Retinal oxygen saturation changes progressively over time in diabetic retinopathy

Purpose According to cross-sectional studies, oxygen saturation is elevated in retinal vessels in diabetic patients. We evaluated how retinal oxygenation (metabolic marker), vessel diameters and retinopathy grade (structural markers) change over time in diabetic patients. Design Prospective cohort study following screening in a hospital setting. Methods Retinal oximetry images were acquired in 214 patients with the Oxymap T1 oximeter. Imaging was repeated after a median of 3.0 years (range 0.76–6.8 years). Oxygen saturation and vessel diameters were measured in the right eye. Semiquantitative grading of retinopathy according to international guidelines and red lesion count were performed on fundus photographs. Results Retinopathy grade according to the international semiquantitative grading system was unchanged. Arteriolar saturation increased by 0.75±0.15 percentage points per year of follow-up (p<0.0001). Venular saturation increased by 1.74±0.26 percentage points per year (p<0.0001) and arteriovenous difference decreased by 0.99±0.20 percentage points per year (p<0.0001). Arteriolar diameters decreased by 2.7±8.5μm (p<0.0001) between visits and venular diameters decreased by 2.4±9.1μm (p = 0.0002). Median increase in red lesion count between visits was 2 lesions (range -128 to 212 lesions, p<0.0001). The change in red lesion count and change in diameters did not correlate with the length of follow-up (p>0.44). Conclusions Oxygen saturation in larger retinal vessels can increase and arteriovenous difference can decrease over time in diabetic patients without any observable changes in retinopathy grade. The results suggest that changes in retinal oxygen saturation may precede progression of diabetic retinopathy or that oxygen saturation is more sensitive to disease progression than retinopathy grade.

Self-Reported DHA Supplementation during Pregnancy and Its Association with Obesity or Gestational Diabetes in Relation to DHA Concentration in Cord and Maternal Plasma: Results from NELA, a Prospective Mother-Offspring Cohort

Maternal supplementation of docosahexaenoic acid (DHA) during pregnancy has been recommended due to its role in infant development, but its effect on materno-fetal DHA status is not well established. We evaluated the associations between DHA supplementation in pregnant women with obesity or gestational diabetes mellitus (GDM) and maternal and neonatal DHA status. Serum fatty acids (FA) were analyzed in 641 pregnant women (24 weeks of gestation) and in 345 venous and 166 arterial cord blood samples of participants of the NELA cohort. Obese women (n = 47) presented lower DHA in serum than those lean (n = 397) or overweight (n = 116) before pregnancy. Linoleic acid in arterial cord was elevated in obese women, which indicates lower fetal retention. Maternal DHA supplementation (200 mg/d) during pregnancy was associated with enhanced maternal and fetal DHA levels regardless of pre-pregnancy body mass index (BMI), although higher arterial DHA in overweight women indicated an attenuated response. Maternal DHA supplementation was not associated with cord venous DHA in neonates of mothers with GDM. The cord arteriovenous difference was similar for DHA between GDM and controls. In conclusion, maternal DHA supplementation during pregnancy enhanced fetal DHA status regardless of the pre-pregnancy BMI while GDM may reduce the effect of DHA supplementation in newborns.

Altered retinal oxygen metabolism in patients with combined ocular and central nervous system sarcoidosis

Objective To evaluate retinal oxygen metabolism by retinal oximetry for ocular and CNS diseases in a cross-sectional study of sarcoidosis. Methods Overall 201 eyes from 103 biopsy-verified sarcoidosis patients were included and divided into four groups depending on the organ affection: (i) sarcoidosis without ocular or CNS affection, (ii) ocular sarcoidosis, (iii) CNS sarcoidosis, and (iv) combined ocular and CNS sarcoidosis. Retinal oximetry was obtained and analysed, with the mean retinal arteriolar and venular saturation as well as arteriovenous difference as principal outcomes. Comparison between groups was done in a multi linear regression model adjusted for age, sex, duration of sarcoidosis, best corrected visual acuity and retinal oximetry quality. Results Mean (s.d.) age was 50.5 (13.4) (95% CI: 47.9, 53.1) years and 52.2% were males. Eyes of the combined Ocular/CNS group had a higher retinal arteriovenous difference than eyes of the Non-ocular/no-CNS group (42.1% vs 37.7%, P = 0.012) but did not differ between other groups. Eyes in the four groups (Non-ocular/no-CNS, Ocular, CNS and Ocular/CNS) did not differ according to retinal arterial (94.5%, 93.5%, 93.5% and 94.5%, respectively) or venular (57.5%, 56.4%, 55.0% and 52.5%, respectively) oxygen saturation. Conclusions The results of this study suggest that eyes of sarcoidosis patients with combined ocular and CNS affection have an altered oxygen metabolism indicating a subclinical eye affection that is not recognized by conventional screening methods.

