Diagnosing DDH

Cite this article as:
Andrew Tagg. Diagnosing DDH, Don't Forget the Bubbles, 2018. Available at:
https://doi.org/10.31440/DFTB.13704

When people approach me to ask about writing for DFTB I usually suggest that they write about what they know.  That is certainly my approach and why I started to write the Normal Neonate series a year ago. The littlest Tagg has just had her year’s check up with the maternal and child health nurse. She thought that tiny Tagg had uneven buttock creases and wanted her assessed for DDH. But how sensitive is this sign?

Lumbar Puncture Needle Depth

Cite this article as:
Henry Goldstein. Lumbar Puncture Needle Depth, Don't Forget the Bubbles, 2018. Available at:
https://doi.org/10.31440/DFTB.14720

Recently, I prepared up to perform a lumbar puncture for the first time in a few months and a quiet voice at the back of my brain whispered ;

How deep would I need to go?
Which length needle would be the best?

I asked a handful of senior and junior colleagues, both at the time and in the writing of this post, and the response was almost universally “deep enough that the CSF comes out.” Certainly true, but not very pragmatic, and lacking the kind of detail I was hoping for…

Background


I know there’s much discussion about the tip shape of a lumbar puncture needle, and in honesty, I’ve yet not read sufficiently to have strong opinions. However, in the fifteen minutes before the procedure, I had a look at the literature around needle length, and swiftly realized there was much more to this than I’d thought. Procedure finished, I was back to the drawing board.

Essentially, the balance is that a needle that is too short won’t reach the sub-arachnoid space, and a needle too long confers additional technical difficulty and increases the risk of going through.

So first, some basic anatomy; the aim of the exercise for lumbar puncture and CSF examination is to be in the sub-arachnoid space. To reach this space, the needle must pass through (in order) skin, superficial fascia, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, dura mater and the arachnoid. I’m no neurosurgeon, but I’m pretty sure that it’s impossible to feel each of these layers on the end of the needle.

Lumbar puncture layers

The anatomical target is either the L3/4 or L4/5 vertebral interspace, which respectively lie one vertebral body above & below the level of Tuffier’s line. Tuffier’s line is the imaginary line running between the superior iliac crests, and is used to demarcate the lower end of the spinal cord (which, in neonates, ends around L3 and moves superiorly with linear growth).

Finding a formula

One of the more widely used formulas is from a 1997 paper where Craig et al. derived an elegant formula that;

 LP needle depth (cm) = 0.03 x height of child (cm).

Easily memorable and from a sample of 107 children receiving an LP with macroscopically clear CSF, the authors’ intention was a formula requiring only one variable that could be obtained in a critically unwell child – height being easily obtained with a measuring tape or Broselow tape.



In my department, the most common single measure recorded is weight; Bilic’s 2003 study of 195 Croatian children (over 3m of age) found the best correlate for LP depth was weight, using the formula

LP depth (cm) = 1.3 + (0.07 x Body weight (kg) )

The above formulae use a single variable and hence are probably more useful and pragmatic in the setting of an unwell child. Several other articles have discussed the most accurate formula for LP depth; all of which are reliant on at least two measured parameters. The following formulae may be more beneficial for elective CSF examination.



Several formulae were derived for LP depth from a cohort of 279 paediatric oncology patients in Malaysia; the best fit for their dataset was

y = 10 (weight (kg)/height (cm)) + 1

For this cohort, the LP depth was measured by perhaps a less reliable method than other datasets described, as the investigators measured the distance from their finger on the needle when pressed to the back at withdrawal. Irrespective, this paper summarizes many of the preceding papers in the discussion section.



Abe and foundation DFTB contributor Loren Yamamoto took a slightly different approach in a 2005 study; they reviewed 175 abdominal CTs to identify spinal canal depth at the iliac crest, deriving the formula of

LP depth (cm) = 1+ 17( weight/height).

Crucially, they went on to compare standard needle sizes to these depths to identify if the needle was too short or too long.

