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Hay fever

=allergic rhinoconjunctivitis due to seasonal triggers, typically grass and/or tree pollen. First described by John Bostock in 1819! More likely if born in early months of year!

So itchy, swollen, watery eyes, runny and/or blocked nose, sneezing. Often itchy throat and ears too. Cobble stone appearance can be seen at the back of throat.

Not dangerous, but can seriously affect quality of life: poor sleep, poor concentration (exams usually at worst time of year), embarrassment about snot. One study showed children in England were less likely to get their predicted exam grades if they had hay fever, especially if prescribed sedating antihistamines.

Associated with other atopic conditions, such as food allergy and asthma. Under recognized as trigger for asthma exacerbations – pollen is too large to trigger the lower airways directly, rather pollen exposure in the upper airways trigger inflammation that travels down over a period of weeks to the lower airways. An exception is when pollen grains are fragmented, as seen in thunder storm asthma [Australia, Clin Exp Allergy. 2018;48:1421‐1428]

There are many different species of grass, but if allergic to one you tend to be allergic to all of them. Trees on the other hand vary, you tend to be allergic to specific groups of trees. In Europe the most important are birch (northern Europe) and olive (Southern Europe). Birch is related to alder, hazel, beech and oak.  Olive is related to ash.  Weeds belong to various unrelated families.

Hazel trees can start producing pollen in February, weeds can continue produce pollen through September! Moulds seem more associated with asthma than hay fever. Cypress blooms in winter! 

It’s not just pollen count – the amount of allergen carried by the pollen varies too. Correlate pretty closely but varies by time and place. Pollen potency varies (4-5 fold difference) geographically, especially grass. France has the highest yearly average grass pollen potency, 7-fold higher than Portugal. Olive pollen from two locations 400km apart varied 4-fold in their allergen potency – in Portugal there are times when pollen from Spain probably more of a problem for triggering hay fever than pollen from “local” trees! [Health Impacts of Airborne Allergen Information Network (HIALINE project)]

Management

Watch the pollen count, and choose activities accordingly. Pollen levels fall in evening in countryside, but in cities not until 1am!

Closing windows, or at least not sitting near windows, washing hair, not drying clothes outside, pollen barrier balms.

Choose where you are going on holiday carefully!

Antihistamines – oral or nasal. Various, some people find one works better than another Sedating antihistamines eg Chlorphenamine should be avoided except at night. Nasal steroids useful if used correctly. Combination steroid/antihistamine available. Leukotriene receptor antagonist licensed for hay fever in children with asthma.

Short courses of oral steroids might be justified for special occasions.

Immunotherapy available – deaths reported in asthmatics with poor control.

Sublingual – age not important cf ability to hold in mouth for 2 minutes. Not approved by SMC in Scotland yet. Combined grass and house dust mite coming.

[Sian Ludman, St Mary’s]

For symptoms all year round (perennial), triggers such as house dust mite and pets are more likely.

Tree nut allergy

Group of nuts that includes hazelnut, almond, brazil nut, cashew, pecan, pistachio, walnut and macadamia. Definition of nut is actually a bit complicated, to do with whether the shell comes off spontaneously or not, but I stick to those defined by food labelling law.

Does not include peanut (a legume), coconut, pine nut, chestnut or tiger nut.

You can be allergic to just one, a couple or the whole lot. Risk of allergy to peanut is higher than if you weren’t allergic to anything.

Hazelnut and cashew allergies are common. Almond rare.

Hazelnut allergy goes along with fruit allergy and oral allergy syndrome.

Cashew allergy goes with pistachio allergy. Cashew allergy is particularly associated with anaphylaxis, even more so than peanut (but less common as allergy and allergen so less well known).

Pecan allergy goes with walnut allergy.

Hazelnut allergy

One of the tree nuts. One of the most common food allergens in the UK. Adults seem to get less severe reactions than children. Anaphylaxis rare compared with peanut and other tree nuts.

Hazel tree is related to birch, and indeed hazelnut allergy can be associated with tree pollen allergy (hay fever), as well as fruit allergies.

Cor a 1 is the least likely to cause systemic reactions, and then only with raw cf roast.  Cor a 8/9/14 associated with systemic, although 8 is LTP so may only be local (and likely fruit allergy too) – probably seen more often in Mediterranean populations. The others are storage proteins so more likely to cause severe reactions.

Cor a 9 and 14 seem most useful  – >1kU/l and/or >5 respectively give specificity of >90% and sensitivity of 83% in kids for “allergy with objective symptoms” viz more than just a tingle/itch. That translates to a negative predictive value of about 93% (PPV not given). [Dutch study, JACI 2013;132(2):393]

German study found  Cor a 14 had best AUC (0.89, cf 0.71 for whole hz).  Level of 0.35 gave 85% sensitivity with 81% specificity.  PPV doesn’t hit 90% until 47.8 though…

Chest X-ray

Interpretation

  • Start outside, work in – soft tissues, then bones, then lungs/heart, finally neck/infradiaphragmatic.
  • Safety check – position of lines/tunes, check apices for pneumothorax, any foreign bodies?

Adequacy

  • Rotation – look at symmetry of clavicles and anterior rib ends.
  • If clavicles high, then lordotic film. May obscure apices.
  • Penetration – should just be able to make out intravertebral spaces, without lung fields being too dark.
  • Inspiration – hila become artificially prominent if underinflated.

Thymus

Pesky thing! Can look like pneumonia. Latter more likely if air bronchograms, volume loss (displaced fissure/trachea/mediastinum), effusion. Classically:

  • indentations where ribs overlie.
  • Pointy outside edge (“sail sign”).
  • No mass effect
  • Lowish density – should still be able to see vascular markings of lung behind

Spinnaker sign is where pneumomediastinum around thymus creates long curving line.

