1. Engagement refers to the mechanism by which the greatest transverse diameter of the head, the biparietal diameter in occiput presentations, passes through the pelvic inlet. A fetus is engaged when the presenting part is at 0 station. In a primiparous patient, it usually occurs in the last 2 weeks of pregnancy; in a multiparous patient, it can occur at the onset of labor.

2. Flexion of the head is necessary to minimize the presenting cross-sectional diameter of the head during passage through the smallest diameter of the bony pelvis. In most cases, flexion is necessary for both engagement and descent and occurs passively.

3. Descent is the downward passage of the fetal presenting part. It is gradually progressive but is not necessarily continuous. Descent is affected by uterine and abdominal contractions, as well as by straightening and extension of the fetal body.

4. Internal rotation occurs with descent and is necessary for the head or presenting part to traverse the ischial spines. This movement essentially turns the head such that the occiput gradually moves from its original, more transverse position anteriorly toward the symphysis pubis or, less commonly, posteriorly toward the hollow of the sacrum. This is known as occiput anterior or occiput posterior, respectively.

5. Extension occurs as the flexed head reaches the anteriorly directed vaginal introitus. The occiput reaches the inferior aspect of the pubic symphysis. The head is born by further extension as it rotates around the pubic symphysis and the occiput, bregma, forehead, nose, mouth, and finally, the chin pass successively over the anterior margin of the perineum. Immediately after its birth, the head drops downward such that the chin lies over the maternal anal region.

6. External rotation or restitution is return of the head to the correct anatomic position with respect to the fetal torso. It follows delivery of the head as it rotates to the transverse position that it occupied at engagement. This is also a passive movement.

7. Expulsion of the remainder of the fetal body then occurs. The shoulders descend in a path similar to that traced by the head (i.e., rotating anteroposteriorly for delivery). First, the anterior shoulder is delivered beneath the symphysis pubis followed by the posterior shoulder across the perineum.

Types

There are three types of vaginal breech deliveries. Spontaneous breech is a breech delivery in which the infant is delivered spontaneously without any manipulation or traction other than supporting the infant. This form of delivery is rare with term infants, and there is little associated traumatic morbidity. Partial breech extraction occurs when the infant is delivered spontaneously as far as the umbilicus and the remainder of the body is extracted. Total breech extraction occurs when the entire body of the infant is extracted by the clinician.

Similar to cephalic presentations, the role of the clinician is to assist the mother in the birthing process and allow maternal expulsive efforts to effect delivery of the infant. Premature or aggressive assistance or traction can significantly increase the risk for fetal or maternal morbidity.

To perform any vaginal breech delivery, the birth canal must be sufficiently large to allow passage of the fetus without trauma and the cervix must be completely effaced and dilated. If these conditions do not exist, cesarean section is indicated. To ensure full cervical dilation in a footling or complete breech, it is important that the feet, legs, and buttocks advance through the introitus to the level of the fetal umbilicus before the clinician intervenes and further delivery is attempted. The mere appearance of the feet through the vulva is not in itself an indication to proceed with delivery. This may be a footling presentation through a cervix that is not completely dilated. In this case there may be time to transfer the patient to the labor and delivery suite, preferably in the knee-chest position to minimize the risk for cord compression.¹⁵ Similarly, if the breech is frank, cervical dilation and outcome are improved if the infant is allowed to deliver to the level of the umbilicus. Before this, as with complete and footling presentations, there may be time to safely transfer the mother to the labor and delivery area. Tocolytics such as subcutaneous terbutaline may be used to inhibit labor until such patients can be safely transferred.¹⁵

Auscultation

Make the initial determination of fetal well-being by assessing the fetal heart rate with a fetoscope, bedside ultrasound, or a fetal Doppler ultrasound device placed firmly on the maternal abdominal wall overlying the fetal thorax and reposition it until fetal heart tones are heard. When a Doppler device is used, apply a conducting gel to the abdominal wall to interface with the Doppler receiver. To avoid confusion of the maternal and fetal heart sounds, palpate the maternal pulse as the fetal heart rate is auscultated.

