Approach to the Cyanosed Baby with Congenital Heart Disease (CCHD)

Ensure that the ABC approach has been followed: make sure the baby’s airway is positioned optimally, give oxygen and breathing support if necessary and then assess and treat any circulatory shock. 

Do not forget to check the glucose.

1. Then do a careful clinical examination of the cardiovascular system

• Listen specifically for an ejection systolic murmur at the left upper sternal border (RV outflow tract murmur) or a continuous murmur (PDA). The absence of any murmur does not exclude CCHD. Useful (but difficult) to hear, is a single second heart sound.
• Do an ECG. Look for anything unusual, but particularly an unusual axis or poor R waves in the left precordial leads.
• Do a CXR. Look especially for oligaemic lung fields and presence of parenchymal infiltrates (suggesting pneumonia).

2. Look for differential oxygen sats

• Measure peripheral sats on the right hand and then on a foot.
• A difference of more than 2% suggests that the PDA is shunting from the main pulmonary artery to the descending aorta and warrants discussion with a cardiologist.
• It is then critical to maintain the patency of the PDA with Prostin (see below).

3. Confirm cyanosis by hyperoxia test

• Baby in room air, do an ABG from the right radial artery
• Place baby in 100% face mask or headbox oxygen for 10 minutes, then repeat the ABG
• PaO₂ unchanged = fixed shunt = CCHD
• Max PaO₂ less than 15kPa = probable CCHD
• Max PaO₂ more than 30kPa = no CCHD (look for other causes: pneumonia, methaemaglobinaemia, AV fistula)

4. Start oral Prostin if hyperoxia test is positive (or inconclusive)

• Insert a nasogastric tube, and confirm its position clinically (confirm again with a CXR later).
• Give a quarter tablet of Prostin, crushed and mixed in 5% dextrose water or N/S per NGT.
• Be sure to flush the emulsion into the stomach with a 2ml DW flush (i.e. don’t let it sit in the NGT). 
• Give this half hourly. If the sats go above 80%, reduce to hourly intervals.

BE AWARE THERE IS A RISK OF APNOEA WITH PROSTIN

The risk is much less with oral Prostin than IV Prostin – but can still occur. Intubation recommended particularly if long distance to transport to referral centre.

5. If the baby remains in trouble

• If the sats remain below 70%, and the ABG remains poor, increase dosing to 15min intervals, and contact a cardiologist urgently.
• A fluid bolus of at least 20ml/kg of Ringer’s Lactate will often help.
• If the baby still remains in trouble, intubate and ventilate, and prepare the baby for urgent transfer – ask Metro Control for the Paediatric Flying Squad (SPRINTT)  (transfer by flight if necessary).
• Consider IV antibiotics if sepsis cannot be excluded

General notes

1. A cyanotic baby with CCHD is usually in LESS respiratory distress than a baby that is cyanotic due to respiratory compromise, or sepsis.  Exclude or treat hypothermia and hypoglycaemia.

2. If the blood gas confirms that the pH, and base excess are normal (even if the PaO₂ is not), then stop nasal prong or facemask oxygen, since high FiO₂ in a CCHD baby may encourage the PDA to close and make things worse.

3. If you have IV Prostaglandin (Alprostadil), then use it if oral Prostin is not working well. This is not generally available in regional hospitals, but ask the transferring doctor/paramedics to bring a few vials. The baby will then need to be intubated and ventilated. [mix 60mcg/kg in 50ml 5%DW. Start at 2.5ml/h (50ng/kg/min), but increase to 5ml/h (100ng/kg/min) if no response. Maintenance infusion = 1-2ml/h if SaO₂ are stable].

4. It is sometimes possible for the cardiologist to fly in with Air Mercy Service to do a balloon atrial septostomy (for TGA) at the nearest peripheral hospital: this can be preferable to transporting a very unstable cyanosed baby over long distances.

5. Never hesitate to discuss any concerns with a cardiologist. The diagnosis of CCHD can only be confidently excluded by an echocardiogram or a sustained return to normal SaO₂ in a stable baby.