Newborn Life Support
Introduction
Passage through the birth canal is a hypoxic experience for the fetus, since
significant respiratory exchange at the placenta is prevented for the 50-75 sec
duration of the average contraction. Though most babies tolerate this well, the
few that do not may require help to establish normal breathing at delivery.
Newborn life support (NLS) is intended to provide this help and comprises the
following elements:
• drying and covering the newborn baby to conserve heat;
• assessing the need for any intervention;
• opening the airway;
• lung aeration;
• rescue breathing;
• chest compression;
• administration of drugs (rarely).
Physiology
If subjected to continuing hypoxia in utero, the fetus will eventually lose
consciousness and stop trying to ‘breathe’, as the neural centres controlling
breathing cease to function due to lack of oxygen. The fetus then enters a period
known as ‘primary’ apnoea.
Up to this point, the heart rate remains unchanged, but soon decreases to about
half the normal rate as the myocardium reverts to anaerobic metabolism - a less
fuel-efficient mechanism. The circulation to non-vital organs is reduced in an
attempt to preserve perfusion of vital organs. The release of lactic acid, a byproduct of anaerobic metabolism, causes deterioration of the biochemical milieu.
If the insult continues, shuddering, whole-body gasps at a rate of about 12 min-1
are initiated by primitive spinal centres. If these gasps fail to aerate the lungs they
fade and the fetus enters a period known as ‘secondary’, or ‘terminal’, apnoea. Up
until now, the circulation has been maintained but, as terminal apnoea progresses,
the rapidly-deteriorating biochemical milieu begins to impair cardiac function. The
heart eventually fails and, without effective intervention, the baby dies. The whole
process probably takes almost twenty minutes in the term newborn human baby.
Thus, in the face of asphyxia, the baby can maintain an effective circulation
throughout the period of primary apnoea, through the gasping phase, and even
for a while after the onset of terminal apnoea. Thus, the most urgent requirement
of any asphyxiated baby at birth is that the lungs be effectively aerated. Provided
the baby’s circulation is sufficiently intact, oxygenated blood will be conveyed
from the aerated lungs to the heart. The heart rate will increase and the brain will
be perfused with oxygenated blood. Following this, the neural centres
responsible for normal breathing will, in many instances, function once again and
the baby will recover.
Merely aerating the lungs is sufficient in the vast majority of cases. However,
though lung aeration is still vital, in a few cases cardiac function will have
deteriorated to such an extent that the circulation is inadequate and cannot
convey oxygenated blood from the aerated lungs to the heart. In this case, a
brief period of chest compression may be needed. In a very few cases, lung
aeration and chest compression will not be sufficient, and drugs may be required
to restore the circulation. The outlook in this last group of infants is poor.
Guideline changes
The following are the main changes that have been made to the NLS guidelines:
• The use of food-grade plastic wrapping is recommended to maintain
body temperature in significantly preterm babies.
• Attempts to aspirate meconium from the nose and mouth of the
unborn baby, while the head is still on the perineum, is no longer
recommended.
• Ventilatory resuscitation may be started with air. However, where
possible, additional oxygen should be available if there is not a rapid
improvement in the infant’s condition.
• Adrenaline (epinephrine) should be given by the intravenous or
intraosseous route, as standard doses are likely to be ineffective if
given via a tracheal tube.
• If there are no signs of life after ten minutes of continuous and
adequate resuscitation efforts, then discontinuation of resuscitation
may be justified.
Sequence of actions
1 Keep the baby warm and assess
Babies are born small and wet. They get cold very easily, especially if they
remain wet and in a draught.
• Whatever the problem, first make sure the cord is securely clamped
and then dry the baby, remove the wet towels, and cover the baby
with dry towels.
• For significantly preterm babies (30 weeks and below), there is now
good evidence that placing the baby under a radiant heater and,
without drying the baby beforehand, immediately covering the head
and body, apart from the face, with food-grade plastic wrapping, is the
most effective way of keeping these very small babies warm during
resuscitation or stabilisation at birth.
• Drying the baby will provide significant stimulation and will allow time
to assess colour, tone, breathing, and heart rate.