The normal baseline fetal heart rate is 110 to 160 beats/min and varies considerably from a baseline measured for a minimum of 2 minutes in a 10-minute segment of time.¹⁶ Rates above or below this range may indicate fetal distress. Accelerations in the fetal heart rate lasting longer than 10 seconds and less than 2 minutes commonly occur during labor and are probably a physiologic response to fetal movement.^3,16,17 Persistent fetal tachycardia occurs most frequently in response to maternal fever or amnionitis but may also indicate fetal compromise.^3,16

As with brief accelerations in the fetal heart rate, a gradual decrease in the fetal heart rate in association with a uterine contraction with an onset to nadir of 30 seconds or more (with the nadir coinciding with the peak of contraction) is termed an early deceleration. Decelerations are physiologic and probably the result of vagal nerve stimulation secondary to compression of the fetal head. Decelerations that occur independently of uterine contractions, are abrupt, or last between 15 seconds and 2 minutes are known as variable decelerations. Late decelerations are those that are delayed in timing with respect to a contraction, with the nadir of the deceleration occurring after the peak of the contraction. Variable decelerations are relatively common and can be further classified according to their severity. Variable decelerations may be temporarily corrected by maternal repositioning. Late decelerations can be an ominous sign and may represent cord compression and uteroplacental insufficiency.3,16,17 It may necessitate emergency delivery.

Changes in the fetal heart rate indicating fetal distress are usually evident immediately after a uterine contraction, and therefore the fetal heart rate is optimally assessed at this time. Formal monitoring of labor should be performed in an obstetrics unit. Fetal monitoring is not performed in the ED, but examples of various fetal heart rate patterns are included for completeness in Figure 56-8.^3,16

Management of Fetal Distress

Definitive evaluation of fetal distress should be performed in the obstetric unit by the delivery team. There is no role for sophisticated fetal monitoring in the ED. In the absence of a dedicated obstetric unit, transfer to another hospital is the only option, albeit a less than ideal one. An EP working in an ED without adequate obstetric backup can do little to effect a positive outcome in high-risk situations. Eclampsia, bleeding, and abnormal fetal presentation may be identified, but the EP needs to focus attention on maternal well-being while expediting transfer, referral, or both. The EP has limited options for managing fetal distress.

If fetal distress is suspected on the basis of the resting fetal heart rate or changes after contractions, change the maternal position, typically into the left lateral decubitus position, and reevaluate. Administer supplemental oxygen to the mother to optimize fetal oxygenation. In the absence of bleeding, perform a vaginal examination to rule out the possibility of umbilical cord prolapse.16,18 Cord prolapse usually occurs at the same time as rupture of the membranes and is diagnosed by palpation of the umbilical cord on vaginal examination or by visualization of the cord protruding through the introitus. Cord prolapse is frequently encountered with breech presentations, multiple pregnancies, and prematurity.^19–21

Management of cord prolapse is directed at sustaining fetal life until delivery is accomplished. Unless immediate delivery is feasible or the fetus is known to be dead, prepare for an emergency cesarean section. If immediate obstetric services are not available, four temporizing measures can be undertaken. (1) Place the patient in the knee-chest or deep Trendelenburg position, and keep the patient in this position until delivery.18,21,22 (2) Minimize compression of the umbilical cord by inserting a sterile gloved hand and exerting manual pressure in the vagina to lift and maintain the presenting part away from the prolapsed cord. (3) After manual elevation of the presenting part, instill 500 to 700 mL of saline into the bladder to raise the presenting part and maintain cord decompression. Once the bladder is filled, remove the vaginal hand.^22,23 (4) Tocolytic therapy can be administered to decrease uterine contractions and improve fetoplacental perfusion.^22,23 Unfortunately and realistically speaking, outcomes of true obstetric emergencies managed solely in the ED are often bleak and essentially out of the hands of the EP.

