Which statement best describes the effect of noninvasive ventilation on gas exchange in acute respiratory failure?

• A. NIV always prevents intubation.
• B. NIV worsens gas exchange.
• C. NIV improves ventilation and gas exchange by reducing work of breathing; if there is no improvement, escalate to invasive ventilation.
• D. NIV has no effect on work of breathing.

Answer: (C)

Noninvasive ventilation improves gas exchange primarily by unloading the work of breathing. By delivering positive pressure during inspiration and maintaining some end-expiratory pressure, NIV augments tidal volume and alveolar ventilation, which helps remove CO2 and improve oxygenation. As the patient’s respiratory muscles work less, there’s a reduction in tachypnea and the overall oxygen delivery and CO2 clearance tend to improve. If the patient shows a real early response—better oxygenation, lower CO2, and softer breathing—continue NIV and monitor closely. If there’s no meaningful improvement or the patient worsens (increasing work of breathing, persistent hypoxemia or hypercapnia, signs of fatigue or hemodynamic instability), it’s appropriate to escalate to invasive ventilation to secure the airway and provide more controlled support.