Which indication justifies the use of FiO2 1.0 on a patient?

The use of FiO2 1.0, or 100% oxygen, is often justified in situations where there is a need to quickly address severe hypoxia or establish a high level of oxygenation in critical circumstances. In the context of a pulmonary embolism, the blood flow to the lungs is obstructed, which can lead to significant ventilation/perfusion (V/Q) mismatch and critical oxygenation issues. Administering 100% oxygen can help improve arterial oxygen saturation and alleviate hypoxemia until further interventions can be performed.

In cases of ventilatory failure or impending ventilatory failure, while some form of supplemental oxygen may be necessary, it generally does not require the immediate administration of 100% oxygen unless there is also an acute hypoxemia that must be addressed. Conditions like myasthenia gravis may lead to respiratory muscle weakness, but the use of 100% oxygen would not specifically target the underlying issue effectively without addressing the ventilatory aspect.

Hence, in patients with pulmonary embolism, the immediate goal is to maximize oxygen delivery and also to provide oxygen in case of severe hypoxemia, making the administration of FiO2 1.0 a suitable choice for such acute management.