Defining the needle depth in this way has several benefits – firstly, it’s relatively prescriptive and secondly, it draws to attention the risks associated with using a needle that is too short (multiple punctures, anatomically impossible to reach the CSF), which amount to avoidable harm. In this context, it’s pertinent to know your tools. That is, identify which spinal needles are available in your department, their lengths and the type of tip.

LP needles are available in the following lengths (mm), depending on the brand, introducer, tip type: 25, 35, 38, 50, 64, 70, 75, 90, 103, 120, 150. Find the stock in your department  and see what’s there.

What about ultrasound?


The use of ultrasound to identify the depth of the spinal cord has been trialed in a number of papers; the two mentioned here were both produced from Addenbrooke’s Hospital in Cambridge, UK.

Firstly, in a neonatal population (105 neonates), weighing between 500g and 4500g, USS was used to measure median spinal cord depth (MSCD). They subsequently derived a formula of

LP depth (median spinal cord depth in mm) =  2(Weight) + 7 mm (R^2 0.76).

Subsequently, this nomogram was validated (albeit by the same author group and unit) in this study.

A later study by the same group undertook USS on 225 children aged 3m to 17 years presenting for echocardiography. The majority of patients were over 5 years of age. MSCD was identified as above, and a number of prediction models developed. The formula put forward by the group as satisfying the inherent tradeoff between accuracy (R^2 =0.72) and utility is

MSCD (mm)=0.4 W (kg)+20

So, does this change my practice? I will admit that I don’t have any of the above formulas fixed in my head, as yet.  Spinal needles in my hospital don’t have depth markings (it would be interesting to know if these exist). Instead, the above information serves to help in selecting a needle, particularly in those patients somewhere between neonate and adult sized. On this basis, I suspect I’m most likely to utilize formulae with weight as the single variable. I also went and re-read Ben Lawton’s post on champagne taps before the next one.

In summary;

  • Formulae are not yet in regular practice to identify needle depth for lumbar puncture.
  • We advocate increased awareness of the depth of the target structure, particularly when it comes to needle selection.
  • A needle can be too short, but it can’t be too long – it just becomes harder to use.

Rachel Callander: Love, Life and Awesomeness at DFTB17

Cite this article as:
Team DFTB. Rachel Callander: Love, Life and Awesomeness at DFTB17, Don't Forget the Bubbles, 2018. Available at:
https://doi.org/10.31440/DFTB.12698

This talk was recorded live at DFTB17 in Brisbane. Watch out for more talks from our inaugural conference in the lead up to DFTB18.. If you haven’t done so yet then book some time off for August and come to Melbourne for our next amazing conference. Check out www.dftb18.com for more details. You can also join Rachel and Mary Freer for a workshop on conversations around caring. See the website for more details.

Fetal Alcohol Spectrum Disorder – Management

Cite this article as:
Mary Hardimon. Fetal Alcohol Spectrum Disorder – Management, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.12615

After taking an extensive history and performing multiple clinical examinations in consultation with allied health staff, you come to the conclusion that Callum has a diagnosis of foetal alcohol spectrum disorder. His mother is mortified about the situation and isn’t sure what this will mean for Callum (both now and in the future) as well as the family.

Trish Woods: Neonatal Retrieval at DFTB17

Cite this article as:
Team DFTB. Trish Woods: Neonatal Retrieval at DFTB17, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.13131

This talk was recorded live at DFTB17 in Brisbane. We’ve got plenty more where this one came from so keep on checking in with us every week. If you think you’ve got the chops to pull it off next year then get in touch with us hello@dontforgetthebubbles.com

Clinical features and diagnosis

Cite this article as:
Mary Hardimon. Clinical features and diagnosis, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.12577

Callum is a 6 year old boy who has been referred to paediatrics by his GP due to school concerns regarding his poor attention span and difficulty with learning and remembering new information. Whilst his peers in year 1 are working on their sight words, Callum is unable to recognize any sight words. He is described as a very social and talkative child although he doesn’t appear to always understand tasks despite being able to repeat the instructions. His parents are concerned as Callum’s older sibling also has learning difficulties. 

