks.

Receptor activity is typically dose dependent and presented the table above in order activity from low to high doses. *It is recommended to begin pacing if the patient’s heart rate does not improve within three doses of atropine. **Epinephrine may be used as an infusion for symptomatic bradycardia refractory to pacing or in patients with malignant arrhythmias (VF/VT) and PEA, dosing can be repeated every 3-5 minutes in cardiac arrest. ***Higher doses of dopamine may be used but are associated with greater arrhythmia and splanchnic vasoconstriction potential.

^¥

Vasopressin can only be used once during ACLS protocols for VF, VT, PEA or asystole.

Legend: AAP: American Academy of Pediatrics, CI=contraindicated, ET=endotracheal, IUGR=intrauterine growth restriction, IV=intravenous, IO=intraosseous, Lact=lactation, LHD=limited human data, ND=no data available, VF=Ventricular Fibrillation, VT=Ventricular Tachycardia, PC=probably compatible, PEA=Pulseless Electrical Activity, PRF=pregnancy risk factor (A=safe per human data, B=animal data shows no risk and no controlled human studies or animal data shows risks but not confirmed in human studies, C=animal studies show risk of teratogenesis no controlled human studies available or no information available in animal or human studies and use indicated only if benefit outweighs risks, D=human evidence of risk demonstrated but benefit of use may be acceptable in certain clinical scenarios (life threatening or serious medical illness with no or less effective safer alternative), X=contraindicated with known unnaceptable fetal risks that do not outweigh maternal medical benefit of treatment.)

References: Briggs G, Freeman R, Yaffe S. Drugs used in Pregnancy and Lactation: Seventh Edition. Lippincott Williams & Wilkins, 2005:1858. Dildy G, Belfort M, Saade G, Phelan J,

H ki G Cl k S C i i l C Ob i F h Edi i Bl k ll P bli hi 2004 691 N th li t d C di A t A i t d ith P Ci l i 2005 112 IV

Hankins G, Clark S. Critical Care Obstetrics: Fourth Edition. Blackwell Publishing, 2004; 691. No authors listed. Cardiac Arrest Associated with Pregnancy. Circulation. 2005;112:IV-

150-IV-153. No Authors Listed. Monitoring and Medications. Circulation 2005; 112:IV-78-IV-83. No authors listed. Management of Cardiac Arrest. Circulation 2005; 112:IV-58-IV-66.