Apparent Life Threatening Events

Apparent Life Threatening Events in Babies – Trouble BRUEing

Brief Resolved, Unexplained Events (previously Apparent Life-Threatening Events) are pretty scary for parents and clinicians…

Whenever I start to think about teaching on a paediatric subject, I feel like I should open with a reminder that being a parent is HARD. It’s REALLY HARD. Especially for first-time parents with newborn babies, lives for whom they are completely responsible and yet their “bundle of joy” is a totally unknown quantity, a law unto itself.

Then imagine that the baby does something WEIRD. Like, properly weird – maybe it seems to stop breathing. Imagine that for a moment – imagine the panic, the terror, the paralysing fear that your tiny, helpless baby might be about to die. What would you do? You’d call an ambulance, of course.

By the time these babies arrive in the ED many are completely fine and sleeping like tiny angels. It’s easy to dismiss parents as being over-anxious, but that’s unfair. Some of these events represent serious underlying pathology and it’s your job to work out which and to reassure and safety net the others. So let’s think about how we can do that.

My four stage approach to Brief Resolved Unexplained Events

I like to think about these events in four stages of action:

  1. Resuscitate
  2. Authenticate
  3. Elucidate
  4. Evaluate/Investigate


It goes without saying that if these babies turn up in ED properly sick, you need to resuscitate them first – but look, I’ve said it anyway 🙂

Authenticate: ALTEs… Or BRUEs?

In babies who are well, the next step is to work out whether this was truly an ALTE (or BRUE), remembering that this is a description of events rather than a diagnosis and is only applicable when there is no identifiable underlying cause.

You might have seen the review over at FOAMCast of a paper updating the definition of ALTEs with a new acronym (Brief Resolved Unexplained Events). This is pretty inconvenient for me as I have always used the acronym ALTE (Apparent Life Threatening Event) to teach the key features of this topic. Thankfully the four clinical features remain the same.

  • Apnoea – this may be fully stopping breathing, or simply unusual sounds/an abnormal pattern. You might be able to differentiate here between central apnoea (whereby respiratory efforts cease altogether) or obstructive apnoea (effort is present but inhibited by mechanical obstruction)
  • Looks different – parents will describe cyanosis or pallor
  • Tone different – this may be increased or reduced tone but not seizure activity
  • Exhibits unconsciousness – the baby does not appear completely alert although it need not necessarily be completely unresponsive

The BRUE definition adds a couple of other elements: the episode should last less than one minute and resolve completely (i.e the child does not need resuscitation when they reach you), and there should be no discernible underlying cause – we’ll talk about this in Evaluate/Investigate.

These episodes are NOT the same as Sudden Infant Death Syndrome (SIDS) although parents often believe their child would have died had they not been there. In truth the resolution without intervention is key – 95% of ALTEs represent physiology or benign pathology. There is no relationship demonstrated between SIDS and ALTEs except for near SIDS (which is how ALTEs were known before they were ALTEs… Or BRUEs… Still with me?).

Edit: in our pre-publication peer review process, Chris Gray wisely explained that at this point in the post he was not sure whether ALTEs and BRUEs are the same thing – so I probably need to explain that BRUE is a new name with a slightly tighter definition but it’s also an American definition – the RCEM curriculum 2015 says ALTE so I would stick with that until they (or your local hospital) changes to BRUE. The strategies around management and investigation are essentially the same.

Consider this hypothetical case:

You are a parent of Alfie, aged 6 days old.

Alfie was born at this hospital by normal vaginal delivery last week at 38 weeks gestation. He was conceived by IVF after you and your partner struggled for some time to get pregnant, but the pregnancy itself was uneventful with normal scans throughout. There were no positive vaginal swabs nor infections or fevers during the labour.

Labour started spontaneously and Alfie was delivered within 8 hours of the spontaneous rupture of membranes. He had his initial babycheck on the postnatal unit performed by one of the midwives and you were all home within 12 hours of his birth.

