Brain and renal oxygenation measured by NIRS related to patent ductus arteriosus in preterm infants: a prospective observational study

Background Patent ductus arteriosus (PDA) is common among preterm neonates. Haemodynamically significant ductus arteriosus (hsPDA) can cause ductal steal and contribute to poor outcomes. Our aim was to evaluate ductus arteriosus patency and significance using two-site near-infrared spectroscopy (NIRS) measurements in preterm infants older than 72 h as a supplemental tool to echocardiography. Methods In this prospective observational study, 123 preterm infants (gestational age (GA) < 32 weeks, birth weight < 1500 g) were enrolled. Sixty-four newborns had closed ductus arteriosus (noPDA), and 41 and 18 patients were assigned to the PDA and hsPDA groups, respectively, per predefined echocardiographic criteria. Cerebral and renal oxygenation were assessed during NIRS monitoring. Results A higher renal mean (±SD) regional tissue oxygen saturation (rSpO2) (76.7 (±7.64)) was detected in the noPDA group than in the PDA (71.7 (±9.02)) and hsPDA (67.4 (±13.48)) groups (p < 0.001). Renal fractional tissue oxygen extraction (FTOE) (0.18 (±0.079)) was lower in the noPDA group than in the PDA (0.23 (±0.092)) and hsPDA (0.24 (±0.117))0.117 groups (p = 0.002). Cerebral oxygenation was significantly lower in the hsPDA group (77.0 (±5.16)) than in the noPDA (79.3 (±2.45)) and PDA (79.7 (±2.27)) groups (p = 0.004). There was no significant difference in cerebral fractional tissue oxygen extraction (FTOE) between any of the groups. Conclusions Our results suggest that renal oxygenation is affected by ductus patency in preterm infants older than 72 h. Significant differences in cerebral oxygenation were observed between the hsPDA group and the PDA and noPDA groups. Trial registration ClinicalTrials.gov Identifier: NCT04295395. Registration date: 4 March 2020. This study was retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04295395.

Reduced exercise capacity in patients with systemic sclerosis is associated with lower peak tissue oxygen extraction: a cardiovascular magnetic resonance-augmented cardiopulmonary exercise study

Background Exercise intolerance in systemic sclerosis (SSc) is typically attributed to cardiopulmonary limitations. However, problems with skeletal muscle oxygen extraction have not been fully investigated. This study used cardiovascular magnetic resonance (CMR)-augmented cardiopulmonary exercise testing (CMR-CPET) to simultaneously measure oxygen consumption and cardiac output. This allowed calculation of arteriovenous oxygen content gradient, a recognized marker of oxygen extraction. We performed CMR-CPET in 4 groups: systemic sclerosis (SSc); systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH); non-connective tissue disease pulmonary hypertension (NC-PAH); and healthy controls. Methods We performed CMR-CPET in 60 subjects (15 in each group) using a supine ergometer following a ramped exercise protocol until exhaustion. Values for oxygen consumption, cardiac output and oxygen content gradient, as well as ventricular volumes, were obtained at rest and peak-exercise for all subjects. In addition, T1 and T2 maps were acquired at rest, and the most recent clinical measures (hemoglobin, lung function, 6-min walk, cardiac and catheterization) were collected. Results All patient groups had reduced peak oxygen consumption compared to healthy controls (p < 0.022). The SSc and SSc-PAH groups had reduced peak oxygen content gradient compared to healthy controls (p < 0.03). Conversely, the SSc-PAH and NC-PH patients had reduced peak cardiac output compared to healthy controls and SSc patients (p < 0.006). Higher hemoglobin was associated with higher peak oxygen content gradient (p = 0.025) and higher myocardial T1 was associated with lower peak stroke volume (p = 0.011). Conclusions Reduced peak oxygen consumption in SSc patients is predominantly driven by reduced oxygen content gradient and in SSc-PAH patients this was amplified by reduced peak cardiac output. Trial registration The study is registered with ClinicalTrials.gov Protocol Registration and Results System (ClinicalTrials.gov ID: 100358).

Impact of Carbon Dioxide on Cerebral Oxygenation and Vital Parameters in Stable Preterm and Term Infants Immediately after Birth

