Obstetric Events

Amniotic Fluid Embolism (Anaphylactoid Syndrome of Pregnancy)


Amniotic fluid embolism (AFE) is thought to be an abnormal maternal immune response to fetal antigens when the maternal-fetal immunological barrier is breached during labor, pregnancy termination, or shortly after delivery. It results in a triad of hypoxemia, hypotension, and coagulopathy.


The etiology of cardiovascular collapse is not clear but may result from activation of a cascade of immune mediators that causes a massive systemic reaction

Typical Situations

  • Active labor

  • Pregnancy termination

  • Cesarean delivery

  • Induction of labor

  • Multiparity

  • Advanced maternal age

  • Ethnic minority groups

  • Placental abnormalities (placental abruption or placenta previa)

  • Operative delivery


  • There are no known measures to prevent AFE

  • Create institutional plan for stat cesarean section of a parturient in cardiac arrest (“Code Blue Obstetrics”)

  • Drill and practice the management of stat cesarean section during cardiac arrest (using simulation if available)


  • Unexplained acute fetal distress may precede maternal deterioration in 20% of cases

  • Premonitory symptoms

    • Restlessness, agitation, paresthesia

  • Pulmonary symptoms

    • Acute onset of dyspnea, pleuritic chest pain, bronchospasm, coughing, or hemoptysis

    • Hypoxemia and cyanosis

    • CXR may initially be normal and later demonstrate ARDS

    • Respiratory arrest

  • Cardiovascular symptoms

    • Arrhythmias

    • Severe hypotension

    • Pulmonary hypertension with RV failure (early, first 30 minutes)

      • ECG signs of right heart strain

    • Left ventricular failure and pulmonary edema (following initial onset)

    • Cardiac arrest (PEA, asystole, VF, VT)

  • Neurologic symptoms

    • Hyperreflexia, seizure, coma

  • Acute severe consumptive coagulopathy

    • DIC

    • Massive hemorrhage

  • Obstetric complications

    • Uterine atony

Similar Events


Patients with AFE can rapidly deteriorate, are at high risk of maternal mortality, and have a high incidence of fetal distress. The key steps are early recognition, supportive management, prompt resuscitation, and delivery of the fetus.

  • Call for help

    • Labor and delivery team and additional anesthesia help

  • If the patient has arrested, start CPR immediately

  • If the patient has NOT arrested, maintain left uterine displacement even if postpartum

  • Ensure adequate oxygenation and ventilation

    • Administer 100% O 2 by a nonrebreathing face mask

    • Patient may require urgent or emergent airway management

      • If urgent airway management is necessary, perform RSI with cricoid pressure

        • Etomidate IV, 0.2 to 0.3 mg/kg, or ketamine IV, 0.5 to 1.0 mg/kg

        • Succinylcholine IV, 1 to 2 mg/kg

      • Intubate the trachea if there is loss of consciousness, respiratory failure, or severe cardiovascular collapse

  • Stop MgSO 4 infusion, if running

    • If Mg 2 + toxicity is suspected, administer CaCl 2 IV, 500 to 1000 mg

  • Initiate basic monitoring if not already present

    • ECG, NIBP, pulse oximeter, RR, level of consciousness, temperature, fetal monitoring

  • Support the circulation

    • Ensure adequate IV access above the diaphragm (2 × large-bore IVs)

    • Rapidly infuse crystalloid and/or colloid

    • Treat hypotension with vasopressors, increasing doses as needed

      • Phenylephrine IV, 50 to 200 µg

      • Ephedrine IV, 5 to 10 mg

      • Epinephrine IV, 10 to 100 µg

      • Consider administering vasopressor infusions if the preceding measures are inadequate (see Event 9, Hypotension )

    • Place an arterial line and consider placement of CVP line for infusion of vasopressors

  • Prepare for massive transfusion and initiate MTP (if available)

    • Send for blood products if they are not already in the room

    • Inform the blood bank that more blood and blood products will be needed emergently

