From the Guidelines
Respiratory failure in asthmatic patients is indicated by signs of impending respiratory failure, including an inability to speak, altered mental status, intercostal retraction, worsening fatigue, and a PaCO2 of 42 mm Hg or greater, as recommended by the Expert Panel report 3 guidelines for the management of asthma exacerbations 1.
Key Indications of Respiratory Failure
- Inability to speak
- Altered mental status
- Intercostal retraction
- Worsening fatigue
- PaCO2 of 42 mm Hg or greater These signs are critical for early recognition and treatment of respiratory failure in asthmatic patients, as delayed intubation can result in complications 1.
Additional Signs of Severe Asthma
Other studies have identified additional signs of severe asthma, including:
- Cannot complete sentence in one breath
- Silent chest, cyanosis, feeble respiratory effort
- Respirations >25/min
- Pulse >110 beats/min
- Bradycardia or hypotension
- Exhaustion, confusion, or coma 1 However, the most recent and highest quality study, 1, prioritizes the signs of impending respiratory failure as the primary indicators of respiratory failure in asthmatic patients.
Importance of Early Recognition and Treatment
Early recognition and treatment of respiratory failure in asthmatic patients are crucial to prevent complications and improve outcomes 1. The Expert Panel recommends that intubation not be delayed once it is deemed necessary, and other treatments, such as intravenous magnesium, heliox, and other treatments, may be attempted in severe cases 1.
From the FDA Drug Label
If a previously effective dosage regimen fails to provide the usual relief, medical advice should be sought immediately, as this is often a sign of seriously worsening asthma that would require reassessment of therapy.
The indications of respiratory failure in asthmatic patients are not directly stated in the provided drug label. However, a sign of seriously worsening asthma is when a previously effective dosage regimen fails to provide the usual relief, which may be an indirect indication of potential respiratory failure.
- Key points to consider are:
- Failure of a previously effective treatment
- Seriously worsening asthma symptoms The FDA drug label does not answer the question.
From the Research
Indications of Respiratory Failure in Asthmatic Patients
The indications of respiratory failure in asthmatic patients can be identified through various clinical and physiological correlates. Some of the key indicators include:
- Accessory muscle use, which may be a sign of severe airflow obstruction 2, 3
- Pulsus paradoxus, a condition where there is a significant decrease in blood pressure during inspiration, which can be a sign of severe asthma 2, 3
- Refusal to recline below 30°, which can indicate severe respiratory distress 2, 3
- A pulse rate of >120 beats/min, which can be a sign of severe asthma and potential respiratory failure 2, 3
- Decreased breath sounds, which can indicate severe airflow obstruction 2, 3
- Hyperinflation of the thorax, which can be a sign of acute severe asthma 4
- Stridulous breathing, which can be a sign of severe airway obstruction 4
- Tachycardia, which can be a sign of severe asthma and potential respiratory failure 4
- Tachypnea, which can be a sign of severe asthma and potential respiratory failure 4
Physiological Correlates
Some of the key physiological correlates of respiratory failure in asthmatic patients include:
- Forced expiratory volume in 1 second (FEV1) of approximately 30% of expected values 4
- Peak flow of approximately 20% of expected values 4
- Residual volume of approximately 40% of expected values 4
- Pulse oximetry values of <90%, which can indicate hypoxemia 2, 3
- CO2 retention, which can be a sign of respiratory failure 2, 3
Management of Respiratory Failure
The management of respiratory failure in asthmatic patients involves intensive pharmacological therapy, particularly with beta-adrenoceptor agonists and corticosteroids 5. In patients requiring mechanical ventilation, the strategy aims to avoid dynamic hyperinflation by enhancing expiratory time to allow complete exhalation 5. Sedation with opioids, benzodiazepines, or propofol may be required to facilitate ventilator synchrony, but neuromuscular blockade should be avoided due to the risk of myopathy 5.