Pulmonary Hypertension of the Newborn
|Reviewed by Simon Rowley and Carl Kuschel
Infants with Persistent Pulmonary
Hypertension of the Newborn (PPHN) are exceptionally unstable and difficult to
manage. After initial resuscitation the management should always be discussed
with the consultant on call.
Pulmonary hypertension of the
newborn with right to left shunt occurs in a variety of clinical situations.
These include Meconium Aspiration Syndrome, hypoplastic lungs, transient
tachypnoea of the newborn, congenital pneumonia and hyaline membrane disease.
Secondary disturbances such as polycythaemia and myocardial failure are
contributory. There is frequently a history of chronic in utero hypoxia, but
some cases remain idiopathic.
- Pulmonary vasoconstriction
is exacerbated by hypoxia, acidosis, and hypercapnia (?secondary to changes
in pH). Meconium may trigger vasoactive process to exacerbate this.
- Anatomic abnormality of the
pulmonary vascular bed (e.g. pulmonary hypoplasia with pulmonary arteriolar
smooth muscle hypertrophy) or chronic in-utero hypotension following chronic
intrauterine hypoxia may also play a role.
- Birth asphyxia with hypoxia,
acidosis and shock is clinically associated with increased responsivity of
the pulmonary vascular bed.
- Group B streptococcal sepsis
via Strep polysaccharide toxins.
- Polycythaemia, hyaline
membrane disease, hypocalcaemia and hypoglycaemia may contribute similarly.
- Structural lung abnormalities
(e.g. congenital diaphragmatic hernia, CCAM, ...) are frequently associated
- This is essentially one of
exclusion of significant cyanotic congenital heart disease and severe
parenchymal lung disease. However, PPHN may coexist with significant
parenchymal lung disease.
- Have a high index of
suspicion for the 'at risk' group in a term baby with respiratory distress
and cyanosis, particularly if there has been a history of intrauterine
hypoxia and meconium exposure or birth asphyxia.
Necessary investigations include
- chest radiograph
- serial arterial blood gases (simultaneous pre- and post-ductal samples may be helpful)
- full blood count
- blood cultures
- blood glucose
This is crucial to exclude cyanotic congenital heart disease (particularly
transposition of the great arteries, and totally anomalous pulmonary venous
return). In the presence of significant parenchymal lung disease,
cardiac assessment is less urgent.
Echocardiography is also useful to
- assess myocardial function, which is often severely affected
- assess the severity of PPHN, and assess responses to treatment.
- Tricuspid regurgitation - allows indirect measurement of the RV pressure and
- Ductual shunting
- Shunting through the foramen ovale
- Click here to see echocardiographic images of PPHN
- The hyperoxic test may play a role in diagnosis if 2D echocardiography is not available. However, severe
PPHN is likely to produce a similar result to cyanotic CHD.
Aims of Management
- Lower pulmonary vascular resistance.
- Maintain systemic blood pressure.
- Reverse right-to-left shunting.
- Improve arteriolar oxygen saturation and oxygen delivery to the tissues.
- Minimise barotrauma.
1. Oxygen and ventilation
- 100% O2
Always start with 100% oxygen
and reduce the FiO2, rather than starting on 25% and increasing.
In the short term there is no risk to a term baby using such measures.
- Normo-ventilation i.e. pO2 7-12 kpa is acceptable if baby stable
- pCO2 5-7 kpa if this can be achieved
- Use of HFOV, particularly in combination with inhaled Nitric Oxide, has been shown to reduce the
need for ECMO.
- Myocardial function is frequently poor, despite reasonable blood pressures.
- Aim to keep the mean arterial pressures above 50mm Hg in term infants
- Use volume (initially normal saline) and dopamine -starting with 5-10 mcg/kg/min and/or
dobutamine 5-10 mcg/kg/min if systemic pressure raises and pulmonary
pressure stays the same, R-L shunt will diminish .
- Adrenaline infusions may be indicated if there is severe myocardial dysfunction
3. Avoid polycythaemia
- Aim to keep the PCV between 0.40 and 0.45.
- Establish the critical pH- preferably 7.45 but may be higher. If there is no dramatic
improvement in PaO2 at a pH >7.6, the infant can be deemed to be
- Use small boluses of
bicarbonate (1-2 mmol/kg) or
a continuous infusion (0.5mmol/kg/hour
initially). Liberal bicarbonate use may result in hypernatraemia
- Many babies are very unstable.
- Consider early use of narcotic infusions.
6. Muscle Relaxation
- This may be necessary to gain initial control in very vigorous babies who are not adequately
sedated with narcotics and are fighting the ventilator to their detriment.
- Use pancuronium 100micrograms/kg/dose PRN preferably for 24 hours or less.
7. Pulmonary vasodilators
- Inhaled nitric oxide (iNO) is the vasodilator of choice.
iNO should be started at 20ppm and reduced to 5ppm as able, according to
response and to stability.
Methaemoglobin levels should be monitored (these are measured
automatically on blood gases).
Nitrogen dioxide (NO2) levels should be monitored and kept
Magnesium sulphate may be
used in refractory cases. The use of MgSO4 is
controversial but may be indicated in selected instances.
- Prostacyclin may also be
used in severe and refractory cases, although it is difficult to obtain
and its use is controversial.
- Tolazoline is no longer
used at NWH. It is a non-registered medication. It has an
unpredictable effect and frequently results in systemic hypotension and
- Inducing alkalosis by
hyperventilation often creates as many problems as it solves and is best
avoided. There can be an improvement in PO2.
- This is essentially prolonged cardio-pulmonary bypass and is provided via PICU at Starship
- Usual criteria are infants who have an
Oxygenation Index (OI) >40 but it may be
appropriate to discuss infants who may potentially require ECMO with the
PICU specialist early rather than when ECMO or death are
imminent. This will be done specialist-to-specialist. The
neurological status of the infant may be an important factor in
determining if ECMO is offered.
where MAP is Mean Airway
PaO2 is the arterial oxygen tension in mmHg (1kPa = 7.5mmHg), and
FiO2 is the fraction of inspired oxygen (100% = 1.0, air = 0.21)
- Weaning such babies is invariably difficult. Steps should be taken one at a time and by small increments once
lability appears to have stabilised.
- Pay careful attention to maintaining normal electrolytes, blood glucose, calcium and nutrition.
- In babies on long term ventilation, particularly if they are growth retarded from the
outset, intravenous nutrition may be required.
|| Drummond WH. Persistent
pulmonary hypertension of the neonate (Persistent fetal circulation syndrome).
1984, Year Book Medical Publishers, In. pg 61-85.
|| Fox WW, Duara S. Persistent
pulmonary hypertension in the neonate: Diagnosis and management. J Pediatr
1983; Vol 103:4 pg 505-514.
|| Drummond WH, Gregory GA, et
al. The independent effects of hyperventilation, tolazoline, and dopamine on
infants with persistent pulmonary hypertension. J Pediatr 1981; 9(4): 603-611
|| Wung J, James LS, et al.
Management of infants with severe respiratory failure and persistence of the
fetal circulation, without hyper- ventilation. Pediatrics 1985; 76:4,
|| Hansen and Corlet from
"Diseases of the Newborn" : Disorders of the transition. Taeusch
Ballard Avery 6th edition -Chapter VIII.
NN, Barrington KJ. Nitric oxide for respiratory failure in infants
born at or near term. Cochrane Database of Systematic Reviews
2000; Issue 2. Update Software.
Collaborative ECMO Trial Group. UK collaborative randomised trial
of neonatal extracorporeal membrane oxygenation. Lancet 1996;