      • If crossmatched blood is not readily available, order uncrossmatched blood

    • Get help to set up a rapid infusor device

  • Transfuse blood products

    • Use a fluid warmer

    • Transfuse with an RBC:FFP ratio of 1:1 or 2:1

      • Transfuse RBCs to maintain hemoglobin > 7 g/dL

      • Transfuse additional FFP if PT/aPTT is prolonged

      • Transfuse platelets if < 50,000/µL

      • Transfuse cryoprecipitate if fibrinogen < 200 mg/dL

  • Consult hematology and the critical care team

  • Maintain normothermia

  • Frequent lab draws (ABG/CBC/PT/aPTT/fibrinogen/metabolic panel/Ca 2 + )

  • At any time, if the patient has no pulse, start CPR immediately (C-A-B: compressions, airway, breathing)


  • Electrolyte abnormalities

  • Massive hemorrhage

  • ARDS

  • Aspiration pneumonitis

  • Cerebral hemorrhage

  • Cerebral anoxia

  • Cardiac arrest or death

  • Fetal distress or death

Suggested Reading

  • 1. Kramer M.S., Rouleau J., Liu S., et. al.: Health Study Group of the Canadian Perinatal Surveillance System: Amniotic fluid embolism: incidence, risk factors, and impact on perinatal outcome. Br J Obstet Gynaecol 2012; 119: pp. 874-879.
  • 2. Knight M., Tuffnell D., Brocklehurst P., Spark P., Kurinczuk J.J.: On behalf of the UK Obstetric Surveillance System: incidence and risk factors for amniotic-fluid embolism. Obstet Gynecol 2010; 115: pp. 910-917.
  • 3. Clark S.L.: Amniotic fluid embolism. Clin Obstet Gynecol 2010; 53: pp. 322-328.
  • 4. Tuffnell D., Knight M., Plaat F.: Amniotic fluid embolism: an update. Anaesthesia 2011; 66: pp. 3-6.
  • 5. Dedhia J.D., Mushambi M.C.: Amniotic fluid embolism. Contin Educ Anaesth Crit Care Pain 2007; 7: pp. 152-156.

  • Cardiac Arrest in the Parturient


    Cardiac arrest in the parturient is the absence of effective mechanical activity of the heart in the pregnant patient.


    • Hypovolemia

    • Hypoxemia

    • PE, venous air embolism, or AFE

    • Toxins (e.g., LAST)

    • Anesthetic complications

    • Uterine atony

    • Hypertensive disease of pregnancy

    • Placental abnormalities (placental abruption or placenta previa)

    • Cardiac disease (MI or ischemia, aortic dissection, cardiomyopathy, Eisenmenger syndrome)

    • Sepsis

    • Tension pneumothorax

    • Cardiac tamponade

    Typical Situations

    • Anesthesia-related

      • Failed or difficult tracheal intubation

      • Unrecognized esophageal intubation

      • Total spinal anesthesia

      • LAST

    • Major hemorrhage

      • Uterine atony

      • Placental abnormalities

        • Placenta previa (placenta located in the lower uterine segment over the cervix)

        • Placenta accreta, increta, or percreta (placenta attaches to, into, or through the myometrium)

        • Placental abruption (premature separation of a normally implanted placenta after 20 weeks’ gestation)

    • Preexisting medical condition

      • Acquired or congenital cardiovascular disease (e.g., peripartum cardiomyopathy, aortic dissection in presence of bicuspid aortic valve, coronary artery disease)

      • History of a PE

    • Other

      • Prostaglandin use in pregnancy

      • Mg 2 + toxicity

      • AFE


    • Create institutional plan for immediate cesarean section of a parturient in cardiac arrest (“Code Blue Obstetrics”)

    • Drill and practice the management of immediate cesarean section during cardiac arrest (using simulation if available)

    • Immediate intervention at first signs of maternal or fetal instability

      • Manually perform left uterine displacement

      • Administer 100% O 2 through a nonrebreathing face mask

      • Ensure adequate IV access

      • Assess for and treat reversible causes (e.g., hypotension)

    • Anesthesia-related issues

      • Evaluate airway and prepare for a difficult intubation

      • Exclude intrathecal and intravascular placement of epidural catheters before administering incremental doses of local anesthetic