Alfie has been exclusively breastfed so far. There has been a little trouble latching on and you’re not sure how much milk he’s actually getting, but he’s passing urine and he has a dirty nappy after almost every feed – a small amount of yellow stool today (it was greener for the last few days and today it looks like it has seeds in it).

He hasn’t cried as much as you expected, just when he’s hungry (which is every 1-2 hours) and he certainly hasn’t had a fever that you’ve noticed. He has been vomiting a small amount of milk back after each feed.

Today while he was in the moses basket about an hour after a feed you noticed he had stopped breathing for a few seconds. You went to pick him up and noticed he had started again but seemed to be breathing very quickly. He looked a normal colour (definitely no pallor or cyanosis). As you were watching he seemed to stop breathing again for another few seconds. You’re not sure exactly how long but it felt like a very long time.

You picked him up and he opened his eyes a bit and then went back to sleep. He seemed to be breathing normally then but you are really worried.

Is this an ALTE/BRUE? The answer is no – it doesn’t meet any of the four criteria. Alfie has periodic breathing – a normal finding in neonates (especially ex-prems). Periodic breathing episodes are characterised by a pattern of alternating breaths and brief respiratory pauses. Although descriptions vary, periodic breathing is usually defined as repetitive cycles of breathing and respiratory pauses that are about 5 to 10 seconds in duration. These pauses may be accompanied by modest oxygen desaturation and bradycardia that do not require clinical intervention. It needs to be differentiated from apnoea of prematurity as it typically does not require intervention.


So history is really important here and that’s because there are a number of other “funny episodes” that kids might display. The definition of BRUE now only applies to those <12 months which is pretty sensible as above this age other strange things are more likely to be going on (see below). We need to take a thorough history of what happened to determine whether the four factors are met.

We also need to take a good neonatal history, including:

  • gestational age at birth (and corrected gestational age now for ex-prems)
  • birth weight
  • feeding: what, how much, how often. Take some time to have a look at the NHS resources for new parents here (click on a link under the newborn tab). Children’s nurses in the ED are a great resource if you’re not sure how much feed a baby should be taking.
  • mode of delivery (normal delivery, assisted delivery, caesarian section – and the indication for this)
  • antenatal scans
  • risk factors for neonatal sepsis (prolonged rupture of membranes, positive maternal swabs, maternal fever during delivery, antibiotics given to either mum, baby or both in the immediate neonatal period)
  • medications and immunisations so far – remember to ask if the baby had the vitamin K injection or oral medication
  • whether there was any resuscitation after birth or if the baby had to go to the neonatal unit (and if so, what for)
  • previous pregnancies
  • the health of siblings and parents (or any unexpected deaths in childhood)

Seeing newborn babies in the ED has led me to develop the first two rules of May.

  1. RULE ONE: When you see a baby in the first week to fortnight (especially a first baby), you MUST ask the parents how things are going. This is a welfare check for a new family under stress and can yield important information as well as an opportunity to reassure new parents that having a newborn isn’t all sunshine and roses. The first week is often very, very difficult particularly for mum (expect her to cry – have tissues ready!) and it’s important to ask specifically about mum’s health. You have a responsibility to her too, even if you are working in a tertiary children’s hospital and don’t generally see adult patients. It’s also worth asking whether mum is breastfeeding and how that’s going (it can be tough to get established and takes longer than people think) and whether mum is taking any medication.
  2. RULE TWO: parents may not have all this information (most of them aren’t medically qualified) but may have brought their red book – if they have their red book, thank them and praise them. Even if it’s pretty sparsely filled there is valuable information in there and it’s helpful for parents to get into the habit of bringing it (and easy to discourage them from doing so by being dismissive of it).
  3. RULE THREE: if the dose you’ve calculated is more than you’d give an adult, it’s wrong (you can have that one for free).

