Acute asthma

Acute asthma attack

An acute, or sudden, asthma attack is usually caused by an exposure to allergens or an upper-respiratory-tract infection. The severity of the attack depends on how well your underlying asthma is being controlled (reflecting how well the airway inflammation is being controlled). An acute attack is potentially life-threatening because it may continue despite the use of your usual quick-relief medications (inhaled bronchodilators). Asthma that is unresponsive to treatment with an inhaler should prompt you to seek medical attention at the closest hospital emergency room or your asthma specialist office, depending on the circumstances and time of day. Asthma attacks do not stop on their own without treatment. If you ignore the early warning signs, you put yourself at risk of developing status asthmaticus.

Life-threatening features:

• Silent chest
• Cyanosis
• Bradycardia (especially despite β₂ agonist)
• Exhausted appearance
• PEFR <30% of predicted

Immediate management:

• Oxygen therapy by tight fitting facemask (60%).
• Nebulised salbutamol 2.5 +/- 0.5mg ipratropium*
• Start glucocorticoid therapy - prednisolone 30-60mg p.o. or hydrocortisone 200mg i.v.
•  Urgent chest X-ray to exclude pneumothorax
• Urgent blood gas**
• Reassess in 15 min or if life-threatening features appear
• Consider i.v. aminophylline if life-threatening features or fails to improve after 15-30 minutes***
• Discuss all patients with ITU - ventilation needed if PEFR continues to fall despite medical therapy, patient becoming drowsy/confused/exhausted or deteriorating blood gases **.

* Alternatively β₂ agonist can be given s.c.

** Beware severe hypoxia (p0₂<8.0 on high inspired O₂) or high/rising pCO₂

*** establish if patient on oral theophylline before giving any aminophylline IV.

Late management: Step down initially by converting from nebulised to usual inhaled device (eg MDI) checking that their technique is adequate. Patient is discharged only when PEFR 'normalised' (80-90% of their best) without dipping. They should also be discharged on high-dose inhaled glucocorticoid, which should continue, until they are reviewed in clinic. The latter is important in preventing early relapse.

Acute asthma

Managing acute asthma in adults
If the patient is acutely distressed, give oxygen and SABA immediately after taking a brief history and physical examination.	[√]
Assess response to treatment using spirometry, oxygen saturation, heart rate, respiratory rate and pulsus paradoxus status.	[√]
Wheeze is an unreliable indicator of the severity of an asthma attack and may be absent in severe asthma.	[√]
Ensure every patient receives adequate follow-up after an acute asthma episode, including review of medications, triggers and asthma action plan.	[√]
Managing acute asthma in children
If the patient is acutely distressed, give oxygen and SABA immediately after taking a brief history and physical examination.	[√]
Emergency management of acute asthma in a child is based on initial administration of salbutamol 4-6 puffs (< 6 years) or 8-12 puffs (≥6 years) via MDI.	I
Load the spacer with one puff at a time and give each puff separately.	III-1
If treatment with an oral corticosteroid (e.g. prednisolone 1 mg/kg up to 60 mg as a single daily dose) has been initiated for a moderate-to-severe acute episode, continue for up to 5 days.	I

Managing acute asthma in adults

If the patient is acutely distressed, give oxygen and SABA immediately after taking a brief history and physical examination. [√] Assess response to treatment using spirometry, oxygen saturation, heart rate, respiratory rate and pulsus paradoxus status. [√] Wheeze is an unreliable indicator of the severity of an asthma attack and may be absent in severe asthma. [√]

