INTRODUCTION
Neonatal resuscitation is an attempt to facilitate the dynamic transition from fetal to neonatal physiology. Neonatal resuscitation skills are essential for all health care providers who are involved in the delivery of newborns. The transition from fetus to newborn requires intervention by a skilled individual or team in approximately 10% of all deliveries.1 One important aspect of performing a successful resuscitation is having a good understanding of the complex dynamics of fetal/neonatal physiology and the adaptations that must be made to transition to extrauterine life.2 A recent systematic review has concluded that basic resuscitation should substantially reduce intrapartum-related neonatal deaths.3
Perinatal asphyxia and extreme prematurity are the two complications of pregnancy that most frequently require a complex resuscitation by skilled personnel. However, only 60% of asphyxiated newborns can be predicted antepartum. The remaining newborns are not identified until the time of birth. Additionally, approximately 80% of low birth weight infants require resuscitation and stabilization at delivery. Nearly one half of newborn deaths (many of which are extremely premature infants) occur during the first 24 hours following birth. To improve the almost stagnant infant mortality rate, it is important that all personnel involved in care of the mother or the newborn at the time of delivery are adequately trained and equipped with the skills of neonatal resuscitation. For the surviving infants, effective management of asphyxia in the first few minutes of life may influence long-term outcome.
This chapter reviews the adaptation to extrauterine life and the steps necessary to optimally resuscitate neonates. The chapter is based on currently available national and international guidelines on the subject. Before enumerating the steps of neonatal resuscitation it is vital to understand the physiologic changes that take place in a baby at the time of birth.
TRANSITION FROM A FETUS TO A NEWBORN
To decrease neonatal morbidity and mortality, the practitioner must be able to rapidly identify infants whose transition from an intrauterine to extrauterine physiology is delayed. Neonatal transition requires spontaneous breathing and successful cardiopulmonary changes, as well as other changes to independent organ system functions. A thorough understanding of normal transitional physiology leads to a better understanding of the needs of the infant who is experiencing difficulties and, therefore, should result in a more effective resuscitative effort.
In utero, the lungs develop steadily from early gestation. The bronchi start developing at 5 weeks of gestation followed by gradual development of bronchioles and circulatory system. However, the alveoli start appearing only after 24 weeks of gestation. This explains the limitations in helping babies below this gestation to survive despite the best of available facilities.
The fetal lung is filled and distended with approximately 20 ml fluid at term. Because of the compressive effect of the fetal lung fluid and the low partial pressure alveolar oxygen (PaO2) in utero, the pulmonary capillary bed and pulmonary blood vessels remain constricted, resulting in high pulmonary vascular resistance and low pulmonary blood flow. Following birth, for the lungs to operate as a functional respiratory unit providing adequate gas exchange, the airways and the alveoli are cleared of fetal lung fluid. A small portion of this fetal lung fluid is removed physically during delivery. During the thoracic squeeze, 25–33% of the fluid may be expressed from the oropharynx and upper airways. Labor is also associated with an increase in catecholamine levels that stimulate lymphatic drainage of the lung fluid. In addition, with the onset of labor, the fetus produces adrenaline and the mother produces thyrotropin-releasing hormone, which stimulates the pulmonary epithelial cells to begin re-adsorption of fluid. These findings could account for the increased incidence of transient tachypnea of the newborn following birth by cesarean delivery without labor.
After birth, lung fluid is removed by several mechanisms, including evaporation, active ion transport, passive movement from Starling forces, and lymphatic drainage. Lung expansion and aeration is also a stimulus for surfactant release. Normally, 80–90% of FRC is established within the first hour of birth in the term neonate with spontaneous respirations. Premature and critically ill infants with surfactant deficiency or dysfunction may have limited ability to clear lung fluid and establish a functional residual capacity.
Stimuli for the first breath may be multi-factorial. The environmental changes that occur with birth (e.g. tactile and thermal changes, increased noise and light) activate a number of sensory receptors that may help initiate and maintain breathing. Clamping of the cord removes the low resistance placenta, causing an increase in systemic vascular resistance and consequently causing an increase in both systemic blood pressure and pulmonary blood flow.
