Acute Severe Asthma Flashcards
How does acute severe asthma present?
Acute breathlessness and wheeze
What should be asked about in the history of acute severe asthma?
- Usual and recent treatment
- Previous acute episodes and their severity
- Best peak expiratory flow rate
- Previous admissions to ICU
What are the differential diagnoses of acute severe asthma?
- Acute infective exacerbation of COPD
- Pulmonary oedema
- Upper respiratory tract obstruction
- Pulmonary embolus
- Anaphylaxis
What investigations should be done in a patient with acute severe asthma?
- PEF if possible
- ABG if saturations <92% or life-threatening features
- CXR if suspicion of pneumothorax, infection, or life-threatening attack
FBC - U&E
How is acute severe asthma managed?
- Assess severity of attack
- Supplmental oxygen
- Salbutamol 5mg or terbutaline 10mg nebulised with oxygen
- If severe/life-threatening, ipratropium 0.5mg/6h added to nebulisers
- Hydrocortisone 100mg IV, or prednisolone 40-50mg PO
What are the criteria for a severe acute asthma attack?
- Unable to complete sentences in one breath
- Respiratory rate >25/min
- Pulse rate >110bpm
- PEF 33-50% of predicted or best
What are the criteria for a life-threatening asthma attack?
- PEF <33% of predicted or best
- Silent chest
- Cyanosis
- Feeble respiratory effort
- Arrhythmias or hypotension
- Exhausion, confusion, or coma
- Normal/high PaCO2, PaO2 of <8kPa or sats <92%
What should be done if a patient presents with a severe or life-threatening asthma attack?
Warn ICU
What oxygen saturations are aimed for in a patient having an acute severe asthma attack?
92%
How often should a patient with acute severe asthma be reassessed after initial management?
Every 15 minutes
What should be done on reassessment of a patient with acute severe asthma?
- Monitor PEF
- Monitor ECG and check for arrhythmias
- Consider single dose of magnesium sulphate 1.2-2g IV over 20min in those with severe/life-threatening features without good initial reponse to therapy
What should be done if PEF <75% on reassessment of a patient with acute severe asthma?
Repeat salbutamol nebulisers every 15-30 minutes, or 10mg/h continuously. Add ipratropium if not already given
What should be done if a patient with acute severe asthma is not improving after management?
- Refer to ICU for consideration of ventilatory support and intensification of medical therapy
- Consider IV salbutamol
What features suggest that IV salbutamol should be considered in a patient with acute severe asthma who is not improving?
- Deteriorating PEF
- Persistent/worsening hypoxia
- Hypercapnia
- ABG showing low pH
- Exhausion, feeble respiratory effort
- Drowsiness, confusion, altered conscious level
- Respiratory arrest
What should be done if a patient with acute severe asthma is improving 15-30 minutes after treatment?
- Continue nebulised salbutamol every 4-6 hours
- Prednisolone 40-50mg PO OD for 5-7 days
- Monitor peak flow and oxygen saturations
- If PEF >75% 1 hour after initial treatment, consider discharge with outpatient follow up
Are antibiotics routinely used in acute asthma?
No
What criteria must be fulfilled before a patient who had acute severe asthma is discharged?
- Stable on discharge medication for 24hours
- Had inhaler technique checked
- Peak flow rate >75% predicted or best, with diurnal variability <25%
- Must be on steroid (inhaled and oral) and bronchodilator therapy
- Must have their own PEF meter and written management plan
- GP appointment organised within 2 days
- Respiratory clinic appointment within 4 weeks
What are the side effects of salbutamol?
- Tachycardia
- Arrhythmias
- Tremor
- Decreased potassium
Describe the use of aminophylline in acute severe asthma
It is used much less frequently, and is not routinely recommended, however it may be initiated by respiratory teams or ICU
What is the mechanism of action of aminophylline?
It inhibits phosphodiesterase, and so increases cAMP
What are the side effects of aminophylline?
- Tachycardia
- Arrhythmias
- Nausea
- Seizures
What safety precautions should be taken when giving a patient aminophylline?
- Monitor ECG
- Aim for plasma concentration 10-20mcg/mL
- Measure plasma potassium
- Don’t load patients already on oral preparations
- Stick with one brand
Why should you aim for a aminophylline plasma concentration of 10-20mcg/mL?
Because serious toxicities, including hypotension, arrhythmias, and cardiac arrest, can occur at concentrations of >25mcg/mL
Why do you need to measure plasma potassium with aminophylline?
Because it can decrease potassium levels
Why should you stick with one brand of aminophylline?
Because bioavailability varies
