Introduction
Rapid and complex physiologic changes occur around the time of birth. The keys to a successful transition are the clearance of lung fluid and the establishment of a functional residual capacity (FRC). These changes are accompanied by an increase in pulmonary blood flow and the onset of regular respiration. Most infants achieve the transition unaided, but approximately 10% need help to establish spontaneous breathing in the first minutes of life. Positive-pressure ventilation is required by approximately 1% of newborn infants and chest compressions and/or drug therapy in fewer than 2 in 1000 live births. Successful aeration of the lungs may reduce the need for more extensive resuscitation. Therefore, ensuring that clinicians acquire and maintain the basic skills necessary to deliver effective respiratory support is vital.
Intrapartum-related neonatal death and neonatal encephalopathy impose a substantial burden worldwide, particularly in resource-limited settings. In response to this problem, since 2005 the evidence base available to guide clinicians has grown considerably. The International Liaison Committee on Resuscitation (ILCOR) has evaluated and synthesized the available evidence and produced four iterations of guidelines, most recently, as of this writing, in 2015. From these guidelines each national resuscitation council (the Neonatal Resuscitation Program Steering Committee in the United States) formulates recommendations suitable for application in its own country.
This chapter outlines the important developments in the assessment and management of babies in the first minutes of life.
Physiology of Transition, Asphyxia, and Resuscitation
Physiology of Normal Transition
At birth, the first spontaneous breath generates a large negative pressure, up to −100 cm H 2 O, inflating the lungs and driving lung fluid distally into the interstitial tissues. Studies of the initiation of respiration in well term infants from more than 50 years ago, and more recently data from preterm infants, demonstrate that the first breaths have a short, deep inspiration, followed by a prolonged phase of chest muscle contraction with a closed (braking), or partially closed (crying), glottis, and then finally a small-volume, short expiration. These breaths push back the air–liquid interface; more volume is inspired than expired and the FRC is established.
As the lungs are aerated, pulmonary vascular resistance falls, and flow through the ductus arteriosus changes from right-to-left to left-to-right. Pulmonary blood flow rises, increasing first the cardiac output and then the heart rate and blood pressure.
Within three breaths carbon dioxide (CO 2 ) starts to be exhaled, increasing to levels of ∼50 mm Hg (∼67 kPa) after 1 minute. Observational studies of newborn term and preterm infants not requiring resuscitation show that the heart rate is typically <100 beats per minute (bpm) at 1 minute of age and rises quickly to >160 bpm by 3 minutes.
Before the umbilical cord is cut, the left ventricular preload is dependent on umbilical blood flow. When the cord is cut, preload and cardiac output fall. As the lungs aerate, pulmonary vascular resistance falls and pulmonary venous return provides most of the ventricular preload. Therefore, delaying cord clamping until after lung aeration may stabilize preload and cardiac output and reduce potential swings in arterial pressures and blood flows, leading to a more stable circulatory transition.
Physiology of Asphyxia
Many pre- and peripartum events can reduce the supply of oxygenated blood to the fetus, resulting in varying degrees of fetal hypoxia–ischemia. Classic studies of acute total hypoxia–ischemia (asphyxia) in animal models have guided our understanding of neonatal asphyxia. The physiologic changes and their response to resuscitation are shown in Figure 26-1 .
At the onset of hypoxia, breathing movements become deep and rapid. As the level of consciousness falls, respiratory efforts stop. This is the period of primary apnea, during which heart rate falls to ∼100 bpm and blood pressure transiently rises before falling. Prior to lung aeration, left ventricular preload comes from umbilical blood flow; early clamping of the umbilical cord in infants who have not aerated their lungs, and who therefore do not have any pulmonary venous return, may exacerbate hypoxia by reducing preload and cardiac output.
As cardiac output falls, there is an increase in noncerebral vascular resistance, redirecting remaining cardiac output to the brain to maintain cerebral blood flow and maximize cerebral oxygen delivery. Spinal reflexes, no longer inhibited by higher (conscious) brain activity, trigger the classic diving reflex: respiratory efforts recommence as slow, deep, effortful gasps. This period lasts for several minutes while heart rate, blood pressure, and oxygen levels fall, and carbon dioxide, lactate, and acidosis increase. Hypoxia and acidosis increase vasoconstriction of the pulmonary vasculature, resulting in reduced pulmonary blood flow, lower left atrial pressure, increased right-to-left shunting, and exacerbation of hypoxia. Animal studies show that eventually all respiratory efforts cease (terminal or secondary apnea), the myocardium fails, cardiac output and blood pressure drop, and without intervention the animal dies. In human infants, this sequence may last up to 20 minutes after the onset of hypoxia.