Table 1. Summary of steps in emergency care of an adult with acute asthma
1.	Take a brief history and perform a rapid physical examination before beginning treatment.
2.	If the patient is acutely distressed, give oxygen and SABA immediately. Consider whether adrenaline is indicated. Oxygen therapy may be associated with respiratory depression and arrest in patients with chronic CO2retention, particularly those with chronic obstructive pulmonary disease (COPD).
3.	Take a more detailed history and complete the physical examination. Initiate treatment with other agents, including systemic corticosteroids, as indicated. Further treatment depends on the severity of the episodeand response to initial treatment (Table 3).
4.	Perform spirometry and/or peak expiratory flow measurement as soon as possible to gain an objective measure of airflow limitation.
5.	Assess progress by continued close monitoring of objective measures of improvement. Spirometry is the most reliable measure of response to treatment. Measurement of PEF may be used if a spirometer is not available. In adults with severe acute asthma, measurement of arterial blood gases after initiating treatment is indicated to assess CO2 retention as well as to enable management of hypoxaemia. Oxygen saturation on oximetry (SaO2) should be kept above 90%. Heart rate, respiratory rate and pulsus paradoxus (abnormal decrease in systolic blood pressure during inspiration) are also useful measures of response. Reduction in wheezing is an unreliable indicator of improvement, as it may indicate deterioration. Intubation and ventilation are indicated for patients with acute respiratory failure that does not respond to treatment and for respiratory arrest or exhaustion suggesting impending respiratory arrest.

Initial assessment

The initial assessment of an adult with acute asthma is summarised in Table 2.

Spirometry is the lung function test of choice for assessing asthma severity during an acute episode (if the patient is able to perform the manoeuvre), and for monitoring the response to treatment.

Patients who are acutely distressed require immediate oxygen and short-acting beta₂ agonist (SABA) before completing a full assessment.