Tocolytic Therapy

Tocolytic therapy is rarely instituted in the ED, and there is no standard mandating its use by the EP. However, under dire circumstances and preferably under obstetric guidance, this intervention may be initiated in the ED. Before instituting pharmacologic tocolytic therapy for either preterm labor or fetal distress, initiate basic maneuvers to improve maternal and fetal status. Because uterine hypoxia may induce uterine contractions, administer supplemental oxygen and infuse 500 mL of crystalloid intravenously. Place the mother in the left lateral decubitus position to improve uterine perfusion.3,18,24 Because uterine, cervical, or urinary tract infections account for 20% to 40% of cases of preterm labor, search for a specific cause and treat infections appropriately.^18,25,26 If the contractions persist and cervical changes are documented despite these basic interventions, consider pharmacologic therapy.^3,18,24 Although tocolytic agents are commonly used and have been shown to prolong pregnancy by 2 to 7 days, there are few data to suggest that tocolysis improves long-term perinatal or neonatal outcome.^3,24,27,28 In addition, none of the commonly used tocolytic medications are approved for use by the U.S. Food and Drug Administration (FDA) as a tocolytic agent. The principal benefit of pharmacologic therapy may be only to prolong pregnancy to allow maternal transfer to a tertiary care facility or to delay delivery sufficiently to improve fetal maturation with corticosteroids.^3,24–26,29 General contraindications to tocolytic therapy include severe preeclampsia, placental abruption, intrauterine infection, advanced cervical dilation, and evidence of fetal compromise or placental insufficiency.²⁴

There are no clear “first-line” tocolytic agents to manage preterm labor (Table 56-1). Clinical circumstances and preferences should dictate treatment. Agents such as calcium channel blockers and the prostaglandin inhibitor indomethacin have shown varying efficacy in clinical trials.^{3,16,24,25,27} The most commonly used tocolytic agents in the United States are the calcium channel blocker nifedipine, magnesium sulfate, and the β₂-receptor agonist terbutaline. Calcium channel blockers are the preferred tocolytics by the World Health Organization.³⁰

β₂-Receptor Agonists

The most commonly used β₂-adrenergic tocolytic agent is terbutaline. The β-mimetic agents react with adrenergic receptors to reduce intracellular ionized calcium levels and prevent the activation of myometrial contractile proteins.³ Although terbutaline stimulates β₂-receptors primarily, it has some β₁-activity, which is responsible for its cardiovascular side effects. Another β-mimetic agent, ritodrine, was the only agent approved for tocolysis in the United States but has been withdrawn from the market.

Terbutaline is commonly used for the treatment of preterm labor.3,25,31 When given subcutaneously, administer terbutaline in a 0.25-mg dose and repeat it every 20 to 60 minutes until contractions cease or intolerable maternal side effects occur.^18,24,32,33 In 2011 the FDA required the addition of a Boxed Warning and Contraindication (“black box warning”) against the use of injectable terbutaline for the prevention or prolonged treatment of preterm labor beyond 48 to 72 hours because of adverse effects, including maternal death.³⁴ Use terbutaline with caution in patients with cardiovascular disease, hypertension, hyperthyroidism, diabetes, and seizures and in those taking other sympathomimetic amines.^24,35 The general clinical side effects of arrhythmias, myocardial ischemia, and pulmonary edema are related to its inherent activity as a β-mimetic drug. Treatment of the majority of side effects is supportive; severe cardiovascular effects may be treated with β-blocking agents.^32,35

Magnesium Sulfate

Magnesium sulfate (MgSO₄) is not approved in the United States for use as a tocolytic agent. Nevertheless, some perinatal centers prefer MgSO₄ over the β-mimetic agents because of its lower incidence of side effects.18,36,37 Even though the use of MgSO₄ as a tocolytic has fallen out of favor, findings of fetal neuroprotective effects have resulted in its ongoing use.^38–41 Although its mechanism of action is not fully understood, magnesium probably decreases myometrial contractility through its role as a calcium antagonist.³ Its fetoprotective effects probably result from noncompetitive antagonism of the N-methyl-d-aspartate receptor or through antiapoptosis and prevention of neuronal cell loss.⁴²

