Erysipelas

Part of a spectrum of infection.

1. Impetigo - see http://adultemergencymedicine.blogspot.com/2018/08/rashes-impetigo.html 

2. Erysipelas is a superficial cellulitis, with similar risk factors. It looks a lot worse than cellulitis with ruptured bullae and vivid bright red erythema. Almost all erysipelas is caused by group A beta haemolytic strep. It can recur due to persistence of risk factors and lymphatic drainage. Complications can include abscesses, gangrene, chronic leg swelling

Signs and symptoms are normally abrupt, affecting predominantly the lower limb and face. It has a sharp raised border, and is bright red and swollen. The swelling may lead to dimpling, blistering, and even necrosis.

3. Cellulitis
Cellulitis is very rarely bilateral. 35-50% of patients will have a leukocytosis, 60-92% will have an elevated ESR, and 75-95% will have an elevated CRP.  Blood cultures are unlikely to be helpful.
Orals are very bioavailable so most of the time are just as good as IVs.

Often caused by strep and staph. Atypicals are common: Cat bites can have pasteurella, sea water Vibrio vulnificus, fresh water Aeromonas hydrophila, fish farms Streptococcus iniae. These atypicals can cause a rapidly progressive cellulitis.

Fascitis necrotizante

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Class I: No signs of systemic toxicity or co-morbidities. Can be managed on POs.
Class II: 2 or more SIRS, but no organ dysfunction, or have a co-morbidity. May need IV outpatient management.
Class III: Sepsis and organ dysfunction, or unstable co-morbidities normally require admission.
Class IV: Severe life threatening infection.

4. Necrotising Fascitis

https://www.dermnetnz.org/topics/erysipelas/
https://journalfeed.org/article-a-day/2018/lrinec-score-physical-exam-or-imaging-for-necrotizing-infection
http://www.emdocs.net/cellulitis-mimics-ed-considerations/
https://first10em.com/cellulitis-antibiotics/
https://www.rcemlearning.co.uk/modules/cellulitis-and-other-skin-infections/
https://journalfeed.org/article-a-day/2018/is-a-blood-culture-needed-in-cellulitis
https://www.rcemlearning.co.uk/references/cellulitis/
http://www.tamingthesru.com/blog/2018/9/3/necrotizing-fasciitis-and-the-spectrum-of-soft-tissue-infections

Tetanus

Wound Management 

In any patient with a wound, first do a risk assessment of the wound, and then their tetanus status:

Tetanus Prone Wound:  >6 hours old and needs surgical treatment
                                      Open compound fracture
                                      Contaminated puncture wound
                                      Clinical evidence of sepsis

High risk tetanus prone wound?   Yes - give immunoglobulin
                                    Heavy contamination with material likely to contain tetanus eg. manure
                                    Extensive devitalized tissue
                                    >24 hours since injury
                                    >10% burns

Tetanus Status Assessment 
Full immunisation - give immunoglobulin if very high risk
Partial immunization - give DTP if next dose due soon, if high risk give immunoglobulin
Not up to date  -give DTP.  Immunoglobulin
Uncertain - give DTP

Immunoglobulin
Give 500iu if it's a high risk tetanus wound
Give 250iu if it's a tetanus prone wound
Need a second dose of Ig if they can't have DTP, or if they have reduced capacity for antibody formation - radiotherapy, hypogammaglobulinaemia

Give both injections in different arms
If have a bleeding disorder, give SC. There is a higher risk of reaction when these are given SC rather than IM.

Tetanus
Tetanus is caused by C. tetani, a gram positive, anaerobic that is commonly found in soil and manure. It produces tetanospasmin, the neurotoxin that causes tetanus. Incubation 10 days. The infection is a  clinical diagnosis, defined as trismus with one or more of the following:
Spasticity
Dysphagia
Respiratory distress
Muscle spasms
Autonomic dysfunction

Treatment
Metronidazole - stop bacterial replication
Diazepam or midazolam - to control muscle spasms
Intravenous tetanus immunoglobulin -5,000 units < 50kg, 10,000 >  50kg. This is the same as the "treatment".
Intubation - may be needed. Sux is safe but there is a very high risk of autonomic instability
Wound cleansing and debridement

SAQ:
A forty eight year old patient attends the emergency department feeling unwell. They have an infected injection site in their anticubital fossa. They have severe trismus, and are writhing around with severe muscle spasms. Sister thinks security needs to escort them out. You suspect that they have a serious and rare infection from their injection site.

