For a patient with mycoplasma pneumonia on volume-controlled ventilation and a PaO2 of 58 torr, what should be recommended first to improve oxygenation?

• A. Increase FIO2 to 1.0
• B. Administer tetracycline
• C. Switch to pressure-controlled ventilation
• D. Increase PEEP to 20 cm H2O

Answer: (D)

In patients with mycoplasma pneumonia experiencing hypoxemia, optimizing oxygenation is a priority. Increasing positive end-expiratory pressure (PEEP) can enhance oxygenation by recruiting collapsed or under-ventilated alveoli, thereby increasing functional residual capacity and improving the surface area available for gas exchange. This can help to improve the patient's PaO2 levels more effectively than merely increasing the fraction of inspired oxygen (FIO2) alone.

Higher levels of PEEP help prevent the collapse of alveoli during exhalation, which is particularly beneficial in patients with pneumonia, where atelectasis can significantly impair gas exchange. In this scenario, increasing PEEP to 20 cm H2O aims to enhance lung recruitment and improve overall oxygenation status.

Other options, such as increasing FIO2 to 1.0, might seem immediate but do not address the underlying issue of lung mechanics and could lead to oxygen toxicity if used excessively. The use of antibiotics like tetracycline is vital for treating the infection but does not provide immediate improvement in oxygenation. Switching to pressure-controlled ventilation may aid in reducing the risk of barotrauma or over-distension but does not directly address the hypoxemia in this case as effectively as optimizing P