EXACERBATIONS ASTHMA
Exacerbations of asthma
The course of asthma may be punctuated by exacerbations characterised by increased symptoms, deterioration in PEF and an increase in airway inflammation. Exacerbations may be precipitated by infections (most commonly viral), moulds (Alternaria and Cladosporium) and on occasion pollen (particularly following thunderstorms). Increases in air pollution are accompanied by increased hospital admissions. Most attacks are characterised by a gradual deterioration over several hours to days but some appear to occur with little or no warning: so-called brittle asthma
Management of mild-moderate exacerbations«
It has been widely believed that an impending exacerbation may be avoided by doubling the dose of ICS; however, recent studies have failed to confirm this. Short courses of 'rescue' oral corticosteroids (prednisolone 30-60 mg daily) are therefore often required to regain control of symptoms. Tapering of the dose to withdraw treatment is not necessary unless given for more than 3 weeks
Indications for 'rescue' courses include==
symptoms and PEF progressively worsening
day by day
fall of PEF below 60% of the patient's personal best recording
onset or worsening of sleep disturbance by asthma
persistence of morning symptoms until midday
progressively diminishing response to an inhaled bronchodilator
symptoms severe enough to require treatment with nebulised or injected bronchodilators
Management of acute severe asthma««
Initial assessment
The features of acute asthma are listed in Box 19.25. An immediate assessment of patients should include their ability to speak, pulse rate, respiratory rate, BP and SaO2. Measurement of PEF is mandatory unless the patient is too ill to cooperate and is most easily interpreted when expressed as a percentage of the predicted normal or of the previous best value obtained on optimal treatment. Arterial blood gas analysis is essential to determine the PaCO2, a normal or elevated level being particularly dangerous. A chest X-ray is not immediately necessary unless pneumothorax is suspected
IMMEDIATE ASSESSMENT OF ACUTE ««
SEVERE ASTHMA
BOX 19.25
(PEF 33-50% predicted(>200I/m--
Respiratory rate≥25/min--
heart rate≥110/min--
Inablity to complet sentences in 1brea--
life threating featurs»»
(PEF 33-50% predicted(>100I/min--
(SpO2<92 or paO2<8 kpa(60mmhg--
normal pacO2--
silent chest--
cyanosis--
feeble respiratory effort--
bradycardia or arrythmias--
hypotension--
exhaustion--
confusion--
coma--
Oxygen««
High concentrations of oxygen (humidified if possible) should be administered to maintain the oxygen saturation above 92% in adults. The presence of a high PaCO2 should not be taken as an indication to reduce oxygen concentration but is a warning sign of a severe or life-threatening attack. Failure to achieve appropriate oxygenation is an indication for assisted ventilation
High doses of inhaled bronchodilators««
Short-acting β2-agonists represent the agent of first choice. In hospital they are most conveniently administered via a nebuliser driven by oxygen but delivery of multiple doses of salbutamol via a metered dose inhaler through a spacer device provides equivalent bronchodilation and may be considered in primary care. Ipratropium bromide provides additional bronchodilator therapy and should be added to salbutamol in patients with acute
severe or life-threatening attacks
Systemic corticosteroids««
Systemic corticosteroids reduce the inflammatory response and hasten the resolution of exacerbations. They should be administered to all patients with an acute severe attack. They can usually be administered orally (prednisolone 30-60 mg), but intravenous hydrocortisone 200 mg may be used in patients who are unable to swallow
or vomiting
Intravenous fluids««
There are no controlled trials to support the use of intravenous fluids but many patients are dehydrated due to high insensible water loss and will probably benefit from hydration therapy. Potassium supplements may be necessary because repeated doses of salbutamol can lower serum potassium
Subsequent management««
If patients fail to improve, a number of further options may be considered. Intravenous magnesium may provide additional bronchodilation in patients whose presenting PEF is < 30% predicted (Box 19.26). Some patients appear to benefit from the use of intravenous aminophylline but careful monitoring is required. Intravenous leukotriene receptor antagonists may soon become available
Monitoring of treatment««
PEF should be recorded every 15-30 minutes and then every 4-6 hours. Pulse oximetry should ensure that SaO2 remains > 92% but repeat arterial blood gases are necessary if the initial PaCO2 measurements were normal or raised, the PaO2 was < 8 kPa (60 mmHg), or the patient deteriorates
DR:Khalid Alshameri
...Davidson's medicin