However, animal models have focused on acute total asphyxia, whereas asphyxia in newborn infants may be intermittent, subacute, or chronic. The varying types of asphyxia make it difficult to translate the knowledge gained from animal models to the different pathophysiologies seen in newborn infants.
Physiology of Resuscitation
The primary aims of resuscitation are to sustain life and prevent brain injury. In the newborn setting the focus is on lung aeration, to reduce pulmonary vascular resistance and increase pulmonary blood flow, and to move oxygenated blood to the coronary arteries to reperfuse the myocardium and increase cardiac output. Newborn resuscitation guidelines focus primarily on good ventilatory support to achieve these goals. Even partial lung aeration will significantly increase pulmonary blood flow.
Infants at the stage of primary apnea may go on to make a successful transition through gasping reflexes; however, at birth it is not possible to be sure of the duration of compromise, or whether the presenting apnea is primary or terminal. The earlier in the asphyxial process that resuscitation is started, the more likely it is to be successful. Animal studies demonstrate that resuscitative efforts are more likely to be successful during primary apnea, and the longer the delay in initiating resuscitation after the last gasp, the longer the time to the first gasp after resuscitation begins. For every 1-minute delay, the time to first gasp extends by ∼2 minutes, and the time to onset of spontaneous respiration extends by ∼4 minutes. The decision whether to intervene at birth is complicated by the fact that healthy babies may not take their first breath for more than 30 seconds, and if decisions to intervene are made too early, unnecessary interventions may be applied. However, if decisions are delayed, there may be further cardiorespiratory compromise. In considering whether to intervene, it is helpful to remember that an infant who has good tone is unlikely to be severely hypoxic, and the key sign of an infant’s condition in the minutes after birth, and response during stabilization, is the heart rate.
Anticipation and Preparation for Resuscitation
The need for respiratory support and other interventions immediately after birth is a relatively frequent emergency. Approximately 5% to 10% of term and late preterm newborns will receive some assistance to establish spontaneous respirations, and the probability increases significantly in the presence of known risk factors. Similar to other emergencies, the best outcome is achieved when there is a skilled, organized, and efficient response from a highly effective team. Ensuring such a response requires comprehensive training, deliberate practice, and careful preparation.
Training
All health providers working with newborns should complete a standardized neonatal resuscitation training course. Examples include the Neonatal Resuscitation Program, developed by the American Academy of Pediatrics and the American Heart Association, and the Newborn Life Support course organized by the U.K. Resuscitation Council. Using adult education principles, these programs focus on the cognitive, technical, and teamwork skills required to resuscitate a newborn in the hospital. Other courses teach similar skills for births occurring outside the typical delivery room setting. By simulating both common and unusual neonatal emergencies, providers can identify weaknesses in their skills and develop proficiency. Although a participant’s knowledge and skills improve after a resuscitation course, both have been demonstrated to decay rapidly over time. Without deliberate practice, providers are unlikely to acquire and maintain competence with infrequently used technical skills such as tracheal intubation and emergency vascular access. Even basic assisted ventilation skills have been shown to decay within months of course completion. The ideal frequency of retraining has not been established; however, several studies have shown that low-intensity/high-frequency practice, as short as 6 minutes every month, may improve skill retention.
Teamwork
A complex neonatal resuscitation requires health providers to precisely execute multiple assessments and interventions within minutes of birth. Although the individual team members may have mastered the skills to resuscitate a newborn, they will not be able to use their skills optimally unless they work together as a team. Poor teamwork and communication are the most common causes of potentially preventable deaths in the delivery room. Simply assembling a team of expert health providers does not ensure that they will work well together. Without practice, even a group of highly skilled neonatal providers are likely to work inefficiently in the high-intensity setting of an unexpected resuscitation. High-fidelity simulation and multidisciplinary teamwork training have been shown to improve teamwork skills and the outcome of resuscitation.
