Lung Rest During Extracorporeal Membrane Oxygenation for Neonatal Respiratory Failure-Practice Variations and Outcomes.

OBJECTIVE: Describe practice variations in ventilator strategies used for lung rest during extracorporeal membrane oxygenation for respiratory failure in neonates, and assess the potential impact of various lung rest strategies on the duration of extracorporeal membrane oxygenation and the duration of mechanical ventilation after decannulation. DATA SOURCES: Retrospective cohort analysis from the Extracorporeal Life Support Organization registry database during the years 2008-2013. STUDY SELECTION: All extracorporeal membrane oxygenation runs for infants less than or equal to 30 days of life for pulmonary reasons were included. DATA EXTRACTION: Ventilator type and ventilator settings used for lung rest at 24 hours after extracorporeal membrane oxygenation initiation were obtained. DATA SYNTHESIS: A total of 3,040 cases met inclusion criteria. Conventional mechanical ventilation was used for lung rest in 88% of cases and high frequency ventilation was used in 12%. In the conventional mechanical ventilation group, 32% used positive end-expiratory pressure strategy of 4-6 cm H2O (low), 22% used 7-9 cm H2O (mid), and 43% used 10-12 cm H2O (high). High frequency ventilation was associated with an increased mean (SEM) hours of extracorporeal membrane oxygenation (150.2 [0.05] vs 125 [0.02]; p \u3c 0.001) and an increased mean (SEM) hours of mechanical ventilation after decannulation (135 [0.09] vs 100.2 [0.03]; p = 0.002), compared with conventional mechanical ventilation among survivors. Within the conventional mechanical ventilation group, use of higher positive end-expiratory pressure was associated with a decreased mean (SEM) hours of extracorporeal membrane oxygenation (high vs low: 136 [1.06] vs 156 [1.06], p = 0.001; mid vs low: 141 [1.06] vs 156 [1.06]; p = 0.04) but increased duration of mechanical ventilation after decannulation in the high positive end-expiratory pressure group compared with low positive end-expiratory pressure (p = 0.04) among survivors. CONCLUSIONS: Wide practice variation exists with regard to ventilator settings used for lung rest during neonatal respiratory extracorporeal membrane oxygenation. Use of high frequency ventilation when compared with conventional mechanical ventilation and use of low positive end-expiratory pressure strategy when compared with mid positive end-expiratory pressure and high positive end-expiratory pressure strategy is associated with longer duration of extracorporeal membrane oxygenation. Further research to provide evidence to drive optimization of pulmonary management during neonatal respiratory extracorporeal membrane oxygenation is warranted

A flexible organic reflectance oximeter array.

Transmission-mode pulse oximetry, the optical method for determining oxygen saturation in blood, is limited to only tissues that can be transilluminated, such as the earlobes and the fingers. The existing sensor configuration provides only single-point measurements, lacking 2D oxygenation mapping capability. Here, we demonstrate a flexible and printed sensor array composed of organic light-emitting diodes and organic photodiodes, which senses reflected light from tissue to determine the oxygen saturation. We use the reflectance oximeter array beyond the conventional sensing locations. The sensor is implemented to measure oxygen saturation on the forehead with 1.1% mean error and to create 2D oxygenation maps of adult forearms under pressure-cuff-induced ischemia. In addition, we present mathematical models to determine oxygenation in the presence and absence of a pulsatile arterial blood signal. The mechanical flexibility, 2D oxygenation mapping capability, and the ability to place the sensor in various locations make the reflectance oximeter array promising for medical sensing applications such as monitoring of real-time chronic medical conditions as well as postsurgery recovery management of tissues, organs, and wounds

Shining new light on mammalian diving physiology using wearable near-infrared spectroscopy

Investigation of marine mammal dive-by-dive blood distribution and oxygenation has been limited by a lack of non-invasive technology for use in freely diving animals. Here, we developed a non-invasive near-infrared spectroscopy (NIRS) device to measure relative changes in blood volume and haemoglobin oxygenation continuously in the blubber and brain of voluntarily diving harbour seals. Our results show that seals routinely exhibit preparatory peripheral vasoconstriction accompanied by increased cerebral blood volume approximately 15 s before submersion. These anticipatory adjustments confirm that blood redistribution in seals is under some degree of cognitive control that precedes the mammalian dive response. Seals also routinely increase cerebral oxygenation at a consistent time during each dive, despite a lack of access to ambient air. We suggest that this frequent and reproducible reoxygenation pattern, without access to ambient air, is underpinned by previously unrecognised changes in cerebral drainage. The ability to track blood volume and oxygenation in different tissues using NIRS will facilitate a more accurate understanding of physiological plasticity in diving animals in an increasingly disturbed and exploited environment

Three dimensional optical imaging of blood volume and oxygenation in the neonatal brain

Optical methods provide a means of monitoring cerebral oxygenation in newborn infants at risk of brain injury. A 32-channel optical imaging system has been developed with the aim of reconstructing three-dimensional images of regional blood volume and oxygenation. Full image data sets were acquired from 14 out of 24 infants studied; successful images have been reconstructed in 8 of these infants. Regional variations in cerebral blood volume and tissue oxygen saturation are present in healthy preterm infants. In an infant with a large unilateral intraventricular haemorrhage, a corresponding region of low oxygen saturation was detected. These results suggest that optical tomography may provide an appropriate technique for investigating regional cerebral haemodynamics and oxygenation at the cotside. (c) 2006 Elsevier Inc. All rights reserved

