Micro Machines: Sick Neonates at #RATH2018

Micro Machines – Sick Neonates at #RATH2018

If there’s one area in paediatric emergency medicine that seems to scare people more than any other, it’s neonates.

It’s hard to fathom how something so small can be so terrifying!

But the good news is that there’s very little new stuff happening in neonatal emergency medicine. That’s good for me, because there’s not much I can tell you here that you don’t already know.

So instead of bringing you anything really cutting edge, I am going to take this opportunity to give you a refresher of the basics of what makes neonates and infants different from other humans, and what that means for you in looking after the neonates in your department.

Micro Machines were marketed as “The Original Scale Miniatures”, but there are a number of ways Micro Machines aren’t quite a scale miniature of a real car. The same can be said of neonates; they aren’t quite scale miniatures of adults as there are some things we need to think about a bit differently. Let’s consider the similarities between neonates and Micro Machines.

Unboxing – the precipitous delivery

Precipitous delivery in ED is quite a lot like unboxing something you bought on the internet. You may have had pictures of the outside which give you an idea of what things are going to be like on the inside, but there’s always that element of uncertainty that makes us really excited – or terrified – about what might really be about to come out.

Neonatal resuscitation is actually pretty straightforward, following an A-B-A-B-C approach.

I’ve posted the algorithm below and clicking on the image will take you to the full-size PDF version but you can also find the latest Resuscitation Updates (2016) at this blog post and in the Resuscitation Crisis Manual.

Now, let’s take a tour of the micro machine that has been brought into the ED, having been born and at some point made it home from hospital. That’s a key issue here – at some point, they have been deemed well enough to survive outside a NICU, so that’s the starting point you’re going to try to get them back to. We’ll take a whirlwind tour of the micromachine itself, and of the common causes of illness that present in ED.

Intrauterine life is essentially high-level, mobile, intensive care. In utero, babies are effectively on ECMO and TPN. We don’t expect adults to do very much when they first come out of ICU, so it’s not surprising that babies don’t do much either

Fuel tanks – everything to do with feeding

What do babies actually do all day? They eat, they sleep, they cry, and they make dirty nappies. So let’s start off with thinking about feeding, since that’s what parents will genuinely be most obsessed with.

Micro machines have small fuel tanks, so they need to be filled up regularly. Feed requirement increases from 60ml/kg on day 1 to 150ml/kg on day 7 in divided feeds, usually 3-4 hourly.

Babies do not tolerate prolonged starvation as their stores are low, leaving them prone to hypoglycaemia.

Those first few weeks of life are often where metabolic disorders present, so have a low threshold for hypoglycaemia screening (bloods and urine) if the blood sugar is less than 2.6mmol/L. Hypoglycaemia can coexist with a number of other conditions, but its presence can be easily missed – so think about it early.

Inborn errors of metabolism and endocrine disorders may present in the neonatal period – in the presence of hypoglycaemia with jaundice or high lactate, consider NBM and IV fluids to break the cycle of toxic metabolite production, and also check ketones and ammonia.

Send a split bilirubin as well as a Coombs test and reticulocyte count – breastmilk jaundice (after first 48h) is unconjungated therefore conjugated >15% of total is always bad. This is a great resource from RCH Melbourne on jaundice in early infancy.

We also need to ensure the right fuel is going in. Breastfed babies may have issues with latching, with maternal milk production requiring top-up feeds, and this can be a very emotive area.

It’s worth thinking about what is going in when we are taking a feeding history – that includes any medication mothers are taking and any they have stopped – opioid withdrawal can present as a jittery, irritable infant and a mother may not always disclose that she has been an opioid user, especially if she is bottle-feeding the infant. Consider “home remedies” and topical therapies and ask about them specifically. Formula fed infants are at risk when feeds are inappropriately diluted, so do ask about feed preparation.

Poor feeding is a nonspecific but early sign of a number of serious pathologies.

Exhaust – everything to do with the gut

As well as crying, babies poop a lot. They will establish a pattern of bowel movement that is their “normal” – and there is a whole spectrum of normal. Meconium – that dark green/black stool – should start to be passed in the first 24h. Beyond this, what comes out depends on what is going in. Breastfed babies tend to have yellow, soft poo which may appear to contain seeds or curds. With formula, babies poo seems to smell more although they may go fewer times in a day. Babies will also vomit; it is usually milky, cream or yellow coloured.

