Is BIPAP (Bilevel Positive Airway Pressure) indicated in acute severe asthma?

BIPAP in Acute Severe Asthma

BIPAP is not routinely recommended for acute severe asthma due to insufficient evidence supporting its efficacy for improving mortality or intubation rates, though it may be considered in select patients not responding to standard medical therapy. 1

Evidence Assessment

The 2017 European Respiratory Society/American Thoracic Society (ERS/ATS) clinical practice guidelines explicitly state they are "unable to offer a recommendation on the use of NIV for ARF due to asthma" due to uncertainty in the evidence 1. This position is based on pooled analyses showing:

• Unclear effect on mortality
• Uncertain impact on intubation rates (RR 4.48,95% CI 0.23–89.23; very low certainty)
• No significant effect on ICU length of stay

While some physiological improvements were noted with NIV:

• Improved FEV1 (mean difference 14.02 higher, 95% CI 7.73–20.32)
• Improved peak expiratory flow (mean difference 19.97 higher, 95% CI 15.01–24.93)

Standard Treatment Approach for Acute Severe Asthma

The established treatment algorithm for acute severe asthma focuses on:

1. High-flow oxygen (40-60%) 1
2. Nebulized β-agonists (salbutamol 10 mg or terbutaline 5 mg) 1
3. Systemic corticosteroids (prednisolone 30-60 mg or IV hydrocortisone 200 mg) 1
4. Ipratropium bromide (0.5 mg nebulized, repeated 6-hourly) 1
5. Continuous monitoring of PEF, oxygen saturation, and blood gases 1

Potential Role of BIPAP in Select Patients

Despite the lack of strong evidence, BIPAP might be considered in specific circumstances:

• In a small subgroup of patients not responding well to standard medical therapy 1
• In patients with asthma who have features resembling COPD (fixed airway obstruction) 1
• When there is a need to avoid intubation in a deteriorating patient 1

A retrospective cohort study across 97 US hospitals showed that NIV was used in only 4% of asthma admissions, with a failure rate (requiring intubation) of 4.7%. Hospital mortality was 2.3% in those who succeeded on NIV versus 15.4% in those who failed NIV and required intubation 1.

Practical Considerations If Using BIPAP

If BIPAP is attempted in select cases:

1. Apply in an ICU or high-dependency setting with close monitoring
2. Ensure capability for immediate intubation if needed
3. Use bilevel positive airway pressure to provide:
   • Airway stenting
   • Optimal oxygen delivery
   • Decreased work of breathing 2

Cautions and Contraindications

BIPAP should be avoided in patients with:

• Decreased level of consciousness
• Inability to protect airway
• Severe respiratory distress requiring immediate intubation
• Hemodynamic instability

When to Consider Intubation

Transfer to ICU and prepare for intubation if there is 1:

• Deteriorating PEF
• Worsening or persistent hypoxia
• Confusion or drowsiness
• Exhaustion, coma, or respiratory arrest

Conclusion

While some small studies suggest physiological benefits of BIPAP in asthma 3, 4, current guidelines do not support its routine use due to insufficient evidence of benefit for critical outcomes like mortality and intubation rates. Standard medical therapy remains the cornerstone of management for acute severe asthma, with BIPAP potentially considered only in select patients under close monitoring.