Neonatal resuscitation

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2.6 Neonatal resuscitation

Gary Williams

Essentials

1 Occasionally deliveries occur in the emergency department when labour cannot be delayed to enable transfer of the patient to a labour ward setting.
2 The emergency department should have available appropriate equipment and guidelines for the resuscitation of the newborn.
3 The unique physiological events at birth affect the resuscitative interventions in the newborn.
4 Ventilation is the main priority in the resuscitation of the newborn.
5 The heart rate is a reliable indicator of the newborn baby’s degree of compromise and response to resuscitation. The easiest way to monitor newborn pulses is by palpation of the umbilicus.
6 Chest compressions are indicated if: (1) absent pulse; or (2) heart rate <60 min–1 despite adequate assisted ventilations for 30 seconds.
7 Compressions and ventilations should be cycled at a ratio of 3 compressions to 1 ventilation to achieve approximately 120 events per minute.
8 The preferred site of the vascular access during neonatal resuscitation is the umbilical vein.
9 Drugs are rarely required in the resuscitation of the newly born.
10 Volume expansion should be with crystalloid 10 mL kg–1 boluses by slow push.

Introduction

Epidemiology

Between 5 and 10% of newborns require some assistance to begin breathing at birth and, in developed countries, approximately 1% need intensive resuscitative measures to restore cardiorespiratory function. It has been estimated that birth asphyxia significantly contributes to approximately 20% of the five million neonatal deaths that occur worldwide each year; outcome might therefore be improved for more than one million newborns per year through effective resuscitation at birth.

Neonatal resuscitation is unique in that it is required at a time when the newborn is undergoing a predetermined process of transition from a liquid filled intrauterine environment to spontaneous breathing of room air. There is an accompanying sequence of dramatic alterations in physiology, each of which may be altered and require correction.

There are two important caveats in this process. First, the achievement of lung expansion with an appropriate oxygen-containing gas leading to establishment of a functional residual capacity and adequate spontaneous ventilation is of primary importance. Second, the significance of a vital sign abnormality depends greatly on the time since birth and the time during which effective resuscitation measures have been administered. For instance, bradycardia immediately after birth prior to any resuscitative manoeuvres likely indicates an intrapartum stress. The same heart rate after 1 to 2 minutes of adequate ventilation suggests a different range of aetiologies and requires a different resuscitative response.

The majority of circumstances where newborn resuscitation is needed can be predicted, allowing opportunity for preparation of appropriate equipment and personnel. Factors placing the newborn at high risk for neonatal resuscitation include those listed in Table 2.6.1, due to maternal, fetal and intrapartum circumstances.

Table 2.6.1 Risk factors for need for neonatal resuscitation

Maternal Fetal Intrapartum Premature or prolonged rupture of membranes Multiple gestation Fetal distress Antepartum haemorrhage Preterm (<35 weeks) or post-term Abnormal presentation Hypertension (>42 weeks) gestation Prolonged or precipitate labour Diabetes mellitus IUGR Thick staining of amniotic fluid Substance abuse Polyhydramnios Instrumental delivery or emergency caesarean section Maternal infection or chronic illness Congenital abnormalities   Absence of antenatal care    

IUGR, intrauterine growth retardation.

Aetiology and pathophysiology

The sequence of physiological changes in the newborn around birth includes:

• Cessation of alveolar fluid production and clearance of this fluid from the gas-exchanging part of the airway.
• Spontaneous respirations and establishment of functional residual capacity (FRC).
• Fall in pulmonary vascular resistance (PVR) (lung expansion, oxygen).
• Rise in systemic vascular resistance (SVR) (umbilical artery constriction).
• Reversal of flow from left to right across foramen ovale and ductus arteriosus.
• Closure of the foramen ovale and ductus arteriosus.

This normal sequence may be interrupted at any point by:

• Inadequate clearance of endogenous lung liquid (precipitate, emergency or operative delivery) or excessive abnormal airway material (blood, mucus, meconium).
• Inadequate respiratory effort (maternal analgesics, central nervous system injury, sepsis) or excursion (congenital thoracic anomalies).
• Pulmonary disease preventing achievement and maintenance of adequate FRC (parenchymal disease, prematurity, space-occupying lesion) with secondary failure to lower PVR normally and possible intrapulmonary shunting.
• Compromised myocardial function (structural or functional cardiac abnormalities, hypoxia secondary to pulmonary dysfunction).

Interventions should occur in a defined sequence recognising the primary and crucial role of adequate ventilation and be guided by frequent reassessment of other vital signs.

Preparation

Summon assistance: if it is anticipated that the infant is at high risk of requiring advanced life support resuscitative intervention, more than one experienced person should be mobilised.
Communicate with colleagues to seek available antenatal and intrapartum data.
In the case of extreme prematurity (≤24 weeks’ gestation) or known congenital anomalies, if time allows, the most senior care provider should seek to discuss with the family their beliefs and desires regarding the extent of resuscitation.1
Prepare the environment: this includes a warm, draught-free area with adequate light, radiant heater, prewarmed blankets and a clock.
Prepare required equipment (Table 2.6.2).
Table 2.6.2 Equipment and drugs recommended for newborn resuscitation

Equipment Drugs Stethoscope Adrenaline (epinephrine) 1 in 1:10000 solution. Suction catheters (6–12 French) and suction Naloxone hydrochloride 1.0 or 0.4 mg mL–1 8 French feeding tube and 20 mL syringe for gastric decompression Dextrose 5% or 10% Face masks NaHCO3 4.2% solution Oropharyngeal (Guedel’s) airways Volume expander (0.9% saline or 4% HSA) Resuscitation system for PPV   Laryngoscope with straight blade   ET tubes 2.5 to 4 mm internal diameter   ET stylets   Tape for ETT and IV fixation   Cannulae, syringes and UV catheterisation equipment  

HSA, human serum albumin; PPV, positive pressure ventilation.

Assessment at birth

At birth the infant should be collected in a warm towel, dried and the umbilical cord clamped. Gentle stimulation may be provided (rubbing the back, flicking soles of feet if required) and an assessment of initial cry, respiratory effort, heart rate, colour and tone should be made virtually simultaneously (Table 2.6.3).

Table 2.6.3 Apgar score

image

Ventilation

The initial assessment is an evaluation of the presence and quality of respirations.

• If respirations are adequate, the heart rate is evaluated.
• If respirations are shallow or slow, a brief period of stimulation may be provided.
• If the infant has not established adequate breathing by 30 seconds, face mask rescue breaths should be administered and if this is not successful with breathing established by 2 minutes, endotracheal intubation should be performed.
• There should be no delay in commencing rescue breaths if the infant is born with, or develops evidence of, asphyxia with signs of flaccidity, pallor and/or bradycardia (heart rate less than 60 min–1).

Artificial ventilation

Various bag and mask systems are available for neonatal resuscitation. T-piece mechanical devices designed to regulate pressure, self-inflating bag or flow-inflating bag are all recognised as acceptable devices for ventilating newborn infants either via a face mask or endotracheal tube. Target inflation pressures, continuous positive airway pressure (CPAP) and long inspiratory times are achieved more consistently using T-piece devices than when using bags but the ability to achieve an increased inspiratory pressure when required in response to altered compliance (even for a few breaths) is greatest with the self-inflating bag. It is suggested in fact that the invariable success of rescue breathing at birth is because the FRC is established by an induced inspiratory effort via Head’s paradoxical reflex (inspiratory effort induced by any lung inflation). The corollary is that face mask rescue breathing is unlikely to be effective in the severely asphyxiated infant.

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