Systemic perfusion assessment in patients with univentricular hemodynamics based on blood gas parameters

The objective: to identify laboratory markers of systemic perfusion in newborns with functional single ventricle on mechanical ventilation after surgical correction. Subjects and methods. Blood gas parameters were retrospectively analyzed in 52 newborns with congenital heart defects with univentricular hemodynamic after surgical correction. All samples were divided into three groups based on arterial blood saturation (SaO2): Group 1 – hypoxia (SaO2 ≤ 65%); Group 2 – normoxemia (SaO2 = 65-85%); Group 3 – hyperoxemia (SaO2 > 85%). Stroke volume and cardiac index were evaluated with echocardiography. The oxygen consumption and carbon metabolism were evaluated by arterial and venous blood gases. Results. The mixed central venous pO2 (PvO2) > 29.5 mm Hg, mixed central venous O2 (SvO2) > 54.5%, arteriovenous difference in saturation (Sa-vO2) < 15.8%, total oxygen content in venous blood (CvO2) > 119 ml/l, oxygen extraction ratio (O2ER) < 19% and the arteriovenous difference in partial pressure of carbon dioxide (dPCO2) < 5.4 mm Hg are cut off criteria for adequate systemic perfusion. PvO2 < 26 mm Hg, SvO2 < 44.5%, Sa-vO 2 > 27%, CvO2 < 88 ml/l, O2ER > 27.7%, dPCO2> 7.9 mm Hg have been associated with decreased systemic perfusion. The logistic regression model including combination of O2ER and dPCO2 predicts adequate systemic flow accuracy of 94.3% (sensitivity 87.5%, specificity 94.7%, p = 0.001). Graphics allow to adapt the mathematical model to clinical practice to verify systemic hypoperfusion in newborns with functional single ventricle. Conclusion: The following cut off parameters allow to assess systemic perfusion in newborns with functional single ventricle: PvO2, SvO2, CvO2, Sa-vO 2, O2ER, and dPCO2. The model for predicting the adequacy of systemic perfusion can be used as an effective tool to monitor hemodynamic status in newborns with functional single ventricle.

Early veno arterial PCO2 difference is associated with outcome in peripheral veno arterial extracorporeal membrane oxygenation

Background: Veno arterial membrane oxygenation (VA ECMO) is increasingly used for cardiogenic failure. However, hemodynamic targets for adequate resuscitation remain a challenge. The PCO 2 gap and the ratio between PCO 2 gap and the arteriovenous difference in oxygen (PCO 2 gap/Da–vO 2 ) are marker of peripheral hypoperfusion. We hypothesized that the PCO 2 gap and the PCO 2 gap/Da–vO 2 ratio might be useful parameters in VA ECMO patients. Methods: We conducted an observational prospective study between September 2015 and February 2017. All consecutive patients >18 years of age who had been treated with peripheral VA ECMO for cardiac failure were included. We compared 2 groups of patients: patients who died of any cause under VA ECMO or in the 72h following VA ECMO weaning (early death group) - and patients who survived VA ECMO weaning more than 72h (surviving group). Blood samples were drawn from arterial and venous VA ECMO cannulas at H0 and H6. The ability of PCO 2 gap and PCO 2 gap/Da–vO 2 to discriminate between early mortality and surviving was studied using ROC curves analysis. Results: We included 20 patients in surviving group and 29 in early death group. The PCO 2 gap was higher in the early death group at H6 (7.4 [5.7–10.1] vs. 5.9 [3.8–9.2], p < 0.01). AUC for PCO 2 gap at H6 was 0.76 (0.61–0.92), with a cut-off of 6.2 mmHg. The PCO 2 gap/Da–vO 2 was higher in the early death group at H0 (2.1 [1.5–2.6] vs. 1.2 [0.9–2.4], p < 0.01) and at H6 (2.1 [1.3–2.6] vs. 1.0 [0.8–1.7], p < 0.01). AUC for PCO 2 gap/Da–vO 2 at H0 and H6 were 0.79 and 0.73 respectively; the cut-off value was 1.4. Conclusions: The PCO 2 gap and the PCO 2 gap/Da–vO2 ratio are associated with early death in patients who undergo VA ECMO.