The first breath must overcome the viscosity of the lung fluid and the intra-alveolar surface tension. This first breath must also generate high trans-pulmonary pressure, which helps drive the alveoli fluid across the alveolar epithelium. With subsequent lung aeration, the intra-parenchymal structures stretch and gases enter the alveoli, resulting in increased PaO2 and pH. The increased PaO2 and pH result in pulmonary vasodilation and constriction of the ductus arteriosus. Thereafter, pulmonary blood flow increases, and spontaneous respiration is established. Within minutes of delivery, the newborn's pulmonary vascular resistance may decrease by 8- to 10-fold, causing a corresponding increase in neonatal pulmonary blood flow. If this transition at the time of birth is disordered because of any reason, cyanosis and hypoxia would rapidly develop.
The fetus or newborn that is subjected to asphyxia begins a “diving” reflex (so termed because of certain similarities to the physiology of diving seals) in an attempt to maintain perfusion and oxygen delivery to vital organs. Hypoxia and acidosis lead to pulmonary arteriolar vasoconstriction. Pulmonary vascular resistance increases, leading to a decreased pulmonary blood flow and increased blood flow directly to the left atrium. Systemic cardiac output is redistributed, with increased flow to the heart, brain, and adrenal gland and decreased flow to the rest of the body. Early in the course of asphyxia, systemic blood pressure increases. However, with ongoing hypoxia and acidosis, the myocardium fails, and bradycardia occurs; this causes a decrease in blood pressure and tissue perfusion, leading to eventual tissue ischemia and hypoxia.
Infants who are undergoing asphyxia have an altered respiratory pattern. Initially, they have rapid respirations. These respiratory efforts eventually cease with continued asphyxia (termed primary apnea). During primary apnea, the infant responds to stimulation with reinstitution of breathing. However, if the asphyxia continues, the infant then begins irregular gasping efforts, which slowly decrease in frequency and eventually cease (termed secondary apnea). Infants who experience 6secondary apnea do not respond to tactile or noxious stimulation and require positive-pressure ventilation (PPV) to restore ventilation. Primary and secondary apnea cannot be clinically distinguished. Therefore, if an infant does not readily respond to stimulation, PPV should be instituted as outlined in the Neonatal Resuscitation Program guidelines. The longer the infant is asphyxiated, the longer the onset of spontaneous respirations is delayed following the initiation of effective ventilation through the use of PPV.
EQUIPMENT REQUIRED FOR RESUSCITATION9
The delivery room should be equipped with all the necessary tools to successfully resuscitate a newborn of any size or gestational age. The equipment should include a radiant warmer, warmed blankets, a source of oxygen, instruments for visualizing and establishing an airway, a source of regulated suction, instruments and supplies for establishing intravenous access, trays equipped for emergency procedures, and drugs that may be useful in resuscitation. The minimum equipment necessary includes the following:
- Respiration– Oxygen supply– Assorted masks– Neonatal bag and tubing to connect to an oxygen source– Manometer– Endotracheal tubes (2.5–4)– Tape and scissors– Laryngoscope (0 and 1 sized blades)– Extra bulbs and batteries– CO2 detectors– Stylet for endotracheal tubes (optional)– Laryngeal mask airway (optional)
- Suction– Bulb syringe– Regulated mechanical suction– Suction catheters (6F, 8F, 10F)– Suction tubing– Suction canister– Replogle or Salem pump (10F catheter)– Feeding tube (8F catheter)– Syringe, catheter tipped, 20 ml– Meconium aspirator
- Fluids– Intravenous catheters (22 g)– Tape and sterile dressing material– Dextrose 10% in water (D10W)– Isotonic saline solution– T-connectors– Syringes, assorted (1–20 ml)
- Drugs - Epinephrine (1:10,000)
- Procedures– Umbilical catheters (2.5F, 5F)– Chest tube (10F catheter)– Sterile procedure trays (e.g. scalpels, hemostats, forceps)
NEONATAL RESUSCITATION PROGRAM9
Numerous sources of information concerning the training of skills and procedures that are needed for the delivery room resuscitation of the newborn are available. One highly respected source of information concerning the preparation and practice of neonatal resuscitation is the Neonatal Resuscitation Program, which has been codeveloped by the American Association of Pediatrics (AAP) and the American Heart Association (AHA), and endorsed by National Neonatology Forum (NNF), India. Elaborated below are the guidelines on neonatal resuscitation as described in the NRP.
