Occurrence of hyperoxia during iNO treatment for persistent pulmonary hypertension of the newborn: a cohort study.

High concentrations of oxygen are often needed to optimize oxygenation in infants with persistent pulmonary hypertension (PPHN), but this can also increase the risk of hyperoxemia. We determined the occurrence of hyperoxemia in infants treated for PPHN. Medical records of infants ≥ 34 + 0 weeks gestational age (GA) who received inhaled nitric oxide (iNO) were retrospectively reviewed for oxygenation parameters during iNO therapy. Oxygen was manually titrated to target arterial oxygen tension (PaO2) 10-13 kPa and peripheral oxygen saturation (SpO2) 92-98%. The main study outcomes were the incidence and duration of hyperoxemia and hypoxemia and the fraction of inspired oxygen (FiO2). A total of 181 infants were included. The median FiO2 was 0.43 (IQR 0.34-0.56) and the maximum FiO2 was 1.0 in 156/181 (86%) infants, resulting in at least one PaO2 > 13 kPa in 149/181 (82%) infants, of which 46/149 (31%) infants had minimal one PaO2 > 30 kPa. SpO2 was > 98% in 179/181 (99%) infants for 17.7% (8.2-35.6%) of the iNO time. PaO2 < 10 kPa occurred in 160/181 (88%) infants, of which 81/160 (51%) infants had minimal one PaO2 < 6.7 kPa. SpO2 was < 92% in 169/181 (93%) infants for 1.6% (0.5-4.3%) of the iNO time.    Conclusion: While treatment of PPHN is focused on preventing and reversing hypoxemia, hyperoxemia occurs inadvertently in most patients. What is Known: • High concentrations of oxygen are often needed to prevent hypoxemia-induced deterioration of PPHN, but this can also increase the risk of hyperoxemia. • Infants with persistent pulmonary hypertension may be particularly vulnerable to the toxic effects of oxygen, and hyperoxemia could further induce pulmonary vasoconstriction, potentially worsening the condition. What is New: • Hyperoxemia occurs in the majority of infants with PPHN during treatment with iNO. • Infants with PPHN spent a considerably longer period with saturations above the target range compared to saturations below the target range.

Oxygen imaging of hypoxic pockets in the mouse cerebral cortex.

Consciousness is lost within seconds upon cessation of cerebral blood flow. The brain cannot store oxygen, and interruption of oxidative phosphorylation is fatal within minutes. Yet only rudimentary knowledge exists regarding cortical partial oxygen tension (Po2) dynamics under physiological conditions. Here we introduce Green enhanced Nano-lantern (GeNL), a genetically encoded bioluminescent oxygen indicator for Po2 imaging. In awake behaving mice, we uncover the existence of spontaneous, spatially defined "hypoxic pockets" and demonstrate their linkage to the abrogation of local capillary flow. Exercise reduced the burden of hypoxic pockets by 52% compared with rest. The study provides insight into cortical oxygen dynamics in awake behaving animals and concurrently establishes a tool to delineate the importance of oxygen tension in physiological processes and neurological diseases.

Femoral blood gas analysis, another tool to assess hemorrhage severity following trauma: an exploratory prospective study.