A common analogy is to compare the resuscitation team with a race car pit crew. Pit crews practice their teamwork in advance and use highly scripted protocols that distribute the work load to ensure that the correct task is performed efficiently by the correct team member. Similarly, high-performance resuscitation teams precisely execute structured protocols that allow them to recognize important patterns, share information efficiently, and trigger the appropriate response. Each team member’s roles and responsibilities are well defined before the resuscitation begins. The team is directed by an identified leader who gives clear direction, delegates responsibilities, and maintains awareness of the entire clinical situation without becoming distracted by individual procedures.
Anticipation
Before every birth, the neonatal health providers should review the pregnancy history with the obstetric care team to determine which personnel should be present at the time of birth. Using a comprehensive list of risk factors, Aziz demonstrated that approximately 80% of newborns who require resuscitation can be identified before birth ( Table 26-1 ) and that the risk can be stratified into categories that correlate with the need for positive-pressure ventilation. When the neonatal team was called to attend a birth, 22% of newborns received positive-pressure ventilation. When the pregnancy was considered high risk, 47% of newborns received positive-pressure ventilation. In a logistic regression model, an increased risk of requiring positive-pressure ventilation was associated with maternal hypertension, oligohydramnios, maternal infection, preterm multiple pregnancy, opiates received during labor, meconium-stained fluid, breech presentation, abnormal fetal heart rate patterns, delivery at 34 to 35 weeks’ gestation, emergency cesarean birth, and shoulder dystocia. However, the individual risk factors had limited discriminatory power and identified many births for which no intervention was needed. To avoid missing a newborn who required resuscitation, the neonatal team attended approximately two-thirds of all births. Moreover, the absence of risk factors did not exclude the possibility that the newborn would require assistance. Among births with no identified risk factor, 7% of newborns received positive-pressure ventilation. This highlights the importance of having adequate personnel available to immediately resuscitate the newborn at every birth.
| Antepartum Risk Factors | Intrapartum Risk Factors |
|---|---|
| Preterm birth at less than 36 weeks’ gestational age Intrauterine growth restriction Polyhydramnios Oligohydramnios Maternal diabetes Maternal hypertension Major fetal anomaly or hydrops Maternal infection Chorioamnionitis | Abnormal fetal heart rate pattern (category II or III) Prolapsed cord Placenta previa Placental abruption Meconium-stained fluid Shoulder dystocia Breech or transverse presentation Vacuum or forceps birth Emergency cesarean birth Opiates received in labor General anesthesia |
Preparation
After evaluating the perinatal risk factors, the necessary personnel should be assembled. The numbers and qualifications of the health providers will vary depending upon the specific circumstances. Every birth should be attended by at least one qualified health provider whose only job is to manage the newborn. At a minimum, this person must be proficient at newborn assessment, the initial steps of newborn care, and positive-pressure ventilation. A rapid and reliable method of calling for additional help is imperative. If important risk factors are identified, at least two qualified providers should be present at the time of birth. Regardless of the setting, every hospital that delivers newborns should have a qualified resuscitation team proficient in all resuscitation skills immediately available if a complex resuscitation is required. The full team should be present at the time of birth if the need for a complex resuscitation is anticipated. If the newborn has cardiorespiratory collapse, multiple procedures will need to be completed without delay. In smaller hospitals the team may comprise personnel from different disciplines, including anesthesiology for airway management and emergency medicine or pediatrics for vascular access.
Once the appropriate personnel are assembled, if there is time before delivery a preresuscitation briefing or “Time Out” should be performed, to discuss the maternal history, review the clinical situation, identify a team leader, plan the response and the possible contingencies, delegate roles and responsibilities, and prepare the necessary equipment ( Tables 26-2 and 26-3 ). The equipment necessary to initiate positive-pressure ventilation should be checked and ready for immediate use at every birth. All equipment necessary to perform a complex resuscitation should be readily available if needed and should be checked and ready for immediate use if a complex resuscitation is anticipated. Using a standardized prebirth checklist helps to ensure adequate preparation, allows rapid identification of missing equipment, improves communication and teamwork, supports quality assurance data collection, and facilitates postresuscitation debriefing.