    • Manage preexisting medical issues in collaboration with specialists

    • In high-risk patients, consider placing invasive monitors

    • Carefully administer medications to parturients

      • Patients with a history of drug allergies

      • Patients with cardiac disease taking tocolytic agents (β-adrenergic agonists)

      • Administer potent drugs through infusion pumps (e.g., MgSO 4 )


    • Unresponsive to verbal commands

    • Absence of pulse oximeter waveform if present

    • Loss of consciousness or seizure-like activity

    • No palpable carotid pulse (palpation of peripheral pulses unreliable)

      • NIBP unmeasurable

    • Absence of heart tones on auscultation

    • Agonal or absent respirations

    • Arrhythmias

      • VT, VF, PEA, asystole

        • Rhythm in PEA may appear normal

    • Significant fall in ET CO 2 if present

    • Cyanosis

    • Regurgitation and aspiration of gastric contents

    • Lack of ventricular contraction on TEE or TTE

    Similar Events


    The key steps are early recognition, prompt resuscitation, and delivery of the fetus. Attempts to transfer patients undergoing CPR to an OR for immediate cesarean section increase maternal and neonatal risk. Perimortem cesarean section should be performed at the site of the arrest to relieve aortocaval compression, increase maternal CO and allow more effective chest compressions.

    • Treat the patient, not the monitor

    • Verify that the patient is unresponsive and has no carotid pulse

      • Other patient monitoring, if present, may confirm absence of circulation (e.g., pulse oximetry, ET CO 2 , arterial line waveform)

    • Call a code

      • Call for labor and delivery team and additional anesthesia help

      • Prepare for stat cesarean section at the site of the arrest with the goal of delivery within 5 minutes

        • A cesarean section will be necessary if no return of spontaneous circulation after 4 minutes

    • Call for the crash cart

      • Apply defibrillation pads on chest

        • Do not delay defibrillation for shockable rhythms

    • Start CPR immediately (C-A-B: compressions, airway, breathing)

      • Chest compressions

        • Place hands slightly higher on sternum

          • Compressions should be at least 100 per minute and at least 2 inches deep

        • Rotate compressors every 2 minutes

        • Allow for complete recoil of the chest with each compression

        • Interruptions in compressions should be less than 10 seconds

        • Adequate compressions should generate an ET CO 2 of at least 10 mm Hg and a diastolic pressure of greater than 20 mm Hg (if an arterial line is in place). You MUST improve CPR quality if above conditions are not met.

      • Airway/ventilation

        • Until the patient is intubated, establish bag mask ventilation with 100% O 2 at a compression to ventilation ratio of 30:2 and prepare for endotracheal intubation

          • Place ETT and then ventilate at a rate of 10 per minute with continuous compressions

    • Assign tasks to skilled responders

      • Ensure adequate IV access

        • If difficult IV access, place IO line

      • Place an arterial line

      • Call for TEE or TTE machine

    • Turn off ALL anesthetics if in use (including epidural infusions)

    • Follow BLS and ACLS guidelines (see Event 2, Cardiac Arrest ) but with modifications for the parturient (see the following)

    • Employ cognitive aids (ACLS guidelines) to help determine diagnosis and treatment

      • Drug therapy, dosages, and defibrillation should follow standard ACLS guidelines

    • ACLS modifications in pregnant patients

      • Place hands slightly higher on sternum while performing chest compressions

      • Immediately intubate with an ETT and ventilate with 100% O 2

        • The routine use of cricoid pressure during cardiac arrest is not recommended, but if used, remove if impairing ventilation and/or intubation

      • Manual left uterine displacement to avoid aortocaval compression

      • Stop MgSO 4 infusion, if running

        • If Mg 2 + toxicity is suspected, administer CaCl 2 IV, 500 to 1000 mg

      • Remove external fetal monitors prior to defibrillation

      • If an internal fetal monitor is present, disconnect from power supply prior to defibrillation

      • If parturient does not respond to resuscitation within 4 minutes, immediate perimortem cesarean section is indicated at the site of the arrest

      • Continue all maternal resuscitative interventions (CPR, positioning, defibrillation, drugs, and fluids) during and after perimortem cesarean section

