Advanced Life Support in Obstetrics (ALSO): Maternal Resuscitation and Trauma (including Amniotic fluid embolism)

[Before or after reviewing this post please review the post Cardiac Arrest in Pregnancy for more information on this topic.]

All that follows is from Chapter K in the Advanced Life Support in Obstetrics (ALSO) Course Manual, May 2010, Maternal Resuscitation and Trauma (including Amniotic fluid embolism):

“. . . cardiac arrest occurs in one in 30,000 pregnancies.”

“This section will therefore first examine causes of cardiopulmonary arrest unique to pregnancy, including amnniotic fluid embolism, magnesium toxicity, preeclampsia/eclampsia, and postpartum hemorrhage. Next, we will review causes of cardiopulmonary arrest that are not limited to pregnancy, including acute coronary syndrome (ACS), cerebrovascular accident (CVA), aortic dissection, pulmonary embolism and trauma. Trauma has specific concerns in pregnancy and so will be discussed later in the chapter. Table 1 summarizes the conditions that may be associated with cardiopulmonary arrest.”

[I’ve only included two of the topics above that are discussed on p. 2 in the manual.]

“Excess magnesium sulfate: Iatrogenic overdose is possible in women with eclampsia who receive magnesium sulfate, particularly if the woman becomes oliguric. Administration of calcium gluconate (1 ampule or 1 g) is the treatment of choice for magnesium toxicity. Empiric calcium administration can be life saving.”

“Aortic dissection: Pregnant women are at increased risk for spontaneous aortic dissection, life threatening pulmonary embolus, and stroke.”

Table 1: Etiologies of cardiac arrest in pregnacy (Adapted from Fillion, DN. Being prepared for pregnant Code Blue. Maternal Child Nursing 1998;23:240-5) 

 Percentages above are those of maternal deaths of live births, United States, 1990

MATERNAL PHYSIOLOGIC CHANGES IN PREGNANCY

“During pregnancy, 20 to 30% of the cardiac output flows to the uterus, compared to less than two percent in women who are not pregnant. In addition, in a supine pregnant woman the uterus can compress the aorta and inferior vena cava enough to sequester up to 30 percent of the blood volume. . . . Delivery, or uterine displacement, relieves aortocaval compression with an increase in cardiac output by 20 to 25%.

“Pregnant women with hemorrhage may lose 1200 to 1500 ml of their blood volume before exhibiting signs of hypovolemia. The clinician’s first indication of significant hemorrhage may be a non-reassuring fetal heart rate pattern. Fluid resuscitation is especially important in pregnancy. Eighty percent of women admitted to the hospital in hemorrhagic shock survive, but have an unsuccessful fetal outcome.

“Hypocapnia (PaCO2 of less than 30 mm Hg) is common in late pregnancy. A PaCO2 of 35 to 40 mm Hg may be associated with impending respiratory failure. Oxygen consumption is increased in pregnancy, hence maintenance of arterial oxygenation is especially important in resuscitation.”

“. . . . Hence the tolerable duration of apnea and/or pulselessness for a pregnant woman is only four minutes. The chance of a successful resuscitation of the mother or fetus decrease after this time. The clinician has four minutes to restore circulation in the mother before she/he must begin dramatic action, hence the ‘four minute rule.'”

MODIFICATIONS OF CPR IN PREGNANCY

“The uterus should be moved off the aorta, vena cava, and pelvic great vessels, due to aortocaval compression by the uterus after 20 weeks. The chest compression force at an angle of 27 degrees of left tilt is 80 percent. Tilt angles over 30 degrees are associated with the patient sliding off the surface; 25 to 30 degrees angle is desirable.”

“Several methods can be utilized to improve the effectiveness of chest compressions:

1. Place intravenous bags or rolled up towels under the right flank and hip.
2. Place the knees of a second rescuer under the right flank and hip.
3. Manually displace the uterus leftward
4. Chest compressions more cephalad on sternum
5. Emergency hysterotomy (cesarean delivery)”

“It is important to ensure that the forces of chest compression are directed toward the spine and not just vertically downward. The latter causes later pressure in patients that are in a lateral tilt position and hence less effective CPR circulation.”

