Which condition indicates that CPAP or PEEP may be needed?

Severe hypoxemia indicates that CPAP (Continuous Positive Airway Pressure) or PEEP (Positive End-Expiratory Pressure) may be necessary. When a patient experiences severe hypoxemia, it means their blood oxygen levels are critically low, potentially leading to severe respiratory distress and inadequate oxygenation of tissues. In such situations, the application of CPAP or PEEP can help improve oxygenation by maintaining airway patency and preventing the collapse of alveoli during exhalation, thereby increasing functional residual capacity.

By providing continuous positive pressure, these interventions enhance ventilation-perfusion matching, improve overall lung mechanics, and facilitate better gas exchange. This is crucial in managing conditions like acute respiratory distress syndrome (ARDS) or other forms of acute respiratory failure, where traditional oxygen therapies may not sufficiently correct the hypoxemia.

In contrast, respiratory alkalosis may indicate hyperventilation but does not necessarily warrant the need for CPAP or PEEP. Normal oxygen levels do not justify the use of these interventions, as the patient's respiratory status is stable. Mild hypoxemia may still allow for other therapeutic measures to be explored before considering CPAP or PEEP, as aggressive intervention might not be immediately necessary.