a) How would you manage the muscle spasms?
Supportive care with diazepam or midazolam.
b) How would you treat their infection?
You suspect tetanus - or you should because of the spasms. The patient needs supportive care, with monitoring and consideration of early intubation. Give metronidazole to prevent bacterial relocation. Give IM tetanus immunoglobulin 150 units/ kg. IV is no longer available. Monitor their renal function.
Wound debridement.
Watch for autonomic instability, and cardiac collapse. Sedation, and morphine to help reduce the amount of free catecholamine can be helpful.
c) How would you confirm infection?
Tetanus is a a clinical diagnosis.
You can look for serum levels, but these take so long for results to come back - don't delay treatment for serological confirmation.
- Tetanus IgG - If the antibody level is >0.1 IU/ml before IgG, this excludes current tetanus infection. - Detection of toxin in serum is a bio-assay and is only performed if the antibody level is below the protective threshold.
- Absence of toxin does not exclude tetanus.
- Detection of C. tetani in wound material or from a pure isolate

References
http://pedemmorsels.com/tetanus-prevention/
http://stemlynsblog.org/tetanus-in-the-ed/
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/441356/IMW166.02_Tetanus_information_for_health_professionals_v1.4__2_.pdf
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/441355/IMW165.02_Tetanus_Immunoglobulin_Handbook_v1.4.pdf
https://www.gov.uk/government/publications/tetanus-the-green-book-chapter-30
https://www.rcemlearning.co.uk/modules/tetanus/
https://www.rcemlearning.co.uk/foamed/september-2017/#1504201252016-ac52229b-9e50

Fascia Iliaca Blocks

Fascia Iliaca blocks are really useful for analgesia for hip fractures. We should be performing them!

Fascia Iliaca or Femoral?
My understanding of this is if we're using a landmark approach, and we use a femoral nerve block the risk of not being in the right soft tissue plane is high. This means that a fascia iliaca block us more likely to be beneficial. The evidence, which I haven't appraised myself, suggests that there's not a significant amount of difference between them all.

Anatomy 

If you look here you can see that the femoral nerve sits, and is enclosed between the fascia lata and the facia iliaca. If you go just lateral to it, you don't know whether you are above or below the fascia iliaca. If you do a fascia iliaca compartment approach, you know you are in the right space.

The podcast from Anatomy for EM is excellent at running through this.

The fascia iliaca compartment contains the three main nerves we are interested in blocking - the femoral nerve, lateral femoral cutaneous and obterator. They provide analgesia for all of the leg except the posterior bit - which the sciatic nerve covers.

Contraindications
· Patient refusal
· Anticoagulation
· Previous femoral bypass surgery
· Inflammation or infection over injection site
· Allergy to local anaesthetics
· Previous femoral bypass surgery

Anaesthetic
We need to use large amounts of local anaesthetic to perform this. 30-40ml should be used for every adult sized patient, and anaesthetic adjusted accordingly.

Our maximum doses are:
Bupivacaine        2mg/kg
Lidocaine            3mg/kg

We normal use 0.25% bupivacaine to provide maximum volume. For a 80kg patient, this would be 160mg which is 60ml of 0.25% bupivacaine. Which is quite a lot. Bupivacaine often works slowly but lasts for a while.

Landmarks 
Place one middle finger on the ASIS and the other middle finger on the pubic tubercle.
Draw a line between these two points.
Divide this line into thirds.
Mark the point 1 - 2 cm caudal from the junction of the lateral and middle third.
This is where you are aiming for.

Ultrasound
Ultrasound for blocks isn't yet common practice. I use it to help avoid accidental intravascular injection - put the probe on where I'm going to inject, and double check.

You can see the two fascial layers on ultrasound, and see the local anaesthetic expand. This video demonstrates the use of ultrasound wonderfully.

Complications
Failure
Infection
Accidental intravascular or intraneural injection
Local anaesthetic toxicity

Links and References
http://www.propofology.com/infographs/fascia-iliaca-block 
http://learned.rocks/cooked-resourced/2016/8/15/nerve-blocks 
http://www.rcemlearning.co.uk/modules/fascia-iliaca-block/ 
https://songsorstories.com/2016/07/31/pop-pop-phew-sounds-to-go-with-blocks/ 
http://www.thegasmanhandbook.co.uk/fascia-iliaca-block.html 
http://stemlynsblog.org/fib-virgil/ 
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