Respiratory Management of the Newborn
inspired oxygen (range: 0.2 to 1.0)
Desirable arterial PO2 is 60-80 mmHg. Choose the FiO2
necessary to achieve this range. Generally, changes in FiO2
are made in 5% increments or decrements.
Inadequate oxygen administration may result in neuronal injury,
pulmonary hypertension, and damage to organs including liver, kidney,
and gut. In VLBW infants, excessive oxygen administration may result in chronic lung
injury and retinopathy of prematurity.
way to monitor administering oxygen is by serial arterial blood gas
measurements. An alternative, continuous, noninvasive technique for
monitoring administration of oxygen is pulse oximetry. Desirable
oxygen saturation for all babies is 84-96%.
(Note: In neonates with ductus-dependent
cyanotic congenital heart disease, the desirable range of oxygen
saturations may be specified by the cardiologists).
Intermittent mandatory ventilation (ventilator
Ventilator rate, expressed in breaths per minute,
influences minute ventilation. A higher rate increases CO2
excretion, whereas a lower rate decreases CO2 excretion.
Desirable arterial PCO2 is 35-45 mmHg.
In a strategy called permissive hypercapnea, the accepted arterial PCO2
range is 45-60 mmHg.
Initial ventilator rate is 30 breaths
per minute. An adjustment in the ventilator rate needs to be made
based on the arterial PCO2. Generally, changes in ventilator
rate are made by increments or decrements of 5 breaths per minute.
Inadequate ventilator rate may result in hypercapnea
and respiratory acidosis. Excessive ventilator rate may result in
hypocapnea and respiratory alkalosis with associated decrease in
cerebral blood flow.
Caution is necessary in setting the ventilator rate
in a neonate with no spontaneous respiratory effort, as in asphyxia or
inspiratory pressure (cmH20)
influences tidal volume. A high PIP increases CO2 excretion
by increasing minute ventilation through tidal volume. A low PIP
decreases CO2 excretion.
Desirable PIP varies depending on the reason for ventilation. A high
PIP is necessary to ventilate a neonate with lung disease and poor lung
compliance. A low PIP is necessary to ventilate a neonate with apnea
from neurologic cause, prematurity, or sedation in the absence of lung
Desirable initial PIP is 20 cmH2O. An adjustment in the
PIP needs to be made based on clinical examination, including chest
excursion and breath sounds.
Inadequate PIP may result in hypoventilation, respiratory acidosis, and
atelectasis. Excessive PIP may result in hyperventilation, respiratory
alkalosis, volutrauma from stretching of lung tissue, and air
dissection, including pneumothorax and pulmonary interstitial emphysema.
compliance of the lung changes, delivery tidal volume will change.
Determination of PIP is
subjective and is based on chest wall excursion; however, tidal volume
can be used as a guide.
Positive end-expiratory pressure (cmH2O)
influences thoracic lung volume at end-expiration. A high PEEP
increases residual lung volume, improves ventilation-perfusion matching
and facilitates oxygenation as well as gas exchange. Excessive PEEP,
however, may decrease lung compliance and compromise cardiac function.
A low PEEP decreases residual lung volume and worsens lung compliance.
Desirable initial PEEP is 4-5 cmH2O. An adjustment in the
PEEP needs to be made based on evaluation of oxygenation, gas exchange,
and chest radiographic findings. Generally, changes in PEEP are made by
increments or decrements of 1 cmH2O. PEEP exceeding 8 cmH2O
is rarely used in the nursery. A low PEEP
may be used in neonates with significant pulmonary air dissection.
administered by nasal prongs or mask is called CPAP (continuous positive airway
pressure). Generally, the PEEP generated within the lung is
approximately half of the CPAP generated within the nasal passages.
Inspiratory time (fraction of second)
determines the length of inspiration in each ventilated breath and
influences the inspiratory/expiratory ratio (I:E ratio)
Desirable initial IT is 0.3 - 0.4 seconds. The IT needs to be
shortened as the ventilator rate is increased. The IT may be
lengthened as the ventilator rate is decreased. Generally
the IT is adjusted to allow the expiratory phase to be at least twice as long as
the inspiratory phase, (I:E ratio 1:2 - 1:4).
Mean airway pressure (cmH2O)
PAW is equal to the area under the pressure curve of
a single respiratory cycle divided by the duration of the cycle.
PAW is influenced by PIP, PEEP, I:E ratio, and
waveform. High PIP, high PEEP, prolonged I:E ratio, and square-wave
form of ventilation increase PAW. Low PIP, low PEEP, shortened I:E
ratio, and sine-wave form of ventilation decrease PAW.
