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ASTHMA

Asthma is a respiratory condition associated with sudden, reversible narrowing of the airways. It is the one of the most common chronic diseases in the UK.

  • Airway obstruction in asthma is reversible (spontaneously or with treatment)
  • The airways are hyper-responsive to a variety of stimuli
  • The bronchi are inflamed.
Asthma UK. Why do people get asthma? https://www.asthma.org.uk/advice/understanding-asthma/causes/
MRC & Asthma UK Centre in Allergic Mechanisms of Asthma www.asthma-allergy.ac.uk

Symptoms of asthma range from mild to severe, and include:

  • Cough
  • Wheeze
  • Chest tightness
  • Breathlessness, and 
  • Variable airflow obstruction 

Symptoms are typically variable, intermittent, worse at night and in the early morning, and/or provoked by triggers, eg, allergens, cold air, emotional stress, exercise, chest infection.

Diagnosis

There is no single diagnostic test for asthma. Diagnosis is based on clinical assessment supported by objective tests that demonstrate variable airflow obstruction or the presence of airway inflammation. Diagnostic tests are typically performed at a single point of time, whereas asthma status varies over time. Results of tests taken when a patient is asymptomatic should be compared with those taken when a patient is symptomatic to detect variation over time.

Primary Care Respiratory Society. Asthma Guidelines in Practice: a PCRS consensus; 2020 (last modified 2022). https://www.pcrs-uk.org/resource/asthma-guidelines-practice
Global Initiative for Asthma (GINA). GINA Report; 2022. https://ginasthma.org/gina-reports/

Recommendations between the BTS/SIGN guideline and that from NICE differed in some instances. The British Thoracic Society, Scottish Intercollegiate Guidelines Network and NICE are working together to produce UK-wide guidance on asthm diagnosis and monitoring and chronic asthma amangement that will update and replace NG80. Progress was delayed because of the need to respond to the COVID-19 pandemic, and a revised timetable will be published in due course. 

Practice Nurse featured article

Spirometry is the investigation of choice for the identification of airflow obstruction. It should be performed by trained healthcare professionals to obtain reliable recordings and to interpret the results. 

In adults with obstructive spirometry, an improvement in FEV1 of 12% or more in response to either β2 agonists or ICS treatment trials, together with an increase in volume of 200ml or more is regarded as a positive test. BTS/SIGN recommend using lower limits of normal to demonstrate airway obstruction. 

Peak expiratory flow monitoring 

  • A peak flow recorded when symptomatic (e.g. during the assessment of an asthma attack) may be compared with peak flow when asymptomatic (e.g. after recovery from an attack) to confirm variability
  • In adults, serial peak-flow records may demonstrate variability in symptomatic patients but should be interpreted with caution, and in context. There is no evidence to support routine use of peak-flow monitoring in the diagnosis of asthma in children.
  • Serial peak flows (at least four readings a day) are the initial investigation of choice in suspected occupational asthma

PEAK EXPIRATORY FLOW (PEF): PAEDIATRIC NORMAL VALUES

For use with EU/EN13826 scale PEF meters only

Peak expratory flow: normal values in children
Height (m) Predicted EU PEFR (l/min)
0.85 87
0.90 95
0.95 104
1.00 115
1.05 127
1.10 141
1.15 157
1.20 174
1.25 192
1.30 212
1.35 233
1.40 254
1.45 276
1.50 299
1.55 323
1.60 346
1.65 370
1.70 393

 

PEAK EXPIRATORY FLOW (PEF) IN ADULTS: NORMAL VALUES (l/min)
Height Age (years)
Men
  15 20 25 30 35 40 45 50 55 60 65 70 75 80
135 454 508 541 559 566 563 554 540 523 503 481 458 434 410
140 467 522 557 575 582 579 570 556 538 517 494 471 446 422
145 479 536 571 590 597 594 585 570 551 530 507 483 458 433
150 491 549 585 604 611 609 599 584 565 543 519 495 469 443
155 502 561 598 618 625 622 612 597 578 555 531 506 480 453
160 512 573 611 631 638 636 625 610 590 567 542 516 490 463
165 523 585 623 644 651 648 638 622 602 578 553 527 500 472
170 532 596 635 656 663 660 650 633 613 589 564 537 509 481
175 542 606 646 667 675 672 661 645 624 600 574 546 518 490
180 551 616 656 678 686 683 672 655 634 610 583 555 527 498
185 559 626 667 689 697 694 683 666 644 619 592 564 535 506
190 568 635 677 699 707 707 693 676 654 628 601 572 543 513
195 576 644 686 709 717 714 703 685 663 637 610 580 551 520
Women
135 379 402 414 417 415 409 400 389 376 362 347 332 317 302
140 387 410 422 426 424 417 408 396 383 369 354 339 324 308
145 394 418 430 434 432 425 416 404 391 376 361 346 330 314
150 401 426 438 442 440 433 423 411 398 383 368 352 336 320
155 408 433 445 449 447 440 430 418 404 389 374 358 341 335
160 414 440 452 456 454 447 437 425 411 395 379 363 347 330
165 420 446 459 463 461 454 443 431 417 401 385 368 352 335
170 426 452 465 469 467 460 450 437 442 407 390 374 357 340
175 431 458 471 475 473 566 455 442 428 412 395 378 361 344
180 437 464 477 481 479 472 461 448 433 417 400 383 366 348
185 442 469 483 487 484 477 466 453 438 422 405 387 370 352
190 447 474 488 492 490 482 471 458 443 427 409 392 374 358
195 451 479 493 497 495 487 476 463 448 431 414 396 378 360