There are a number of key intestinal issues we need to think about in super sick babies. Bile-staining of vomiting is a cause for concern, but be sure to elicit what is meant by bile as a common lay interpretation is that bile is stomach contents and that bile is anything vomited up. Remember that bile is green. To be honest, if you’re not at a paediatric surgical centre, bilious vomiting in a neonate should prompt planning to transfer the child at the same time as undertaking further investigations. As far as investigations go, AXR may not be your friend – it can be misleadingly normal or abnormal and is definitely useful in retrospect – but what use is that? Examination is far more useful. Masses may be palpable in the abdomen – you won’t find them unless you are gentle and thorough.

Failure to pass that meconium stool should prompt you to consider obstruction, particularly if there is also abdominal distension and bilious vomiting. There are many possible cause, but you can’t fix any of them without a surgeon.

Malrotation with midgut volvulus peaks in the first month of life; the baby will present with bilious vomiting, and if the malrotation does not spontaneously reduce there will be evolving distension and gut ischaemia, and eventually peritonism and shock. XRs may show a double-bubble sign but can be unhelpfully normal initially. Get the baby to a surgeon.

Intussusception does not usually present with bilious vomiting; classically the history is of a colicky baby with some non-bilious vomiting but they can just be quiet, listless, pale and unwell-looking without an obvious cause. Rule out other important stuff like hypoglycaemia while preparing to transfer to a paediatric centre – get the baby to a surgeon!

Hypertrophic pyloric stenosis presents with non-bilious vomiting, typically in weeks 3-5 of life and in first born males (but remember that patients don’t read the books – it can happen in male or female babies, regardless of birth order and earlier or later than that). If they present later they may have dehydration and the classic biochemical changes of hypochloraemia, hypokalaemic metabolic alkalosis. Surgery is usually delayed until acid/base status has been corrected, so you can start some fluid resuscitation with 0.9% saline with 5% dextrose and potassium, while getting the baby to a surgeon. Again, the RCH Melbourne guide to pyloric stenosis is really helpful.

The management of all this stuff is pretty standard – NBM, NGT, IV access for maintenance fluids and analgesia, consider antibiotics and get the baby to a surgeon! Even if the condition can be managed medically it can be hard to tell and that decision is best left in expert hands.

Engine problems – cardiac presentations

Cardiac problems present in three ways and may be more common than sepsis. It usually presents within the first two weeks, typically around day 5-6 at the time of duct closure.

  • Shock due to obstruction of systemic circulation (usually duct-dependent lesion)
  • Cyanosis due to obstruction to pulmonary circulation
  • Heart failure

Start with an ECG as monitors lie and SVT is common and easily treatable (although structural lesions may coexist)

Be cautious with fluids – it’s reasonable to try a small bolus e.g. 5ml/kg but if there is no clinical response, hold off from giving any more.

Remember that the blood supply to the right hand is pre-ductal, and that feet are post-ductal. A difference of 3% or more suggests shunting is occurring.

Prostaglandin E1 (alprostadil) buys you time but can be tricky to get hold of/prepare, so think of it early – start at 0.05mcg/kg/min and expect apnoea (a common side effect of the medication in neonates); be ready to intubate. You can increase to 0.1mcg/kg/min after 10mins if no effect is observed; then reduce to 0.01mcg/kg/min once you see improvement.

Correction of calcium and glucose improves cardiac function so this can be helpful. Chest XR may help confirm diagnosis and reveal pulmonary oedema – consider furosemide 1mg/kg IV if the baby is fluid overloaded.

Ultimately, you’ll need to get specialist help and plan for transfer to a centre with cardiac surgery. Your receiving paediatric cardiac centre or retrieval service will be able to advise you on choice of pressor/inotrope if required; for the shocked baby, we need to avoid reduction of pulmonary vascular resistance – avoid hyperventilation, permit a degree of hypoxia and avoid injudicious inotropes. For the cyanosed baby, adrenaline can increase the SVR and improve systemic circulation. But definitely take advice on this one!

Soft top – respiratory problems

Lack of a calcified thoracic cage is at the heart of many respiratory problems in neonates. Muscles fatigue quickly, so apnoea will happen readily and can be easy to miss while you are distracted by other things. Feeding is a double whammy as babies struggle to feed and breathe during viral upper respiratory tract infections with nasal congestion, and a full stomach (either with milk or air from crying) restricts diaphragmatic movement. Considering they didn’t do any actual breathing in utero, babies are trying to make up for it on the outside, but their aerodynamics are poor – they don’t have a great capacity to increase the efficacy of their breathing other than by increasing respiratory rate.

