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CDHB

Asthma

Asthma is a clinical syndrome characterized by variable airflow obstruction secondary to inflammation of the airways. An acute asthmatic episode is usually the result of exposure to a trigger agent which may be either specific (pollen, animal dander, viral infection) or non specific. Typical symptoms include dyspnoea, wheeze, chest tightness and cough. They vary from being almost undetectable to severe, unremitting and sometimes life threatening.

The aims of hospital management are:

• To prevent death.
• To restore the patient's clinical condition and lung function.
• To maintain optimum lung function and prevent early relapse.

The assessment of the severity of an acute attack of asthma and the immediate treatment occur in parallel.

The severity of asthmatic episodes is frequently underestimated by both the patient and doctor. It is therefore essential to measure severity objectively so that rational decisions regarding investigation and immediate treatment can be made.

All patients should have the following measured:

• PEFR/spirometry.
• Respiratory rate.
• Pulse, blood pressure, temperature.
• Pulse oximetry. ABG in moderate or severe asthma.

At Christchurch Hospital the Asthma Admission Form should be used for ALL admissions.

Guidelines for Assessing the Severity of Acute Asthma

Individual features should not be interpreted in isolation. An overall assessment of severity should be made using clinical judgement and the following guidelines:

Severity Assessment in Acute Asthma

DANGER SIGNS: Exhaustion, confusion, cyanosis, bradycardia, unconsciousness, silent chest on auscultation, signs of respiratory muscle fatigue (indrawing of lower costal margin, paradoxical breathing). See Life-Threatening Asthma.

Management of Asthma

Specific treatment is dependent on severity. All patients should be treated with a bronchodilator in the first instance. Other therapy is added depending on the response and reassessment of severity. Nebulizer treatment should be changed to an inhaler with spacer as soon as practicable.

Immediate Management of Asthma

Subsequent Management of Acute Asthma Episode

Depends on the severity of the attack and the patient's response to initial treatment.

• General Measures
  • Observation: Close observation should continue in patients with severe asthma until there is objective evidence of sustained improvement.
  • Positioning: Recommend sitting upright and/or leaning forward.
  • Continue Treatment
    • Oxygen - according to arterial blood gases/oximetry.
    • Beta₂ agonist - if condition improving continue to give 4 hourly.
  • Monitoring: Repeat PEFR (or FEV₁) 15-30 minutes after starting treatment then as required depending on severity. Arterial blood gases should be repeated within two hours of starting treatment in the following circumstances:
    • The initial PaO₂ <60 mm Hg.
    • The initial PaCO₂ high normal or raised.
    • The patient's condition deteriorates.

  Measure and record heart rate and respiratory rate, at least QID.

• Investigations in hospital

  All patients admitted to hospital should have:

  • CBC + diff.
  • Na, K, glucose, creatinine.
  • ECG - in patients over 40 years of age.
• Indications for CXR
  • Severe or life-threatening asthma attack - during resuscitation.
  • Moderate to severe attack not responding to initial treatment.
  • Patient suspected of having developed a complication or in whom another condition/diagnosis is suspected (see below).
• Failure to Improve
  • Worsening asthma - check the adequacy of treatment e.g., check drugs given, dosage and adequacy of drug delivery.

    Therapeutic options:

    • Increase the dose/frequency of beta₂ agonist.
    • Add ipratropium bromide 0.5 mg q6h via a nebulizer.
    • Consider using an intravenous bronchodilator.
  • Consider the possibility of a complication or an alternative diagnosis:
    • Pneumonia.
    • Pneumothorax.
    • Cardiac arrhythmia.
    • Left ventricular failure.
    • Laryngeal or tracheal obstruction.
    • Acute Respiratory Distress Syndrome (ARDS).
    • Pulmonary embolism.
    • Post transfusion acute lung injury.

All patients who fail to improve or deteriorate despite initial treatment, must be monitored closely and discussed with the appropriate Consultant or the Respiratory Physician on call.

• Unhelpful Treatments
  • Sedatives are usually contraindicated.
  • Antibiotics are not indicated unless there is evidence of bacterial infection (fever, purulent sputum, CXR opacity).
  • Percussive physiotherapy.
• Indications for Intensive Care

  Patients with the following features usually require observation and management in ICU:

  • Hypoxaemia: PaO₂ <60 mm Hg despite receiving high flow oxygen.
  • Hypercapnia: PaCO₂ >50 mm Hg or rising and acidosis.
  • Increasing fatigue.
  • Confusion, drowsiness, impaired level of consciousness.
  • Respiratory arrest.

Management During Recovery and Following Discharge

Once the acute episode has been brought under control, attention must be directed towards:

• Interval asthma control.
• Severity assessment - what is the risk of severe asthma recurring?
• Self-management skills.
• Smoking status.

Interval Asthma Control

• Interval asthma control should be assessed by specific questioning directed at the following features:
  • Nocturnal waking and morning chest tightness.
  • Interference with exercise.
  • Use of rescue bronchodilator.
  • Peak flow values.
  • Days off work or school.
  • Use of corticosteroids and nebulizer for exacerbations.
  • Compliance with preventer therapy.