| Introduce team members Review maternal history and risk factors Identify team leader Review anticipated clinical scenarios Describe the planned response and contingencies Delegate roles and responsibilities Prepare supplies and equipment Are special consultants or equipment needed? “If any team member identifies concerns or safety issues, alert the team leader immediately.” |
| NEONATAL RESUSCITATION SUPPLIES AND EQUIPMENT | |
|---|---|
| Basic Supplies Radiant warmer with servo-control sensor Warm towels/blankets Clock with second hand Stethoscope Pulse oximeter, sensor, and sensor cover Electronic cardiac monitor and leads Gloves and gowns Suction Equipment Bulb syringe Mechanical suction Suction catheters (5-6 F, 8-12 F) 8-F feeding tube and 20-mL syringe Meconium aspirator Positive-Pressure Ventilation Equipment Resuscitation bag or T-piece and mask Compressed air and oxygen Oxygen blender and flowmeter tubing Intubation Equipment Laryngoscope (sizes 0 and 1) Tracheal tubes (ID 2.5, 3.0, 3.5) Stylet Measuring tape Tape or securing device Scissors CO 2 detector Laryngeal mask or other supraglottic device | Medications Epinephrine 1:10,000 (0.1 mg/mL) Normal saline (50- to 250-mL bag) Syringes (1, 3, 20, to 60 mL) Umbilical Vessel Catheterization Kit Sterile gloves Antiseptic solution Umbilical tie Small clamp (hemostat) Forceps Scalpel Umbilical catheters (single lumen), 3.5F or 5 F Three-way stopcock Syringes (3-5 mL) Intraosseous needle (18 gauge or 15 mm) For Very Preterm Food-grade plastic wrap or bag Exothermic mattress For Thoracentesis and Paracentesis Antiseptic solution 18- or 20-gauge percutaneous catheter-over-needle device Three-way stopcock Syringe (20- to 60-mL) |
Clinical Assessment, Apgar Score, Saturation, and Heart Rate Monitoring
Initial assessment of the newborn baby must be rapid and accurate to identify babies who need resuscitation and to evaluate the effectiveness of interventions.
Clinical Evaluation
The Apgar score was first published in 1953 and represents an important landmark in the care of newly born infants. It marked the author’s reaction to the scant attention paid to newborns in the delivery room at that time: “nine months observation of the mother surely warrants one minute’s observation of the baby.” For many decades the score ( Table 26-4 ) and its five components have been used “as a basis for discussion and comparison of the results of obstetric practices, types of maternal pain relief and the effects of resuscitation.” Conventionally, scores are assigned at 1 and 5 minutes of life, although it has been acknowledged that assessment and intervention may be required before 1 minute. The precision and accuracy of the component signs have been evaluated. Observers have been found to disagree about the presence or absence of cyanosis, and the correlation between color and oxygen saturation is poor. Assessment of color no longer forms part of the ILCOR guidelines for resuscitation. Heart rate determined by auscultation of the chest or palpation of the cord has long been considered critical in monitoring the need for and effectiveness of resuscitation. However, both methods of clinical measurement have been shown to be inconsistent and systematically underestimate heart rate by approximately 15 to 20 bpm relative to measurement by electrocardiogram. Assessment of respiration is also difficult. Although no studies have evaluated spontaneously breathing infants, assessment of chest rise in those being ventilated indicates that observers differ substantially in their perceptions of chest rise and there is considerable disparity between clinical assessment and objective tidal volume measurements. Not surprisingly, studies of the precision and accuracy of the Apgar score have shown that experienced observers differ considerably in their assessments. Hence, clinicians need to be aware of the limitations of clinical signs obtained in the delivery room.
| Sign | SCORE | ||
|---|---|---|---|
| 0 | 1 | 2 | |
| Heart rate | Absent | Slow (<100 bpm) | >100 bpm |
| Respirations | Absent | Slow, irregular | Good, crying |
| Muscle tone | Limp | Some flexion | Active motion |
| Reflex irritability | No response | Grimace | Cough, sneeze, cry |
| Color | Blue or pale | Pink body, blue extremities | Completely pink |
Pulse Oximetry and Electrocardiography
Pulse oximetry has been used for decades to safely administer oxygen to infants in the intensive care unit. Advances in technology have enabled reliable readings of both oxygen saturation and heart rate to be obtained within the first 90 seconds of life. Continuous display, particularly of heart rate, means that resuscitation can be continued without interruption for intermittent auscultation. The sensor should be attached to the right hand or wrist to measure preductal saturations. Normal ranges of saturation measurements and heart rate have been defined by monitoring healthy term infants not requiring any interventions after delivery. Electrocardiography provides an alternative method of measuring heart rate in the delivery room and is now the recommended method of obtaining an accurate number immediately after birth. Katheria et al. have shown that it provides data more quickly than the pulse oximeter. Both methods require further evaluation to determine whether their use improves outcomes for at-risk infants.