    • Continually reassess patient without interrupting chest compressions

      • Resumption of spontaneous circulation

        • ECG and return of palpable pulse or BP

        • Pulse oximetry waveform

    • Consider postresuscitation hypothermia for brain protection


    • Aspiration of gastric contents

    • Laceration of liver

    • Pneumothorax or hemothorax

    • Rib fracture

    • Hypoxic brain injury

    • Multiorgan failure

    • Maternal death

    • Fetal death

    Suggested Reading

  • 1. Ramsay G., Paglia M., Bourjeily G.: When the heart stops: a review of cardiac arrest in pregnancy. J Intensive Care Med 2012; 28: pp. 204-214.
  • 2. Jeejeebhoy F.M., Zelop C.M., Windrim R., et. al.: Management of cardiac arrest in pregnancy: a systematic review. Resuscitation 2011; 82: pp. 801-809.
  • 3. Hui D., Morrison L.J., Windrim R., et. al.: The American Heart Association 2010 guidelines for the management of cardiac arrest in pregnancy: consensus recommendations on implementation strategies. J Obstet Gynaecol Can 2011; 33: pp. 858-863.
  • 4. Neumar Robert W., Otto Charles W., Link Mark S., et. al.: Part 8: Adult Advanced Cardiovascular Life Support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2010; 122: pp. S729-S767.
  • 5. Vanden Hoek T.L., Morrison L.J., Shuster M., et. al.: Part 12: Cardiac Arrest in Special Situations: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation 2010; 122: pp. S829-S861.
  • 6. Lipman S., Daniels K., Cohen S.E., Carvalho B.: Labor room setting compared with the operating room for simulated perimortem cesarean delivery: a randomized controlled trial. Obstet Gynecol 2011; 118: pp. 1090-1094.

  • Difficult Airway in the Parturient


    Difficult airway in the parturient includes difficult mask ventilation, difficult placement of an SGA, or difficult tracheal intubation.


    • Patient factors (specific to pregnancy)

      • Airway edema

      • Increased Mallampati score compared to nonpregnant state

      • Breast engorgement

      • High risk of regurgitation

      • Decreased functional residual capacity

      • Increased O 2 consumption

      • Increased risk of bleeding from mucosal surface

    • Other anatomical causes of a difficult airway

      • Full dentition

      • Obesity/short neck

    • Physician factors

      • Inexperience with airway management in the parturient

      • Failure to respond effectively to a rapidly deteriorating situation

    • Equipment factors

      • Inexperience with equipment

      • Inadequate backup or alternative airway adjuncts or intubating devices

    Typical Situations

    • Cesarean section under general anesthesia

      • Contraindication to neuraxial anesthesia

      • Failure of neuraxial technique

      • Insufficient time to place or dose neuraxial anesthetic

      • Maternal refusal to have neuraxial anesthesia

    • Maternal and preexisting anatomic abnormalities

    • Local anesthetic toxicity requiring airway management

    • Nonobstetric surgery during pregnancy


    • Perform a complete airway assessment prior to inducing anesthesia (general or neuraxial)

    • In patients with known or anticipated difficult airway, perform awake fiberoptic intubation

    • Alert the obstetric team to the increased probability of difficult airway management during general anesthesia

    • Consider early placement of an epidural catheter in patients at risk of difficult intubation or stat/urgent cesarean section and ensure that the catheter is functional

    • Optimize patient positioning prior to induction of general anesthesia

    • Prepare for a difficult intubation and have contingency plans if you cannot ventilate and/or cannot intubate

      • Consider videolaryngoscope as primary choice for intubation

    • Review and practice difficult airway/failed intubation algorithm


    • Failure to intubate the trachea after two attempts by an experienced anesthesia professional

      • Difficult insertion of laryngoscope

        • Small or restricted mouth opening

        • Masseter spasm secondary to succinylcholine

      • Difficult visualization of vocal cords

      • Difficult passage of ETT through vocal cords

    • Failure to successfully mask ventilate after induction of anesthesia

    • Failure to successfully place an SGA

    Similar Events


    Obstetric patients have a higher risk of both difficult and failed intubation

    • If difficult airway is known or anticipated, perform an awake fiberoptic intubation since this may be the safest option