Fetal alcohol spectrum disorder

Cite this article as:
Mary Hardimon. Fetal alcohol spectrum disorder, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.12421

Callum is a 6 year old boy who has been referred to paediatrics by his GP due to school concerns regarding his poor attention span and difficulty with learning and remembering new information. Whilst his peers in year 1 are working on their sight words, Callum is unable to recognize any sight words. He is described as a very social and talkative child although he doesn’t appear to always understand tasks despite being able to repeat the instructions. His parents are concerned as Callum’s older sibling also has learning difficulties. On your thorough history, you note that Mum consumed alcohol during pregnancy and you wonder whether this child could have FASD… 

 

Why is diagnosis important?

  • Allows focused interventions that better benefit the child
    • Early diagnosis enables early intervention6
    • Is a recognised diagnosis with NDIS!1 (permanent impairment – no further assessment required)
    • May be eligible for a Centrelink carers allowance2
  • Comfort” may be found in a “label” by the family (regardless of the perceived guilt that you may assume would occur)
  • Help to develop appropriate expectations for the young person and their family3
  • Can allow medical practitioner to better “screen” for associations (physical and behavioural/cognitive)
  • Allows identification of women at risk of harm from alcohol and allow referral and treatment which may in turn prevent the birth of a subsequent affected child6

What is it?

 

Fetal alcohol spectrum disorder (FASD) is a non-diagnostic umbrella term used to describe the permanent, severe neurodevelopmental impairments that may occur as a result of maternal alcohol consumption during pregnancy.4 A history of alcohol consumption during pregnancy alone is not sufficient for diagnosis however; further assessment and clinical examination is required before assigning this significant label (with significance applicable not only for the child but also the family).

FASD is an umbrella term that includes a range of disorders3 including:

  • Fetal alcohol syndrome (FAS) – the most common clinically recognisable manifestation of FASD
  • Partial fetal alcohol syndrome
  • Alcohol related neurodevelopmental disorder (ARND)
  • Neurobehavioural disorder associated with prenatal alcohol exposure
  • Alcohol related birth defects (ARBD)

Diagnostic criteria for foetal alcohol spectrum disorders3

 FASD Diagnostic criteria
 Fetal alcohol syndrome

At least two characteristic facial features

Growth retardation

Clear evidence of brain involvement

Neurobehavioral impairment

With or without documented prenatal alcohol exposure

Partial fetal alcohol syndrome

With documented prenatal alcohol exposure:

§  At least two characteristic facial features

§  Neurobehavioral impairment

Without documented prenatal alcohol exposure:

§  At least two characteristic facial features

§  Growth retardation OR clear evidence of brain involvement

§  Neurobehavioral impairment

Alcohol-related neurodevelopmental disorder

Documented prenatal alcohol exposure

Neurobehavioral impairment

(This diagnosis cannot be definitively diagnosed in children <3 years of age)

Alcohol-related birth defects

Documented prenatal alcohol exposure

At least one specific major malformation associated with prenatal alcohol exposure

Neurobehavioral disorder associated with prenatal alcohol exposure

Documented prenatal alcohol exposure

Neurobehavioral impairment and onset in childhood

Facial features, growth retardation, and clear evidence of brain involvement not necessary (but may be present)

Not better explained by other teratogens; genetic or medical conditions; or environmental neglect

Is it actually still 'a thing' anymore considering all the media around women not drinking during pregnancy?

 

Fetal alcohol spectrum disorder is the leading cause of preventable non-genetic intellectual disability in Australia.4,5

Up to 50% of Australian women report drinking during pregnancy. Binge-drinking occurs in 4 – 20% of pregnancies, with a peak in Indigenous Australians with approximately 22% of Aboriginal women stating that they binge drink during pregnancy.5

www.starkmhar.org/training-and-events/fasd-awareness-day

But how much is too much?

