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Hey Reader,

Welcome to another edition of Bursting The Bubbles, DTFB's newsletter with some top tips, evidence highlights, and the best dad jokes.

This week we look at lactate, urticaria, and your favourite type of noodle.

Let's do it...

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WEEKLY BUBBLE WRAP: IS LACTATE A HELPFUL SCREENING TOOL?

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What’s it about?

This retrospective observational cohort study looked at whether lactate can be used to predict the need for acute resuscitation in paediatric emergency department (PED) patients.

The study included all patients (aged 0-17 years) admitted to Copenhagen University Hospital’s PED between 1st Jan 2019 and 1 Jan 2021. Patients were included if they had lactate measured as part of their acute PED evaluation.

Lactate levels were reported separately in several sets of patients:

1) Those with need of acute resuscitation (fluid bolus of 20 mL/kg or more, respiratory support with oxygen saturation less than 90%, and/or cases referred to PICU)

2) Those without the need for acute resuscitation

3) Those with samples taken after inhalation of salbutamol

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A total of 1355 children were included. 14 children (1%) needed acute resuscitation, 1314 children didn’t need acute resuscitation, and 27 children had lactate measurements after inhaled beta-2-agonists.

There was no difference in lactate levels in children who received acute resuscitation compared with those who did not receive acute resuscitation (median lactate 1.7 mmol/L vs 1.6 mmol/L; P > 0.05). Acute resuscitation was not more frequently required in children with lactate greater than 4 mmol/L compared to children with lactate of less than 4 mmol/L (1 of 28 [3.6%] vs 13 of 1341 [1.0%]; P > 0.05).

In children who did not need acute resuscitation, the 95th percentile of lactate was 3.2 mmol/L, and 392 (28.9%) had a lactate greater than 2.0 mmol/L.

Older age and venous sampling were associated with lower lactate. Lactate was not associated with sex, PEWS, or duration of hospital admission.

The 95th percentile for lactate after inhaled beta-2-agonist was 5.0 mmol/L with a median of 2.6 mmol/L. They had significantly higher lactates than the cohort of children with acute illness without the need for acute resuscitation (P < 0.001).

For more about lactate see the post on DFTB.

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Why does it matter?

The early recognition of critical illness is essential in reducing morbidity and mortality, but these children frequently present with initially subtle signs and symptoms. Multiple tools, including Paediatric Early Warning Scores (PEWS), have been introduced in an attempt to improve on the ability to identify unwell children and at risk of deterioration. Within some paediatric emergency departments, serum lactate is now being used as a screening tool for critical illness. It is therefore essential for us to know how accurate and reliable a measure this is.

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Clinically relevant bottom line:

This study does not support the routine use of lactate as a screening tool.

In addition, the reported 95th percentile lactate of 3.2mmol/L in children not in need of acute resuscitation is considerably higher than the generally recognised acceptable cut-off level of 2.0mmol/L. This is, in itself, important and should help prevent excess concern in patients who are otherwise clinically stable.

Based on this study, we should be very cautious in using lactate as a screening tool for the early recognition of critical illness in PED.

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Reviewed by: Lizzie Binham. Read the full Bubble Wrap here.

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TOPIC OF THE WEEK: URTICARIA

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What are important questions to ask in the history?

Ask about the progress of the illness and then ask specifically about the symptoms of generalised allergic reaction or anaphylaxis symptoms. If there are any signs of anaphylaxis, the patient needs adrenaline.

Ask about the progress of the rash – when lesions appeared and their duration and recurrence, distribution, size, and shape.

Clarify events in the hours prior to urticaria (ingestion, exercise, temperature extremes, or insect bites)

Check for a history of urticaria with infections or after previous medication/drugs, and any history of allergy

Ask about recent illness/new medication/travel history

Do a systems review and screen for signs of systemic disorder – fever, weight loss, arthralgias, arthritis, or bone pain.

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What are the key examination findings?

Look for symptoms suggestive of anaphylaxis or the presence of wheals.

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How would you describe the lesions?

This is urticaria or hives. It has a polymorphic appearance – the lesions are well-circumscribed and may vary from small flat papules to raised, erythematous plaques, often with central pallor

It may be round, oval, or serpiginous (snake-like) and can vary in size, from less than 1 cm to several centimetres in diameter.