Intervention Basics: Warmth, Position, Suction, Stimulation
The basic steps of newborn care include ensuring adequate warmth, positioning the baby’s head and neck so that the airway is open, clearing the airway of secretions if necessary, and providing gentle stimulation.
Warmth
Newborns lose heat and rapidly become hypothermic without adequate attention to thermal regulation. Hypothermia after birth is associated with increased mortality and morbidity including respiratory distress, late-onset sepsis, metabolic acidosis, and hypoglycemia. The delivery room should be appropriately warm and free from draughts. Immediately after birth, a vigorous term newborn may be placed on the mother’s chest or abdomen and covered with a warm, dry blanket. Warmth will be maintained by drying the newborn’s skin and maintaining direct skin-to-skin contact with the mother. A nonvigorous newborn should be placed on a warm, dry blanket under a prewarmed radiant heat source, the skin dried, and the wet linen removed. The baby should remain uncovered to allow visualization and effective radiant warming. Newly born infants without evidence of hypoxic injury should have their temperature maintained between 36.5 and 37.5° C. If the baby remains under the radiant warmer for more than a few minutes, a servo-controlled temperature sensor should be used to adjust the radiant warmer’s output and avoid overheating.
Very preterm newborns will require additional interventions to prevent hypothermia, which are discussed later in this chapter.
Position
The infant should be placed supine with the head and neck in a neutral or slightly extended position. This has been called the “sniffing” position ( Fig. 26-2 ). This position opens the baby’s airway, aligns the posterior pharynx and trachea, and allows unrestricted air movement. Excessive flexion or extension of the baby’s neck may cause airway obstruction. If the baby has a prominent occiput, it may be helpful to place a small towel or blanket roll under the baby’s shoulders to lift the shoulders and straighten the neck.
Suction
If the newborn is vigorous after birth, a soft cloth or towel may be used to gently wipe the baby’s face, mouth, and nose. Among vigorous newborns, there is no benefit to routine oropharyngeal, nasopharyngeal, or gastric suction, and this practice may interfere with pulmonary transition and the initiation of feeding. Gentle oral and nasal suction should be reserved for babies who are having difficulty breathing, who have secretions obstructing their airway, or who require positive-pressure ventilation. Prolonged, vigorous, or deep pharyngeal suction should be avoided because it may cause bradycardia and traumatize tissues.
Meconium-Stained Amniotic Fluid
The approach to babies born through meconium-stained amniotic fluid has evolved over recent years. Large, multicenter, randomized trials have shown no benefit from routine intrapartum oropharyngeal suction or from tracheal suction of the vigorous newborn. Previous treatment guidelines from ILCOR recommended selective tracheal intubation and suction for nonvigorous newborns in an attempt to prevent meconium aspiration syndrome. These recommendations were based on nonrandomized observational studies completed in the 1970s. A 2015 small randomized controlled trial among nonvigorous infants born through meconium-stained fluid found that tracheal suction did not reduce the incidence of meconium aspiration syndrome or other adverse outcomes. At present, there is no high-quality evidence to support a recommendation for routine intubation and tracheal suction of nonvigorous newborns born through meconium-stained fluid. Given the potential complications associated with tracheal intubation, additional evidence from randomized controlled trials is needed to inform this practice. The 2010 ILCOR statement recommends against routinely performing endotracheal suction of babies born through meconium-stained amniotic fluid.
Stimulation
The process of positioning and drying the newborn often provides sufficient stimulation to initiate spontaneous respirations. If the newborn is not breathing, brief additional stimulation by rubbing the newborn’s back, trunk, or extremities may be helpful. If the baby does not rapidly initiate spontaneous respirations, positive-pressure ventilation is indicated. Continuing to stimulate an apneic newborn is not helpful and delays appropriate interventions.
