• Bronchospasm causes constriction of the bronchi's smooth muscles, leading to narrowed airways and is characterized by airway inflammation, coughing and generalized wheezing.
• In severe cases, air movement, especially during exhalation, may be significantly reduced, resulting in limited wheezing, air trapping, and increased respiratory secretions, causing mucus plugging.
• More time spent in the exhalation phase increases the inspiration-to-expiration ratio (I:E) and is a sign of bronchospasm
• Bronchospasm impairs ventilation, leading to potential oxygenation issues not solely due to oxygen exchange failure but often due to inadequate alveolar ventilation.
• In severe asthma cases, there's a risk of critically high carbon dioxide (CO₂) levels due to reduced ventilation. Key signs of worsening respiratory function include diminished breath sounds, reduced effort, fatigue, altered consciousness, and a dropping respiratory rate, indicating imminent respiratory failure
• Breath stacking in severe asthma refers to a dangerous situation where a patient is unable to fully exhale before taking another breath. This leads to increased lung volume with each successive breath, as air gets trapped in the lungs due to severe airway obstruction.

Not all wheezing is asthma, and not all asthma wheezes. Beware the silent chest.

• Bronchodilator therapy, including salbutamol and ipratropium-bromide, improves clinical outcomes for bronchospasm. Salbutamol and ipratropium can be co-administered in the same nebulizer. Deliver bronchodilator therapy via the most appropriate method, MDI or nebulizer.
• Administer intramuscular epinephrine in cases of severe bronchospasm or if respiratory arrest is imminent to open the airways and provide relief quickly. Intravenous epinephrine is for ACP use and should be used in severe bronchospasm or if respiratory arrest is imminent. Epinephrine, as an adrenergic agonist, can produce dramatic bronchodilation in critically ill patients.
• Glucocorticoids (i.e., dexamethasone) can be given in cases of acute asthma exacerbations where a patient does not show sustained improvement or worsens after one bronchodilator, or has a history of severe or recurrent exacerbations. If the first round of salbutamol and ipratropium do not provide sustained improvement and repeat salbutamol is required, dexamethasone should be included in the treatment plan.
• Magnesium sulfate is for ACP use and, given intravenously, can produce bronchodilation through the relaxation of smooth muscle.
• Continuous Positive Airway Pressure (CPAP) is an option for optimizing oxygenation in patients who have already received bronchodilator therapy.

Cardiac arrest considerations: For all asthmatic patients in cardiac arrest, and especially for patients in which ventilation is complex, the possible diagnosis of tension pneumothorax should be carefully considered and treated with extreme caution. In addition, MDI delivery of salbutamol can be considered during ventilation after cardiac arrest procedures are well-established (i.e., high-quality CPR, defibrillation).

• Consider the risk of infectious disease exposure when performing interventions that produce aerosols.  Nebulized medications should be given with caution to patients with a fever and a history of a respiratory illness.  Use appropriate PPE as necessary.  Applying a surgical mask over a nebulizer is not an effective reverse isolation technique.
• Bronchospasm is a disease of ventilation.  Although the oxygen saturation may be low, this is a result of alveolar hypoventilation and does not necessarily represent a fundamental failure of oxygen uptake or delivery.  Do not over-focus on oxygenation to the exclusion of ventilation.  Recall that the elimination of carbon dioxide from the body depends on minute ventilation (which is in turn based on tidal volume and respiratory rate).  Critical hypercarbia can develop in acute severe asthma; the patient’s level of consciousness and respiratory effort must be monitored closely and aggressive action taken to support ventilation if deterioration becomes evident.
• Signs of impending respiratory failure include decreased air entry and respiratory effort, fatigue, decreasing level of consciousness, and declining respiratory rate.
• Salbutamol often provokes coughing and may temporarily worsen audible bronchospasm.  Allow the nebulized medication to run its course before making additional treatment decisions unless the patient is deteriorating rapidly.  In some cases, continuous nebulizer therapy can be beneficial in optimizing drug delivery to the tissues of the bronchi and should be considered if the patient continues to be significantly short of breath, but able to ventilate effectively, following the initial dose of salbutamol. 
• Ipratropium is an anticholinergic agent that reduces airway secretions and acts synergistically with salbutamol as a bronchodilator.  Its activity is limited to the lung parenchyma and there is little risk of systemic toxicity. 

Refusal of care instructions and guidelines must be followed for patients who decline to be taken to hospital. 

• Signs of acute severe asthma include tachypnea (> 30 breaths/minute), tachycardia, accessory muscle use during inspiration, diaphoresis, the inability to speak in full sentences, and the inability to lie supine.  Note that not all patients with severe bronchospasm will exhibit these signs.
• Patients with bronchospasm typically have a prolonged expiratory phase, often 2-3 times longer than their inspiratory phase; this is the result of the effort required to exhale against the constricted airways.  In the absence of audible wheezes in a patient who is visibly short of breath, consider the inspiratory-expiratory ratio as an additional piece of information. 
• Obtaining a medical history from an acutely short of breath patient can be difficult.  It is critical to ask concised, targeted questions to maximize the information return, and to minimize exertion for the patient.  Investigations should be tailored towards developing an understanding of the potential for deterioration as opposed to solely establishing the severity of the disease.  Severity directs the intensity of intervention, whereas a history helps predict the likely course or potential for exacerbations.  
  • WHIPS is a mnemonic to help direct a clinical history for bronchospasm:
    • Worst you've ever had?
    • Hospital visits?
    • ICU stays?
    • Puffer requirements?
    • Steroid requirements? 
• Questions should be formulated so that the patient can answer with single words or head movements.  
  • Past medical history considerations
    • Hospital visits or admissions for asthma: number of previous visits or admissions; frequency of visits or admissions.
  • Current prescription drug use
    • Use of corticosteroids
    • Use of bronchodilators
    • Changes to medication doses or frequency
• A history of repeated hospital visits for asthma, with or without a concurrent history of increasing bronchodilator use, is predictive for severe disease and places the patient at risk for heightened mortality.

Asthma

Respiratory Distress NYD

1. Fanta CH, et al. Acute exacerbations of asthma in adults: Home and office management. UpToDate. 2021.
2. Wenzel S. et al. Treatment of severe asthma in adolescents and adults. UpToDate. 2021.

• 2023-09-29: updated EMR and PCP interventions to add salbutamol (EMR) and ipratropium, dexamethasone (PCP)
• 2023-12-18: removed COVID-related restrictions, added information about BCEHS Respiratory Assessment Course