The lesions are intensely pruritic and you may see excoriation. This itchiness may disturb sleep and the symptoms often seem most severe at night.

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What is the classic pattern of lesions in urticaria?

Urticaria is transient, and lesions usually appear and get larger over the course of minutes to hours and then disappear within 30 minutes to 24 hours. Lesions may coalesce as they enlarge. If the patient or parents are unsure of the duration of the lesions, mark a lesion with a pen to see how long it takes to resolve. Despite being incredibly itchy, they are usually not painful and they resolve without leaving a mark (unless there are scratch marks).

If the lesions are long-lasting, painful, or leave residual bruising, the diagnosis of urticarial vasculitis should be considered. This is much rarer than urticaria.

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You’re not sure it is urticaria? What is the differential diagnosis of urticaria?

The presence or absence of pruritus is a helpful clinical feature.

Non-pruritic differentials include viral exanthems; auriculotemporal syndrome; Sweet syndrome.

Pruritic differentials include atopic dermatitis; contact dermatitis; drug eruptions; insect bites; erythema multiforme minor.

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What are the most common causes of acute urticaria in paediatrics?

• Idiopathic (often the majority)
• Infections (mainly viral upper respiratory tract infections). Acute urticaria may develop during or following a viral or bacterial infection,
• Food and drugs (allergic and pseudoallergic). Acute urticaria is one of the main manifestations of IgE-mediated food allergy, but food allergens are responsible for less than 7% of all cases of urticaria. IgE-mediated reactions usually present with urticaria within minutes to two hours following exposure to the allergen. Beta-lactams (penicillins and cephalosporins) are the most commonly reported antibiotics, although antibiotics from virtually all classes have been reported. Consider an allergic cause if episodes occur under similar circumstances e.g. following ingestion or exercise. Food-dependent exercise-induced anaphylaxis is an IgE-mediated hypersensitivity to food and anaphylaxis which only occurs when both the food is ingested and exercise takes place. (i.e. intake of these foods is tolerated in the absence of exercise which distinguishes it from food allergy). Implicated food products are wheat (most common), cereals, shellfish, nuts, vegetables, fresh fruit, eggs, and milk.
• Stings (e.g. bees, wasps). N.B. Bedbugs, fleas, and mites can cause papular urticaria which resolves over weeks.

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What are some other causes of urticaria?

Direct mast cell activation. Drugs, foods, and plants can cause urticaria due to mast cell degranulation through a non-IgE-mediated mechanism. Drug examples include opioids such as morphine and codeine, muscle relaxants, vancomycin, radiocontrast media, dextromethorphan (a cough suppressant), and anaesthetic muscle relaxants. Some foods such as tomatoes and strawberries cause generalised urticaria or contact urticaria through non-immunologic mechanisms. These foods are sometimes referred to as “pseudoallergens.” Note, IgE-mediated allergies to these foods are also possible.

NSAIDs. There are unusual in that they can cause urticaria via two mechanisms

• Pseudoallergy due to abnormalities in arachidonic acid metabolism. This is not a true allergy but a pseudoallergic reaction because the mechanism is nonimmunologic. This can be seen with any COX-1 enzyme inhibitor (e.g. ibuprofen or aspirin).
• Allergic – a specific NSAID can also cause acute urticaria in patients who are allergic to that one agent. These reactions are presumed to represent true, immunologic allergy.

Other types of physical/inducible urticaria include:

Dermographic urticaria (whereby rubbing or scratching induces wheals), cold exposure, sudden changes in body temperature, delayed pressure or vibration against the skin, exercise (with elevation of body temperature, which does not occur in hot bath), exposure to sunlight (solar urticaria), or other stimuli (cholinergic urticaria), and aquagenic urticaria (rare).

Urticaria can also occur as a part of a disease process or autoimmune disease process, such as: serum sickness; urticarial vasculitis; mastocytosis; systemic lupus erythematosus; rheumatoid arthritis; Sjögren syndrome; Coeliac disease; other autoimmune disease; or immunoglobulin A (IgA) vasculitis (Henoch-Schönlein purpura)

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What is the management of acute urticaria?