Other things you might want to ask about include the relationship between the event and feeding, toileting, sleeping etc. It’s important to ask what the parents did when the baby had this strange episode – did they do chest compressions or mouth-to-mouth? Some parents, particularly those of babies who have been on the neonatal unit, will have been trained in basic resuscitation. Did they shake the baby or do anything else? It is important to mention, as always, that we must have the possibility of non-accidental injury at the back of our minds and fully examine these children from head to toe.

Consider the next case:

You are a parent of Sufiyah.

Sufiyah is a twin and is 5 weeks old. She and Ayla were born by normal vaginal delivery at 34 weeks. The pregnancy had been uneventful although you weren’t quite expecting the girls to be so early. It has been hard work since then; the girls were kept in for 5 days after they were born to ensure they were establishing feeds ok. They were a little bit small when they were born (Sufiyah was 2.9kg) but they have been gaining weight well. They are demand breast fed as much as possible but have required bottle top-ups: you are using SMA Gold.

You don’t have any other children (thank goodness! Your hands are quite full with these two) although you do have a large extended family; lots of your partner’s siblings and the twins’ cousins have been visiting over the last few weeks and your mother-in-law came to stay two weeks ago to help out. Sufiyah has been well other than a snuffly nose over the last few days. She has had good wet nappies and normal stool.

Today when you were bottle-feeding Sufiyah she had a sudden strange episode. She seemed to be gasping for breath and her breathing sounded awful. She felt very stiff in your arms; maybe her back was arched? It all happened very quickly. Then there was a period when she didn’t seem to breathe at all and was very red in the face. You admit you had a bit of a panic and handed her to your mother-in-law (you thought Sufiyah was dying and you didn’t know what to do). You remember that she felt floppy at this point. Your mother-in-law blew on Sufiyah’s face for a while. You aren’t sure if this made any difference but after what seemed like ages she seemed to settle down and her face went back to a normal colour.

That was all about an hour ago. You drove here immediately in the car with both babies and you are very worried.

Sufiyah may have had an ALTE/BRUE. She meets the four key criteria (apnoea, looks different, tone different, extra sounds). As this was a transient episode which resolved spontaneously and was related to feeding, it is likely that this was prompted by laryngospasm or reflux.

Older children may do other funny things though:

You are a parent of Dylan, who is 13 months old.

Dylan was born at 42/40 by elective caesarean section. He is your second child; you have an older daughter, Rebecca.

The pregnancy was uneventful; Dylan went home with you on day two and other than coughs and colds has not had any significant illnesses since. He has been immunised to date.

He does not take any medications or have any allergies and been well recently.

This afternoon he was playing with Rebecca when he fell over and bumped his head. He started to cry and you went to comfort him but then he looked very strange. It was as if he was trying to cry but no sound was coming out and he went red in the face. He made some choking noises. After a long period of kicking and waving his arms soundlessly he let out a cry and then collapsed, by which time his lips had gone blue. You were very alarmed and you thought he was dead.

You called 999 immediately but during the call you noticed he was still breathing and before you could follow the call handler’s instructions he had woken up and started crying again. He seems to be totally back to normal now but you were terrified and you want to know whether this means that Dylan has epilepsy and what you should do if it happens again. 

Dylan has had a breath-holding spell. Breath-holding spells typically occur in children 6-24 months of age and are triggered by an emotional challenge, such as pain, anger, or fear. Simple breath-holding attacks occur when the child simply holds their breath – there is no major alteration to circulation or oxygenation and the child recovers quickly without consequence. There’s a fantastic (and short!) podcast on the subject over at PEMblog – check it out.

Cyanosing breath-holding attacks feature a prolonged expiration, which causes a rapid rise in intra-thoracic pressure and a reduction in venous return (similar to a prolonged valsalva), during which the child becomes dusky or cyanosed. When the child eventually breathes in there is ultimately an increase in cardiac output and blood pressure, detected by baroreceptors which trigger a reflexive bradycardia and often a loss of consciousness. Recovery is usually rapid and there is no post-ictal period, incontinence or other hallmarks of seizure activity.

Pallid breath-holding attacks are similar although the child becomes pale rather than cyanosed.