Macular Retinal Vessel Oxygen Saturation Elevation in Chinese Central Serous Chorioretinopathy

Purpose. To evaluate the retinal vessel oxygen saturation in central serous chorioretinopathy (CSC) cases among the Chinese. Methods. Relative oxygen saturation of retinal blood vessels was measured in 33 Chinese patients with single-eye CSC using the Oxymap T1 retinal oximeter. The contralateral eyes were the control. The mean saturation of the retinal arteriole (AS) and venule (VS), arteriovenous difference (AVS), and arteriole and venule diameters (AD, VD) was analyzed in the optic disc area and macular region. Results. In the optic disc area, the inferotemporal quadrant (TI) AS (93.2 ± 10.2%) and inferonasal quadrant (NI) VS (61.3 ± 7.3%) were higher in the affected eyes than in the contralateral eyes (88.7 ± 7.7% and 56.9 ± 6.5%) and AVS in NI (36.7 ± 10.4%) decreased compared to the contralateral eyes (41.5 ± 11.2%). The VD in TI was expanded (19.9 ± 2.5 pixels versus 18.1 ± 3.4 pixels). Around the macular region, AS was 93.6 ± 7.6%, higher than in the contralateral eyes (89.5 ± 6.3%). No other significant changes were found. Conclusions. AS increased in the TI, and VS decreased in the NI in the eyes with CSC. In addition, AS also increased around the macular region, suggesting that these are contributors to CSC pathophysiology.

Oxygen Saturation in Closed-Globe Blunt Ocular Trauma

Purpose. To evaluate the oxygen saturation in retinal blood vessels in patients after closed-globe blunt ocular trauma.Design. Retrospective observational case series.Methods. Retinal oximetry was performed in both eyes of 29 patients with unilateral closed-globe blunt ocular trauma. Arterial oxygen saturation (SaO2), venous oxygen saturation (SvO2), arteriovenous difference in oxygen saturation (SO2), arteriolar diameter, venular diameter, and arteriovenous difference in diameter were measured. Association parameters including age, finger pulse oximetry, systolic pressure, diastolic pressure, and heart rate were analyzed.Results. The mean SaO2in traumatic eyes (98.1%±6.8%) was not significantly different from SaO2in unaffected ones (95.3%±7.2%) (p=0.136). Mean SvO2in traumatic eyes (57.1%±10.6%) was significantly lower than in unaffected ones (62.3%±8.4%) (p=0.044). The arteriovenous difference in SO2in traumatic eyes (41.0%±11.2%) was significantly larger than in unaffected ones (33.0%±6.9%) (p=0.002). No significant difference was observed between traumatic eyes and unaffected ones in arteriolar (p=0.249) and venular diameter (p=0.972) as well as arteriovenous difference in diameter (p=0.275).Conclusions. Oxygen consumption is increased in eyes after cgBOT, associated with lower SvO2and enlarged arteriovenous difference in SO2but not with changes in diameter of retinal vessels.

The Changes of Retinal Saturation after Long-Term Tamponade with Silicone Oil

Purpose.To evaluate the effects of long-term tamponade with silicone oil on retinal saturation.Methods.A total of 49 eyes that received tamponade with silicone oil were included. The patients were divided into 3 groups (3–6 months, 6–9 months, and >9 months) according to the duration of silicone oil tamponade. Retinal oximetry was performed using the Oxymap system before and 2 months after silicone oil removal.Results.The mean retinal oxygen saturation before silicone oil removal was 107% ± 12% in the arterioles and 60% ± 10% in the venules, with an overall arteriovenous difference (AVD) of 47% ± 14%. The AVD in the >9-month group was significantly higher than that in the 3–6-month group (54% ± 16% versus 44% ± 11%,P=0.042). After silicone oil removal, the AVD in the >9-month group was significantly decreased (45% ± 9% versus 54% ± 16%,P=0.009); additionally, the arterioles were significantly wider than before surgery (10.8 ± 0.7 pixels versus 10.4 ± 0.9 pixels,P=0.015).Conclusions.The tamponade with silicone oil for more than 9 months will cause the alterations of retinal saturation and the narrowing of retinal arterioles, which may further interfere with the oxygen metabolism in the retina.