Reassess these observations regularly (particularly the heart rate)
every 30 sec or so throughout the resuscitation process. The first sign
of any improvement in the baby will be an increase in heart rate.
Consider the need for help; if needed, ask for help immediately.
• A healthy baby will be born blue but will have good tone, will cry within
a few seconds of delivery, will have a good heart rate (the heart rate
of a healthy newborn baby is about 120-150 beats min-1), and will
rapidly become pink during the first 90 sec or so. A less healthy baby
will be blue at birth, will have less good tone, may have a slow heart
rate (less than 100 beats min-1), and may not establish adequate
breathing by 90-120 sec. An ill baby will be born pale and floppy, not
breathing and with a slow or very slow heart rate.
• The heart rate of a baby is best judged by listening with a
stethoscope. It can also be felt by gently palpating the umbilical cord
but a slow rate at the cord is not always indicative of a truly slow heart
rate - feeling for peripheral pulses is not helpful.
2 Airway
Before the baby can breathe effectively the airway must be open.
• The best way to achieve this is to place the baby on his back with the
head in the neutral position, i.e. with the neck neither flexed nor
extended. Most newborn babies will have a relatively prominent
occiput, which will tend to flex the neck if the baby is placed on his
back on a flat surface. This can be avoided by placing some support
under the shoulders of the baby, but be careful not to overextend the
neck.
• If the baby is very floppy it may also be necessary to apply chin lift or
jaw thrust.
3 Breathing
• If the baby is not breathing adequately by about 90 seconds give 5
inflation breaths. Until now the baby's lungs will have been filled
with fluid. Aeration of the lungs in these circumstances is likely to
require sustained application of pressures of about 30 cm of water for
2-3 sec – these are 'inflation breaths'.
• If the heart rate was below 100 beats min-1 initially then it should
rapidly increase as oxygenated blood reaches the heart. If the heart
rate does increase then you can assume that you have successfully
aerated the lungs. If the heart rate increases but the baby does not
start breathing for himself, then continue to provide regular breaths at
a rate of about 30-40 min-1 until the baby starts to breathe on his own.
• If the heart rate does not increase following inflation breaths, then
either you have not aerated the lungs or the baby needs more than
lung aeration alone. By far the most likely is that you have failed to
aerate the lungs effectively. If the heart rate does not increase, and
the chest does not passively move with each inflation breath, then you
have not aerated the lungs.
Consider:
o Is the baby’s head in the neutral position?
o Do you need jaw thrust?
o Do you need a longer inflation time?
o Do you need a second person’s help with the airway?
o Is there an obstruction in the oropharynx (laryngoscope and
suction)?
o What about an oropharyngeal (Guedel) airway?
• Check that the baby's head and neck are in the neutral position, that
your inflation breaths are at the correct pressure (30 cm of water) and
applied for the correct time (2-3 sec inspiration), and that the chest
moves with each breath. If the chest still does not move, ask for help
in maintaining the airway and consider an obstruction in the
oropharynx, which may be removable by suction under direct vision.
An oropharyngeal (Guedel) airway may be helpful.
• If the heart rate remains slow (less than 60 min-1) or absent following 5
inflation breaths, despite good passive chest movement in response
to your inflation efforts, start chest compression.
4 Chest compression
Almost all babies needing help at birth will respond to successful lung
inflation with an increase in heart rate followed quickly by normal breathing.
However, in some cases chest compression is necessary.
• Chest compression should be started only when you are sure that
the lungs have been aerated successfully.
• In babies, the most efficient method of delivering chest compression
is to grip the chest in both hands in such a way that the two thumbs
can press on the lower third of the sternum, just below an imaginary
line joining the nipples, with the fingers over the spine at the back.
• Compress the chest quickly and firmly, reducing the antero-posterior
diameter of the chest by about one third.
• The ratio of compressions to inflations in newborn resuscitation
is 3:1.
• Chest compressions move oxygenated blood from the lungs back to
the heart. Allow enough time during the relaxation phase of each
compression cycle for the heart to refill with blood. Ensure that the
chest is inflating with each breath.