Table 2. Initial assessment of acute asthma in adults
Findings	Mild	Moderate	Severe and life-threatening*
Physical exhaustion	No	No	Yes Paradoxical chest wall movement may be present
Talks in	Sentences	Phrases	Words
Pulse rate	< 100/min	100-120/min	More than 120/min†
Pulsus paradoxus	Not palpable	May be palpable	Palpable‡
Central cyanosis	Absent	May be present	Likely to be present
Wheeze intensity	Variable	Moderate to loud	Often quiet
PEF	More than 75% predicted (or best if known)	50-75% predicted (or best if known)	Less than 50% predicted (or best if known) or less than 100 L per min#
FEV1	More than 75% predicted	50-75% predicted	Less than 50% predicted or less than 1 L
Oximetry on presentation	-	-	Less than 90% Cyanosis may be present**
Arterial blood gases (assay)	Not necessary	Necessary if initial response poor	Necessary††
Other investigations	Not required	May be required	Check for hypokalaemia Chest X-ray to exclude other pathology (e.g. infection, pneumothorax)
*Any of these features indicates that the episode is severe. The absence of any feature does not exclude a severe attack. †Bradycardia may be seen when respiratory arrest is imminent. ‡Paradoxical pulse is more reliable in severe obstruction. Its presence (especially if > 12 mmHg) can identify patients who need admission.  Absence in those with severe exacerbations suggests respiratory muscle fatigue. #Patient may be incapable of performing test. ** Measurement of oxygen saturation is required: many patients look well clinically and may not appear cyanosed despite desaturation. ††PaCO2 > 50 mmHg indicates respiratory failure. PaO2 < 60 mmHg indicates respiratory failure.  History The following information should be obtained as soon as possible after the patient presents with acute asthma: the cause of the present exacerbation (e.g. upper respiratory tract infection, allergen exposure, food allergy) the duration of symptoms (with increasing duration of the attack, exhaustion and muscle fatigue may precipitate ventilatory failure) the severity of symptoms, including exercise limitation and sleep disturbance details of all current asthma medications, doses and amounts used, including the time of the last dose. (Distinguish between preventer medications and reliever medications used for the acute attack) medication adherence history details of other medications. (Check whether the person has used any medications that might aggravate asthma, including complementary/herbal medications.) prior hospitalisations and Emergency Department visits for asthma or anaphylaxis, particularly within the last year exposure to nonsteroidal anti-inflammatory drugs or aspirin prior episodes of severe life-threatening asthma (e.g. admissions to intensive care unit, ventilation) significant coexisting cardiopulmonary disease the presence of underlying chronic obstructive pulmonary disease (indicates risk of CO2 retention) known immediate hypersensitivity to food, bee sting or drugs smoking history.  Management The initial management of adults with acute asthma is summarised in Table 3. For information on the assessment of severity, see Table 2. Initial assessment of acute asthma in adults. Table 3. Initial management of adults with acute asthma Treatment Mild episode Moderate episode Severe episode Hospital admission Probably not necessary Admit Admit. Consider admission to intensive care unit. Oxygen Flow rate adjusted to achieve SaO2 > 90%. Frequent measurement of arterial blood gases is indicated in severe asthma and those not responding to treatment. SABA via MDI + spacer 8-12 puffs salbutamol 8-12 puffs salbutamol every 1-4 hours 8-12  puffs salbutamol every 15-30 minutes or *SABA nebulised, e.g. salbutamol or terbutaline, with O2 8 L/min   One salbutamol 5 mg/2.5 mL nebule or One terbutaline 5 mg/2 mL respule) or Salbutamol 1 mL of 5 mg/mL solution + 3 mL saline One salbutamol 5 mg/2.5 mL nebule  or One terbutaline 5 mg/2 mL respule orSalbutamol 1 mL of 5 mg/mL solution + 3 mL saline 1-4 hourly   Salbutamol 1 mL of 5 mg/mL solution + 3 mL saline every 15-30 mins   If no response, give salbutamol 250 mcg (0.5 mL of 500 mcg/mL solution) IV bolus over one minute then IV 5-10 mcg/kg/hour Nebulised ipratropium bromide Not necessary Optional Ipratropium bromide 2 mL 0.05% (500 mcg) with salbutamol 2 hourly Oral corticosteroids e.g. prednisolone Yes (consider) Yes 0.5-1.0 mg/kg initially Yes 0.5-1.0 mg/kg initially Intravenous steroids e.g. hydrocortisone (or equivalent) Not necessary †Hydrocortisone 250 mg (or equivalent) ‡Hydrocortisone 250 mg 6 hourly for 24 hours then review Theophylline/ aminophylline - - #Aminophylline 25 mg/mL: give 6 mg/kg slow IV injection then 0.3-0.6 mg/kg/hour IV infusion Adrenaline Not indicated Not indicated 5 mL of 1:10,000 solution slowly IV if anaphylaxis present Chest X-ray Not necessary unless focal signs present Not necessary unless focal signs present, or no improvement to initial treatment Necessary if no response to initial therapy or pneumothorax suspected Observations Regular Continuous Continuous Other     Treat for hypokalaemia if present *SABA via MDI and spacer is as effective as nebulisation in patients with moderate-to-severe acute asthma, other than those with life-threatening asthma (e.g. patients requiring ventilation) †Use IV corticosteroids in moderate acute asthma if oral route not convenient ‡ Either oral or IV corticosteroids can be given initially. Follow with oral course. # Alternative to IV salbutamol Patients with moderate-to-severe acute asthma require admission to hospital (consider intensive care) and continuous observation. In adults with mild acute asthma, admission to hospital is usually not necessary. Observe patients for 1 hour after the episode is controlled to ensure full recovery. For information on community-based management of acute or subacute deterioration in symptom control and lung function, see Managing exacerbations. Give SABA via MDI plus spacer immediately Initially give 8-12 puffs salbutamol (100 mcg/dose) via MDI and spacer. Repeat as necessary (e.g. repeat every 15-30 minutes in a severe episode, 1-4 hours after the first dose in a moderately severe episode). The use of SABAs by intermittent inhalation via MDI plus spacer is now recommended in the management of acute asthma, whether mild, moderate or severe. Delivery of SABA via MDI and spacer is equally effective as nebulisation in patients with moderate-to-severe acute asthma, other than those with life-threatening asthma (e.g. patients requiring ventilation).1 In patients who can inhale