Note: These features are itemized on the Asthma Admission Form used at Christchurch Hospital. Copies are available from the Department of General Medicine or Respiratory Ward 25.

Note: Patients with unstable features or poor compliance should be referred to a Respiratory Physician, preferably while in hospital.

Severity Assessment

• The risk of a severe or fatal asthma attack is higher when any of the following features are present:
  • Hospital admission for asthma in the last 12 months.
  • Previous severe asthma requiring ventilation or ICU admission.
  • Frequent attendances to the emergency department.
  • Nocturnal symptoms.
  • Precipitous asthma episodes in the past - severe episodes coming on over less than 3 hours.
  • Frequent requirement for courses of oral steroids.
  • Poor self-management skills.
  • Poor social circumstances.
  • Psychological impairment.

Asthma Self-Management Skills

• The circumstances surrounding admission to hospital should be reviewed carefully:
  • Was there an avoidable precipitant?
  • How did the patient react to worsening asthma?
  • Does the patient have a written Asthma Self-management Plan? Did they follow the instructions contained in the plan?
  • Was there any delay in seeking help?
• The key to asthma control is education and good self-management skills. Admission to hospital does not necessarily mean a failure of self-management but may provide an important learning opportunity.

  All patients should have the following while recovering from an acute attack:

  • Assessment of education needs - refer if appropriate to Clinical Nurse Specialist (Respiratory Outpatient Unit) or respiratory physiotherapist.
  • Check inhaler technique and instruction on the use and interpretation of readings from a peak flow meter. Consider single inhaler therapy.
  • Introduction to the Asthma Self-Management Plan and basic self-management skills.
  • An arrangement for ongoing follow-up and education as an outpatient.

Smoking Status

• Give nicotine replacement and smoking cessation advice and support if required. Current smoking is associated with reduced effectiveness of inhaled corticosteroids. See Nicotine Dependent Patients.

Options for Ongoing Education as an Outpatient

• Respiratory Physician.
• Clinical Nurse Specialist - Respiratory Outpatient Unit.
• General Practitioner/Practice Nurse.
• Respiratory Educators/Health Promoters - Asthma Canterbury, 275 Cashel Street, PO Box 13 091, Christchurch. Email office@asthmacanty.org.nz. (03) 366 5235, fax (03) 366 5209.

Treatment on Discharge

• This will obviously vary from case to case but usually the patient will receive:
  • Inhaled corticosteroid - beclometasone or budesonide 800-2000 microgram daily or fluticasone 500-1000 microgram daily. This high dose must be reviewed on follow-up.
  • Prednisone 40 mg mane for 1 week then 20 mg mane for 1 week (longer courses may be required for chronic severe asthma).
  • A long acting beta₂ agonist (e.g., salmeterol) may be appropriate in some patients, but is best started once they have recovered from an acute attack. It should be considered in patients with frequent daytime and nocturnal symptoms. Long-acting beta₂ agonists should be added only in patients who are already taking inhaled steroids.
  • Short acting beta₂ agonist inhaler to use as required (NOT regularly).
  • Advice regarding common side effects of these medications:
    • Short acting beta₂ agonists: palpitations, anxiety, cramps.
    • Inhaled steroids: dysphonia, thrush - use mouth rinsing and a spacer.
    • Prednisone (short courses): euphoria or dysphoria, hypertension, hyperglycaemia, indigestion, insomnia.

Note: Patients prescribed inhaled aerosolized corticosteroids should be encouraged to use a large volume spacer device.

Single Inhaler Therapy for Asthma

'Single inhaler therapy' (otherwise known as single maintenance and reliever therapy or SMART™) is the use of a combination inhaled steroid / beta₂ agonist preparation as a preventer and a reliever. The only products able to be used in this way in New Zealand currently are those containing formoterol and budesonide (Symbicort™ and Vannair™). Seretide™ (salmeterol / fluticasone) should not be used in single inhaler therapy, because of the slower onset of action of salmeterol. For more information about the use of single inhaler therapy, see http://ndhadeliver.natlib.govt.nz/delivery/DeliveryManagerServlet?dps_pid=IE768736&dps_custom_att_1=ilsdb .

There is no evidence available to guide the decision when to restart single inhaler therapy following an exacerbation. Pragmatically it seems sensible to restart single inhaler therapy close to discharge, but to remind the patient to seek early medical advice if they are using more than 8 puffs of their combination product daily, or if symptoms are not improving.

Exhaled Nitric Oxide

Exhaled nitric oxide is a new breath test for detection of eosinophilic airway inflammation, usually in the context of asthma. High levels predict increased likelihood of response to inhaled steroids. Exhaled nitric oxide is useful for diagnosis of asthma, and for titrating steroid treatment. There may be a role for assessment of compliance with inhaled steroid treatment. Exhaled nitric oxide assessment can be ordered via the Respiratory Physiology Laboratory. For help interpreting the result, please contact the Acute Respiratory Physician on call.

Topic Code: 1643