Assessment of Rest Hypoxemia: Is there a Place for the 100% Oxygen Test for Pathological Shunt Detection?

F Bregeon

doi:10.26717/bjstr.2020.29.004871

Abstract

A Sow1,2*, J Finance1,3*, A Boussuges1,4, S Delliaux1,5, J Guinde1, PA Thomas3,6, M Reynaud-Gaubert3,7 and F Bregeon1,3* Author Affiliations 1Service des Explorations FonctionnellesRespiratoires Centre Hospitalo-Universitaire Nord, Pôlethoracique et cardio-vasculaire, France 2Laboratoire de Physiologie et d’ExplorationsFonctionnelles, Faculté de Médecine, de Pharmacie et d’Odontologie de l’Université Cheikh Anta Diop, Sénégal 3Aix-Marseille Université, IRD, MEPHI, IHU Méditerranée Infection, France 4Institut de Recherche Biomédicale des Armées (IRBA), Brétigny sur Orge 5INSERM, INRA, C2VN, Aix Marseille Université, France 6Department of Thoracic Surgery and Esophageal Diseases, Hôpital Nord, Assistance Publique-Hôpitaux de Marseille, Aix-Marseille University, France 7Service des Maladies RespiratoiresRares, Mucoviscidose, Pneumologie, Hôpital Nord, Assistance Publique-Hôpitaux de Marseille, Aix- Marseille University, France Received: August 13, 2020 | Published: August 31, 2020 Corresponding author: F Bregeon, Service des Explorations FonctionnellesRespiratoires Centre Hospitalo-Universitaire Nord, Pôlethoracique et cardio-vasculaire, Aix-Marseille Université, IRD, MEPHI, IHU Méditerranée Infection, France J Finance, Service des Explorations FonctionnellesRespiratoires Centre Hospitalo-Universitaire Nord, Pôlethoracique et cardiovasculaire, Aix-Marseille Université, IRD, MEPHI, IHU Méditerranée Infection, France DOI: 10.26717/BJSTR.2020.29.004871

Highlights

Rest hypoxemia can be attributed to alteration of lung oxygenation function inducing abnormal distribution of the ventilation perfusion ratio (VA/Q) or disorders of the alveolarcapillary diffusion [1] leading to a shunt effect called functional shunt
When compared to a predicted exploration strategy based on shunt value and Pulmonary Functional Tests (PFTs) abnormalities, the actual exploration strategy showed good concordance in Hyperoxia Test (HT)- patients and some discrepancies in HT+ ones, but most of the time, there was a clinical reason to explain why a HT+ patients was no further investigated with echocardiography
HT appeared as an easy–to-do diagnostic tool in hypoxemic patients that could help to rule out pathologic shunt and to screen those eligible for more complex specialized exploration

Summary

Introduction

Rest hypoxemia can be attributed to alteration of lung oxygenation function inducing abnormal distribution of the ventilation perfusion ratio (VA/Q) or disorders of the alveolarcapillary diffusion [1] leading to a shunt effect called functional shunt. When rest hypoxemia associates with normal or moderately altered Pulmonary Functional Tests (PFTs) results and normal imaging results of lung parenchyma, one should evoke an anatomic shunt. Even a shunt effect seems explained by abnormal PFTs, hypoxemia can lead to elevated lung arterial resistances, and right-sided pressures favoring Patent Foramen Ovale (PFO) anatomic and functional shunts can coexist and may interfere [2,3] on blood oxygenation, as possibly observed in COPD patients, Pulmonary Hypertension (PH), in sleep apnea disorders or in patients with unexplained refractory hypoxemia. The Hyperoxia Test (HT) has been proposed to quantify the shunt fraction but it is often requested as a first-line diagnostic tool, without clear guidelines on its place in the strategy for diagnosing hypoxemia

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