BACKGROUND: Veno-arterial carbon dioxide tension difference (ΔPCO2) and mixed venous oxygen saturation (SvO2) have been shown to be markers of the adequacy between cardiac output and metabolic needs in critical care patients. However, they have hardly been assessed in trauma patients. We hypothesized that femoral ΔPCO2 (ΔPCO2 fem) and SvO2 (SvO2 fem) could predict the need for red blood cell (RBC) transfusion following severe trauma. METHODS: We conducted a prospective and observational study in a French level I trauma center. Patients admitted to the trauma room following severe trauma with an Injury Severity Score (ISS) > 15, who had arterial and venous femoral catheters inserted were included. ΔPCO2 fem, SvO2 fem and arterial blood lactate were measured over the first 24 h of admission. Their abilities to predict the transfusion of at least one pack of RBC (pRBCH6) or hemostatic procedure during the first six hours of admission were assessed using receiver operating characteristics curve. RESULTS: 59 trauma patients were included in the study. Median ISS was 26 (22-32). 28 patients (47%) received at least one pRBCH6 and 21 patients (35,6%) had a hemostatic procedure performed during the first six hours of admission. At admission, ΔPCO2 fem was 9.1 ± 6.0 mmHg, SvO2 fem 61.5 ± 21.6% and blood lactate was 2.7 ± 1.9 mmol/l. ΔPCO2 fem was significantly higher (11.6 ± 7.1 mmHg vs. 6.8 ± 3.7 mmHg, P = 0.003) and SvO2 fem was significantly lower (50 ± 23 mmHg vs. 71.8 ± 14.1 mmHg, P < 0.001) in patients who were transfused than in those who were not transfused. Best thresholds to predict pRBCH6 were 8.1 mmHg for ΔPCO2 fem and 63% for SvO2 fem. Best thresholds to predict the need for a hemostatic procedure were 5.9 mmHg for ΔPCO2 fem and 63% for SvO2 fem. Blood lactate was not predictive of pRBCH6 or the need for a hemostatic procedure. CONCLUSION: In severe trauma patients, ΔPCO2 fem and SvO2 fem at admission were predictive for the need of RBC transfusion and hemostatic procedures during the first six hours of management while admission lactate was not. ΔPCO2 fem and SvO2 fem appear thus to be more sensitive to blood loss than blood lactate in trauma patients, which might be of importance to early assess the adequation of tissue blood flow with metabolic needs.

Oxygen-binding properties of blood in insulin resistance with different asprosin content.

The oxygen-binding properties of blood were studied in male patients with insulin resistance (IR) with different levels of asprosin. The content of asprosin, parameters of blood oxygen transport function, as well as gas transmitters, nitrogen monoxide and hydrogen sulfide, were determined in the venous blood plasma. In the studied IR patients with increased blood asprosin content, impaired blood oxygenation was noted; IR patients with normal body weight had increased hemoglobin affinity for oxygen, while in IR patients with overweight and the 1st degree obesity, this parameter decreased. The detected increase in the concentration of nitrogen monoxide and the decrease in hydrogen sulfide may be important for the oxygen-binding properties of the blood and the development of metabolic imbalance.

Effect of the change of mechanical ventilation mode on cerebral oxygen saturation level in neonates.

BACKGROUND: This study aimed to apply near-infrared spectroscopy (NIRS) to monitor cerebral oxygen saturation (SrO2) level in neonates before and after the change of mechanical ventilation mode, and thus, the effects of the change of mechanical ventilator mode on SrO2 level in neonates were assessed. METHODS: This trial was designed as an observational study .A total of 70 neonates who were admitted to the Department of Neonatology of Beijing Luhe Hospital Affiliated to Capital Medical University (Beijing, China) between September 2019 and October 2021 and required respiratory support were included. The variations of SrO2 level before and after the change of mechanical ventilation mode, including changing from Synchronized intermittent mandatory ventilation (SIMV) to noninvasive ventilation (NIV, group 1), and from NIV to oxygen inhalation (group 2), were monitored by Enginmed EGOS-600 A. The changes of SrO2 level at 30 min before and 1 h after the change of ventilation mode were compared between the two groups. RESULTS: The SrO2 level in the group 1 30 min before, as well as 10 min, 30 min, and 1 h after the change of ventilation mode was 62.54 ± 3.36%, 65.43 ± 3.98%, 64.38 ± 4.23%, and 64.63 ± 3.71%, respectively. The SrO2 level at all the points after the change of ventilation mode increased compared with 30 min before the change (P < 0.05). The SrO2 level in the group 2 at each time point was 62.67 ± 4.69%, 64.61 ± 5.00%, 64.04 ± 4.48%, and 64.55 ± 4.32%, respectively. Compared with 30 min before ventilator weaning, the SrO2 level at all the points after ventilator weaning increased (P < 0.05). Peak inspiratory pressure (PIP) excluding Nasal Continuous Positive Airway Pressure (NCPAP)) in group 1 was lower than that before extubation, and the difference was statistically significant (P = 0) (Table 7). CONCLUSIONS: SrO2 level showed an increasing trend after the change of ventilation mode, and the increase of SrO2 level at 10 min after the change of ventilation mode was the most prominent. From SIMV to NIV, increased SrO2 levels may be associated with decreased PIP.