Oxygen
Oxygen is perhaps the most widely used drug in neonatology, but until recently remained poorly evaluated. An appreciation of its life-sustaining properties is now balanced by an understanding of its potential toxicity, even from a relatively short period of resuscitation. A substantial body of evidence from animal models is now supplemented by findings from human trials, which indicate that the use of 100% oxygen increases mortality rates compared with the use of air. However, uncertainty remains regarding the effects on long-term neurodevelopment. International guidelines for the resuscitation of term infants now recommend commencing resuscitation with air. Kattwinkel suggested using pulse oximetry in the delivery room to titrate oxygen therapy to achieve normoxia. The establishment of a normal range for term babies provides targets for clinicians, but the optimal increments and timing of changes remains uncertain. It is vital that operators continue to ensure adequate ventilation throughout the resuscitation and are not distracted by making frequent adjustments to oxygen concentrations. Although no compelling evidence exists, current ILCOR guidelines recommend the use of 100% oxygen whenever cardiac compressions are provided. The use of oxygen in the preterm infant may have a different risk/benefit profile, and recommendations are detailed in a subsequent section of this chapter.
Ventilation
Any newborn infant who does not initiate regular respiration, or who fails to respond to initial measures of drying, wrapping, and gentle stimulation, should be given positive-pressure support. This is typically first applied noninvasively using a face mask or nasal prong(s) and a pressure-generating device. If the infant is making inadequate respiratory effort, continuous positive airway pressure (CPAP) may be sufficient to aid lung inflation, to establish FRC, and to regularize breathing. An infant who has no respiratory effort, or is bradycardic (heart rate <100 bpm), or remains hypoxic despite CPAP support, should be given positive-pressure inflations, ideally with positive end-expiratory pressure (PEEP). The aim of positive-pressure ventilation is to provide effective ventilation and gas exchange, without causing lung injury, which can occur within a few large-volume positive-pressure inflations (volutrauma). Actions to prevent lung injury include avoiding large tidal volumes and facilitating formation and maintenance of FRC.
Observation of the first breaths in well infants suggests that prolonged (sustained) initial inflations may be advantageous; this idea is supported by studies of sustained inflation in preterm animal models, which show rapid lung inflation without overexpansion, immediate development of appropriate FRC, and uniformly aerated lungs without serious side effects. Randomized trials of sustained inflations at birth in preterm infants have produced mixed results, and as of this writing further large trials are under way. Standardization of pressure and duration for sustained inflations is difficult; spontaneous breathing, glottic closure, and face mask leak make delivered tidal volumes variable. Sustained inflations have been included in some resuscitation guidelines, whereas others state insufficient evidence to recommend their implementation.
The ideal target volumes for ventilation of term and preterm infants after birth have not been established; animal studies demonstrate that initial high tidal volumes are detrimental. Aiming for volumes <8 mL/kg seems reasonable, but tidal volumes are difficult to measure with standard delivery room equipment and are consequently rarely targeted or measured at birth. Clinicians rely on setting peak pressure and clinical signs as a proxy for “appropriate” volume delivery. Guidelines suggest peak pressures should begin in the range of 20 to 30 cm H 2 O, and these have been shown to produce adequate tidal volumes. Infants without any respiratory effort may require higher pressures initially, which should be reduced as the lungs aerate and become more compliant. The actual delivered volume will vary owing to many factors: spontaneous breathing effort, lung compliance, laryngeal closure, face mask leak, obstruction at the mouth and nose, and the resuscitation device used. The result is that delivered tidal volumes vary widely and can be much higher than those generated during spontaneous breathing. A rising heart rate is a good sign that effective ventilation is being delivered and is preferable to using achievement of peak pressure or assessing chest rise, neither of which is reliable.
Although use of PEEP in the delivery room is not strongly supported by clinical evidence, it is a well-established technique with convincing animal data to support its use in establishing FRC, whether or not a sustained inflation is given. A “standard” level of PEEP may not suit all infants, and published guidelines do not recommend specific levels. The reported typically used level of PEEP in the delivery room is 5 cm H 2 O. Infants who have not fully established FRC are likely to have higher oxygen requirements and may benefit from higher PEEP.