MgSO₄ is generally administered at a dose of 4 to 6 g intravenously over a period of 20 to 30 minutes, followed by a maintenance intravenous infusion beginning at 1 to 3 g/hr.24,43 Infusion of MgSO₄ often produces sweating, warmth, and flushing. Rapid parenteral administration may cause transient nausea, vomiting, headache, or palpitations.^24,25,37 The major side effect of magnesium therapy is impairment of the muscles of respiration with subsequent respiratory arrest, an effect not usually seen until the serum magnesium level exceeds 10 mEq/L. At levels of 12 mEq/L or greater, respiratory arrest may occur.³⁵

The first sign of magnesium toxicity, a decrease in the patellar reflex, typically occurs as serum magnesium levels exceed 4 mEq/L, with loss of the reflex as levels increase further. The dosing and ongoing maintenance of magnesium therapy should be guided by the clinical status of the patient rather than by laboratory values. Monitor the patellar reflex throughout therapy. Because magnesium is almost totally excreted by the kidney, it is contraindicated in the presence of renal failure. Monitor urinary output and renal function throughout therapy. If respiratory depression develops, inject 10 mL of a 10% solution of calcium gluconate or calcium chloride over a 3-minute period as an antidote. For severe respiratory depression or arrest, prompt endotracheal intubation may be lifesaving.³

Calcium Channel Blockers

Calcium antagonists inhibit the influx of calcium ions through the muscle cell membrane and reduce uterine vascular resistance. The decrease in intracellular calcium also results in decreased myometrial activity. Although dosing regimens vary, nifedipine is frequently given as an initial loading dose of 30 mg orally and then 10 to 20 mg every 4 to 6 hours.24,32 When oral nicardipine (Cardene) was compared with MgSO₄, less time was required to achieve tocolysis, 3.3 versus 5.3 hours, respectively. Preterm labor also recurred less frequently with nicardipine.⁴⁴ The calcium channel blocker–induced decreased vascular resistance can lead to maternal hypotension and thus decreased uteroplacental perfusion.

Prostaglandin Inhibitors

Prostaglandins are smooth muscle stimulants. Prostaglandin synthetase inhibitors inhibit cyclooxygenase and thereby prevent the conversion of free arachidonic acid to prostaglandin. Because the prostaglandin E and F series are mediators of uterine contractions, a decrease in production results in decreased contractile activity.³² Indomethacin is administered as an initial oral or rectal dose of 50 to 100 mg followed by 25- to 50-mg doses every 6 hours for a total of 48 hours.²⁴ Ketorolac can be used as an alternative with a 60-mg intramuscular loading dose, followed by 30 mg intramuscularly every 6 hours for 48 hours.²⁴ Side effects include oligohydramnios and premature closure of the ductus arteriosus.

Steroids

In addition to tocolytics, patients in preterm labor and less than 34 weeks’ gestation are candidates for antenatal steroid administration. This may reduce the incidence of neonatal respiratory distress syndrome, intraventricular hemorrhage, and necrotizing enterocolitis.²⁴ Appropriate patients should receive betamethasone, 12 mg intramuscularly every 24 hours for a total of two doses, or dexamethasone, 6 mg intramuscularly every 12 hours for a total of four doses.

Technique for Uncomplicated Delivery

Although complete sterility is not a priority, when time permits, use sterile technique and equipment. Wear sterile gloves, a gown, mask, and eye protection. Clean the perineum and vulva as for a vaginal examination and drape with sterile towels so that only the immediate area about the vulva is exposed. Be careful to avoid fecal contamination of the infant or perineum.

Ideally, place the patient on a delivery table in the dorsal lithotomy position to increase the diameter of the pelvic outlet (Fig. 56-10, step 1). Alternatively, position the patient on a stretcher with her hips and knees partially flexed, her thighs abducted, and the soles of her feet placed firmly on the stretcher. Additional personnel may assist in keeping the patient in this position. If the foot of the bed cannot be removed, enhance the delivery position by placing the underside of a bedpan under the patient’s buttocks to provide additional space between the bed and the perineum.

