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Right-to-left interatrial shunt in ARDS: dramatic improvement in prone position
A Legras1, P F Dequin, E Hazouard
1Service de Réanimation médicale, Hôpital Bretonneau, Tours, France.
Intensive Care Medicine
|May 26, 1999
Summary
Patients with patent foramen ovale and severe ARDS experienced improved oxygenation when placed in the prone position. This positional change reduced right-to-left shunting, enhancing blood oxygen levels.
Area of Science:
- Cardiology
- Pulmonology
- Critical Care Medicine
Background:
- Patent foramen ovale (PFO) can cause right-to-left atrial shunting, exacerbated by increased right-sided cardiac pressures or respiratory factors.
- Platypnea-orthodeoxia syndrome involves anatomical changes in the right atrium contributing to shunting.
- Severe ARDS presents significant hypoxemia challenges in critically ill patients.
Observation:
- A patient with ARDS secondary to invasive fungal infection and a history of PFO with paradoxical embolisms developed severe respiratory failure.
- Despite mechanical ventilation and antifungal therapy, the patient's hypoxemia persisted.
- The patient was repositioned to the prone position, leading to a dramatic improvement in blood gas values.
Findings:
- Transcranial Doppler with bubble study confirmed a massive right-to-left shunt in the supine position.
- The right-to-left shunt significantly decreased upon transitioning to the prone position.
- Arterial oxygen tension/fractional inspired oxygen ratio improved from 59 to 278 torr after prone positioning.
Implications:
- Prone positioning may reduce right-to-left shunting in patients with PFO and severe ARDS.
- This reduction in shunting could be a key mechanism for improved oxygenation in the prone position for these patients.
- Further investigation into the hemodynamic effects of prone positioning in PFO patients with ARDS is warranted.