Alcohol is a teratogen with irreversible central nervous system effects.3 The teratogenic effects vary depending on:

  • Quantity of alcohol
  • Pattern  of alcohol consumption
  • Maternal and foetal genetics
  • Maternal age
  • Maternal nutrition
  • Smoking

Australian and international guidelines advise that there is no safe level of alcohol consumption during pregnancy, with alcohol avoidance being the goal.7 As such, the level of danger has not been determined. Some suggestions have been that the foetus is more at risk where:

  1. >6 drinks per week for >2 weeks
  2. >3 drinks per occasion on >2 weeks
  3. Documentation of alcohol related social or legal problems
  4. Documentation of intoxication by blood, breath or urine alcohol testing

 

What are the consequences of alcohol during pregnancy?

It has the potential to cause harm at all stages of gestation.

  • First trimester à facial anomalies and major structural anomalies including brain anomalies
  • Second trimester à increased risk of spontaneous abortion
  • Third trimester à weight, length and brain growth

Neurobehavioural/neurodevelopmental effects may occur throughout gestation/pregnancy, even in the absence of facial or structural brain anomalies.3

https://www.cdc.gov/dotw/fasd/index.html

 

 

References 

1

2 https://www.humanservices.gov.au/customer/forms/sa426

3 Weitzman C, Rojmahamongkol P. 2016 September 13.  “Fetal alcohol spectrum disorder: Management and prognosis”. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA.

4 Australian Medical Association. 2016 August 24. “Fetal Alcohol Spectrum Disorder (FASD) – 2016.” Barton, ACT. Link: https://ama.com.au/position-statement/fetal-alcohol-spectrum-disorder-fasd-2016

5 Parliament of Western Australia. September 2012. “Foetal Alcohol Spectrum Disorder: the invisible disability.”  Perth, WA. Link: https://www.parliament.wa.gov.au/Parliament/commit.nsf/%28Report+Lookup+by+Com+ID%29/1740F63B37A1314A48257A7F000766DD/$file/Final+FASD+Report+with+signature.pdf

6 Elliot, E. British Medical Journal. 2017 January 11. “Fetal Alcohol Spectrum Disorder” Westmead, Australia.

7 National Health and Medical Research Council. (2009). “Australian Guidelines to Reduce Health Risks from Drinking Alcohol.” Canberra, Australia.

8 Department of Health and Human Services – USA. April 2015. “Fetal Alcohol Exposure”. United States of America. Link: https://pubs.niaaa.nih.gov/publications/fasdfactsheet/fasd.pdf

The 8th Bubble Wrap

Cite this article as:
Grace Leo. The 8th Bubble Wrap, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.12183

With millions upon millions of journal articles being published every year it is impossible to keep up.  Every month we ask some of our friends from the world of paediatrics to point out something that has caught their eye.

DFTB go to Berlin – #SMACCmini

Cite this article as:
Tagg, A. DFTB go to Berlin – #SMACCmini, Don't Forget the Bubbles, 2017. Available at:
https://dontforgetthebubbles.com/dftb-go-to-berlin-smaccmini/

Having flown 16,893 kilometres to visit family, a short hop over the Berlin was nothing. This year Tessa and I were honoured to be able to help out with SMACCmini – the paediatric workshop before the main event.  DasSMACC is the second-most* anticipated conference of the year and we wanted to make sure the delegates left better able to look after critically unwell children.

The 7th Bubble Wrap

Cite this article as:
Grace Leo. The 7th Bubble Wrap, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.11992

With millions upon millions of journal articles being published every year it is impossible to keep up.  Every month we ask some of our friends from PERUKI (Paediatric Emergency Research in UK and Ireland) to point out something that has caught their eye.

NETS knowledge

Cite this article as:
Andrew Tagg. NETS knowledge, Don't Forget the Bubbles, 2017. Available at:
https://doi.org/10.31440/DFTB.11487

When I’m not working in the emergency department, playing with my children or doing DFTB ‘stuff’ I work for the state retrieval service. As the name Adult Retrieval Victoria implies I spend my time moving and coordinating the movement of critically ill or injured adults around the state. There is a dearth of retrieval textbooks out there and so I was excited to see the Oxford Handbook of Retrieval Medicine make it into print.