Normal values for EU scale peak flow meters; derived from modified Nunn and Gregg values/Miller MR. Airways J 2004; 2/ 2: 80-2.

 

Challenge tests 

Referral for challenge tests (direct or indirect) should be considered in adults with no evidence of airflow obstruction on initial assessment, in whom other objective tests are inconclusive but where asthma remains a possibility 

Fractional exhaled nitric oxide (FeNO)

A positive FeNO tests suggests eosinophilic inflammation and provides supportive but not conclusive evidence for an asthma diagnosis.

FeNO levels are:

  • Increased in patients with allergic rhinitis exposed to allergen, even without respiratory symptoms
  • Increased by rhinovirus infection in healthy individuals but this effect is inconsistent in people with asthma
  • Increased in men, tall people, and by consumption of dietary nitrates
  • Lower in children
  • Reduced in cigarette smokers
  • Reduced by inhaled or oral steroids

In steroid-naïve adults, a FeNO of 40 parts per billion (ppb) or more is regarded as positive; in schoolchildren, a FeNO level of 35 ppb or more is regarded as a positive test.

Structured clinical assessment

Undertake a structured clinical assessment to assess the initial probability of asthma, based on:

  • History of recurrent episodes of symptoms, ideally corroborated by variable peak flows when symptomatic and asymptomatic
  • Symptoms of wheeze, cough, breathlessness and chest tightness that vary over time
  • Recorded observation of wheeze by healthcare professional
  • Personal/family history of other atopic conditions
  • No symptoms or signs to suggest alternative diagnoses

Probability of asthma 

High probability 

  • Record the patient as likely to have asthma, code as suspected asthma, and commence carefully monitored initiation of treatment (typically 6 weeks of ICS)
  • Assess baseline status using a validated question (Asthma Control Questionnaire or Asthma Control Test and lung function tests (spirometry or peak expiratory flow)
  • At follow-up, assess symptomatic response and lung function
  • If response is good (clinically important improvement and/or substantial increase in lung function), confirm diagnosis.
  • Adjust treatment according to the response (down-titrate ICS dose) to the lowest dose that maintains the patient free of symptoms.
  • Provide self-management education and a personalised asthma action plan (PAAP)
  • If objective response is poor or equivocal, discuss adherence, recheck inhaler technique and arrange further tests or consider alternative diagnoses. Usually appropriate to withdraw the treatment.

Low probability 

If there is a low probability of asthma and/or an alternative diagnosis is more likely, investigate for the alternative diagnosis. Reconsider asthma if the clinical picture changes or an alternative diagnosis is not confirmed. Undertake or refer for further tests to investigate for a diagnosis of asthma.

Intermediate probability 

Adults and children who have some but not all of the typical features of asthma or who do not respond well to initial treatment have an intermediate probability of asthma and require further assessment and diagnosis before a diagnosis can be made. Be aware that some conditions can overlap or mimic asthma, including COPD, obesity, anxiety/panic or dysfunction breathing. Spirometry, with bronchodilator reversibility if appropriate, is the preferred initial test for investigating intermediate probability of asthma in adults and in children old enough to produce reliable results.

ASTHMA REVIEW 

The core components of an asthma review that should be assessed and recorded at least annually are current symptoms, future risk of attacks, management strategies, supported self management and growth in children. 

Use a validated asthma control questionnaire or asthma control test to assess current symptom control and to predict the risk of future attacks.

Identifying people with poor symptom control and at future risk of asthma attacks enables targeting of care for the individual patient, by:

  • Increasing frequency of review
  • Commencing/increasing preventer medication
  • Personalisation of an asthma plan
  • Avoiding triggers such as smoking
  • Shifting the balance of necessity/concerns for ICS treatment

Observe and assess inhaler technique at every review. 

 

Inhaler technique and choice of device 

  • Prescribe inhalers only after patients have received training in the use of the device and have demonstrated satisfactory technique.
  • In children aged 5-12 and adults, a pMDI + spacer is as effective as any other hand-held inhaler, but some [adult] patients may prefer some types of DPI.
  • The choice of device may be determined by the choice of drug

If the patient is unable to use a device satisfactorily an alternative should be found

  • The patient should have their ability to use the prescribed inhaler device (particularly for any change in device) checked by a competent healthcare professional
  • The medication needs to be titrated against clinical response to ensure optimum efficacy
  • Reassess inhaler technique as part of the structured clinical review
  • Generic prescribing of inhalers should be avoided as this might lead to people with asthma being given an unfamiliar inhaler device which they are not able to use properly

Asthma UK. Animated interactive demos covering all types of inhaler https://www.asthma.org.uk/advice/inhalers-medicines-treatments/using-inhalers/

PHARMACOLOGICAL MANAGEMENT 

Before initiating a new drug therapy, practitioners should check adherence with existing therapies and check inhaler technique.