well enough to use an MDI, the use of IV SABA gives no advantage over inhaled treatment. Continuous nebulisation and intravenous therapy are alternatives in severe asthma. However, adverse events are more frequent. Use a nebuliser instead if the person cannot inhale adequately: a 5 mg nebule of salbutamol with 2 mL saline or 1 mL of salbutamol solution (5 mg/mL) with 3 mL saline as needed. If available give wall oxygen at a flow of 8-10 L/min. A mouthpiece delivers considerably more drug to the lung than a facemask. If no response to SABA via inhaler or nebuliser, give salbutamol 250 mcg IV bolus then 5-10 mcg/kg/hour by IV infusion. Salbutamol 8-12 puffs via MDI (100 mcg/dose) is equivalent to 5 mg via nebuliser. Alternatives are: terbutaline (Bricanyl) 500 mcg/dose 4-6 puffs eformoterol (Oxis Turbuhaler) 6 or 12 mcg/dose can be used. Up to 48 mcg in divided doses over 30 mins has been shown to be safe and effective. Start systemic corticosteroids All patients with moderate-severe acute asthma will require a course of systemic corticosteroids in addition to inhaled corticosteroids (ICS). Commence a short course of oral corticosteroids (e.g. prednisolone 0.5-1.0 mg/kg for 7-10 days) Alternatively, corticosteroids can be given IV: hydrocortisone 100 mg 6 hourly or 40-120 mg methylprednisolone once daily or 4-12 mg dexamethasone once daily. There is no significant advantage to using more than 400 mg hydrocortisone per day (200 mg per day is adequate for most patients.7 Oral corticosteroids can be substituted when oral intake resumes. ICS should be continued, but it is not clear whether this provides any additional benefit over systemic corticosteroids alone. The roles of other agents in acute asthma care in adults Nebulised ipratropium bromide given in addition to SABA may improve bronchodilation. If using nebulised SABA, add ipratropium bromide 2 mL 0.05% (1 mg) with salbutamol 2 hourly. Aminophylline 25 mg/mL IV (6 mg/kg IV slow injection then 0.3-0.6 mg/kg/hour infusion) can be used as an alternative to IV salbutamol when an acute episode does not respond to inhaled SABA. However, the use of intravenous aminophylline is unlikely provide a significant benefit in addition to therapeutically effective SABAs (i.e. where not compromised by concurrent use of beta blockers), and may increase adverse effects including nausea and vomiting. Injection rate should not exceed 25 mg/minute to reduce the risk of hypotension, seizures and arrhythmia. Serum levels should be monitored for both maximal effect and toxicity. Magnesium sulphate (via nebuliser or IV, as available) can be added to improve airflow, although the evidence to support this is not strong.Suggested doses are 1.2-2 g of MgSO4 IV over 20 min or 2.5 mL isotonic MgSO4 (250 mmol/L) by nebuliser Adrenaline is required for respiratory arrest or exhaustion suggesting impending respiratory arrest. Give 5 mL of 1:10,000 solution slowly IV. An alternative is 0.5 mL of 1:1,000 (0.5 mg) solution IM, but IV is the preferred route due to unpredictable absorption and the possible need for another injection with IM administration. Other investigations Arrange chest X-ray if there is no response to initial therapy, if focal signs are present or if pneumothorax is suspected. Check for hypokalaemia and correct if present. Follow-up care after an acute asthma episode   Ensure every patient receives adequate follow-up after an acute asthma episode, including review of medications, triggers and asthma action plan. [√]    This is a valuable opportunity to review the patient's overall asthma management. Review of maintenance medications and asthma control is necessary e.g. : Was previous baseline asthma control adequate? Is the patient's asthma action plan up to date? Follow-up care is crucial for those who do not require hospitalisation: Identify trigger factors Provide a written asthma action plan for the patient and their carers Recommend rapid-onset beta2 agonists as required for symptom control Use spirometry to monitor lung function and reassess the treatment plan as necessary. Consider adding a LABA if patients are not already taking ICS-LABA combination therapy. Re-evaluate ICS dose and back-titrate at next review. Patients who are hospitalised will require follow-up care on discharge, including: discharge summary to the patient's usual GP appointment with the patient's usual GP within 1 week ± outpatient department appointment with a consultant physician in 2 weeks interim written asthma action plan. Managing acute asthma in children   If the patient is acutely distressed, give oxygen and SABA immediately after taking a brief history and physical examination. [√] Emergency management of acute asthma in a child is based on initial administration of salbutamol 4-6 puffs (< 6 years) or 8-12 puffs (≥6 years) via MDI. (I) Load the spacer with one puff at a time and give each puff separately. (III-1) If a course of oral corticosteroids (e.g. prednisolone 1 mg/kg up to 60 mg as single daily dose) has been initiated for a moderate-to-severe acute episode, continue for up to 5 days. (I)   Table 4 summarises steps in the emergency care of a child with acute asthma. Table 4. Summary of steps in emergency care of a child with acute asthma 1. Take a brief history and perform a rapid physical examination (Table 5). 2. Give salbutamol via MDI plus spacer immediately: usually 6 puffs for children under 6 years and 12 puffs for children 6 years and over. If the patient is acutely distressed, give oxygen immediately. (Table 6). The MDI used with a spacer has replaced the nebuliser as the standard method of delivering SABAs in hospital-based care of children with acute asthma (Table 6). Each puff is given separately: the spacer should only be loaded with one puff at a time. The total dose (up to 12 puffs) is based on medical assessment in addition to the child's age. With experience, parents learn to judge SABA dose requirement. 3. Complete a full assessment and initiate other treatment, including systemic corticosteroids and oxygen as indicated  Adrenaline may be indicated if asthma occurs as part of an anaphylactic reaction, depending on severity. There is now convincing evidence that intravenous magnesium sulphate provides additional benefit in children with severe asthma treated with bronchodilators and corticosteroids. Magnesium sulphate has an excellent safety profile and its place in the management of acute severe asthma is similar to that of aminophylline.11  4. Closely monitor response to treatment and repeat SABA as indicated