Assessment at Birth
Those newly born infants who do not require resuscitation can generally be identified by a rapid assessment of the following four characteristics:
- Was the infant born after a full-term gestation?
- Is the amniotic fluid clear of meconium and evidence of infection?
- Is the infant breathing or crying?
- Does the infant have good muscle tone?
If the answer to all four of these questions is “yes,” the infant does not need resuscitation.
If the answer to any of these assessment questions is “no,” there is general agreement that the infant should receive 1 or more of the following four categories of action in sequence:
- Initial steps in stabilization (provide warmth, position, clear airway, dry, stimulate, reposition)
- Ventilation
- Chest compressions
- Administration of epinephrine and/or volume expansion
Fig. 1.1: Suggested algorithm for management of baby in the labor room30
The decision to progress from one category to the next is determined by the simultaneous assessment of three vital signs: respirations, heart rate, and color. Approximately, 30 seconds are allotted to complete each step, re-evaluate, and decide whether to progress to the next step (Fig. 1.1).
INITIAL STEPS9
Maintain Temperature
The initial steps of resuscitation are to provide warmth by placing the infant under a radiant heat source, position the head in a “sniffing” position 9to open the airway, clear the airway with a bulb syringe or suction catheter, and dry the infant and stimulate breathing.
Very low birth weight (<1500 g) preterm infants are likely to become hypothermic despite the use of traditional techniques for decreasing heat loss.10 For this reason it is recommended that additional warming techniques be used, such as covering the infant in plastic wrapping and placing him or her under radiant heat. Other techniques to maintain temperature during stabilization of the infant in the delivery room (e.g. drying and swaddling, warming pads, increased environmental temperature, placing the infant skin-to-skin with the mother and covering both with a blanket) have also been used. Hyperthermia should be avoided. The goal is to achieve normothermia and avoid iatrogenic hyperthermia.
Clearing the Airway of Meconium
Aspiration of meconium before delivery, during birth, or during resuscitation can cause severe aspiration pneumonia. One obstetrical technique to try to decrease aspiration has been to suction meconium from the infant's airway after delivery of the head but before delivery of the shoulders (intrapartum suctioning). Although some studies suggested that intrapartum suctioning might be effective for decreasing the risk of aspiration syndrome, subsequent evidence from a large multicenter randomized trial did not show such an effect.11 Therefore, current recommendations no longer advise routine intrapartum oropharyngeal and nasopharyngeal suctioning for infants born to mothers with meconium staining of amniotic fluid.
Traditional teaching recommends that meconium-stained infants have endotracheal intubation immediately following birth and that suction be applied to the endotracheal tube as it is withdrawn.12 This practice offers no benefit if the infant is vigorous, i.e., has strong respiratory efforts, good muscle tone, and a heart rate >100 beats per minute (bpm). Endotracheal suctioning should be performed only for infants who are not vigorous.
Periodic Evaluation at 30 second Intervals
Further resuscitative efforts are guided by simultaneous assessment of respiration, heart rate, and color. After initial respiratory efforts the newly born infant should be able to establish regular respirations that are sufficient to improve color and maintain a heart rate >100 bpm. Gasping and apnea indicate the need for assisted ventilation.13 Increasing or decreasing heart rate can also provide evidence of improvement or deterioration.