Ventilation rates of 40 to 60 per minute are recommended (unless chest compressions are being given concurrently) and match the typical respiratory rates of healthy newborns. The duration of each inflation is operator dependent and may, following the initial inflations, be best timed to coincide with and to reflect spontaneous inspiratory times of newborn infants, at about 0.3 seconds. Set gas flow will vary with the pressure device being used. T-piece ventilation is susceptible to fluctuations in PEEP and tidal volume with flow changes, and the manufacturer’s recommendations regarding flow should be followed.
If, during mask ventilation, chest wall movement is poor or absent and heart rate does not improve, corrective steps need to be taken. These include repositioning of the head to ensure neutral position and reapplication of the mask to reduce leak and nasal obstruction. Other measures to consider include increasing the applied peak pressure, opening the mouth, suctioning secretions, holding the mask on the face with two hands, and using an oropharyngeal airway.
Once heart rate exceeds 100 bpm and spontaneous breathing is established, positive-pressure ventilation can be stopped; CPAP should be continued in premature infants. Positive-pressure ventilation must continue if spontaneous respiration is inadequate or if the heart rate remains less than 100 bpm. Endotracheal intubation should be considered for infants who do not develop adequate respiratory effort or who remain bradycardic and/or hypoxic despite adequate mask ventilation. Options for the management of preterm infants who require ongoing respiratory support include intubation and surfactant administration in the delivery room or initial CPAP support with rescue intubation and surfactant treatment only if required.
Pressure Sources
In resource-limited settings there may be no device available to generate positive-pressure support. Mouth-to-mouth resuscitation can be used, but it carries the risk of infection. Mouth-to-mask or mouth-to-tube ventilation may be viable options and carry somewhat lower risks of infection.
Worldwide, many devices are available for generating positive pressure in the delivery room ( Fig. 26-3 ). The choice of device may be made based on cost; availability of a gas supply; desire to deliver sustained inflations, PEEP, and CPAP; or personal preference ( Table 26-5 ).
| Device | Self-Inflating bag | Flow-Inflating bag | T-Piece | Ventilator |
|---|---|---|---|---|
| Can function without gas supply | ✓ | – | – | – |
| Achieves accurate, consistent peak pressure | – | – | ✓ | ✓ |
| Measures delivered peak pressure | – | – | ✓ | ✓ |
| Potential to deliver sustained inflation | – | Possible with experience | ✓ | – |
| Delivers PEEP | Possible with PEEP valve | Possible with PEEP valve | ✓ | ✓ |
| Delivers CPAP | – | – | ✓ | ✓ |
| Delivered pressures are independent of gas flow | ✓ | ✓ | – | ✓ |
| Measures delivered tidal volume | – | – | – | Possible with some ventilators |
Self-inflating bags (SIBs) reexpand after compression. They are the only devices that can be used without a gas supply and may be the most useful for those with limited resources. Several types and sizes of SIBs exist; the smallest size, ∼240 mL, is for newborns. The peak pressure delivered by an SIB depends on how hard and fast the bag is squeezed. Although SIBs usually incorporate a valve to limit the maximum delivered pressure, it can be inadvertently or manually overridden to deliver higher pressures. Pressures >100 cm H 2 O have been reported, resulting in excessive tidal volumes. It is difficult to give consistent peak pressures with an SIB, even when using a manometer. If a PEEP valve is attached, some PEEP can be generated, but again this is inconsistent and lower with slower inflation rates. SIBs cannot deliver CPAP or sustained inflations and therefore may not be the optimal device for stabilizing preterm infants. SIBs entrain room air during reexpansion but can still deliver up to 70% inspired oxygen when used without a reservoir bag.
A flow-inflating bag (FIB) needs a continuous gas supply to inflate the bag. Like the SIB, delivered pressure and volume depend on how hard the bag is squeezed. A pressure-limiting valve can be attached, and a manometer is recommended to increase the consistency of peak pressure delivery. PEEP can be generated by controlling the rate of gas flow from the back of the bag, although this requires experience; many operators find the FIB more difficult to use than the SIB. Experienced FIB users can deliver sustained inflations with an FIB, but the delivered pressure fluctuates. It is very difficult to deliver reliable CPAP using an FIB.