Initial treatment of new ­onset urticaria (with or without angioedema) should focus on the short ­term symptomatic relief with a non-sedating second or third-generation H1-antihistamine during the day and consideration of a sedating H1-antihistamine at night.

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If urticaria is severe, an H2 antihistamine can be added.

If prominent angioedema or persistent symptoms despite the above, a brief course of oral glucocorticoids can be considered in addition to the above therapy. They are not routinely prescribed.

If symptoms do not recur over several days after stopping glucocorticoids, then antihistamines can be discontinued also. For patients whose symptoms recur when medications are discontinued, antihistamines should be reinstituted and used at the lowest effective dose.

Steroid creams do not work.

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Check out Clementine David's full post here.

HIGHLIGHT: THE BUCKLED TRIAL

Should we use ultrasound to diagnose distal forearm fractures in children and adolescents?

Distal forearm fractures are common in children and adolescents, but the best method for diagnosing them is still debatable. X-ray (radiography) is the standard imaging technique used in emergency departments. However, ultrasound is gaining popularity due to its portability, affordability, and lack of ionising radiation. To determine the effectiveness of ultrasound, a recent study compared its diagnostic capabilities to radiography for distal forearm fractures in children and adolescents, with the primary outcome of functional recovery of the arm.

Snelling PJ, Jones P, Bade D, Bindra R, Byrnes J, Davison M, George S, Moore M, Keijzers G, Ware RS; BUCKLED Trial Group. Ultrasonography or Radiography for Suspected Pediatric Distal Forearm Fractures. N Engl J Med. 2023 Jun 1;388(22):2049-2057. doi: 10.1056/NEJMoa2213883. PMID: 37256975.

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How did we perform the BUCKLED study?

The BUCKLED RCT was an open-label, multicentre, non-inferiority, randomized trial conducted across four hospitals in Australia. The trial enrolled 270 participants, aged 5 to 15 years, who presented to the emergency department with an isolated distal forearm injury. Participants were randomly assigned to receive either ultrasound or x-ray as the initial diagnostic imaging method.

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​Ultrasound was performed by a trained clinician – an emergency physician, nurse practitioner, or physiotherapist. If the participant had a buckle fracture or no fracture, they could be discharged immediately. If they had a cortical break, they went on to have x-ray imaging and routine follow-up in the fracture clinic. The primary outcome was the physical function of the affected arm at four weeks using the Pediatric Upper Extremity Short Patient-Reported Outcomes Measurement Information System (PROMIS) score, with higher scores indicating better function.

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What were the results of the study?

The study found that ultrasound was non-inferior to radiography in terms of the physical function of the arm at four weeks. The mean PROMIS scores at four weeks in the ultrasonography group were similar to those in the radiography group, with a mean difference of only 0.1 points. The confidence interval was within the noninferiority margin of -5 points, indicating that ultrasound was as effective as x-ray for diagnosing forearm fractures.

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Additional findings

No clinically important fractures were missed using ultrasound or x-ray. The emergency department length of stay was reduced by an average of 15 minutes per participant in the ultrasound group. There was also a 2/3 reduction in the number of X-rays required if ultrasound was used first.

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The bottom line

Ultrasound is a reliable alternative to X-ray for diagnosing distal forearm fractures in children and adolescents.
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Ultrasound can be used safely and effectively within the current emergency department system.
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Further research is needed to explore its usefulness in settings with limited access to X-rays.

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To read more about this see Peter Snelling and Ben Lawton's full post here.

EVENT OF THE WEEK

This week saw World Prematurity Day.

Looking after premature babies is one of the most challenging parts of paediatrics.

Check out this DFTB post for a reminder of one of its complications.

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TIP OF THE WEEK

Download and practice using the Mersey Burns or NSW trauma app for sizing and fluid calculations now to ensure it is familiar in an emergency.

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Check out our DFTB Burns Module.

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JOKE OF THE WEEK

What do you call a fake noodle?

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An impasta!

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That's it for this week, Reader.

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Remember, your work makes a difference in the lives of paediatric patients every day.

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Stay tuned for next week's edition of Bursting The Bubble.

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From Tessa (on behalf of Team DFTB)

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