Spontaneous Vertex Delivery

Spontaneous delivery of a vertex-presenting infant is divided into three phases: delivery of the head, delivery of the shoulders, and delivery of the body and legs.

Complex Deliveries

Episiotomy

Routine use of episiotomy is no longer recommended, but it is still performed with some frequency.⁵³ Selected indications include breech delivery, shoulder dystocia, occiput-posterior presentations, and imminent perineal tear (Box 56-1). It may also be necessary to expedite delivery in situations of fetal distress. Two types of episiotomy are used: median (midline) and mediolateral (Fig. 56-17). The median approach is the easiest type to perform and repair, results in the least amount of blood loss, heals more rapidly with minimal discomfort, and is generally more common in the United States. A major complication of median episiotomy is potential inadvertent extension of the incision into the anal sphincter or rectum, which results in third- and fourth-degree lacerations, respectively.^3,15,54,55 A mediolateral episiotomy seldom results in extension into the anal sphincter, but blood loss is greater, repair is more difficult, and healing may be more painful.^3,15

Immediate Postpartum Hemorrhage

The average blood loss with a vaginal delivery is estimated to be approximately 500 mL.⁵⁶ There is no exact definition of postpartum hemorrhage, but a general guide is maternal blood loss greater than 500 mL or bleeding that exceeds a clinician’s estimate of “normal.”⁴ Postpartum hemorrhage is divided into early hemorrhage, which occurs within 24 hours of delivery, and late hemorrhage, which occurs more than 24 hours and up to 6 weeks after delivery.

Postpartum hemorrhage is not necessarily sudden and massive. It is frequently characterized by persistent moderate bleeding until serious hypovolemia develops. Observe carefully for blood loss, including evaluation of uterine size and consistency, during the early postpartum period. The most common cause of early postpartum hemorrhage is uterine atony, which is involved in up to 80% of cases.⁵⁷ Less common causes include lacerations of the lower genital tract, retained placenta or placental fragments, coagulation disorders, uterine rupture, uterine inversion, and placental site bleeding.⁴

Indications

Although the lower limit of fetal viability varies among institutions, performance of PCS before approximately 24 weeks is not generally indicated.¹⁸ If the duration of gestation is not known from the history, estimate fetal maturity quickly by calculating gestational age on the basis of the date of the patient’s last normal menstrual period or by measuring the height of the uterine fundus. Between 18 and 30 weeks’ gestation, the age of the fetus in weeks will correspond to the distance in centimeters from the uterine fundus to the symphysis pubis (e.g., at 28 weeks’ gestation the fundus lies approximately 28 cm above the symphysis pubis or halfway between the umbilicus and the costal margin).⁷⁵ Establish criteria for intervention prospectively at each institution in accordance with the institution’s neonatal care policies.^18,75

Survival of the infant is directly related to the time elapsed from maternal cardiac arrest to delivery, prompt performance of cardiopulmonary resuscitation (CPR) on the mother, the maturity of the fetus, pre-arrest health status of the mother, and in certain circumstances, the availability of neonatal intensive care facilities.68,70,73 In accordance with advanced cardiac life support guidelines, initiate CPR immediately on recognition of maternal arrest and continue it until the infant has been delivered. The anatomic and physiologic changes of pregnancy will inhibit the effectiveness of CPR on the mother. Aortocaval occlusion by the gravid uterus may occur after 20 weeks’ gestation. It can reduce venous return and compromise maternal cardiac output, especially in the supine position. For this reason, it is advisable to perform CPR in the left lateral, head-down position or to have an assistant manually displace the uterus away from the inferior vena cava.⁷¹ In addition, the decreased functional residual capacity of the lungs may impede ventilation efforts. Under these conditions, CPR generates only 30% to 40% of normal cardiac output, which severely compromises placental perfusion. The potential for infant survival decreases and the chance of neurologic damage increases as the time from maternal cardiac arrest to PCS rises (Table 56-3). When PCS is performed within 5 minutes, neonatal outcome is best, but not guaranteed; from 5 to 10 minutes, good; from 10 to 15 minutes, fair; and from 15 to 20 minutes, poor. Make every attempt to begin PCS within 4 minutes of cardiopulmonary arrest and complete the procedure within 5 minutes of arrest.^18,70,73,75 Fetal prognosis is generally better in the later stages of pregnancy and after the sudden death of a previously healthy mother rather than death secondary to chronic illness.^68,70,75