Remote Blood Oxygen Estimation From Videos Using Neural Networks.

Peripheral blood oxygen saturation (SpO 2) is an essential indicator of respiratory functionality and received increasing attention during the COVID-19 pandemic. Clinical findings show that COVID-19 patients can have significantly low SpO 2 before any obvious symptoms. Measuring an individual's SpO 2 without having to come into contact with the person can lower the risk of cross contamination and blood circulation problems. The prevalence of smartphones has motivated researchers to investigate methods for monitoring SpO 2 using smartphone cameras. Most prior schemes involving smartphones are contact-based: They require using a fingertip to cover the phone's camera and the nearby light source to capture reemitted light from the illuminated tissue. In this paper, we propose the first convolutional neural network based noncontact SpO 2 estimation scheme using smartphone cameras. The scheme analyzes the videos of an individual's hand for physiological sensing, which is convenient and comfortable for users and can protect their privacy and allow for keeping face masks on. We design explainable neural network architectures inspired by the optophysiological models for SpO 2 measurement and demonstrate the explainability by visualizing the weights for channel combination. Our proposed models outperform the state-of-the-art model that is designed for contact-based SpO 2 measurement, showing the potential of the proposed method to contribute to public health. We also analyze the impact of skin type and the side of a hand on SpO 2 estimation performance.

Updated meta-analysis on intraoperative inspired fraction of oxygen and the risk of surgical site infection in adults undergoing general and regional anesthesia.

This updated meta-analysis aims at exploring whether the use of systematic high vs low intraoperative oxygen fraction (FiO2) may decrease the incidence of postoperative surgical site infection during general (GA) or regional anesthesia (RA). PubMed, Cochrane CENTRAL, ClinicalTrials.gov databases were searched from January 1st, 1999 and July, 1st 2022, for randomized and quasi-randomized controlled trials that included patients in a high and low FiO2 groups and reported the incidence of SSI. The meta-analysis was conducted with a DerSimonian and Laird random-effects model. Thirty studies (24 for GA and 6 for RA) totaling 18,055 patients (15,871 for GA and 2184 for RA) were included. We have low-to-moderate-quality evidence that high FiO2 (mainly 80%) was not associated with a reduction of SSI incidence compared to low FiO2 (mainly 30%) in all patients (RR 0.90, 95%CI 0.79-1.03). Moderate inconsistency existed between studies (I2 = 38%). Subgroup analyses showed a moderate protective effect in patients undergoing GA (RR 0.86, 95%CI 0.75-0.99) (low level of evidence), while high FiO2 was not associated with a reduction of SSI in patients undergoing RA (RR 1.17, 95%CI 0.90-1.52) (moderate level of evidence). Sensitivity analyses restricted to patients ventilated without nitrous oxide (n = 20 studies), to patients operated from abdominal surgeries (n = 21 studies), and to patients suffering from deep SSI (n = 13 studies), all showed the absence of any significant effect of high FiO2. As a conclusion there is no compelling evidence that high FiO2 can improve postoperative patient's outcome on its own when good SSI prevention practices are properly applied. Recent well-designed and adequately powered randomized controlled trials add further weight to these results.

Non-invasive estimation of hemoglobin, bilirubin and oxygen saturation of neonates simultaneously using whole optical spectrum analysis at point of care.

The study was aimed to evaluate the performance of a newly developed spectroscopy-based non-invasive and noncontact device (SAMIRA) for the simultaneous measurement of hemoglobin, bilirubin and oxygen saturation as an alternative to the invasive biochemical method of blood sampling. The accuracy of the device was assessed in 4318 neonates having incidences of either anemia, jaundice, or hypoxia. Transcutaneous bilirubin, hemoglobin and blood saturation values were obtained by the newly developed instrument which was corroborated with the biochemical blood tests by expert clinicians. The instrument is trained using Artificial Neural Network Analysis to increase the acceptability of the data. The artificial intelligence incorporated within the instrument determines the disease condition of the neonate. The Pearson's correlation coefficient, r was found to be 0.987 for hemoglobin estimation and 0.988 for bilirubin and blood gas saturation respectively. The bias and the limits of agreement for the measurement of all the three parameters were within the clinically acceptance limit.

Effects of percutaneous transluminal angioplasty and associated factors in access hand oxygenation in patients undergoing hemodialysis.