Patients’ inhaler technique is often poor. Selecting an appropriate inhaler device in discussion with the patient, and regularly checking that they are using it correctly, in addition to checking the level of adherence, are key to achieving good asthma control.

SABA 

All patients with symptomatic asthma should be prescribed a short-acting β2 agonist (SABA). Anyone prescribed more than one SABA inhaler device a month should be identified, have their asthma assessed urgently, and measures take to improve asthma control if this is poor.

ICS

Inhaled corticosteroids (ICS) are the recommended preventer drug for adults and children for achieving overall treatment goals: 

  • No daytime symptoms
  • No night-time awakening due to asthma 
  • No need for rescue medication 
  • No asthma attacks 
  • No limitations on activity, including exercise 
  • Normal lung function (in practical terms, FEV1 and/or PEF >80% predicted or best)
  • Minimal side effects from medication 

ICS should be considered for adults, children aged 5-12 and children under the age of 5 with any of the following features:

  • Using SABA more than three times a week
  • Symptomatic three time a week or more
  • Waking one night a week

In addition, ICS should be considered in adults and children aged 5-12 who have had an asthma attack requiring oral corticosteroids in the last two years.

Start patients at a dose of ICS appropriate to severity of disease, usually low dose for adults and very low dose for children (refer to summary of product characteristics for individual product). Titrate the dose to the lowest at which effective control of asthma is maintained. High dose ICS should only be used after referring the patient to specialist care. 

There are alternative preventer therapies but these are less effective than ICS.

  • Leukotriene receptor antagonists (LTRA) – some beneficial clinical effect. May be used in children under 5 years who are unable to take ICS
  • Sodium cromoglicate and nedocromil sodium – of some benefit in adults and effective in children aged 5-12
  • Theophyllines – some beneficial effect
  • Antihistamines and ketotifen – ineffective 

Initial add-on therapy 

Some patients with asthma may not be adequately controlled with low-dose ICS.

The first choice as add-on therapy to ICS in adults is an inhaled long-acting β2 agonist (LABA), which should be considered before increasing the dose of ICS

In children aged 5 and over, an inhaled LABA or an LTRA can be considered as initial add-on therapy

MART

The use of a single combination inhaler for maintenance and reliever therapy (MART) is an alternative approach to the introduction of a fixed-dose twice-daily combination inhaler. It relies on the rapid onset of reliever effect with formoterol, and by including a dose of ICS ensures that as the need for a reliever increases, the dose of preventer medication is also increased. (A PAAP must be provided with a MART regime).

Combination inhalers are recommended to guarantee that the LABA is not taken without ICS, and to improve inhaler adherence.

If control remains poor on low-dose (adults) or very low-dose (children) ICS plus LABA:

  • Re-check diagnosis
  • Assess adherence to existing medication
  • Check inhaler technique.

If more intense treatment is appropriate, consider:

  • Increasing dose of ICS to medium (adults) or low (children 5-12 years). If no improvement when LABA is added consider stopping LABA before increasing dose of ICS
  • Consider adding an LTRA
  • The addition of a long-acting muscarinic antagonist (LAMA) to ICS plus LABA may confer some additional benefit although results of clinical trials are currently inconclusive.
  • Theophyllines may improve lung function and symptoms but are associated with an increase in adverse events.
  • All patients whose asthma is not adequately controlled on recommended initial controller therapies should be referred for specialist care

Once asthma is controlled, decreasing treatment is recommended. Regular review as treatment is decreased is important. 

Practice Nurse featured articles 

Remote control: the respiratory annual review in lockdown and beyond Beverley Bostock

Inhaler devices, technique and errors: an overview 

Moving on up - combination inhalers and beyond Beverley Bostock

What should we be doing for our patients with difficult or severe asthma Charlotte Renwick, Katie Stokes, Samantha Walker

Annual reviews in long term conditions Katherine Ellerby

Choosing and using inhalers: what's the formula? Beverley Bostock-Cox 

Childhood asthma - a challenge for the future Viv Marsh & Steve Holmes 

Inhaled therapy: all in the technique. Rachel Booker 

Asthma in children: diagnostic and management dilemmas Rachel Booker 

Ten second test in the diagnosis and management of asthma Carol Stonham 

Practice Nurse Curriculum Modules 

Diagnostic criteria in Asthma & COPD

Respiratory disease: Signs and Symptoms

Respiratory disease: Guidelines and Management

Respiratory disease: Management of acute exacerbations  

 

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