B is done... on to Part C

So results are out and despite some controversy over the fire alarm at one venue I have passed part B, so the focus for this blog may change a little bit to part C, I still have some draft posts for part B topics and they will also find their way out in the next couple of weeks.

A Bolus is a bonus - fluid management in children

So fluids in kids is an easy topic for an exam as it follows clear rules, however it is tricky for ED doctors as most of us have limited paediatric exposure and it has some important differences to the management of adults. Children are far more prone to fluid shifts and the therefore poor fluid management of children can kill.

Below are a few simple rules aimed at giving safe answers that are suitable for an exam, the reality of the matter in the ED is that if you are in doubt there are all sorts of useful resources that can guide you e.g. your boss or the paediatric reg/ PICU. There are even apps to help with the calculations.

For the purposes of the below assume I am referring to 0.9% sodium chloride unless stated otherwise.

Step 1:

Know the child's weight, you cannot proceed without this, but you may have to work it out:

• 0-12  months: weight = (0.5 x age in months) + 4
• 1-5 yrs: weight = (2x age in years) + 8
• 6-12 years: weight = (3x age in years) + 7

Step 2:

Bolus for the shocked child: know the cause of shock

• Sepsis: 20ml per Kg
• Hypovolaemia/ trauma: 10ml per kg
• DKA: 10 ml per kg - do not exceed 30ml per kg in total - 
• and if you are managing a child with DKA and needing fluid boluses you should probably not be managing them on your own!!!

Step 3:

Maintenance fluids: "4-2-1 rule"

• 4mls per Kg for the first 10 kgs
• 2mls per Kg for 10-20 kgs
• 1mls per Kg for 20+ Kg

Worked example:

22kg child =

4mls x 10 +

2mls x 10+

1ml x 2 = 22 ml/ hr

Don't forget that maintenance will need to consider potassium and dextrose to be included in regime.

Step 4:

Special circumstances:

• DKA: can't stress this one enough - cautious fluid is the order of the day and rehydration may be undertaken over a 48 hr period!!!
• Burns: remember Parkland 4x %BSA X Weight - give half over first eight hours from injury and then second half over next sixteen hours.
• Dehydration: similar to burns you can calculate the deficit by working out the %dehydration x weight.
• Hypoglycaemia - weight x 2mls - here the fluid is 10% dextrose

Questions:

1) What is your estimated weight for a seven year old boy?

2) What would be a suitable maintenance fluid regime for this child?

3) He has sustained 6% partial thickness burns, what are his fluid requirements over the first 24 hours.

4) How much dextrose would a hypoglycaemic 6 month old require?

Diabetic Ketoacidosis- Glucagon is the Problem!

Another common topic and also a frequent presentation to the ED is DKA. On the whole I think of this as straight forward ie bang up some fluids and insulin and it'll sort itself out! That being said when you actually read about it things are a little bit more complicated.

Your hospital will have it's own policy and approach, but a nice little guide has been produced by the Joint British Diabetes Societies Inpatient Care Group:

http://www.bsped.org.uk/clinical/docs/DKAManagementOfDKAinAdultsMarch20101.pdf

Let's start with some background to put things in perspective:

• It is potentially life threatening, although mortality rates have fallen in the last 20 years from 7.96% to 0.67%!
• Cerebral oedema especially in children and adolescents is the most serious complication.
• The typical fluid deficit in DKA may be 100 ml/kg!
• It is now possible to measure blood ketones at the bedside.
• The treatment of DKA has developed and will continue to develop as our understanding increases.

The rest of this post is about adults, there are key differences in the management of children/ adolescents.

Definition:

1. Blood glucose >11
2. Ketones > 3 (or 2+ on urine)
3. pH <7.3 or bicarb <15

Pathophysiology:

Its a lack of insulin, right? Well yes and no.

Type one diabetics have impaired insulin production and therefore cannot bring their sugars down, but Insulin also acts to oppose other hormones (glucagon). It is this lack of opposition that causes the metabolism of fatty acids which in turn produces the ketones. So it is good to think of it as unopposed gluconeogenesis: the production of ketones lowers the pH and therefore gives us the acidosis ie. not a sugar problem.

Bang up some fluids and give insulin:

Treatment is aimed at correct the abnormalities and these patients are certainly dry and in need of lowering their blood sugars, but actually we need to think of treatment goals as switching off the gluconeogenesis and ketone production.

