Effects of short-term hyperoxia on erythropoietin levels and microcirculation in critically Ill patients: a prospective observational pilot study.

Abstract

BACKGROUND:

The normobaric oxygen paradox states that a short exposure to normobaric hyperoxia followed by rapid return to normoxia creates a condition of 'relative hypoxia' which stimulates erythropoietin (EPO) production. Alterations in glutathione and reactive oxygen species (ROS) may be involved in this process. We tested the effects of short-term hyperoxia on EPO levels and the microcirculation in critically ill patients.

METHODS:

In this prospective, observational study, 20 hemodynamically stable, mechanically ventilated patients with inspired oxygen concentration (FiO2) ≤0.5 and PaO2/FiO2 ≥ 200 mmHg underwent a 2-hour exposure to hyperoxia (FiO2 1.0). A further 20 patients acted as controls. Serum EPO was measured at baseline, 24 h and 48 h. Serum glutathione (antioxidant) and ROS levels were assessed at baseline (t0), after 2 h of hyperoxia (t1) and 2 h after returning to their baseline FiO2 (t2). The microvascular response to hyperoxia was assessed using sublingual sidestream dark field videomicroscopy and thenar near-infrared spectroscopy with a vascular occlusion test.

RESULTS:

EPO increased within 48 h in patients exposed to hyperoxia from 16.1 [7.4-20.2] to 22.9 [14.1-37.2] IU/L (p = 0.022). Serum ROS transiently increased at t1, and glutathione increased at t2. Early reductions in microvascular density and perfusion were seen during hyperoxia (perfused small vessel density: 85% [95% confidence interval 79-90] of baseline). The response after 2 h of hyperoxia exposure was heterogeneous. Microvascular perfusion/density normalized upon returning to baseline FiO2.

CONCLUSIONS:

A two-hour exposure to hyperoxia in critically ill patients was associated with a slight increase in EPO levels within 48 h. Adequately controlled studies are needed to confirm the effect of short-term hyperoxia on erythropoiesis.

TRIAL REGISTRATION:

ClinicalTrials.gov ( www.clinicaltrials.gov ), NCT02481843 , registered 15th June 2015, retrospectively registered.

• Authors: Abele Donati, Elisa Damiani, Samuele Zuccari, Roberta Domizi, Claudia Scorcella, Massimo Girardis, Alessia Giulietti, Arianna Vignini, Erica Adrario, Rocco Romano, Laura Mazzanti, Paolo Pelaia, Mervyn Singer
• Journal: BMC anesthesiology (BMC Anesthesiol) Vol. 17 Issue 1 Pg. 49 (03 23 2017) ISSN: 1471-2253 [Electronic] England
• PMID: 28335733 (Publication Type: Journal Article, Observational Study)

Chemical References

• Reactive Oxygen Species
• Erythropoietin
• Glutathione

Topics

• Aged
• Aged, 80 and over
• Case-Control Studies
• Critical Illness
• Erythropoietin (blood)
• Female
• Glutathione (blood)
• Hemodynamics (physiology)
• Humans
• Hyperoxia (blood, physiopathology)
• Male
• Microcirculation (physiology)
• Microscopy, Video
• Middle Aged
• Pilot Projects
• Prospective Studies
• Reactive Oxygen Species (blood)
• Spectroscopy, Near-Infrared