<b><i>Introduction:</i></b> Carbon dioxide (pCO₂) induces changes in the tone of cerebral vessels. The aim of the present study was to evaluate the impact of pCO₂ on cerebral regional tissue oxygen saturation (crSO₂), cerebral fractional tissue oxygen extraction (cFTOE), and cerebral tissue oxygen extraction (cTOE), measured with near-infrared spectroscopy (NIRS), in preterm and term infants 15 min after birth. <b><i>Methods:</i></b> Post hoc analyses of secondary outcome parameters of prospective observational studies were performed. Stable preterm and term infants with cerebral NIRS monitoring (INVOS 5100C) until minute 15 after birth and a blood gas analysis, performed between minutes 14–18 after birth, were included. Heart rate (HR) and arterial oxygen saturation (SpO₂) were recorded. pCO₂ was correlated with crSO₂, cFTOE, cTOE, SpO₂, HR, and partial pressure of oxygen (pO₂). <b><i>Results:</i></b> Eleven preterm infants with a median (IQR) gestational age of 34.8 (32.7–36.1) weeks were analyzed. Mean ± SD pCO₂ was 53.5 ± 4.2 mm Hg. At minute 15 after birth, crSO₂ was 82.6 (74.3–91.3)%, cFTOE 0.15 ± 0.09, cTOE 14.6 ± 8.4%, SpO₂ 97.4 ± 2.1%, and HR 152 (136–167) bpm. pCO₂ correlated negatively with crSO₂ (<i>p</i> = 0.012) and positively with cFTOE (<i>p</i> = 0.035) and cTOE (<i>p</i> = 0.037). Eighty-four term infants with a gestational age of 39.0 (38.5–38.9) weeks were analyzed. pCO₂ was 53.5 ± 6.3 mm Hg. At minute 15 after birth, crSO₂ was 84.4 (80.8–85.1)%, cFTOE 0.14 ± 0.08, cTOE 13.6 ± 7.9%, SpO₂ 96.5 ± 2.6%, and HR 155 (153–163) bpm. pCO₂ did only negatively correlate with pO₂ (<i>p</i> = 0.034) in term infants. <b><i>Conclusion:</i></b> In preterm infants, higher pCO₂ was associated with lower crSO₂ and higher cFTOE/cTOE. In term infants, no associations were observed. The present findings suggest that the vasodilatative effect of pCO₂ is less pronounced in preterm infants during immediate postnatal transition.

Complex protocol of cardiopulmonary bypass

Background. Innovative advances in cardiac surgery to reduce the negative impact of cardiopulmonary bypass (CPB) require a comprehensive solution. The ultimate questions of present interest remain the prevention of hypoxia, the composition of the priming volume of the oxygenator, the state of erythrocytes and their energy potential, the level of hemolysis, the pathogenetic approach to the correction of electrolytes during perfusion, as well as the biocompatibility of the extracorporeal circuit. The study aimed to create the protocol for cardiopulmonary bypass, which includes the possibility of reducing the negative effects of synthetic polymers of the extracorporeal circuit; reducing the hydrodynamic load on the tissue; carrying out a more physiological correction of the acid-base state; improving the energy potential of cells; correction of electrolyte balance during cardiopulmonary bypass ta­king into account the stages of the surgical operation. Materials and methods. The study included 225 patients who underwent cardiac surgery using cardiopulmonary bypass. The patients were divided into three groups. The first group consisted of 75 people, whose extracorporeal contour was treated with the adaptive composition by a special technique. After centrifuging the patient’s blood, serum was obtained, which was diluted in a solution of 0.9% NaCl and treated with the oxygenator circuit. The second group included patients (n = 75) in whom fructose-1,6-diphosphate (FPD) was used in the perfusion regimen. The drug was administered intravenously at a dose of 10 g at a rate of 10 ml/min in two stages: 5 g of FPD were injected immediately before the start of perfusion and 5 g before the patient was warmed up. The third group was the control group. Perfusion was performed using a membrane oxygenator in a non-pulsating blood flow mode with a prime of 1.3–1.6 L to achieve moderate hemodilution (Ht — 25 ± 2 g/L). A hyperosmolar priming volume with a total osmolarity of up to 510.6 mmol/L was used. The basic solutions were volutens, reosorbilact, mannitol 15%, Soda-buffer 4.2%. Hemogram (Hb, Ht, MCV, MCH, MCHC, RDWa, RDW%, hemolysis), oxygen transport: saturation of arterial (SaO2%) and venous blood (SvO2%), partial pressure of oxygen in arterial (PaO2) and venous blood (PvO2), oxygen delivery index (IDO2), oxygen consumption index (IVO2), oxygen extraction (O2ER), and oxygen extraction index (O2EI) were studied. The research of morphological changes in erythrocytes was carried out. Results. Our study aimed to develop and implement into practice an optimized cardiopulmonary bypass protocol based on the results obtained. The previous studies have shown that treatment of the oxy-genator circuit with the adaptive composition creates a protective layer of autoalbumin on the inner surface of the extracorporeal circuit, and the use of a drug with the active fructose-1,6-diphosphate ingredient during perfusion allows correcting hypophosphatemia, reducing the energy deficiency of the cells. In these two groups, in comparison with the control one, after CPB, there was a lower level of hemolysis, a lower number of echinocytes, and spherocytes. The three groups used the hyperosmolar priming ­volume. Before perfusion, there were the following indices: IDO2 — 332.00 ± ± 84.84 ml/(min • m2), IVO2 — 76.07 ± 28.34 ml/(min • m2), O2ЕR — 22.91 ± 6.33 %, O2EI — 22.47 ± 6.32 %, BE = –0.78 ± 2.13 mmol/L. At 10 min after CPB, there were the following indices: IDO2 — 579.7 ± 112.3 ml/(min • m2), IVO2 — 30.91 ± 13.31 ml / (min • m2), O2ER — 5.35 ± 2.07 %, O2EI — 5.26 ± ± 2.08 %, BE = 0.82 ± 2.03 mmol/L. IDO2 increased due to the oxygenator gas exchange, and the decrease in IVO2, O2ЕR, O2EI can be explained by the patient’s cooling. At the warming stage, there were the indices: IDO2 — 598.8 ± 114.9 ml/(min • m2), IVO2 — 108.10 ± 33.11 ml/(min • m2), O2ER — 18.04 ± 4.14 %, O2EI — 17.95 ± 4.15 %, BE = –0.11 ± 8.88 mmol/L. IDO2 — 305.7 ± 60.9 ml / min • m2), IVO2 — 77.15 ± 24.29 ml/(min • m2), O2ЕR — 25.36 ± 6.5 %, O2EI — 25.34 ± 6.5 %, BE = –0.36 ± 2.20 mmol/L. After CPB, the rate of diuresis was 11.88 ± 5.31 ml/kg/h, the relative hydrobalance after CPB was 9.67 ± 8.12 ml/kg. Our proposed protocol for cardiopulmonary bypass includes the basic points: 1) treatment of the oxygenator contour with the adaptive composition; 2) in patients with an initially low level of phosphorus, administration of the drug of fructose-1,6-diphosphate by the scheme; 3) the use of a hyperosmolar priming volume of the oxygenator; 4) correction of electrolytes taking into account the stages of cardiac surgery. Conclusions. The proposed procedure for the treatment of the extracorporeal oxygenator circuit is simple and affordable, improves the biocompatibility of the oxygenator. The use of a hyperosmolar priming volume avoids the volume load and provides an adequate gas transport function of the blood. The application of FPD makes it possible to reduce hemolysis and protect erythrocytes, correct electrolytes by taking into account the stages of operations and the peculiarities of CPB.