Healthy infants born at term may take up to 10 minutes to achieve a preductal oxygen saturation of 95% and nearly 1 hour to achieve postductal saturation 95%.24–26 Central cyanosis is determined by examining the face, trunk, and mucous membranes. Acrocyanosis (blue color of hands and feet alone) is usually a normal finding at birth. Pallor or mottling may be a sign of decreased cardiac output, severe anemia, hypovolemia, hypothermia, or acidosis.
Administration of Oxygen
Supplementary oxygen is recommended whenever positive-pressure ventilation is indicated for resuscitation; free-flow oxygen should be administered to infants who are breathing but have central cyanosis. The standard approach to resuscitation is to use 100% oxygen. Concerns about potential oxidant injury should caution the clinician about the use of excessive oxygen, especially in the premature infant. The controversy regarding the use of room air in neonatal resuscitation is discussed later.
POSITIVE-PRESSURE VENTILATION
If the infant remains apneic or gasping, if the heart rate remains below100 bpm 30 seconds after administering the initial steps, or if the infant continues to have persistent central cyanosis despite administration of supplementary oxygen, start positive-pressure ventilation.
Initial Breaths and Assisted Ventilation
In term infants, initial inflations—either spontaneous or assisted—create a functional residual capacity.14,15 Average initial peak inflating pressures of 30 to 40 cm H2O (inflation time undefined) usually successfully ventilate unresponsive term infants. Assisted ventilation rates of 40 to 60 breaths per minute are commonly used. The primary measure of adequate initial ventilation is prompt improvement in heart rate. Chest wall movement should be assessed if heart rate does not improve. The initial peak inflating pressures should be individualized to achieve an increase in heart rate and/or movement of the chest with each breath. In summary, assisted ventilation should be delivered at a rate of 40 to 60 breaths per minute to promptly achieve or maintain a heart rate >100 bpm.
Effective ventilation can be achieved with a flow-inflating bag, a self-inflating bag, or with a T-piece. Laryngeal mask airways (LMAs) that fit over the laryngeal inlet have also been shown to be effective for ventilating newly born near-term and full-term infants. The data on the use of these 11devices in small preterm infants is still limited and, therefore, not recommended. Presently available information suggests that when bag-mask ventilation has been unsuccessful and endotracheal intubation is not feasible or is unsuccessful, the LMA may provide effective ventilation. There is insufficient evidence to support the routine use of the LMA as the primary airway device during neonatal resuscitation, in the setting of meconium stained amniotic fluid, when chest compressions are required, in very low birth weight infants, or for delivery of emergency intratracheal medications.
Assisted Ventilation of Preterm Infants
When ventilating preterm infants after birth, excessive chest wall movement may indicate large-volume lung inflations, which should be avoided. Monitoring of pressure may help to provide consistent inflations and avoid unnecessary high pressures. If positive pressure ventilation is required, an initial inflation pressure of 20 to 25 cm H2O is adequate for most preterm infants. If prompt improvement in heart rate or chest movement is not obtained, higher pressures may be needed. If it is necessary to continue positive-pressure ventilation, application of positive end-expiratory pressure may be beneficial. Continuous positive airway pressure in spontaneously breathing preterm infants after resuscitation may also be beneficial.16 A recent study suggests that airway obstruction occurs in the majority of the very low birth weight infants who receive ventilation with a face mask during resuscitation and the use of a colorimetric carbon dioxide detector can facilitate its recognition and management.17
Endotracheal intubation may be indicated at several points during neonatal resuscitation:
- When tracheal suctioning for meconium is required
- If bag-mask ventilation is ineffective or prolonged
- When chest compressions are performed
- When endotracheal administration of medications is desired
- For special resuscitation circumstances, such as congenital diaphragmatic hernia or extremely low birth weight
After endotracheal intubation and administration of intermittent positive pressure, a prompt increase in heart rate is the best indicator that the tube is in place.19 Exhaled CO2 detection is effective for confirmation of endotracheal tube placement in infants, including very 12low birth weight infants. Other clinical indicators of correct endotracheal tube placement are evaluation of condensed humidified gas during exhalation and the presence or absence of chest movement, but these have not been systematically evaluated in neonates. Except for intubation to remove meconium, exhaled CO2 detection is the recommended method of confirmation.