Pneumothoraces are rare but they do happen and are poorly tolerated. Image (CXR, ultrasound) or transilluminate and consider the need to drain if in respiratory distress/low SpO2, compromised circulation. You can perform needle aspiration with a 24g needle, three-way-tap and a syringe, or you may be able to get a Safe-T-centesis which is a pigtail intercostal catheter – your neonatal unit may have one.

Limited momentum (speed/distance) – major trauma

Neonates rarely sustain major trauma mechanisms (except NAI) because they are non-mobile and thus unable to generate significant momentum without the help of someone bigger. Head injuries are most common particularly in dropped babies – remember that subgaleal haemorrhage can be significant in a child with a small circulating volume (80ml/kg = 320ml for a 4kg baby eg a can of soda) and can cause shock.

Poorly secured vehicle – sepsis

Sepsis is often at the forefront of our mind when treating sick neonates. Big bad organisms are Group B Streptococcus, Staph. aureus, E. coli and Listeria. Infection may coexist and/or precipitate one of the other pathologies, so many sick babies also get antibiotic cover. Ampicillin and gentamicin or ampicillin and cefotaxime will treat most causative pathogens. You may want to add flucloxacillin to cover Staph. aureus or even vancomycin if MRSA is a possibility.

Omphalitis is a nasty infection exclusive to neonates; it is a cellulitis of the umbilical stump with some very nasty consequences. It’s rare and many stumps are a little bit red, so it’s easy to miss. What we are looking for is erythema around the umbilical stump, extending to the abdominal wall – if we see this in an unwell baby we should assume badness. Organisms are usually polymicrobial and complications can include necrotising fasciitis (10%), peritonitis, portal vein thrombosis, abscess or spontaneous bowel evisceration. There’s a great post on omphalitis here at PEMMorsels.

In general, sick babies with neonatal sepsis may also need fluid boluses and pressor support with early escalation to paediatric ICU setting if they are not responding.

Defective steering – seizures

Seizures in neonates are rarely a standalone diagnosis; most are associated with hypoxia, hypoglycaemia or intracranial badness (trauma or infection). Consider acyclovir to cover H. simplex encephalitis and look for causes. A venous blood gas is a great place to start.

No air conditioning – hypothermia

Babies are also poorly insulated and prone to getting cold quickly – when assessing and treating neonates, use a resuscitaire or warming pad to maintain warmth during procedures if possible.

Babies also have very sensitive and reactive vasomotor tone, meaning they can quickly change their skin perfusion leading to pallor, cyanosis or mottling. This may happen in response to temperature but be wary of overlooking skin perfusion as an important clinical indicator.

How can we put all this together?

There are a couple of nice acronyms to help us remember the common problems that cause neonates to present in need of resuscitation.

You might have heard of THE MISFITS; I also like NEO SECRETS.

Essentially, there are three things we will always need to do for sick neonates:

  1. Take a good history, particularly of feeding
  2. Perform a thorough, top-to-toe examination
  3. Check a blood sugar (and maybe a VBG while we are there)

Then there are three things we need to consider:

  1. How sick is this baby – do we have the resources necessary to look after them here, or do we need to transfer them out?
  2. Do we need to get IV access and take more bloods? (Do we need to give antibiotics and fluids?)
  3. Do we need to perform XRs or an ECG, make the child NBM and pass an NGT?

 

Further Resources (blogposts and podcasts):

PEM Playbook on the Sick Neonate

emDOCs.net on the sick neonate

Paediatric and Neonatal Resus updates from #smaccMINI at #smaccDUB

Sick Baby: undifferentiated infant under 3 months at EMPEM.org

Thanks to:

The St Emlyn’s Team for Peer Review (especially Ross Fisher)

Katie Rasmussen for Peer Review

Sam Immens for the idea of unboxing as a metaphor (which I’ve shamelessly stolen)

 

Nat

@_NMay

Before you go please don’t forget to…

Posted by Natalie May

Dr. Natalie May, MBChB, MPHe, MSc, PGCert Medical Education, FRCEM, FACEM is section lead for paediatrics and medical education. She is an Editorial Board Member of the St Emlyn’s blog and podcast. She is a specialist in Emergency Medicine (Australia) and a Specialist in Emergency Medicine with Paediatric Emergency Medicine (UK). She works as Staff Specialist in Prehospital and Retrieval Medicine with the Ambulance Service of New South Wales (aka Sydney HEMS). She also works as aStaff Specialist, Emergency Medicine, St George Hospital (South Eastern Sydney Local Health District). Her research interests include medical education, particularly feedback; gender inequity in healthcare; paediatric emergency medicine. You can find her on twitter as @_NMay

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