Status asthmaticus

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Lakshmi Gopalakrishnan, M.B.B.S. [2]

Overview

Status asthmaticus is an acute exacerbation of asthma that does not respond to standard bronchodilator and corticosteroid therapy. Symptoms include chest tightness, rapidly progressive dyspnea, non-productive cough and wheezing. Status asthmaticus if left untreated may result in severe bronchospasm, mucus plugging and rapidly develops acidosis and respiratory failure as a consequent of carbon di oxide retention and hypoxemia.

Epidemiology

Approximately 10% of the US population is affected by asthma and an increased prevalence of 60% is observed in all age groups, with status asthmaticus requiring the highest rates of hospitalization.[1]

Predisposing factors

  • Increase use of bronchodilator despite resistance,
  • Frequent exacerbations despite the use of corticosteroids,
  • Despite adhering to therapy, a peak flow rate of less than 10% from baseline,
  • Frequent hospitalization for acute attacks,
  • History of syncope or seizure during an acute asthmatic attack,
  • Oxygen saturation lower than 92% despite supplemental oxygen,
  • Airway obstruction is significantly reduced, resulting in severe impairment of air motion that leads to a silent chest with the absence of wheeze suggestive of an imminent respiratory arrest.

Diagnosis

History and Symptoms

Physical Examination

Vital Signs

General Physical Examination

  • Sit upright with arms extended to support the upper chest (tripod position) that assists the use of accessory muscles of respiration
  • Peak flow rate measurement is a simple bedside method to assess the severity of airway obstruction. A red zone indicates less than 50% of the usual or normal peak flow reading signifying a severe airway obstruction.

Respiratory Examination

Inspection
  • Use of accessory muscles of respiration such as sternocleidomastoid and scalene muscles, correlates with the disease severity
  • Intercostal retractions
  • Paradoxical thoraco-abdominal breathing
Auscultation
  • High-pitch prolong polyphonic expiratory wheeze
  • Bilateral crackles
  • Air entry may or may not be reduced depending on the disease severity
  • Absence of wheeze and breath sounds secondary to severe airway obstruction may represent a silent chest which is an ominous sign of imminent respiratory failure.

Cardiovascular Examination

Progressive untreated airway obstruction and increased work of breathing eventually leads to worsening hypoxemia, hypercarbia and increased air trapping with compromised stroke volume that results in bradycardia, hypotension, hypoventilation and subsequent cardiorespiratory arrest.

Neurological Examination

  • Level of consciousness ranges from lethargy, agitation to even loss of consciousness or seizure, secondary to severe airway obstruction, hypoxia and carbon-di-oxide retention.
  • Unable to speak in full sentences

Laboratory Tests

  • Measurement of oxygen saturation by pulse oximetry may be useful to identify patients with acute severe asthma who may rapidly progress to respiratory failure and thereby require more intensive therapy.[2]

Pulmonary Function Test

FEV1 lower than 60% predicted is strongly suggestive of severe airway obstruction

ECG

The presence of supraventricular tachycardia on ECG should raise a suspicion of theophylline toxicity.

Imaging Modalities

High-resolution CT may reveal several structural changes related to small-airway disease including cylindrical bronchiectasis, bronchial wall thickening, and air trapping.[3]

References

  1. Gorelick M, Scribano PV, Stevens MW, Schultz T, Shults J (2008) Predicting need for hospitalization in acute pediatric asthma. Pediatr Emerg Care 24 (11):735-44. DOI:10.1097/PEC.0b013e31818c268f PMID: 18955910
  2. Overall JE (1975) Rating session. Video taped interviews and BPRS ratings. Psychopharmacol Bull 11 (1):15. PMID: 1121560
  3. Robards VL, Lubin EN, Medlock TR (1975) Renal transplantation and placement of ileal stoma. Urology 5 (6):787-9. PMID: 1094668


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