The course of asthma may be punctuated by exacerbations characterised by increased symptoms, deterioration in PEF and an increase in airway inflammation. Exacerbations may be precipitated by infections (most commonly viral), moulds (Alternaria and Cladosporium) and on occasion pollen (particularly following thunderstorms). Increases in air pollution are accompanied by increased hospital admissions. Most attacks are characterised by a gradual deterioration over several hours to days but some appear to occur with little or no warning: so-called brittle asthma
Management of mild-moderate exacerbations«
It has been widely believed that an impending exacerbation may be avoided by doubling the dose of ICS; however, recent studies have failed to confirm this. Short courses of 'rescue' oral corticosteroids (prednisolone 30-60 mg daily) are therefore often required to regain control of symptoms. Tapering of the dose to withdraw treatment is not necessary unless given for more than 3 weeks
Indications for 'rescue' courses include==
symptoms and PEF progressively worsening
day by day
fall of PEF below 60% of the patient's personal best recording
onset or worsening of sleep disturbance by asthma
persistence of morning symptoms until midday
progressively diminishing response to an inhaled bronchodilator
symptoms severe enough to require treatment with nebulised or injected bronchodilators
Management of acute severe asthma««
Initial assessment
The features of acute asthma are listed in Box 19.25. An immediate assessment of patients should include their ability to speak, pulse rate, respiratory rate, BP and SaO2. Measurement of PEF is mandatory unless the patient is too ill to cooperate and is most easily interpreted when expressed as a percentage of the predicted normal or of the previous best value obtained on optimal treatment. Arterial blood gas analysis is essential to determine the PaCO2, a normal or elevated level being particularly dangerous. A chest X-ray is not immediately necessary unless pneumothorax is suspected
IMMEDIATE ASSESSMENT OF ACUTE ««
SEVERE ASTHMA
BOX 19.25
(PEF 33-50% predicted(>200I/m--
Respiratory rate≥25/min--
heart rate≥110/min--
Inablity to complet sentences in 1brea--
life threating featurs»»
(PEF 33-50% predicted(>100I/min--
(SpO2<92 or paO2<8 kpa(60mmhg--
normal pacO2--
silent chest--
cyanosis--
feeble respiratory effort--
bradycardia or arrythmias--
hypotension--
exhaustion--
confusion--
coma--
Oxygen««
High concentrations of oxygen (humidified if possible) should be administered to maintain the oxygen saturation above 92% in adults. The presence of a high PaCO2 should not be taken as an indication to reduce oxygen concentration but is a warning sign of a severe or life-threatening attack. Failure to achieve appropriate oxygenation is an indication for assisted ventilation
High doses of inhaled bronchodilators««
Short-acting β2-agonists represent the agent of first choice. In hospital they are most conveniently administered via a nebuliser driven by oxygen but delivery of multiple doses of salbutamol via a metered dose inhaler through a spacer device provides equivalent bronchodilation and may be considered in primary care. Ipratropium bromide provides additional bronchodilator therapy and should be added to salbutamol in patients with acute
severe or life-threatening attacks
Systemic corticosteroids««
Systemic corticosteroids reduce the inflammatory response and hasten the resolution of exacerbations. They should be administered to all patients with an acute severe attack. They can usually be administered orally (prednisolone 30-60 mg), but intravenous hydrocortisone 200 mg may be used in patients who are unable to swallow
or vomiting
Intravenous fluids««
There are no controlled trials to support the use of intravenous fluids but many patients are dehydrated due to high insensible water loss and will probably benefit from hydration therapy. Potassium supplements may be necessary because repeated doses of salbutamol can lower serum potassium
Subsequent management««
If patients fail to improve, a number of further options may be considered. Intravenous magnesium may provide additional bronchodilation in patients whose presenting PEF is < 30% predicted (Box 19.26). Some patients appear to benefit from the use of intravenous aminophylline but careful monitoring is required. Intravenous leukotriene receptor antagonists may soon become available
Monitoring of treatment««
PEF should be recorded every 15-30 minutes and then every 4-6 hours. Pulse oximetry should ensure that SaO2 remains > 92% but repeat arterial blood gases are necessary if the initial PaCO2 measurements were normal or raised, the PaO2 was < 8 kPa (60 mmHg), or the patient deteriorates
DR:Khalid Alshameri
...Davidson's medicin
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