1. Fluid resuscitation - the link at the top contains a bit of debate as to the fluid to give, but essentially 0.9% Chloride is the answer because you can add potassium when it is needed.
2. Insulin- fixed rate infusion based on weight (0.1 units/kg/hr) - this corrects the sugars but also suppresses ketogenesis!
3. Monitor K+ and add it to fluids given - remember insulin will push it into intracellular space.
• hypokalaemia is a complication of treatment.
4. Give glucose when blood glucose is <14 - DKA is not a sugar problem but the production of ketones driven by glucagon, what we don't want is the sugar to fall and the gluconeogenesis to begin again!!!

What should I be worried about?

Things to worry about are the complications mentioned above: cerebral oedema and hypokalaemia.

Other things that warrant a higher level of care (HDU/ ITU) include:

• pH <7.1
• bicarb <5
• cardiovascular compromise
• Blood ketones >6
• Hypokalaemia on admission
• Anion gap >16
• Reduced GCS

Question:

A 36 year old lady who frequently attends the department with diabetic problems presents with a three day history of abdo pain and vommiting. She ways 65kg. Her observations are as follows: HR 117, Bp 109/76, RR 30, Sats 99% (21%). The results of her blood gas are as follows:

• pH: 7.23,
• Pa O2: 10
• Pa CO2: 1.4
• HCO3: 11.2
• Glucose: 36

a) What are the diagnostic criteria for Diabetic Ketoacidosis (DKA)? (3)

b) Write an appropriate prescription for an insulin regime in this patient. (2)

c) Give three features that should trigger discussion with critical care? (3)

d) What would be an appropriate fluid regime for this patient? (2)

Clever Marks:

Another question could quite easily ask you to calculate the anion gap - I have left this out of the gas information as I intend to do another medical maths entry on this topic.

Completely unpredictable...

So sometimes the exam just contains weird and wonderful things that you wouldn't expect - innervation of the female genital tract being an often quoted example. Then again other questions that come out of left field can with hindsight be identified as a popular issue around the time the exam was set. Another example that fits this is a major incident question following the 7/7 bombings.

So in light of that what sort of sort things have sprung to my mind? (if you can think of others please post in the comments).

1. Measles- recent outbreak in Wales. Questions could easily cover rashes/ other child infections and vaccination schedules. Also could be extended to meningitis or other infections amongst students
2. Over crowding: http://www.bbc.co.uk/news/health-24432072 a BIG issue at the moment, CEM have released a statement this week and did you know they have a document detailing their recommendations for dealing with over crowding (released approx a year ago!) www.collemergencymed.ac.uk/code/document.asp?ID=6296
3. Paracetamol - recent guideline change (again about a year ago).

Other things to think about:

• Capacity
• Consent
• DVLA guidance
• Child protection.

Question:

a) What markers indicate a department is overcrowded?

b) What steps can be taken in the ED to facilitate flow?

c) Define boarding.

d) At what point does the ED become responsible for a patient?

e) What steps can be taken to improve output problems?

Bloodbourne Infections and Needlestick Injury

Needlestick injuries and other exposures are a risk that all healthcare workers are exposed to. Out of hours they may easily present to the ED and are therefore on the syllabus for CT3 - they have also appeared in part B. Questions around rates of seroconversion, vaccinations and risks could easily appear in part A.

The Syllabus includes the following:

The health protection agency have a useful tutorial/ elearning http://www.health-protection-update.org.uk:8100/tutorials/needlestick/

Points to consider:

Risks:

Donor - Known blood HIV, Hepatitis B/C or High risk group - IVDU/ High prevalence Country

Fluid- Blood/ CSF/ Peritoneal or Pleural Fluid/ Breast Milk

Mechanism- hollow needles/ visible blood/ needle that has been in vein or artery/ deep wound/ not --------------------- through gloves/ injection of contaminated material

Disease Specifics:

The risks of transmission differ for the 3 main infections:

Hep B (30%) > Hep C (3%) > HIV (0.3.%)

Management:

It is necessary to take a relevant history including the risk factors and the vaccination status of the patient. The main point of management is to make a risk assessment and decide of post-exposure prophylaxis (PEP) is needed - you will have a local policy for this and it may well involve your oncall microbiologist. Follow up will be necessary however this is likely to be by occupational health rather than the ED.

• HIV - PEP available to high or unknown risk - many side effects and interatctions to consider
• Hep B - need to know immunisation status - immunoglobulin available
• Hep C - no PEP available