CHEST COMPRESSIONS
Chest compressions are indicated for a heart rate that is less than 60 bpm despite adequate ventilation with supplementary oxygen for 30 seconds. Because ventilation is the most effective action in neonatal resuscitation and because chest compressions are likely to compete with effective ventilation, rescuers should ensure that assisted ventilation is being delivered optimally before starting chest compressions. Compressions should be delivered on the lower third of the sternum to a depth of approximately one third of the anterior-posterior diameter of the chest.9,20 Two techniques have been described:
- Compression with 2 thumbs with fingers encircling the chest and supporting the back (the 2 thumb-encircling hands technique)
- Compression with 2 fingers with a second hand supporting the back.
Because the 2 thumb-encircling hands technique may generate higher peak systolic and coronary perfusion pressure than the 2-finger technique is recommended. However, when access to the umbilicus is desired for catheterization, the 2-finger technique may be preferable.
Compressions and ventilations should be coordinated to avoid simultaneous delivery.21 The chest should be permitted to fully re-expand during relaxation; there should be a 3:1 ratio of compressions to ventilations with 90 compressions and 30 breaths to achieve 120 events per minute to maximize ventilation at an achievable rate. Respirations, heart rate, and color should be reassessed about every 30 seconds, and coordinated chest compressions and ventilations should continue until the spontaneous heart rate is >60 bpm.
Drugs are rarely indicated in resuscitation of the newly born infant. If the heart rate remains <60 bpm despite adequate ventilation with 100% oxygen and chest compressions, administration of epinephrine or volume expansion, or both, may be indicated. Rarely, buffers, a narcotic antagonist, or vasopressors may be useful after resuscitation.
Route and Dose of Epinephrine Administration
Past guidelines recommended that initial doses of epinephrine be given through an endotracheal tube because the dose can be administered more quickly. However, studies have shown that currently recommended doses of epinephrine are ineffective when given through the endotracheal route and IV route should be used as soon as venous access is established. The recommended IV dose is 0.01 to 0.03 mg/kg per dose. While access is being obtained, administration of a higher dose (up to 0.1 mg/kg) through the endotracheal tube may be considered, but the safety and efficacy of this practice have not been evaluated. The concentration of epinephrine for either route should be 1:10 000 (0.1 mg/ml).
Volume Expansion
Consider volume expansion when blood loss is suspected or the infant appears to be in shock (pale skin, poor perfusion, weak pulse) and has not responded adequately to other resuscitative measures. An isotonic crystalloid rather than albumin is the solution of choice for volume expansion in the delivery room.23 The recommended dose is 10 ml/kg, which may need to be repeated. When resuscitating premature infants, care should be taken to avoid giving volume expanders too rapidly, because rapid infusions of large volumes have been associated with intraventricular hemorrhage.
Naloxone
Administration of naloxone is not recommended as part of initial resuscitative efforts in the delivery room. The preferred route is IV or intramuscular and the recommended dose is 0.1 mg/kg for babies born to mothers exposed to opioid analgesics during labor. Naloxone should be avoided in infants whose mothers are suspected of having had long-term exposure to opioids. Naloxone may have a shorter half-life than the original maternal opioid. Therefore, the neonate should be monitored closely for recurrent apnea or hypoventilation. Subsequent doses of naloxone may be required.
POST-RESUSCITATION CARE
Infants who require resuscitation are at risk for deterioration after their vital signs have returned to normal. Once adequate ventilation and circulation have been established, the infant should be maintained in or transferred to an environment in which close monitoring and anticipatory care can be provided.
GLUCOSE
Low blood glucose has been associated with adverse neurologic outcome in a neonatal animal model of asphyxia and resuscitation.24 Infants who require significant resuscitation should be monitored and treated to maintain glucose in the normal range.