In addition to fetal benefits, PCS may improve maternal outcome. Emptying the uterus by PCS removes the aortocaval compression, thereby resulting in a 30% increase in cardiac output, which increases the likelihood of maternal survival.76,77 CPR should continue during and after the procedure. PCS in itself may represent the most important variable for successful maternal resuscitation.^68,70,78

Limited resources often place the EP in the difficult situation of deciding whether to continue efforts to resuscitate the mother or to attempt to deliver the fetus under less than ideal conditions. The decision to perform this procedure may be one of the most challenging that an EP will encounter. In the absence of immediate obstetric backup, it is reasonable to proceed with PCS if initial maternal resuscitation efforts are unsuccessful. Prolonged attempts to resuscitate the mother are unlikely to benefit either the mother or the fetus.

Technique

The most experienced person present should perform the PCS, preferably an obstetrician. Under ideal circumstances a neonatologist should also be in attendance, so contact them as soon as possible. However, do not delay the procedure to allow time for their arrival. Also, time should not be wasted searching for fetal heart tones or attempting to evaluate fetal viability with ultrasonography.

Extract the infant rapidly while avoiding fetal and maternal injury (Fig. 56-20). Hence, do not waste time preparing a sterile operating field or transporting the patient to an operating suite outside the ED. Use a large (e.g., No. 10) blade and make a midline vertical incision through the abdominal wall that extends from the symphysis pubis to the umbilicus. Carry the incision through all abdominal layers and into the peritoneal cavity. In most gravid women the hyperpigmented “linea nigra” is apparent, and when present, use this as a guide for the incision. If available, place retractors in the abdominal wound and draw them laterally to expose the anterior surface of the uterus. Reflect the bladder inferiorly. If full, aspirate the bladder to evacuate it and permit better access to the uterus. While avoiding injury to fetal parts, make a small (≈5-cm) vertical incision through the uterus until amniotic fluid is obtained or the uterine cavity is clearly entered. Insert the index and long fingers into the incision and use them to lift the uterine wall away from the fetus. Use bandage scissors to extend the incision vertically to the fundus until a wide exposure is obtained. Gently deliver the infant, suction the mouth and nose, and clamp and cut the cord. Because the incision is relatively high in the uterus, the infant’s head may not be readily accessible to the clinician. In this case, grasp the infant’s feet and deliver the infant through maneuvers similar to those used for a breech delivery.

Evaluation

Traditionally, the Apgar scoring system, applied at 1 and 5 minutes after birth, has been the standard of newborn evaluation (Table 56-4).^3,80 In general, the higher the score, the better the condition of the infant. Waiting for the traditional 1-minute Apgar score to indicate the need for resuscitation has been replaced by the concept of “the golden minute.” Begin basic resuscitation maneuvers, reevaluation, and positive pressure ventilation (PPV), if required, by the first 60 seconds after birth. Use the heart rate and respiratory effort to guide resuscitation efforts because skin color does not reliably predict oxygenation status in the newborn period.⁴⁵