Initial assessment

The initial assessment of a child with acute asthma is summarised in Table 5.

Table 5. Initial assessment of acute asthma in children
Symptoms	Mild	Moderate	Severe and life-threatening*
Altered consciousness	No	No	Agitated Confused/drowsy
Oximetry on presentation (SaO2)	94%	94-90%	Less than 90%
Talks in	Sentences	Phrases	Words Unable to speak
Pulse rate	Less than 100 beats/min	100-200 beats/min	More than 200 beats/min
Central cyanosis	Absent	Absent	Likely to be present
Wheeze intensity	Variable	Moderate to loud	Often quiet
PEF**	More than 60% predicted or personal best	40-60% predicted or personal best	Less than 40% predicted or personal best Unable to perform
FEV1	More than 60% predicted	40-60% predicted	Less than 40% predicted Unable to perform
*Any of these features indicates that the episode is severe. The absence of any feature does not exclude a severe attack.  **Children under 7 years old are unlikely to perform PEF or spirometry reliably during an acute episode. These tests are usually not used in the assessment of acute asthma in children.

Children who are acutely distressed require immediate oxygen and short-acting beta₂ agonist (SABA) before completing a full assessment.

Management

The management of acute episodes is based on salbutamol delivered via MDI and spacer, repeated at 20-minute intervals until control is achieved (Table 6).

Table 6. Initial management of children with acute asthma
Treatment	Mild episode	Moderate episode	Severe and life-threatening episode
Hospital admission necessary	Probably not	Probably	Yes: consider intensive care
Supplementary oxygen	Probably not required	May be required. Monitor SaO2	Required. Monitor SaO2. Arterial blood gases may be required.
Salbutamol1*	4-6 puffs (under 6 years) or 8-12 puffs (6 years and over). Review in 20 mins	6 puffs (under 6 years) or 12 puffs (6 years and over). If initial response inadequate, repeat at 20-minute intervals for two further doses. Then give every 1-4 hours.	6 puffs (under 6 years) or 12 puffs (6 years and over) every 20 mins for three doses in first hour. If life-threatening episode, use continuous nebulised salbutamol. If no response, bolus IV salbutamol 15 mcg/kg over 10 mins then 1 mcg/kg/min thereafter.
Ipratropium14	Not necessary	Optional	2 puffs (under 6 years) or 4 puffs (6 years and over) every 20 minutes x 3 doses in first hour or nebulised ipratropium
Systemic corticosteroids	Yes (consider)	Oral prednisolone 1 mg/kg daily for up to 3 days	Oral prednisolone 1 mg/kg/dose daily for up to 5 days Methylprednisolone IV 1 mg/kg 6 hourly on Day 1, 12 hourly on Day 2 then daily
Magnesium11	No	No	Magnesium sulphate 50% 0.1 ml/kg (50 mg/kg) IV over 20 mins then 0.06 ml/kg/hr (30 mg/kg/hr): target serum Mg 1.5-2.5 mmol/L
Aminophylline15	No	No	Only in Intensive Care: loading dose 10 mg/kg Maintenance 1.1 mg/kg/hour if under 9 years or 0.7 mg/kg/hour if 9 years and over
Chest X-ray	Not necessary unless focal signs present	Not necessary unless focal signs present	Necessary if no response to initial therapy or pneumothorax is suspected
Observations	Observe for 20 mins after dose	Observe for 1 hour after last dose	Arrange for admission to hospital
*In children with severe acute asthma that does not respond to initial treatment with inhaled SABA, bolus IV salbutamol 15 mcg/kg over 10 mins is effective and can avoid the need for continuous IV salbutamol and ICU admission.16,17