“A mechanical wedge (the Cardiff wedge**), may be available for use in specialized controlled setting. Despite all the maneuvers, CPR in pregnancy should NOT be considered effective circulation, even with the necessary positioning, hence the need to relieve the aortocaval compression. (See Emergency Hysterotomy below [discussed in the text])

TRAUMA IN PREGNANCY

“Trauma complicates one in twelve pregnancies, and is the leading causeof death among pregnant women. . . . Head injury and hemorrhagic shock account for over 85 percent of all maternal trauma deaths.”

“The placenta is an inelastic organ attached to an elastic organ (the uterus). Accelerations or decelerations may deform the uterus and shear the placenta off of its implantation site, creating an abruption. The risk of abruption is independent of placental location.

“Gastric emptying time is prolonged during pregnancy. As such, the clinician should always assume the stomach of the pregnant patient is full. Early gastric tube compression should be considered.

MINOR TRAUMA

“The most common trauma related occurrence among pregnant women is a minor trauma, such as a fall, minor auto accident, or blow to the abdomen, which causes little or no maternal injury. . . . Abruption usually becomes apparent shortly after injury, fetal monitoring of women who experience trauma beyond 20 weeks gestation should be initiated as soon as the patient is stabilized. The patient should be monitored by cardiotocograth for a minimum of four hours but may be extended to a six hour minimum. In 100% of patients found subsequently to have a placental abruption, eight or more contractions per hour present in the first four hours. The Kleihauer Betke test should be done to detect fetal maternal transfusion, regardless of Rh status in order to determine the degree of fetal maternal hemorrhage. The presence of uterine contractions and fetal red blood cells in the maternal circulation are good indicators of fetal risk from abruption, rupture of membranes, or premature labor.”

“Monitoring should be continued for a minimum of 24 hours if there is presence of uterine contractions, nonreassuring fetal heart rate patterns, vaginal bleeding, significant uterine tenderness, or serious maternal injury or rupture of membranes occurs during the initial 4 to 6 hours monitoring.. If none of these concerning findings is present, then the patient may be discharged home with instructions to return if she develops vaginal bleeding, leakage of fluid, decreased fetal movement or severe abdominal pain.”

AMNIOTIC FLUID EMBOLISM

“Amniotic fluid embolism (AFE) is rare, with an estimated incidence of 1:15,200 and 1:53,800 deliveries in North America and Europe, respectively.”

“In the past, the maternal mortality rate from this complication was initially estimated at 85%, with half of the deaths occurring in the first hour. With the advent of intensive care units, population-based data now suggest that the case fatality rate and perinatal mortality associated with AFE are 13 to 30% and 9 to 44%, in North America and Europe respectively.”

“Pathophysiologic studies suggest that left heart failure and pulmonary vasospasm are primary etiologic factors in the cardiovascular collapse, but that the underlying mechanism may be in anaphylactic like event with an associated 41% incidence of atopy or allergy. The hemodynamic response in AFE is biphasic, with initial pulmonary hypertension and right ventricular failure, all of by left ventricular failure. Disseminated intravascular coagulopathy (DIC) is the most common complication, possibly due to the large amount of tissue factor in amniotic fluid.”

“The management of amniotic fluid embolism is largely supportive. And aggressive medical approach seems justified and can certainly do no harm for patients who survived the initial catastrophic event.”

“When an obstetric patient collapses unexpectedly, the primary ABCD’s should be attended to, with the airway secured and ventilation assured, using endotracheal intubation if necessary.”

“Coagulation factors should be assessed every two hours and blood component therapy initiated is needed with packed red cells, platelets (if the platelet count is less than 50,000), fresh frozen plasma, cryoprecipitate.”

* Maternal cardiac arrest associated with attempted fetal injection of potassium chloride. Full text pdf.  Int J Obstet Anesth. 2004 Oct;13(4):287-90. Abstract: We report a case of maternal cardiac arrest immediately after attempted fetal cardiac injection of potassium chloride. Prompt institution of maternal cardiac life-support protocols resulted in successful maternal resuscitation. The management of this case as well as that of fetal cardiac injections of potassium chloride is reviewed.

**I did a quick Google search on the Cardiff Wedge and it is apparently not commercially available. However, to see a picture of the device go to Resuscitation In Pregnancy, BMJ. 2003 November 29; 327(7426): 1277–1279. The device could be easily constructed.”