    • Prepare primary and backup airway equipment

      • Have contingency plans if primary plan fails

    • Before induction of general anesthesia

      • Position patient appropriately (e.g., “ramp” patient for intubation, especially if obese)

      • Maintain left uterine displacement

      • Administer sodium citrate 0.3 M PO, 30 mL

      • Administer ranitidine IV, 50 mg, and metoclopramide IV, 10 mg

      • Preoxygenate with 100% O 2 with anesthesia breathing circuit

      • Prep and drape the patient BEFORE general anesthesia is induced

    • If unanticipated difficult intubation after induction

      • Call for additional anesthesia help stat if not already present (e.g., anesthesia professional, anesthesia tech)

      • Call surgeon capable of establishing surgical airway and obtain equipment for surgical airway

      • Call for difficult airway cart or supplies (including videolaryngoscope)

        • Have help set up additional airway equipment

      • Ensure adequate oxygenation and ventilation (may be difficult)

        • Place an oral airway

        • Consider two-person bag valve mask technique

        • Apply continuous cricoid pressure

        • Reposition the patient’s head and neck

      • Most experienced person should perform second laryngoscopy

        • Use videolaryngoscope

        • Use appropriately styleted ETT or bougie

        • Adjust cricoid pressure if it is impairing ventilation or intubation

        • Use smaller ETT

    • If intubation fails on second attempt

      • Place an SGA (e.g., LMA) to maintain oxygenation and ventilation

        • If SGA placement is successful, clinical situation will dictate whether or not to continue the anesthetic with this airway and deliver the fetus or awaken the patient

          • Confirm ventilation with ET CO 2

          • Maintain cricoid pressure after placement of SGA

        • After delivery, consider whether to attempt tracheal intubation through the SGA (see Event 3, Difficult Tracheal Intubation )

    • If SGA placement is UNSUCCESSFUL, attempt face mask ventilation

    • If face mask ventilation is adequate, but intubation is not possible

      • Wake the patient up and reevaluate for awake fiberoptic intubation

      • Patient will be at increased risk of awareness with prolonged intubation attempts

    • If face mask ventilation is UNSUCCESSFUL, decide whether to awaken the patient or establish a surgical airway

      • If muscle relaxation is wearing off, awaken the patient


        • Move early and aggressively to emergency cricothyrotomy or other emergency surgical airway. DO NOT WAIT for the O 2 saturation to fall precipitously

        • Consider transtracheal jet ventilation, weighing the significant risk of the procedure

    • If surgical airway is established, consider whether to awaken the patient or proceed with cesarean section

    • Failed airway management may result in maternal cardiac arrest (see Event 82, Cardiac Arrest in the Parturient )


    • Hypoxemia

    • Aspiration of gastric contents

    • Esophageal intubation

    • Airway trauma/bleeding/swelling

    • Dental damage

    • Cerebral anoxia

    • Awareness

    • Fetal death

    • Maternal death

    Suggested Reading

  • 1. Berg C.J., Callaghan W.M., Syverson C., Henderson Z.: Pregnancy-related mortality in the United States, 1998 to 2005. Obstet Gynecol 2010; 116: pp. 1302-1309.
  • 2. Hawkins J.L., Chang J., Palmer S.K., Gibbs C.P., Callaghan W.M.: Anesthesia-related maternal mortality in the United States: 1979–2002. Obstet Gynecol 2011; 117: pp. 69-74.
  • 3. Quinn A.C., Milne D., Columb M., Gorton H., Knight M.: Failed tracheal intubation in obstetric anaesthesia: 2 yr national case–control study in the UK. Br J Anaesth 2013; 110: pp. 74-80.
  • 4. Rucklidge M., Hinton C.: Difficult and failed intubation in obstetrics. Contin Educ Anaesth Crit Care Pain 2012; 12: pp. 86-91.
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    Feb 22, 2019 | Posted by in ANESTHESIA | Comments Off on Obstetric Events

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