Other normal things

Azygos lobe – normal variant where RUL has near vertical line extending up and out, giving impression of mediastinal mass.

Mach effect – a line parallel to heart border, looks like pneumocardium but actually optical illusion where your eye “detects” border where there isn’t one…

One diaphragm usually higher than other – both ok, as long as no more than 2cm (one rib space).

Other

Hilum – rings or tram lines suggest bronchitis. Round opacity adjacent to and larger than ring suggests vascular prominence due to left to right shunt.

Silhouette sign – where heart border and/or diaphragm obscured in lower zone due to consolidation in lower lobe (left or right).

Effusion – vertical line at costophrenic angle.

Round pneumonia – will have air bronchograms, compare mass.

Collapse vs consolidation – sharp lower border is the fissure so if deviated then collapse.

Pneumothorax – lucency without clear edge may suggest lung hyperinflation eg bronchial atresia.

If edge projects below diaphragm then likely to be skin fold!

Foreign body – get expiratory film, which will enhance air trapping.

VATER/VACTERL

VATER and VACTERL

Acronym for:

  • vertebral defects,
  • anal atresia,
  • tracheoesophageal fistula with
  • esophageal atresia [so should be VATOR in UK]
  • and radial dysplasia.

Nearly all cases sporadic, with no recognized teratogen or chromosomal abnormality. More common in infants of diabetic mothers.

VACTERL is the expanded syndrome, acronym for

  • vertebral anomalies, anal atresia,
  • cardiac malformations (Ventricular septal defects, Patent ductus arteriosus, Tetralogy of Fallot, Transposition of the great arteries),
  • tracheoesophageal fistula, esophageal atresia
  • renal anomalies (urethral atresia with hydronephrosis), and
  • limb anomalies (hexadactyly, humeral hypoplasia, radial aplasia, and proximally placed thumb).

Diagnosis made if 3 or more defects are present.

CHARGE sequence

Stands for:

  • coloboma of the eye;
  • heart anomaly (Tetralogy of Fallot, ASD, DORV);
  • atresia choanae (failure of nasal passages to form – causes feeding difficulties);
  • retardation of mental and somatic development;
  • genital abnormalities eg microphallus (also hypogonadism, so delayed pubertal development in both sexes);
  • ear abnormalities and/or deafness.

Note that none of the letters used in the acronym are the same as used in VACTERL.

Facial palsy, cleft palate, and dysphagia are commonly associated.

The term CHARGE should be restricted to infants with multiple malformations and choanal atresia and/or coloboma, combined with other cardinal malformations (heart, ear, and genital), for a total of at least 3 cardinal malformations. Growth retardation is not one of the cardinal features.

Mostly isolated, mutation in CHD7 gene (associated with increasing paternal age).

Cobalamin related metabolic disorders

Amino acid homocysteine is converted to methionine (“remethylated”) – cobalamin is involved in some of these processes, folate metabolism also important.

Various disorders.

Variety of presentations, at different ages:

  • Neurological (central and peripheral)
    • Feeding difficulties, apnoea in babies
    • Seizures
    • Subacute combined degeneration of spinal cord (peripheral neuropathy, ataxia, incontinence)
    • Acute and/or chronic encephalopathy – hypotonia, regression
    • Neuropsychiatric problems
  • vascular problems (stroke/embolism)
  • bone marrow (megaloblastic anaemia, cytopenia) – folate related
  • Atypical HUS
  • Glomerulopathy

Investigations

  • High homocysteine, usually
  • Vitamin B12 and folate, for differential
  • Methylmalonic acid (in urine)
  • Acylcarnitine
  • Methionine (usually goes low)

Treatment

Start intramuscular B12 (hydroxocobalamin) as soon as samples collected, to prevent end organ damage.

Betaine should be started if high homocysteine with low methionine found, helps push conversion to methionine.

Homocystinuria

Autosomal recessive condition of high homocysteine in blood and urine, causing similar neurological problems, thrombosis, Marfanoid appearance, downward subluxing lenses.

Needs low methionine diet. Betaine supplements help.

Clinical teaching techniques

Set expectations – that most learning happens during daily patient care as part of the team.

Modelling – think aloud, to externalize reasoning (in short spells!)

1-2 minutes direct observation.  Feedback perhaps after a number of episodes – one thing done well, one thing that could be done differently?

Send student ahead (“scouting“).

Self- explanation – without any instructions, student finds own explanations for results, obs, management plan etc.

SNAPPS – summarize case, narrow differential, analyse differential, probe [ask questions] where uncertain, plan, select an issue related to case for self directed learning.  1-2 mins only.

Tell me story backwards – Diagnosis, then supporting evidence, then why other diagnoses excluded.  Only then plan.

Contrastive example – ask student to give alternative diagnosis and balance probabilities.

Post it Pearls – record thoughts (not just pearls!) during clinic/ward round, review at end.

Diagnostic challenge – one person/team defends working diagnosis. Other asks about worse case scenario, or alternative diagnosis, investigations done or not done, and checks with patient themselves!

[Operation Colleague, from University of Glasgow; HPE Bytes]

GIRFEC

Getting it right for every child. A framework for dealing with children and young people, looking at a range of values (SHANARRI).

Children and Young People (Scotland) Act 2014 made provision for Named Person and Child’s plan, but after review in 2019, amid privacy concerns (brought by Christian Institute, among others), government decided not to pursue legislation. Supreme court found that “duty to share information”, although well intentioned, was potentially at odds with article 8 of European convention on Human rights (“Privacy and family life”).

[https://www.gov.scot/publications/getting-right-child-practice-development-panel-report/]