In hemodialysis (HD) patients with arteriovenous fistula (AVF), changes in systemic or peripheral tissue circulation occur non-physiologically via the presence of AVF; however, associations between blood flow and tissue oxygenation in the brain and access hand are uncertain. In this study, 85 HD patients with AVF were included and evaluated for changes in flow volume (FV) and regional oxygen saturation (rSO2) in the brain and hands with AVF before and after percutaneous transluminal angioplasty (PTA). Furthermore, we evaluated the factors that determine access hand rSO2 without stenosis after PTA. Brachial arterial FV increased after PTA (p < 0.001), and carotid FV decreased (p = 0.008). Access hand rSO2 significantly decreased after PTA (p < 0.001), but cerebral rSO2 did not significantly change (p = 0.317). In multivariable linear regression analysis of factors associated with access hand rSO2, serum creatinine (standardized coefficient: 0.296) and hemoglobin (standardized coefficient: 0.249) were extracted as independent factors for access hand rSO2. In conclusion, a decrease in access hand oxygenation and maintenance of cerebral oxygenation were observed throughout PTA. To maintain access hand oxygenation, it is important to adequately manage Hb level and maintain muscle mass, in addition to having an AVF with appropriate blood flow.

Arterial oxygen and carbon dioxide tension and acute brain injury in extracorporeal cardiopulmonary resuscitation patients: Analysis of the extracorporeal life support organization registry.

BACKGROUND: Acute brain injury (ABI) remains common after extracorporeal cardiopulmonary resuscitation (ECPR). Using a large international multicenter cohort, we investigated the impact of peri-cannulation arterial oxygen (PaO2) and carbon dioxide (PaCO2) on ABI occurrence. METHODS: We retrospectively analyzed adult (≥18 years old) ECPR patients in the Extracorporeal Life Support Organization registry from 1/2009 through 12/2020. Composite ABI included ischemic stroke, intracranial hemorrhage (ICH), seizures, and brain death. The registry collects 2 blood gas data pre- (6 hours) and post- (24 hours) cannulation. Blood gas parameters were classified as: hypoxia (<60mm Hg), normoxia (60-119mm Hg), and mild (120-199mm Hg), moderate (200-299mm Hg), and severe hyperoxia (≥300mm Hg); hypocarbia (<35mm Hg), normocarbia (35-44mm Hg), mild (45-54mm Hg) and severe hypercarbia (≥55mm Hg). Missing values were handled using multiple imputation. Multivariable logistic regression analysis was used to assess the relationship of PaO2 and PaCO2 with ABI. RESULTS: Of 3,125 patients with ECPR intervention (median age=58, 69% male), 488 (16%) experienced ABI (7% ischemic stroke; 3% ICH). In multivariable analysis, on-ECMO moderate (aOR=1.42, 95%CI: 1.02-1.97) and severe hyperoxia (aOR=1.59, 95%CI: 1.20-2.10) were associated with composite ABI. Additionally, severe hyperoxia was associated with ischemic stroke (aOR=1.63, 95%CI: 1.11-2.40), ICH (aOR=1.92, 95%CI: 1.08-3.40), and in-hospital mortality (aOR=1.58, 95%CI: 1.21-2.06). Mild hypercarbia pre-ECMO was protective of composite ABI (aOR=0.61, 95%CI: 0.44-0.84) and ischemic stroke (aOR=0.56, 95%CI: 0.35-0.89). CONCLUSIONS: Early severe hyperoxia (≥300mm Hg) on ECMO was a significant risk factor for ABI and mortality. Careful consideration should be given in early oxygen delivery in ECPR patients who are at risk of reperfusion injury.

Neural signal variability relates to maladaptive rumination in depression.

