Retinal oximetry measures systemic hypoxia in central nervous system vessels in chronic obstructive pulmonary disease

Abstract

BackgroundDetermination of the blood oxyhemoglobin saturation in the retinal vessels of the eye can be achieved through spectrophotometric retinal oximetry which provides access to the state of oxyhemoglobin saturation in the central nervous system circulation. The purpose of this study was to test the capability of the Oxymap T1 oximeter to detect systemic hypoxemia and the effect of supplemental oxygen on retinal vessel oxyhemoglobin saturation.MethodsOxygen saturation of hemoglobin in retinal arterioles and venules was measured in 11 subjects with severe chronic obstructive pulmonary disease (COPD) on long term oxygen therapy. Measurements were made with and without their daily supplemental oxygen. Eleven healthy age and gender matched subjects were measured during ambient air breathing for comparison of oxyhemoglobin saturation in retinal arterioles and venules. Retinal arteriolar oxyhemoglobin saturation in COPD subjects inspiring ambient air was compared with finger pulse oximetry and blood samples from radial artery.ResultsCOPD subjects had significantly lower oxyhemoglobin saturation during ambient air breathing than healthy controls in both retinal arterioles (87.2%±4.9% vs. 93.4%±4.3%, p = 0.02; n = 11) and venules (45.0%±10.3% vs. 55.2%±5.5%, p = 0.01). Administration of their prescribed supplemental oxygen increased oxyhemoglobin saturation in retinal arterioles (87.2%±4.9% to 89.5%±6.0%, p = 0.02) but not in venules (45.0%±10.3% to 46.7%±12.8%, p = 0.3). Retinal oximetry values were slightly lower than radial artery blood values (mean percentage points difference = -5.0±5.4, 95% CI: -15.68 to 5.67) and finger pulse oximetry values (-3.1±5.5, 95% CI: -14.05 to 7.84).ConclusionsThe noninvasive Oxymap T1 retinal oximetry detects hypoxemia in central nervous system vessels in patients with severe COPD compared with healthy controls. The instrument is sensitive to changes in oxygen breathing but displays slightly lower measures than finger pulse oximetry or radial artery measures. With further technological improvement, retinal oximetry may offer noninvasive “on-line” measurement of oxygen levels in central circulation in general anesthesia and critically ill patients.

In vivo photoacoustic imaging of chorioretinal oxygen gradients

“…6 Focal retinal hypoxia is thought to underlie the pathophysiology of many ocular diseases, such as diabetic retinopathy, 7,8 glaucoma, 9,10 and retinal venous occlusion. 11 Thus, the ability to image retinal oxygen gradients could be very valuable in treating and diagnosing retinal disease. Also, chorioretinal vasculature imaging has a significant role for diseases, such as neovascular age-related macular degeneration (AMD).…”

Looking into the eye of patients with chronic obstructive pulmonary disease: an opportunity for better microvascular profiling of these complex patients

“…The authors demonstrated that retinal oximetry detected lower oxyhaemoglobin saturation in patients with COPD breathing ambient air compared to healthy controls (Eliasdottir et al. ). Furthermore, they showed that retinal oximetry is able to capture an increase in retinal arteriole oxyhaemoglobin saturation when the COPD subjects inspired supplemental oxygen.…”

“…Therefore, measurement of oxyhaemoglobin saturation by retinal oximetry may be a more reliable and relevant method to determine organ oxygenation and hypoxia in patients with COPD than measurements of peripheral oxyhaemoglobin saturation (Heistad & Abboud 1980;Van de Louw et al 2001;Wilson et al 2010). Eliasdottir et al (2017) determined the blood oxyhaemoglobin saturation in the retinal vessels in patients with COPD, who were on long-term oxygen therapy based on the criteria for experiencing sustained hypoxia (defined as an arterial oxyhaemoglobin saturation of <90%), and healthy subjects. The authors demonstrated that retinal oximetry detected lower oxyhaemoglobin saturation in patients with COPD breathing ambient air compared to healthy controls (Eliasdottir et al 2017).…”

“…Eliasdottir et al (2017) determined the blood oxyhaemoglobin saturation in the retinal vessels in patients with COPD, who were on long-term oxygen therapy based on the criteria for experiencing sustained hypoxia (defined as an arterial oxyhaemoglobin saturation of <90%), and healthy subjects. The authors demonstrated that retinal oximetry detected lower oxyhaemoglobin saturation in patients with COPD breathing ambient air compared to healthy controls (Eliasdottir et al 2017). Furthermore, they showed that retinal oximetry is able to capture an increase in retinal arteriole oxyhaemoglobin saturation when the COPD subjects inspired supplemental oxygen.…”

The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation

“…The mean of the retinal SaO 2 readings by Oxymap, measured in healthy persons, was lower by 5% than finger SaO 2 , measured by pulse oximetry, with 95% CI of −2 to 12% [ 71 ]. Measurements of mean retinal SaO 2 in patients with systemic hypoxemia were lower by 2% with 95% CI of −3 to 11% compared to invasive femoral SaO 2 values [ 72 ]. No significant correlation was found between individual retinal and finger SpO 2 [ 72 , 73 , 74 ].…”