In a very few babies inflation of the lungs and effective chest compression
will not be sufficient to produce an effective circulation. In these
circumstances drugs may be helpful.
5 Drugs
Drugs are needed only if there is no significant cardiac output despite
effective lung inflation and chest compression.
• The drugs used are adrenaline (1:10,000), sodium bicarbonate
(ideally 4.2%), and dextrose (10%). They are best delivered close to
the heart, usually via an umbilical venous catheter.
• The recommended dose for adrenaline is 10 microgram kg-1
(0.1 ml kg-1 of 1:10,000 solution). If this is not effective a dose of up
to 30 microgram kg-1 (0.3 ml kg-1 of 1:10,000 solution) may be tried.
• The dose for sodium bicarbonate is between 1 and 2 mmol of
bicarbonate kg-1 (2 to 4 ml kg-1 of 4.2% bicarbonate solution).
• The dose of dextrose recommended is 250 mg kg-1 (2.5 ml kg-1 of
10% dextrose).
• Very rarely, the heart rate cannot increase because the baby has lost
significant blood volume. If this is the case, there is often a clear
history of blood loss from the baby, but not always. Use of isotonic
crystalloid rather than albumin is preferred for emergency volume
replacement. A bolus of 10 ml kg-1 of 0.9% saline or similar given
over 10 - 20 sec will often produce a rapid response and can be
safely repeated if needed.
Explanatory Notes
Meconium
A large multicentre, randomised, controlled study1 has shown that attempts to
aspirate meconium from the nose and mouth of the unborn baby while the head
is still on the perineum (so-called intrapartum suctioning) does not prevent
meconium aspiration syndrome and this practice is no longer recommended.
Another large multicentre, randomised, controlled study2 has shown that attempts
to remove meconium from the airways of vigorous babies after birth also fail to
prevent this complication.
However, if babies are born through thick meconium and are unresponsive (or
‘not vigorous’) at birth, the oropharynx should be inspected and cleared of
meconium. If intubation skills are available, the larynx and trachea should also
be cleared. It is acknowledged that no proof of the efficacy of this practice exists.
Air or 100% oxygen
Concern about possible injurious effects of excess oxygen, particularly in preterm
infants, and the apparent effectiveness of air in some limited, randomised,
controlled, human studies of resuscitation at birth, has resulted in a minor change
in the guidelines.
There is no evidence to suggest that any one concentration of oxygen is better
than another when starting resuscitation. Some clinicians may wish to start with
air. However, where possible, it is recommended that additional oxygen should
be available for use if there is not a rapid improvement in the infant’s condition.
Equally, hyperoxia should be avoided, especially in the preterm infant.
Route and dose of adrenaline
Adrenaline should be used in a concentration of 1:10,000 (100 microgram ml-1).
It is best given intravenously or by the intraosseous route. The standard
recommended dose by these routes is 10 – 30 microgram kg-1 (0.1 – 0.3 ml kg-1
of 1:10,000). Do not use a higher dose by these routes as it is harmful.
Guidelines 2000 endorsed the use of adrenaline via the tracheal tube until an
intravenous route had been established. Data now suggest that standard doses
given via the tracheal tube are likely to be ineffective.
Induced hypothermia
Induced hypothermia may reduce the neurological damage associated with
moderate post-asphyxial encephalopathy. However, as yet there are insufficient
data to recommend routine use of modest systemic or selective cerebral
hypothermia following resuscitation of infants with suspected asphyxia. Further
randomised clinical trials are needed to determine which infants benefit most and
which method of cooling is most effective.
References
1. Vain NE, Szyld EG, Prudent LM, et al. Oropharyngeal and
nasopharyngeal suctioning of meconium-stained neonates before delivery
of their shoulders: multicentre, randomised controlled trial. Lancet 2004:
364; 597-602.
2. Wiswell TE, Gannon CM, Jacob J, et al. Delivery room management of
the apparently vigorous meconium-stained neonate: results of the
multicenter international collaborative trial. Pediatr 2000; 105: 1-7.
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