PAW is computed and displayed on the ventilator.
Measurement of PAW incorporates PIP, PEEP, and IT.
High PAW (~10 cmH2O) may be required
during acute phase of neonatal lung disease, when compliance is low.
High PAW may cause impairment of venous return by over expanded lungs
during recovery phase of neonatal lung disease, when compliance is
Tidal volume (ml). 5 ml/kg initial calculation.
Certain ventilators deliver a preset VT. All
have the ability to set a peak pressure safety valve.
VT influences minute ventilation, which can be
calculated as follows:
Minute ventilation (ml) = Tidal volume (ml) x
ventilator rate (bpm) (remember the baby may contribute
significant minute ventilation with spontaneous breathing).
PTV (Assist Control)
Patient triggered ventilation
Patient triggered ventilation
is a ventilator mode in which the patientís inspiratory effort triggers
a controlled positive pressure inflation. During PTV, all of the
infantís respiratory efforts can trigger a positive pressure inflation.
Devices developed to detect the patientís inspiratory effort include
those that detect a change in abdominal expansion, esophageal pressure,
airflow, airway pressure, and impedance. Each of these devices needs to
be sensitive and fast in response.
cannot be used in infants with no spontaneous respiratory effort.
Synchronized intermittent mandatory ventilation
is a ventilator mode in which the maximum number of breaths that can be
triggered is determined by a preset SIMV rate. For example, if the SIMV
rate is set at 20 bpm and the infant is breathing at 60 bpm, 20 breaths
will be triggered with a positive pressure inflation, whereas the
remaining 40 breaths will be of a variable pressure, each dependent on
the inspiratory effort of the infant.
may improve ventilation by decreasing discordance between breaths
initiated by the infant and those that are initiated by the ventilator.
MMV is a ventilator mode in which a
minimum minute volume (VT x Rate) is set.
The maximum number of breaths that
can be delivered is determined by a preset MMV rate. In MMV, if the
patient is apneic, they will receive the set number of breaths at
the set tidal volume.
As the patient breathes and
generates some part of the set minute volume, the ventilator will
wean away some or all of the set breaths and allow the patient to
breathe on their own.
The high respiratory rate needs to
be properly set in this mode.
XI. Pressure Support (CPAP)
High frequency oscillation Ventilation
involves oscillation at a tidal volume of 50-100% of anatomic
respiratory dead space and a frequency of 180-900 breaths per minute (3-15 Hz). Please note: 1 Hz = 60 bpm.
may be used in infants with refractory respiratory failure (e.g.
pulmonary hypoplasia, congenital diaphragmatic hernia, severe hyaline
membrane disease), air dissection (e.g. pulmonary intestinal emphysema,
recurrent pneumothorax), and refractory hypoxemia (e.g. persistent
When using HFOV, the following variables need to be set: frequency (Hz),
oscillatory amplitude (∆-P), and mean airway pressure (PAW)
Guideline for frequency:
Body Weight(g) Frequency (Hz)
<1000 g 12-15 Hz
Guidelines for oscillatory amplitudes: Start with 20, increase gradually
until chest wall vibration is apparent. Increase ∆-P to increase CO2
excretion, decrease ∆-P to decrease CO2 excretion.
Guidelines for mean airway pressure: Start with +-2 cmH2O
higher than the PAW required during conventional mechanical
ventilation. High PAW promotes alveolar expansion and is indicated in
conditions in which the lung volumes are low. Low PAW may be useful in
infants with high lung volumes, cardiac compromise from over expanded
lungs, and pulmonary air dissection.
increases the risk of periventricular-intraventricular hemorrhage in
X. a/A Ratio
(713 X FiO2) - PaCo2
atmosphere pressure 760 mmHg minus water vapor pressure 47 mmHg
=Fraction of inspired oxygen
= partial pressure of arterial oxygen
= partial pressure of arterial carbon dioxide
ratio decreases with increasing sickness.
ratio < 0.2 is one of the indications for surfactant administration
ratio is useful in assessing the ventilatory progress.
OI= FiO2 X PAW
FiO2 = fraction of inspired oxygen
PAW = mean airway pressure
PaO2 = partial pressure of arterial oxygen
OI increases with increasing respiratory illness
OI values may be interpreted as follows:
Mild to moderate
Moderate to severe
Evaluate for ECMO
(Extracorporeal Membrane Oxygenation)