Stabilization Technique

Following delivery of the infant and cutting of the umbilical cord, place the newborn on the side in the sniffing position and the neck in a neutral or slightly extended position.⁸¹ Place a rolled blanket or towel under the back and shoulders of the supine infant to elevate the torso 2 to 2.5 cm because this may help maintain head position.^80,81 Prevent heat loss in the newborn because cold stress can increase oxygen consumption and impede effective resuscitation.⁸¹ Avoid hyperthermia, however, because it is associated with perinatal respiratory depression.^81,82 Place the infant under a radiant warmer, rapidly dry the skin, and wrap the infant in warmed blankets to reduce heat loss.^45,80,81 Alternatively, use the mother’s body as a heat source for the newborn. If initial evaluation indicates that the infant is stable, dry and place the infant skin to skin on the mother’s chest or abdomen, and cover both with blankets.^80,81

Vigorous newborns should not be routinely suctioned after delivery, even those delivered through meconium-stained fluid.45,83 Reserve suctioning (including suctioning with a bulb syringe) immediately after birth for babies who exhibit obvious obstruction to spontaneous breathing or require PPV. Despite a paucity of data to support the practice, endotracheal suctioning is still recommended for nonvigorous babies born through meconium-stained amniotic fluid.⁴⁵ If suctioning is necessary, first clear secretions from the mouth and nose with a bulb syringe or suction catheter (8 or 10 Fr). Aggressive pharyngeal suctioning can cause laryngeal spasm and vagal bradycardia, so limit the depth and duration of suctioning and do not exceed a negative pressure of 100 mm Hg.⁸¹

For newborns who do not quickly respond to conservative measures, PPV is indicated. Most newborns who require PPV can be adequately ventilated with a bag and mask. Perform assisted ventilations at a rate of 40 to 60/min (30 breaths/min if mechanical compressions are being performed). Typically, higher inflation pressures (≥30 to 40 cm H₂O) and longer inflation times are required for the first several breaths than for subsequent breaths. Visible chest expansion is a more reliable indicator of appropriate inflation pressure than a specific manometer reading.80,81 Because bag-valve-mask ventilation can produce gastric distention and impede respiration, insert an orogastric tube (8 Fr) in infants undergoing prolonged PPV.⁸¹

Endotracheal intubation may be indicated when bag-valve-mask ventilation is ineffective, when tracheal suctioning for meconium is required, when chest compressions are performed, or when prolonged PPV is required.45,80 Alternatively, a neonatal laryngeal mask airway may provide effective airway management, especially in the case of ineffective bag-valve-mask ventilation or failed endotracheal intubation.⁴⁵ Use of the laryngeal mask airway, however, has not been adequately studied in preterm infants and those with deliveries complicated by meconium-stained fluid. Its use, therefore, cannot be recommended in these situations.⁴⁵

Monitor the heart rate during the course of neonatal evaluation and stabilization by either direct auscultation over the chest or palpation of the pulse at the base of the umbilical cord. A readily discernible heartbeat of 100 beats/min or greater is acceptable. If the heart rate is less than 60 beats/min despite adequate ventilation and oxygenation for 30 seconds, institute chest compressions while continuing to ventilate.⁴⁵ Deliver chest compressions on the lower third of the sternum and not over the xiphoid to avoid damage to the liver.⁸⁰ There are two techniques for performing chest compressions in the newborn. In the preferred method, two thumbs of the resuscitator’s hands are positioned side by side over the lower third of the sternum just below the nipple line. If the infant is large or the resuscitator’s hands are too small to encircle the chest, two-finger compressions with the ring and middle fingers may be used.^45,80 The depth of compression should be approximately one third to one half the AP diameter of the newborn’s chest such that a palpable pulse is generated.⁴⁵ Coordinate compressions and ventilations to avoid simultaneous delivery, which may compromise the efficacy of ventilation. The compression-to-ventilation ratio should be 3 : 1 with 90 compressions and 30 breaths to achieve approximately 120 events/min.⁴⁵ If the heart rate remains less than 60 beats/min despite these interventions,⁴⁵ establish an umbilical or intravenous line and initiate appropriate drug therapy. Alternatively, use intraosseous access, but this may not be as effective in a preterm infant.⁸¹ The medications most commonly used during neonatal resuscitation are listed in Table 56-6.^45,81

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