Dictionary of Allergies .. Recognition of severe asthma

Recognition of severe asthma, Αναγνώριση του σοβαρού άσθματος. Asthma prevalence and mortality have been increasing over the past 2 decades, despite advances in medical therapy. In 2003 the National Health Interview Survey reported over 4,000 asthma-related deaths. A small proportion of people with severe asthma use a large proportion of health-care resources and bear the burden of asthma-related morbidity and mortality. The management of acute asthma is complex and evolving. Understanding the phenotypes and pathophysiology of acute asthma will lead to increased recognition and characterization of populations at risk for fatal asthma. The early identification and appropriate management of acute asthma is critical in decreasing asthma morbidity and mortality.

Near-fatal asthma continues to be a significant problem despite the decline in overall asthma mortality[1]. Acute severe asthma is challenging to the clinician both in terms of recognition and appropriate treatment. About 30% of these episodes need admission to the medical intensive care unit with a mortality of 8%.

Relapse rates vary from 7 to 15% depending on how well the patient is managed[2]. Two distinctive phenotypes of near-fatal asthma have been identified: one with eosinophilic inflammation associated with a gradual onset and a slow response to therapy and a second phenotype with neutrophilic inflammation that has a rapid onset and rapid response to therapy. Patients who develop sudden-onset near-fatal asthma seem to have massive allergen exposure and emotional distress. In stable condition, near-fatal asthma frequently cannot be distinguished from mild asthma. Diminished perception of dyspnea plays a relevant role in treatment delay, near-fatal events, and death in patients with severe asthma.

Reduced compliance with anti-inflammatory therapy and ingestion of medications or drugs (heroin, cocaine) have been associated with fatal or near-fatal asthma[1].

Severe asthma can be recognized if there is: 1) Evidence for severe airflow obstruction (prolonged expiratory phase of respiration, use of accessory muscles, radiographic evidence of hyperinflation, pulsus paradoxus  2) Evidence of tissue hypoxia: (cyanosis, arterial oxygen saturation >90%, mental status changes, tachycardia, and EKG abnormalities. 3) Evidence of respirator muscle fatigue (exhaustion, paradoxical diaphragmatic movement and CO2 retention).

References

Restrepo RD, Peters J. Near-fatal asthma: recognition and management. Curr Opin Pulm Med. 2008 Jan;14(1):13-23.

2. Kaza V, Bandi V, Guntupalli KK. Acute severe asthma: recent advances. Curr Opin Pulm Med. 2007 Jan;13(1):1-7