Rumination is a common feature of depression and predicts the onset and maintenance of depressive episodes. Maladaptive and adaptive subtypes of rumination contribute to distinct outcomes, with brooding worsening negative mood and reflection related to fewer depression symptoms in healthy populations. Neuroimaging studies have implicated several cortical midline and lateral prefrontal brain regions in rumination. Recent research indicates that blood oxygen level-dependent (BOLD) signal variability may be a novel predictor of cognitive flexibility. However, no prior studies have investigated whether brooding and reflection are associated with distinct patterns of BOLD signal variability in depression. We collected resting-state fMRI data for 79 women with different depression histories: no history, past history, and current depression. We examined differences in BOLD signal variability (BOLDSD) related to rumination subtypes for the following regions of interest previously implicated in rumination: amygdala, medial prefrontal, anterior cingulate, posterior cingulate, and dorsolateral prefrontal cortices (dlPFC). Rumination subtype was associated with BOLDSD in the dlPFC, with greater levels of brooding associated with lower BOLDSD in the dlPFC, even after controlling for depression severity. Depression history was related to BOLDSD in the dlPFC, with reduced BOLDSD in those with current depression versus no history of depression. These findings provide a novel demonstration of the neural circuitry associated with maladaptive rumination in depression and implicate decreased prefrontal neural signal variability in the pathophysiology of depression.

Oxygen-Saturation Targets for Critically Ill Adults Receiving Mechanical Ventilation.

BACKGROUND: Invasive mechanical ventilation in critically ill adults involves adjusting the fraction of inspired oxygen to maintain arterial oxygen saturation. The oxygen-saturation target that will optimize clinical outcomes in this patient population remains unknown. METHODS: In a pragmatic, cluster-randomized, cluster-crossover trial conducted in the emergency department and medical intensive care unit at an academic center, we assigned adults who were receiving mechanical ventilation to a lower target for oxygen saturation as measured by pulse oximetry (Spo2) (90%; goal range, 88 to 92%), an intermediate target (94%; goal range, 92 to 96%), or a higher target (98%; goal range, 96 to 100%). The primary outcome was the number of days alive and free of mechanical ventilation (ventilator-free days) through day 28. The secondary outcome was death by day 28, with data censored at hospital discharge. RESULTS: A total of 2541 patients were included in the primary analysis. The median number of ventilator-free days was 20 (interquartile range, 0 to 25) in the lower-target group, 21 (interquartile range, 0 to 25) in the intermediate-target group, and 21 (interquartile range, 0 to 26) in the higher-target group (P = 0.81). In-hospital death by day 28 occurred in 281 of the 808 patients (34.8%) in the lower-target group, 292 of the 859 patients (34.0%) in the intermediate-target group, and 290 of the 874 patients (33.2%) in the higher-target group. The incidences of cardiac arrest, arrhythmia, myocardial infarction, stroke, and pneumothorax were similar in the three groups. CONCLUSIONS: Among critically ill adults receiving invasive mechanical ventilation, the number of ventilator-free days did not differ among groups in which a lower, intermediate, or higher Spo2 target was used. (Supported by the National Heart, Lung, and Blood Institute and others; PILOT ClinicalTrials.gov number, NCT03537937.).

fMRI spectral signatures of sleep.

Sleep can be distinguished from wake by changes in brain electrical activity, typically assessed using electroencephalography (EEG). The hallmark of nonrapid-eye-movement (NREM) sleep is the shift from high-frequency, low-amplitude wake EEG to low-frequency, high-amplitude sleep EEG dominated by spindles and slow waves. Here we identified signatures of sleep in brain hemodynamic activity, using simultaneous functional MRI (fMRI) and EEG. We found that, at the transition from wake to sleep, fMRI blood oxygen level-dependent (BOLD) activity evolved from a mixed-frequency pattern to one dominated by two distinct oscillations: a low-frequency (<0.1 Hz) oscillation prominent in light sleep and correlated with the occurrence of spindles, and a high-frequency oscillation (>0.1 Hz) prominent in deep sleep and correlated with the occurrence of slow waves. The two oscillations were both detectable across the brain but exhibited distinct spatiotemporal patterns. During the falling-asleep process, the low-frequency oscillation first appeared in the thalamus, then the posterior cortex, and lastly the frontal cortex, while the high-frequency oscillation first appeared in the midbrain, then the frontal cortex, and lastly the posterior cortex. During the waking-up process, both oscillations disappeared first from the thalamus, then the frontal cortex, and lastly the posterior cortex. The BOLD oscillations provide local signatures of spindle and slow wave activity. They may be employed to monitor the regional occurrence of sleep or wakefulness, track which regions are the first to fall asleep or wake up at the wake-sleep transitions, and investigate local homeostatic sleep processes.