Monday, January 19, 2015

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COPD exacerbation - definition, assessment, management

COPD exacerbation:

Definition:
Exacerbation of COPD is defined as an acute episode, characterized by the worsening of the patient’s respiratory symptoms that is beyond normal daily variations and that will eventually lead to a change in his medications.
Those having 2 or more exacerbations per year are known as “frequent exacerbators”.

Precipitating factors:
1) Respiratory tract infections – viral or bacterial. Most common cause. There may be an increased bacterial burden in the lower airways or new strains of bacteria are acquired during an exacerbation. Commonly implicated viruses
include rhinovirus, respiratory syncytial virus, coronavirus and influenza virus.
2) Air pollution.
3) Interruption of maintenance therapy.
4) Unknown causes – 30% cases.


Diagnosis:
Diagnosis should be made clinically whereby the patient complains of an acute aggravation of his symptoms out of proportion to his day to day variations. 

Assessment:
Medical history:
1) Severity of COPD before this exacerbation
2) Duration of the worsening or any new symptoms
3) Number of previous exacerbations or hospitalizations
4) Associated comorbidities
5) Present medications
6) Previous uses of mechanical ventilation.
Clinical examination:
1) Use of accessory respiratory muscles or paradoxical chest wall movements
2) Development of central cyanosis or exacerbation of pre-existing cyanosis
3) Change in mental status
4) Development of peripheral edema
5) Hemodynamic instability




Tests to assess severity include:
1) Pulse oximetry – good for monitoring.
2) Arterial blood gases and acid base status – shows whether there is an acute or acute on chronic respiratory failure.
3) Chest radiography – excludes alternative diagnoses and can show infections.
4) EKG – may help to assess any pre-existing cardiac problems.
5) Complete blood count – white cells may be elevated, hematocrit may be elevated
6) Blood biochemistry.
Spirometry is difficult to perform during an exacerbation and it may not be of enough accuracy. Therefore it is not recommended.

Treatment:
More than 80% of cases can be managed as outpatients but if the following conditions are seen, it is better to admit and if necessary give intensive care:
1) Dyspnea occurring at rest
2) Old age
3) Frequent exacerbator
4) Failure of response to change in/addition of medication to control the exacerbation
5) New onset of arrhythmias or peripheral edema.


Medical therapy consists of:
1) Short acting inhaled bronchodilators – beta-2 agonists with or without anti-cholinergics are preferred. It is better to use a nebulizer as the patient usually is dyspneic and lacks coordination to inhale from a metered-dose inhaler. IV methylxanthines are considered as second line of therapy for bronchodilation and are to be used only in selected cases, especially if there is poor response to short acting inhaled bronchodilators.
2) Corticosteroids – oral prednisone 40 mg/day for 5 days has been shown to shorten recovery time and improve lung function as well as arterial hypoxemia.
3) Antibiotics – these are indicated if the patient has clinical signs of bacterial infections e.g. increased in sputum purulence.  Procalcitonin III may help to indicate antibiotic therapy as it is increased in cases of bacterial infections. Usually in the following conditions antibiotics should be considered:
- 3 cardinal symptoms present: increase in dyspnea, sputum volume and sputum purulence,
- 2 cardinal symptoms, with purulence being one of the symptoms,
Antibiotics are recommended for 5-10 days.
4) Adjunct therapies – proper control of comorbidities is advised. Thromboprophylactic measures should be enhanced.

Respiratory support:
1) Oxygen therapy: Oxygen is titrated to correct the hypoxemia of the patient aiming to achieve a saturation of 88-92%. Usually Venturi masks are preferred to nasal prongs. After 30-60 minutes of oxygen therapy, arterial blood gases should be checked.
2) Non-invasive mechanical support
3) Invasive mechanical support.

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