Nebulised salbutamol is reserved for life-threatening episode. For dose-equivalence information on nebules and MDIs see Table 7. Salbutamol dose equivalents.

Table 7. Salbutamol dose equivalents
Salbutamol via MDI and spacer	is equivalent to
6 puffs (children under 6 years)	2.5 mg nebule
12 puffs (children 6 years and over)	5 mg nebule

Managing a severe acute asthma episode in a child

Arrange for admission to hospital and consider intensive care.

• Initially, give salbutamol 6 puffs (children under 6 years) or 12 puffs (children 6 years and over) every 20 mins for the first hour (i.e. three doses).
• If the episode appears to be life threatening, use continuous nebulised salbutamol.
• If no response, give salbutamol 15 mcg/kg IV over 10 mins, then 1 mcg/kg/min infusion.
• Give supplementary oxygen and monitor SaO₂ by oximetry. Arterial blood gases may also be required.
• Give systemic corticosteroids, either:
• Begin a course of oral prednisolone (1 mg/kg/dose daily up to 60 mg for up to 5 days); or
• Give methylprednisolone IV 1 mg/kg up to 60 mg every 6 hours on Day 1, then every 12 hours on Day 2, then daily.
• Give ipratropium 2 puffs (children under 6 years) or 4 puffs (children 6 years and over) every 20 minutes for the first hour (i.e. three doses). Nebulised ipratropium may be used as an alternative.
• Give magnesium sulphate 50% 0.1 ml/kg (50 mg/kg) IV over 20 minutes, then 0.06 ml/kg/hr (30 mg/kg/hr). Target serum magnesium 1.5-2.5 mmol/L.
• Aminophylline, if used, should only be given in an intensive care unit. Give a loading dose of 10 mg/kg then a maintenance dose of 1.1 mg/kg/hour (children under 9 years old) or 0.7 mg/kg/hour (children 9 years and over).
• Arrange chest X-ray if there is no response to initial therapy or if pneumothorax is suspected.

Managing a moderate acute asthma episode in a child

Children with moderate acute asthma may require hospital admission.

• Initially, give salbutamol 6 puffs (children under 6 years) or 12 puffs (children 6 years and over).
• If initial response is inadequate, repeat at 20-minute intervals for two further doses, then give every 1 to 4 hours.
• Monitor oxygen saturation using oximetry. Supplemental oxygen may be required.
• Begin a course of oral prednisolone 1 mg/kg daily for up to 3 days.
• Chest X-ray is not necessary unless focal signs are present.
• If the child is not admitted to hospital, observe for at least 1 hour after the last dose of medication.

Managing a mild acute asthma episode in a child

Initially, give salbutamol 6 puffs (children under 6 years) or 12 puffs (children 6 years and over).

• Review response after 20 minutes and repeat if necessary as for moderate acute episodes.
• Consider beginning a short course of oral corticosteroids (prednisolone 1 mg/kg daily for up to 3 days).
• Observe for at least 20 minutes after the last dose before allowing the child to go home.

Follow-up care after an acute asthma episode

• Give further SABA doses as needed, up to 3-4 hourly
• Give a short course of oral corticosteroids (e.g. prednisolone 1 mg/kg as single daily dose for up to 5 days). In children taking high-dose ICS it may be necessary to taper the dose over 3-5 days before ceasing.
• Provide clear instructions about when to return if asthma worsens. See Asthma action plans.
• Arrange follow-up appointment with regular practitioner to review overall management within 2 weeks.