Intraoperative hyperglycemic stress response and tissue perfusion in cardiac surgery

Background and aim of the study Approximately 30% of patients undergoing cardiac surgery have a history of diabetes and 60-80% of patients without diabetes have stress hyperglycemia. We examined patients undergoing cardiac surgery to determine the presence of stress hyperglycemia and its relationship to tissue perfusion. Methods Hemodynamic parameters, central venous oxygen saturation, lactate,oxygen delivery and consumption, oxygen extraction rate were analyzed at four intraoperative time points. Results The stress-induced hyperglycemic response during cardiac surgery was more severe in patients without diabetes. When focusing on the oxygen extraction rate in terms of tissue oxygenation, diabetic patients had 1.22 times higher and significant oxygen extraction rate than non-diabetic patients. Conclusions Although lactate values were slightly higher and central venous oxygen saturation were slightly lower in the diabetic group, considering the fact that oxygen extraction rate reflects the total outcome of small changes in all these parameters, we can emphasize the conclusion that diabetic patients undergoing cardiac surgery have greater tissue oxygen demand/supply imbalance compared to non-diabetic patients. In our study, this tissue oxygenation defect in diabetic patients was not found to be directly correlated with blood glucose levels. Perhaps, even if the disease is under control, the negative effects of diabetes on all systems have accumulated and led to such a result.

Retinal Oxygen Metabolism and Haemodynamics in Patients With Multiple Sclerosis and History of Optic Neuritis

Vascular changes and alterations of oxygen metabolism are suggested to be implicated in multiple sclerosis (MS) pathogenesis and progression. Recently developed in vivo retinal fundus imaging technologies provide now an opportunity to non-invasively assess metabolic changes in the neural retina. This study was performed to assess retinal oxygen metabolism, peripapillary capillary density (CD), large vessel density (LVD), retinal nerve fiber layer thickness (RNFLT) and ganglion cell inner plexiform layer thickness (GCIPLT) in patients with diagnosed relapsing multiple sclerosis (RMS) and history of unilateral optic neuritis (ON). 16 RMS patients and 18 healthy controls (HC) were included in this study. Retinal oxygen extraction was modeled using O2 saturations and Doppler optical coherence tomography (DOCT) derived retinal blood flow (RBF) data. CD and LVD were assessed using optical coherence tomography (OCT) angiography. RNFLT and GCIPLT were measured using structural OCT. Measurements were performed in eyes with (MS+ON) and without (MS-ON) history for ON in RMS patients and in one eye in HC. Total oxygen extraction was lowest in MS+ON (1.8 ± 0.2 μl O2/min), higher in MS-ON (2.1 ± 0.5 μl O2/min, p = 0.019 vs. MS+ON) and highest in HC eyes (2.3 ± 0.6 μl O2/min, p = 0.002 vs. MS, ANOVA p = 0.031). RBF was lower in MS+ON (33.2 ± 6.0 μl/min) compared to MS-ON (38.3 ± 4.6 μl/min, p = 0.005 vs. MS+ON) and HC eyes (37.2 ± 4.7 μl/min, p = 0.014 vs. MS+ON, ANOVA p = 0.010). CD, LVD, RNFLT and GCIPL were significantly lower in MS+ON eyes. The present data suggest that structural alterations in the retina of RMS patients are accompanied by changes in oxygen metabolism, which are more pronounced in MS+ON than in MS-ON eyes. Whether these alterations promote MS onset and progression or occur as consequence of disease warrants further investigation.Clinical Trial Registration:ClinicalTrials.gov registry, NCT03401879.