Published studies have reported some degree of resuscitation being required in up to 5-14% of neonates overall, although this may be higher in selected cases. Most neonates require assisted ventilation only. The need for resuscitation may often be predicted from the events and course of the pregnancy and labour (including the presence of meconium, the fetal heart rate and pH during labour and the mother’s condition), although up to a third of cases occur after apparently normal labours.
There has been a trend in recent years for paediatricians not to attend uncomplicated elective caesarean sections, since surveys have suggested that the requirement for neonatal resuscitation is low in such cases, especially when the indication for caesarean section is previous operative delivery, and when regional anaesthesia is used. In such situations, anaesthetists should not take on the responsibility of resuscitating the neonate, since their primary responsibility is to care for the mother. However, all personnel in the delivery suite (including obstetric anaesthetists) should be competent at basic neonatal resuscitation.
Problems and special considerations
Cardiovascular
The change from fetal to adult circulation normally accompanies delivery and the inspiration of air into the lungs. If there is poor lung inflation, high inflation pressures, hypercapnia, hypothermia or acidosis, the circulation (which remains transitional for about 2 weeks after birth in term neonates) may return to the fetal configuration.
The neonate relies on a fast heart rate for cardiac output since stroke volume is relatively fixed. The neonatal heart responds to hypoxaemia with bradycardia, which in turn worsens oxygen delivery. The initial treatment is oxygenation.
Respiratory
The squeezing of the chest during vaginal delivery helps to expel the fluid contained within the lungs in babies born this way. In babies born by caesarean section, this effect is absent and respiratory support is more likely to be required, especially superimposed on the underlying reason for emergency operative delivery. Uterine contractions themselves help to expel fluid, and even a short labour may be beneficial.
The first breath needs to overcome the forces tending to keep the alveoli collapsed, and thus requires greater effort.
If meconium is present, its dispersal throughout the lungs during resuscitation may result in the meconium aspiration syndrome.
Hypoxaemia typically leads to vigorous respiratory efforts followed by a period of primary apnoea (accompanied by bradycardia), during which stimulation may provoke respiration. After a few gasps a period of terminal apnoea ensues, during which active resuscitation is required. It is possible for both stages to occur in utero if the fetus is hypoxic.
Evidence of tissue damage (including brain tissue) caused by hyperoxia, especially after a period of asphyxia, has led to the avoidance of high concentrations of oxygen for neonatal resuscitation, with air being the gas recommended initially.
Management options
Appropriate equipment includes an oxygen source, funnel, bag and facepiece, suction, laryngoscopes, tracheal tubes (sizes 2.5-3.5 mm, non-shouldered) and a radiant heater. The laryngeal mask airway has been used for neonatal resuscitation and has been suggested as being faster, more reliable and thus safer than tracheal tubes, although its use is not yet widespread.
The basic principles of the ‘ABC’ of resuscitation apply in neonatal resuscitation, with a focus on ventilation over drug administration. The latest Resuscitation Council (UK) algorithm is shown in Figure 160.1.
Vigorous oropharyngeal suction may cause apnoea. If meconium aspiration is suspected, direct laryngoscopy and pharyngeal or laryngeal suction under direct vision is preferred, with tracheal intubation if meconium is seen below the cords. Gentle suction and removal of meconium should take place before lung inflation unless the heart rate is under 60 beats/minute.
It is recommended that the pulse oximetry sensor be positioned on the right hand to provide an accurate measurement of oxygen saturation in the preductal circulation.
If controlled ventilation is required, the first breath should be held for 2-3 seconds to help expand the alveoli, with subsequent breaths lasting for 0.5-1.0 seconds. A maximum of 30-35 cmH2O should be administered (20-25 cmH2O if preterm). If heart rate does not increase or oxygenation (as indicated guided by oximetry) remains unacceptable despite effective ventilation, oxygen should be considered instead of air.
Cardiac massage is performed either by encircling the baby’s chest with the hands and compressing the sternum with the thumbs, or by using the index and middle fingers. The sternum should be depressed 1-2 cm. Compressions should occur at 120/minute, at a ratio of 3:1 with breaths. ECG monitoring may aid the accurate assessment of neonatal heart rate.
Intravenous access is usually obtained most easily with an umbilical venous catheter - the single umbilical vein is accompanied by two umbilical arteries, which aids its identification. Drugs are rarely required; doses are given in Table 160.1. The cannula should be flushed with saline after each drug is administered. The intraosseous route has also been used.
The neonate should be kept warm and dry throughout resuscitation, with the body temperature maintained between 36.5 and 37.5 °C.
Therapeutic hypothermia should be considered for babies at term or near-term with evolving moderate or severe hypoxic-ischaemic encephalopathy.
Figure 160.1 Algorithm for neonatal resuscitation. Reproduced with permission from Resuscitation Council (UK). Resuscitation and support of transition of babies at birth, 2015. www.resus.org.uk/resuscitation-guidelines/resuscita tion-and-support-of-transition-of-babies-at-birth.
Key points
• Some degree of neonatal resuscitation is required in up to 5-14% of deliveries overall, but the incidence is higher in selected cases.
• The anaesthetist’s first duty is to the mother.
• Before delivery, it should be possible to predict two-thirds of cases in which neonatal resuscitation will be required.
• Basic principles are similar to those of adult resuscitation, but with more emphasis on lung inflation and less on drugs.
Table 160.1 Drugs used in neonatalresuscitation
|
Drug |
Dose |
Notes |
|
Naloxone |
100 pg/kg IM |
Should be considered if maternal opioids given |
|
Adrenaline |
10 pg/kg IV (0.1 ml/kg of a 1:10,000 solution) initially; 10-30 pg/kg IV if ineffective |
If no significant cardiac output despite effective significant lung inflation and chest compression 50-100 pg/kg intratracheally is roughly equivalent to 10 pg/ kg IV |
|
Volume expansion |
10-20 ml/kg |
0.9% saline initially |
|
Sodium bicarbonate 4.2% |
1-2 mmol/kg IV (2-4) ml/kg |
High concentrations of bicarbonate have been associated with intraventricular haemorrhages |
IM, intramuscular; IV, intravenous.
Further reading
Berger TM. Neonatal resuscitation: foetal physiology and pathophysiological aspects. Eur J Anaesthesiol 2012; 2: 362-70.
Guay J, Lachapelle J. No evidence for superiority of air or oxygen for neonatal resuscitation: a meta-analysis. Can J Anesth 2011; 58: 1075-82.
Resuscitation Council (UK). Resuscitation and support of transition of babies at birth. London: Resuscitation Council, 2015, www.resus.org.uk/resuscitation-guidelines/resuscitation-and-sup port-of-transition-of-babies-at-birth (accessed December 2018).