INDUCED HYPOTHERMIA
There is insufficient data to recommend routine use of modest systemic or selective cerebral hypothermia after resuscitation of infants with suspected asphyxia. Further clinical trials are needed to determine which infants benefit most and which method of cooling is most effective. Avoidance of hyperthermia (elevated body temperature) is particularly important in infants who may have had a hypoxic-ischemic event.
GUIDELINES FOR WITHHOLDING AND DISCONTINUING RESUSCITATION
It is possible to identify conditions associated with high mortality and poor outcome in which withholding resuscitative efforts may be considered reasonable, particularly when there has been the opportunity for parental agreement.9 Non-initiation of resuscitation and dis-continuation of life-sustaining treatment during or after resuscitation are ethically equivalent, and clinicians should not hesitate to withdraw support when functional survival is highly unlikely. The following guidelines must be interpreted according to current regional and national outcomes:
- When gestation, birth weight, or congenital anomalies are associated with almost certain early death and when unacceptably high morbidity is likely among the rare survivors, resuscitation is not indicated. Examples may include extreme prematurity (gestational age ≤ 23 weeks or birth weight ≤ 400 g), anencephaly, and chromosomal abnormalities incompatible with life, such as trisomy 13.
- In conditions associated with a high rate of survival and acceptable morbidity, resuscitation is nearly always indicated. This will generally include infants with gestational age >24 weeks (unless there is evidence of fetal compromise such as intrauterine infection or hypoxia-ischemia) and those with most congenital malformations.
- In conditions associated with uncertain prognosis in which survival is borderline, the morbidity rate is relatively high, and the anticipated burden to the child is high, parental desires concerning initiation of resuscitation should be supported.
Infants without signs of life (no heart beat and no respiratory effort) after 10 minutes of resuscitation show either a high mortality or severe neuro-developmental disability.25 After 10 minutes of continuous and adequate resuscitative efforts, discontinuation of resuscitation may be justified if there are no signs of life.
NEWER FRONTIERS IN RESUSCITATION — ROOM AIR VERSUS 100% OXYGEN
Oxygen is a drug with the potential for serious adverse effects that must be considered. Oxygen free radicals are capable of tissue injury and have been implicated in several disease states in the neonate. The use of lower oxygen concentrations when resuscitating the neonate may decrease the number of oxygen free radicals and their damaging adverse effects. In one study, resuscitation with room air was shown to be as effective as 100% oxygen at lowering pulmonary vascular resistance. Other investigations have shown that there are no benefits in raising the pO2 higher than 50 mm Hg. One meta-analysis of 4 studies in infants showed a decrease in mortality and no evidence of harm when resuscitating with room air compared with 100% oxygen.26
Although large controlled multicentered trials have been performed indicating room air (FiO2 = 0.21) is just as effective as 100% oxygen when resuscitating term infants, long-term outcomes are pending. The only follow-up study looking at these infants at 18–24 months showed no significant difference in somatic growth or neurologic handicaps when comparing infants resuscitated in room air to those who received 100% oxygen.27 Currently, supplemental oxygen should be provided whenever PPV is required during resuscitation. Free-flowing oxygen should also be used in infants with central cyanosis. Clinicians may begin resuscitation with an oxygen concentration of less than 100% and may even consider starting with room air as new research data become available.
Current research studies indicate that the immediate outcomes of both approaches in the term infant without underlying lung disease are similar. The results of these studies highlight that, in situations in which 100% oxygen is not available, the resuscitation should proceed with the use of room air and a self-inflating bag.28 In another such study involving very low birth weight (VLBW) babies, authors conclude that delivery room resuscitation of VLBW infants can be initiated with less oxygen even with room air without concomitant overt morbidity. This change was associated with more infants with an initial PaO2 < 80 mm Hg and lower saturation values on admission as well as a lower FiO2 requirement at 24 h.29
CONCLUSIONS
Neonatal resuscitation is an ever evolving field in which new research leads to revision of the practice guidelines. This subject is a very vital component of essential newborn care and requires adequate attention. Each health functionary attending delivery of a neonate should be trained in the art and science of neonatal resuscitation.
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