A T-piece device is flow-controlled and pressure-limited; it also requires a continuous gas supply to operate. Gas flow through a ported expiratory valve is used to generate PEEP. Peak pressure is achieved by occluding the port in the expiratory valve with a finger. Inflation time depends on how long the port is occluded. T-pieces are easy to use and are preferred by both experienced and inexperienced operators. T-pieces deliver more accurate and consistent peak and PEEP pressures than other devices, resulting in more stable tidal volume delivery, including with new operators. However, operators are less responsive to changing lung compliance than when using other devices. The T-piece effectively delivers CPAP while the port is open, and occlusion of the port efficiently delivers sustained inflations of any duration or pressure. Therefore, T-pieces may be the optimal device for providing respiratory support for preterm infants at birth. However, no clinical trials have demonstrated superiority of one resuscitation device over another. If either a T-piece device or an FIB is used, there must be a backup SIB for use in the event of failure of the compressed gas source.
Finally, infants can also be stabilized using a ventilator. Ventilators can provide accurate delivery of peak and PEEP pressures, sustained inflations, CPAP, synchronization, and tidal volume measurement.
Interfaces
Positive-pressure ventilation is most often delivered via a face mask. Although the principles of face mask ventilation are simple, good technique is essential. To achieve reasonable stable tidal volumes, a good seal must be achieved between the mask and the face. Without a good seal, there will be substantial leak around the mask, and inadequate ventilation will ensue. Masks are available in a number of sizes and shapes. The most commonly used masks are round and have cushioned rims. Choosing the correct mask size is important. The mask should extend from the chin tip but not encroach upon the eyes. For a single operator, the two-point top hold provides the most stable application. The mask should be rolled rather than directly placed onto the face. A finger positioned on the baby’s chin tip may be used to align the lower edge of the mask, which can then be rolled gently upward ( Fig. 26-4 ). An alternative interface is a cut-down endotracheal tube placed 3 to 4 cm inside the nose. A randomized trial of 300 infants showed no difference in efficacy between this interface and a face mask.
Endotracheal Intubation
Indications for intubation after birth vary depending on gestational age, respiratory effort, response to noninvasive ventilation, and the skill and experience of the resuscitator. International resuscitation guidelines suggest intubation be considered at several stages : if the heart rate is <100 bpm after 30 seconds of effective positive-pressure ventilation, if the infant continues to be apneic despite adequate mask ventilation, if mask ventilation is prolonged or ineffective, or if there are congenital anomalies affecting transition, such as diaphragmatic hernia. Infants without a detectable heartbeat should be intubated and ventilated as soon as possible; the endotracheal route of adrenaline administration may be needed prior to intravenous access being established. Neonatal intubation is a difficult skill to acquire and maintain. Fewer infants are now intubated and skills are declining. Junior trainees are successful in less than half of intubation attempts; they take longer to perform intubations, frequently longer than the recommended 30 seconds, with consequent clinical deterioration in the infant.
Intubation Equipment and Procedure
Equipment for endotracheal intubation should be readily available wherever infants may be born. The required items are outlined in Table 26-6 . The infant should be placed supine in a neutral position, avoiding both flexion and hyperextension of the neck, which make the glottis hard to visualize.
| Positive-pressure delivery device (self-inflating bag/flow-inflating bag with manometer and positive end-expiratory pressure valve if possible, or T-piece device) Air/oxygen supply with flowmeter and blender Neonatal cushioned round face masks in range of sizes Pulse oximeter (attached to right hand/wrist) Laryngoscope(s) with straight blades, Miller sizes 00, 0, and 1 Uncuffed, uniform-diameter, radio-opaque, endotracheal tubes, with a standard curve, depth marked, in sizes 2.5-, 3.0-, 3.5-, and 4.0-mm internal diameter Stylet (optional) Magill forceps (for nasal intubation) Neonatal stethoscope Colorimetric carbon dioxide detector Suction equipment and suction catheters (5-, 6-, 8-, and 10-F size) Equipment to secure the endotracheal tube in place (adhesive tape/ties/hat) |
The tip of the laryngoscope should be advanced over the tongue, either to the vallecula or over the top of the epiglottis and elevated (not rotated) to reveal the vocal cords ( Fig. 26-5 ). The laryngoscope should remain midline and support the tongue toward the left of the mouth, leaving sufficient space to see the larynx while passing the endotracheal tube (ETT). If the laryngoscope is advanced too far, the larynx will not be visible. Gentle external cricoid pressure may help to bring the anterior larynx into view.
