# Permissive Hypoxemia With Partial Pressure of Oxygen in Arterial Blood (PaO2) at Less Than 50 mmHg: A Case of Successful Ventilator Weaning for COVID-19-Associated Acute Respiratory Failure

## TL;DR

A 70-year-old woman with severe COVID-19 lung failure was successfully weaned off a ventilator using a strategy that allowed low blood oxygen levels.

## Contribution

This case report presents a rare successful outcome using permissive hypoxemia with PaO2 below 50 mmHg in an adult with severe respiratory failure.

## Key findings

- A permissive hypoxemia strategy with PaO2 below 50 mmHg was successfully used to wean a patient from mechanical ventilation.
- The patient was discharged home three weeks after admission without complications.
- The case supports the use of individualized lung-protective strategies over rigid oxygenation targets in severe respiratory failure.

## Abstract

Permissive hypoxemia is a ventilation strategy that intentionally tolerates mild to moderate hypoxemia to minimize lung injury. Unlike conventional management, which aims for normal oxygen levels, permissive hypoxemia maintains a partial pressure of oxygen in arterial blood (PaO2) of 55-60 mmHg and an arterial oxygen saturation (SaO2) of 88-92%. This approach ensures sufficient oxygen delivery for vital functions while reducing mechanical stress on the lungs from high oxygen concentrations and airway pressures, which can lead to lung injury. This flexible, individualized strategy prioritizes lung protection over achieving absolute oxygenation values.

A woman in her 70s, with COVID-19-associated pneumonia, was admitted with severe acute respiratory failure and required mechanical ventilation. Despite a lung-protective ventilation strategy, her oxygenation remained poor. A permissive hypoxemia strategy was reluctantly initiated, which allowed her PaO2 to drop below 50 mmHg. Under strict monitoring of her symptoms, vital signs, and lactate levels, she was successfully weaned from mechanical ventilation without her respiratory status or other organ systems worsening.

The patient was discharged home walking approximately three weeks after admission, with no other complications. To our knowledge, few reports have described an adult patient who successfully tolerated a PaO₂ below 50 mmHg. This case underscores the importance of a rigorous selection of patients and a comprehensive assessment of their overall condition. It demonstrates that a personalized approach, rather than simply adhering to a high oxygenation target, can lead to successful outcomes in severe respiratory failure, affirming that cautious and well-considered attempts in challenging cases are worthwhile.