Question

A critically ill patient with COVID-19 is admitted to the ICU and is currently on mechanical ventilation. The \(PaO_2/FiO_2\) ratio is 100, indicating severe ARDS. Which of the following is the most appropriate ventilatory strategy?

• A. High PEEP and low tidal volume
• B. High PEEP and high tidal volume
• C. Low PEEP and low tidal volume
• D. Low PEEP and high tidal volume

Hint:

ARDS ventilation = low tidal volume plus adequate/high PEEP.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The patient has severe Acute Respiratory Distress Syndrome (ARDS) secondary to COVID-19. We need to identify the lung-protective ventilation strategy used in ARDS.
Step 2: Detailed Explanation:

Lung Protective Ventilation: ARDS causes diffuse alveolar damage and "baby lung" (the volume of functional, aerated lung is small). High tidal volumes can cause "volutrauma" (overdistention of alveoli).

Low Tidal Volume (LTVV): ARDSNet protocols recommend a tidal volume of 6 mL/kg of predicted body weight. This reduces mortality compared to traditional high tidal volumes (12 mL/kg).

Positive End-Expiratory Pressure (PEEP): In ARDS, many alveoli collapse (atelectasis). High PEEP is used to "recruit" these collapsed alveoli, keeping them open throughout the respiratory cycle to improve oxygenation and prevent "atelectrauma" (repetitive opening and closing).

P/F Ratio: A ratio of 100 indicates severe ARDS. In such cases, higher PEEP levels are typically required to maintain adequate oxygenation (PaO$_2$).

Summary: The combination of low tidal volume to prevent overdistension and high PEEP to maintain recruitment is the standard of care for severe ARDS.

Step 3: Final Answer:
The optimal strategy is high PEEP and low tidal volume to maximize oxygenation while minimizing barotrauma and volutrauma.