Complex breath holding attacks begin as those above but then the child displays twitching or apparent seizure activity – however, EEGs recorded during this period are normal and the child recovers quickly (although the parents may take a little longer!). These are known as reflex anoxic seizures and there is no association with epilepsy. Footage recorded on smartphone can be helpful in diagnosis and parents should be encouraged to do this. It is sensible to check an ECG for long QT and there is some rather controversial evidence that treating a coexisting iron deficiency might be helpful – but don’t go looking for this in the ED (see also this Cochrane review and this twitter conversation if you’re really interested!).

In any case children usually grow out of these episodes by the time they start school. They can sometimes be confused with “tet spells” (or hypercyanotic spells) where children with Tetralogy of Fallot (or other cyanosing heart conditions with VSD) become very cyanosed and squat to improve preload and systemic vascular resistance – take a careful history and examine thoroughly! Which leads us on to…


Respiratory syncytial virus Nutritional errors
Congenital malformations of the brainstem Anomalies of mitochondrial fatty acid oxidation
congenital metabolic disease Messyndrome Cardiomyopathy Intracranial hypertension
Intanal infection
airway cysts
NAI intracranial haemorrhage Leigh syndrome Chemolaryngeal reflex M Accidental smothering Vasovagal reflexes Intussusception Medications Muscular problems or Volvulus Idiopathic
Galactosaemia Dumping MCADD Drug toxicity Aspiration and choking asphyxia developmental deficits
brain tumour Airway obstructions breath-holding spells
Obstructive sleep apnoea Reye syndrome Abnormalities of great vessels
Word ItOut

So, going back to ALTEs/BRUEs. There is an identifiable underlying cause in around 50-70% of cases, of which:

  • 50% are related to digestive problems (e.g. reflux)
  • 20% are related to neurological problems
  • 20% are related to respiratory problems (including respiratory viruses)
  • 5% are related to cardiac problems
  • 2-5% are related to metabolic problems

And your history and examination will hopefully lead you in one of these directions. But what to do if not?

Like everything in Emergency Medicine, you need to know who not to send home. There are important red flags which would necessitate a referral to the paediatric in-patient team for further assessment (I’m not brave enough to send these patients home). And as for the rest: most will be absolutely fine BUT remember these parents are seriously spooked (as you might expect) and a period of inpatient observation is usually a relief for them as well as a sign you are taking their concerns seriously.

Red flags for Brief Resolved Unexpected Events

Neonates (definitely <28/7) Prematurity (<37/40 at birth) Multiple ALTES
Appearing unwell Severe/prolonged ALTE episode Medical illness
Concerns for NAI
FH for sudden death (esp neonate)

This might be under your paediatric ED (if you have the ability to observe paediatric patients for a short period of time) or the inpatient specialty but the focus is on not over-investigating: I would suggest observing the next feed or two with SpO2 monitoring and considering a pertussis swab (if there are twins I would suggest admitting both). If, after this period of time, everything seems to be back to normal and the parents feel reassured you can consider discharging with safety netting and health visitor review.

Management of Brief Resolved Unexpected Events


So that’s a whirlwind tour of some of the weird and wonderful things children might do to bring them to the ED and how you might approach them. Resuscitate, authenticate, elucidate, evaluate and above all, be thorough and be kind.

The Podcast

We’ve published two podcasts on this topic to help reinforce your learning.

Further Reading

Cite this article as: Natalie May, "Apparent Life Threatening Events in Babies – Trouble BRUEing," in St.Emlyn's, September 2, 2016,

11 thoughts on “Apparent Life Threatening Events in Babies – Trouble BRUEing”

  1. This is brilliant Nat thanks. I can echo your sentiments that despite being an EM Dr having your newborn is properly hard and when they do something unusual it is terrifying.

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  4. Thanks for the good podcast info/education. I would like to know your opinion about the general agreement about BRUE being a subset of ALTE or ALTE is now considered the thing of the past !

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