Introduction
Acute severe asthma or status asthmaticus is a severe asthma that is unresponsive to repeated courses of standard medication.
It is a medical emergency that requires immediate recognition and treatment.
Clinical Features
Patients with acute severe asthma typically have:
- The inability to complete a sentence in one breath
- A respiratory rate of 225 breaths per minute.
- Tachycardia ≥ 110 beats per minute (pulsus paradoxus not particularly useful as it is only present in 45% of cases)
- Peak expiratory flow rate (PEFR) of less than 50% of predicted normal or best
Features of life-threatening attack are:
- A silent chest cyanosis or feeble respiratory effort
- Exhaustion, confusion or coma
- Bradycardia or hypotension
- PEFR < 30% of predicted normal or best (approximately 150L/min in adults)
- Arterial blood gases: -Normal or high PaCO2 > 6kPa (45mmHg)
- Severe hypoxaemia PaO₂ < 8 kPa (60mmHg) despite oxygen therapy
- A low and falling arterial PH
- e.g. <7.35
- SPO₂ <92%
Differential Diagnosis
- Acute infective exacerbation of COPD
- Acute pulmonary oedema
- Tension pneumothorax
- Pulmonary embolism
- Anaphylaxis
Complications
- Respiratory failure (type 1)
- Pneumothorax or pneumomediastinum
- Cardiac arrest
- Hypoxaemia with hypoxic ischaemic CNS injury
- Toxicity from medications
Investigations
- Pulmonary function tests
- Arterial blood gases
- CXR
- Sputum culture if yellowish, offensive or copious.
- Blood culture if pyrexial
- FBC and ESR
- EUCr
Management
A medical emergency thus intervention is started immediately along with history taking and physical examination.
- Quickly assess severity of attack.
- Alert ICU if life-threatening
- Sit patient up and give high dose Oxygen 40-60% via a non rebreathing bag
- Nebulised salbutamol 5mg is given.
- This can be repeated 4 hourly for 4 doses
- IV Hydrocortisone sodium succinate 200mg 4 hourly for 24 hours.
- Prednisolone is continued at 40-60mg orally daily for 2 weeks.
- Nebulised ipratropium bromide 0.5mg may be added.
If life-threatening features are present:
- Inform ICU and senior colleagues.
- Add MgSO, 1.2-2g IV over 20mins
- Give salbutamol nebulizer every 15mins or 10mg continuously per hour.
- Monitor ECG; watch for arrhythmias.
Further management
- If patient is improving: 40-60% oxygen
- Tab Prednisolone 40-50mg per day for at least 5days.
- Nebulised salbutamol 4 hourly
- Monitor peak flow and oxygen saturations
If patient is not improving after 15-30mins:
- Continue 100% oxygen and steroids
- IV Hydrocortisone 100mg or Tab prednisolone 30mg if not already given..
- Give salbutamol nebulizer every 15mins or 10mg continuously per hour.
- Continue ipratropium 0.5mg every 4 – 6hrs
If patient still not improving:
- Discuss with ICU and seniors
- Continue 100% oxygen
- Repeat nebulised salbutamol every 15mins or give IV infusion 3-20ug/min –
- consider Aminophylline: load with 5mg/kg IVI over 20mins, then 500ug/kg/hr.
If still no improvement or life-threatening features are present;
- consider transfer to ICU.
- Do arterial blood gases and if PaCO, >7kPa, ventilation may be required.
Monitoring Treatment
- Repeat peak expiratory flow (PEF) 15-30mins after initiating treatment
- Pulse oximeter monitoring: maintain SAPO,>92%
- Check Arterial blood gas (ABG) within 2hrs if: initial PaCO, was normal or raised or initial PaO, <8kPa (60mmHg) or patient is deteriorating.
- Record PEF pre- and post-ß-agonist in hospital at least 4 times.
Once patient is improving,
- Wean down and stop Aminophylline over 12-24hours.
- Reduce nebulised salbutamol and switch to inhaled ß-agonist
- Initiate inhaled steroids and stop oral steroids if possible.
- Continue to monitor PEF.
- Look for deterioration on reduced treatment and beware of early morning dips in PEF
- Look for the cause of the acute
exacerbation and admission and take care of it.
Discharge
Patients before discharge, must have:
- Been stable on discharge medications
- Had inhaler technique checked
- PEF >75% Predicted or best with diurnal variability <25%
- Steroids (inhaled and oral) and
bronchodilator therapy - Own a PEF meter and have management plan
- Respiratory clinic appointment within 4 weeks and GP appointment within a week.
Common Adverse Drug Effects
- Oxygen: seizure, retinal detachment, Acute respiratory distress syndrome (ARD) etc
- Steroids: diabetes mellitus, osteoporosis, proximal myopathy, PUD, Cushing’s syndrome, growth retardation.
- Beta-agonists: fine tremors, nervous tremors, palpitation, headache ,muscle cramps, tachycardia, arrhythmias,
peripheral vasodilatation, insomnia, hypokalemia - Ipratropium: taste disorders, GERD, Pharyngitis, dysuria, insomnia
- Aminophylline: palpitations,
tachycardia, arrhythmia, nausea,
vomiting, gastric irritation, headache, convulsion, hypertension (better avoided in the elderly, patients with arrhythmias, high BP) - MgSO: nausea, vomiting, flushing of
skin, hypotension, arrhythmias,
respiratory depression and muscle
weakness.