Cyanosed neonate assessment

Differential diagnosis

Sepsis

Consult sepsis for more detail but note the following:

• Sepsis with a low output state may cause:
  • poor pulses
  • severe metabolic acidosis
  • blunted response to HT
  • absent respiratory distress (if no primary lung pathology).
• Differentiating the infant in severe septic shock from other causes of cyanosis is very difficult and no safe clinical measures exist. Thus, generally all infants with central cyanosis should be commenced on parental antibiotics early until further investigation is possible.

Persistent pulmonary hypertension of the newborn (PPHN)

Consult PPHN for more detail but note:

• PPHN results from an altered pulmonary vasoreactivity and increased pulmonary vascular resistance, causing a right to left ductal shunt.
• Most infants present with respiratory distress and cyanosis.
• Usually the infant is tachypnoeic, shows labile oxygenation and has evidence of right ventricular strain (prominent right ventricle impulse and tricuspid regurgitation murmur).
• There is usually a pre and post-ductal difference of 10-15 per cent in SaO2 and 10-15 mmHg PaO2. Despite this a degree of clinical variability exists depending on the severity, stage of disease and underlying pathology.
• If PPHN is suspected hyperventilation for 10 minutes is a useful clinical test when other investigative options are unavailable.
• Infants with PPHN show improved oxygenation (PaO2 increasing by > 30 mmHg) when pH is raised to 7.55. Prolonged hyperventilation is not recommended due to the cerebral effects of prolonged hypocapnia.
• Differentiating PPHN from duct-dependent pulmonary cardiac lesions can be very difficult; if uncertainty exists a PG infusion is generally the safest option for transport and infants with PPHN may show some improvement on infusions of 50-60 nanog/kg/min.

Issue to note about cardiac causes for cyanosis:

• Generally an infant with cyanosis and a murmur has a high probability of a cardiac cause.
• Absence of peripheral pulses further raises this probability.
• Infants presenting with cyanosis due to a cardiac cause have a high probability of a duct dependent lesion involving either of the following conditions.

Duct-dependent pulmonary circulation

• critical pulmonary stenosis
• transposition of the great arteries.

Presenting with:

• cyanosis
• tachypnoea without respiratory distress
• adequate perfusion initially.

Duct-dependent systemic circulation (critically obstructed systemic circulation)

• coarctation of the aorta
• hypoplastic left heart syndrome
• critical aortic stenosis.

Presenting with:

• cardiac failure with systemic hypoperfusion
• poor or absent peripheral pulses
• increasing metabolic acidosis
• cyanosis may not develop until the latter stages of the clinical course.

Management of cardiac causes

Aim to maintain adequate tissue perfusion and duct patency rather than correcting the cyanosis.

Minimise pulmonary blood flow:

• moderate PEEP (4-6 cm H20)
• ventilate in air if possible
• aim for a CO2 of 37-45 mmHg
• SaO2 75-85 per cent.

Maximise tissue perfusion with:

• fluid resuscitation (saline 10ml/kg boluses)
• low-dose inotropes (dopamine/dobutamine), see shock
• sodium bicarbonate if BE > -10 (dose (mmol) = BE *wt/4).

Consider muscle relaxants, sedation and respiratory ventilation if the infant is distressed.

Achieve ductal patency with prostaglandin E1.

When to give prostaglandin E1 (PG) infusion

Give prostaglandin E1 (PG) infusion in these situations:

• In a cyanotic infant in whom cardiac disease is suspected there should be a low threshold for starting PG following consultation with PIPER.
• Even in a stable infant the risk of withholding PG is usually greater than the risks associated with PG due to the risk of rapid clinical deterioration when the duct closes, especially in a transport environment.
• There is evidence that infants with suspected duct dependent cardiac lesions transported with prostaglandin have better outcomes than those in which prostaglandin is withheld. The overall risk to the infant is low.
• There are no true contraindications to PG but infants with TAVPD may worsen on PG.
• If the diagnosis is uncertain a trial of PG for 30-60 minutes with repeat ABG may be warranted and will usually outweigh the risks of delaying treatment.

Dosage

Dosage guidelines include the following:

• When the duct is still open the priority is to prevent further loss of patency.
• A starting dose of 10 nanogram/kg/min infusion in 5 per cent dextrose or normal saline is adequate.
• If no improvement in SaO2 then increase dose by 10 nanogram/kg/min increments up to 50 nanogram/kg/min until SaO2 improves.
• Prostaglandin can be given via a peripheral line or UVC.
• Infants in extremis will usually have a closed duct and a higher starting dose of 100 nanogram/kg/min will be required to reopen the duct.
• When saturations improve then dose can be decreased to a dose to maintain ductal patency.

See the Drug Calculator

Side effects of prostaglandin E1 (PG) infusion

Most frequent side effects include:

• fever 12 per cent
• apnoea 12 per cent
• flushing 10 per cent
• hypotension
• tachycardia.

Apnoea rarely occurs at 10 ncg/kg/min and is not an indication to decrease the dose if the infant is responding clinically.

Ensure adequate respiratory support.

The likelihood of apnoea is very high at a dose of 100 ncg/kg/min and most infants on this dose should have ventilatory support.

Close observation is mandatory following commencement of PG infusion and assisted ventilation,volume expansion or inotrope infusion are frequently required.

Who to intubate?

The threshold to intubate an infant on a PG infusion will be lower in a transport or remote setting. Factors to consider:

• presence of apnoea
• the distance to the receiving hospital
• gestation of the infant
• clinical state of the infant (metabolic acidosis, shock, severe distress and tachypnoea)
• high PG dose required to achieve ductal patency.

In a stable infant with a PG responsive ductal lesion transport without intubation maybe appropriate.

Conversely, it would generally be appropriate to electively intubate an infant requiring high dose PG (although these infants usually require respiratory support for other reasons).

Clinical

• Clinical Pediatric Emergency Medicine (2008) Evaluation and management of the cyanotic neonate
• Learn Pediatrics - Approach to neonatal cyanosis

References

• Penny DJ, Shekerdemian LS. Management of the neonate with symptomatic congenital heart disease. Arch Dis Child Fetal Neonatal Ed 2001; 84: F141 - F145.
• Hellstrm-Westas L et al. Long-distance transports of newborn infants with congenital heart disease. Pediatr Cardiol 2001; 22: 380-384
• Buck ML. Prostaglandin E1 treatment of congenital heart disease: use prior to neonatal transport. DICP Ann Pharmacother 1991; 25: 408 - 9
• Barry PW, Ralston C. Adverse events occurring during interhospital transfer of the critically ill. Arch Dis Child 1994; 71: 8-11
• Jaimovich DG, Vidyasagar D (Ed). Handbook of pediatric and neonatal transport medicine. Ch 8. 2nd Ed. 2002. Hanley & Belfus. Pp 93 - 125
• Myung K Park. Pediatric cardiology for practitioners. 3rd Ed. 1996. Mosby-Year Book (St Louis)