• Complete asthma pathway

Symptoms and signs

• Cannot complete sentences in one breath
• Respiration ≥25 breaths/min
• Pulse ≥110 beats/min
• Use of accessory muscles
• Peak expiratory flow (PEF) <50% of predicted or best (if known)

Life-threatening features

• PEF <33% of predicted or best (if known)
• SpO₂ <92%
• Silent chest, cyanosis, or feeble respiratory effort
• Bradycardia or hypotension
• Exhaustion, confusion or coma
• Patients with severe/life-threatening attacks:
• may not be distressed and
• may not have all these abnormalities

Investigations

Only investigations needed before immediate treatment are:

• PEF
• Oximetry
• If SpO₂ <92% or patient has any life-threatening features or not responding to treatment, measure arterial blood gases (ABG)

ABG markers of a life-threatening attack

• Normal or high PaCO₂ (>4.6 kPa)
• Severe hypoxia: PaO₂ <8 kPa irrespective of treatment with oxygen
• Low pH (or high H⁺)

• Oxygen: follow Hypoxaemia guideline
• CO₂ retention not usually aggravated by oxygen therapy in asthma
• Salbutamol 5 mg or terbutaline 10 mg plus ipratropium 500 microgram via oxygen-driven nebuliser 6-8 L/min oxygen
• Either prednisolone tablets 40 mg
• if taking maintenance prednisolone, increase daily dose by 40 mg; maximum 60 mg
• Or hydrocortisone (preferably as sodium succinate) 100 mg slow IV bolus
• Or both if very ill
• No sedatives of any kind
• If symptoms and signs suggest a bacterial infection, prescribe antimicrobials
• Chest physiotherapy not indicated
• Assess and treat hypovolaemia and electrolyte imbalance - see Adult fluid management guideline and Electrolyte disturbances guidelines:
  • Hypokalaemia, Hyperkalaemia, Hyponatremia or Hypernatremia

Further investigations

• Chest X-ray
• U&E (use green top bottle for accurate K⁺ concentration)
• FBC
• If patient taking theophylline/aminophylline, serum theophylline

Patients with life-threatening features

• Ask medical SpR, staff physician or consultant physician, ideally respiratory, to review urgently
• stay with patient
• Give magnesium sulphate 2g made up to 50 mL with sodium chloride 0.9% by IV infusion over 20 min if not already given earlier (e.g. in ambulance)
  • ensure cardiac monitoring and oximetry in situ as risk of hypotension
  • never give second dose of magnesium sulphate without discussion with consultant respiratory physician
• Speak to critical care unit (CCU) and transfer patient urgently if continues to deteriorate with:
  • falling PEF, worsening or persisting hypoxia, or hypercapnia
  • exhaustion, feeble respirations, confusion, or drowsiness
  • coma or respiratory arrest
• En-route to CCU, ensure patient is accompanied by a doctor (usually an anaesthetist) prepared to intubate if patient’s clinical condition requires it

• Admit to a respiratory ward or acute medical unit
• Lower threshold for admission in patients with:
• history of non-adherence
• lives alone, mental health issues, learning difficulties
• previous near fatal attack/difficult asthma
• presenting at night
• pregnancy
• Correct disturbances in fluid and electrolyte balance, especially potassium (K⁺)
• always use commercially produced pre-mixed bags of infusion fluid

If patient improving

• Continue oxygen. See Hypoxaemia guideline
• Prednisolone daily at dose in Immediate treatment section
• if unable to tolerate oral medication, hydrocortisone 100 mg 6-hrly as slow IV bolus over 1 min
• Nebulised salbutamol 2.5 mg plus ipratropium 250 microgram 6-hrly
• Continue regular inhaled/oral preventer medication
• Refer to asthma team
• Change to discharge medication 24 hr before discharge

If patient not improving after 15-30 min

• Continue oxygen to maintain SpO₂ >94%
• Give nebulised salbutamol 5 mg more frequently, up to every 15-30 min
• Give ipratropium 500 microgram 4-hrly until patient improving
• Once patient improving, reduce nebulised salbutamol to 2.5 mg and ipratropium to 250 microgram 6-hrly

If patient still not improving after 60 mins

• Ask medical senior physician, ideally respiratory, to review urgently
• Give magnesium sulphate 2g made up to 50 mL with sodium chloride 0.9% by IV infusion over 20 min if not already given earlier (e.g. in ambulance)
  • ensure cardiac monitoring and oximetry in situ as risk of hypotension
  • never give second dose of magnesium sulphate without discussion with consultant respiratory physician
• Senior clinician to consider use of aminophylline or salbutamol by infusion - see Aminophylline guideline and Salbutamol guideline for doses
  • if patient already taking oral theophylline DO NOT give loading dose IV aminophylline
  • cross oral theophylline off prescription chart
• If any life-threatening features present (see above), transfer to CCU
  • refer to respiratory physician
• En-route to CCU, ensure patient accompanied by a doctor (usually an anaesthetist) prepared to intubate

• Repeat measurement of PEF 15-30 min after starting treatment then according to response
• Oximetry: maintain SpO₂ 94-98%
• Record heart rate and respiratory rate
• Repeat blood gas measurements within 2 hr of starting treatment if:
• initial PaO₂ <8 kPa (60 mmHg), unless subsequent SpO₂ >92%, or
• initial PaCO₂ normal or raised, or
• patient deteriorates
• In patients requiring frequent doses of salbutamol nebuliser, repeat serum potassium within 2 hr of starting treatment and repeat 2-hrly
• potentially serious hypokalaemia especially likely to occur in patients taking corticosteroids, theophylline and diuretics, and who are hypoxic
• For monitoring of aminophylline infusion see Aminophylline guideline
• Chart PEF before and 15-20 min after giving nebulised or inhaled salbutamol
• at least four times daily until stable;
• then change to morning and evening before salbutamol dose

• Carefully assess reasons for asthma attack to provide a personal asthma plan to prevent relapse, optimise treatment, and prevent delay in seeking assistance in future
• Check inhaler technique

Requirements for discharge

• Stable taking discharge medication for 24 hr and have had inhaler technique checked and recorded
• PEF >75% of predicted or best and PEF diurnal variability <25% unless discharge agreed with respiratory physician
• Treatment with oral corticosteroids for ≥7 days or until improved
• if patient on maintenance steroid treatment, discuss tapering course of steroids with asthma team
• if not on maintenance dose and course less then 3 weeks long, can stop without tapering
• Inhaled corticosteroids in addition to bronchodilators
• Own PEF meter (prescribable) - advise patient to record PEF morning and evening before inhalers
• A written personal asthma action plan
• Had reason for exacerbation discussed
• Details of admission, discharge and potential best PEF sent to GP on discharge documentation

Follow-up

• GP follow-up within 2 days
• Make outpatient clinic follow-up with asthma team
• Complete discharge checklist at the back of the care pathway