The Role of rescue therapies in the treatment of severe ARDS

ARDS is characterized by a non-cardiogenic pulmonary edema with bilateral chest radiograph opacities and hypoxemia refractory to oxygen therapy. It is a common cause of admission to the ICU due to hypoxemic respiratory failure requiring mechanical ventilation. Corticosteroids are not recommended in ARDS patients. Rescue therapies alleviate hypoxemia in patients unable to maintain reasonable oxygenation: recruitment maneuvers, prone positioning, inhaled nitric oxide, high-frequency oscillatory ventilation, and extracorporeal membrane oxygenation improve oxygenation, but their impact on mortality remains unproven. Restrictive fluid management seems to be a favorable strategy with no significant reduction in 60-d mortality. Future studies are needed to clarify the efficacy of these therapies on outcomes in patients with severe ARDS, and institution of these therapies may be considered on a case-by-case basis

Triazole-Directed Pd-Catalyzed C(sp2)–H Oxygenation of Arenes and Alkenes

Selective Pd-catalyzed C(sp2)–H oxygenation of 4-substituted 1,2,3-triazoles is described. Unlike previous metal-catalyzed C–H functionalization events, which preferentially occur at the activated heterocyclic C–H bond, the regioselective oxygenation of the arene/alkene moiety is now achieved featuring the unconventional role of a simple triazole scaffold as a modular and selective directing group.MINECO for a Ramon y Cajal research contract (RYC-2012-09873)

Different patterns of cerebral and muscular tissue oxygenation 10 years after coarctation repair

The purpose of this study was to assess whether the lower exercise tolerance in children after coarctation repair is associated with alterations in peripheral tissue oxygenation during exercise. A total of 16 children after coarctation repair and 20 healthy control subjects performed an incremental ramp exercise test to exhaustion. Cerebral and locomotor muscle oxygenation were measured by means of near infrared spectroscopy. The responses of cerebral and muscle tissue oxygenation index (cTOI, mTOI), oxygenated (O(2)Hb), and deoxygenated hemoglobin (HHb) as a function of work rate were compared. Correlations between residual continuous wave Doppler gradients at rest, arm-leg blood pressure difference and local oxygenation responses were evaluated. Age, length, and weight was similar in both groups. Patients with aortic coarctation had lower peak power output (Ppeak) (72.3 +/- 20.2% vs. 106 +/- 18.7%, P < 0.001), VO(2)peak/kg (37.3 +/- 9.1 vs. 44.2 +/- 7.6 ml/kg, P = 0.019) and %VO(2)peak/kg (85.7 +/- 21.9% vs. 112.1 +/- 15.5%, P < 0.001). Cerebral O(2)Hb and HHb had a lower increase in patients vs. controls during exercise, with significant differences from 60 to 90% Ppeak (O(2)Hb) and 70% to 100% Ppeak (HHb). Muscle TOI was significantly lower in patients from 10 to 70% Ppeak and muscle HHb was significantly higher in patients vs. controls from 20 to 80% Ppeak. Muscle O(2)Hb was not different between both groups. There was a significant correlation between residual resting blood pressure gradient and Delta muscle HHb/Delta P at 10-20W and 20-30W (r = 0.40, P = 0.039 and r = 0.43, P = 0.034). Children after coarctation repair have different oxygenation responses at muscular and cerebral level. This reflects a different balance between O-2 supply to O-2 demand which might contribute to the reduced exercise tolerance in this patient population

Prone position: Does it help with acute respiratory distress syndrome (ARDS) requiring extracorporeal membrane oxygenation (ECMO)?

Introduction: Lung protective ventilation therapy with low tidal volume-high PEEP is the standard treatment for the patients with acute respiratory distress syndrome (ARDS). Oscillators are occasionally used for salvage ventilation in cases where poor compliance restricts the use of traditional ventilation with ARDS. In addition to ventilator therapy, prone positioning has been used to improve oxygenation. We presented a challenging case of ARDS, which failed medical management extracorporeal membrane oxygenation (ECMO) support and oscillatory ventilation. Prone positioning was initiated which improved oxygenation, respiratory compliance and posterior atelectasis. Case presentation: A 41-year-old morbid obese female developed ARDS due to influenza pneumonia. The patient remained hypoxic despite optimum medical and ventilator management and required veno-venous extracorporeal membrane oxygenation (VV ECMO). CT scan of the chest showed ARDS with posterior consolidation. Despite ARDSnet ventilation support, antiviral therapy and ECMO support, there was no clinical improvement. High frequency oscillatory ventilation was initiated on ECMO day #13, which resulted in no respiratory improvement over the next 5 days. On ECMO day #18, the patient was placed on a Rotaprone? bed Therapy, utilizing a proning strategy of 16 hours a day. The clinical improvements observed were resolving of the consolidation on CXR, improvements in ventilatory parameters and decreased oxygen requirements. The patient was successfully weaned off ECMO on POD#25 (8 days post prone bed). Conclusions: Prone position improved oxygen saturation and pulmonary compliance in severe ARDS requiring ECMO and it might facilitate early weaning

Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation by tissue optical properties, an effect that causes spectral corruption. Predictions of the spectral variations of light fluence in tissue are challenging since the spatial distribution of optical properties in tissue cannot be resolved in high resolution or with high accuracy by current methods. Spectral corruption has fundamentally limited the quantification accuracy of optical and optoacoustic methods and impeded the long sought-after goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical but still unattainable target for the assessment of oxygenation in physiological processes and disease. We discover a new principle underlying light fluence in tissues, which describes the wavelength dependence of light fluence as an affine function of a few reference base spectra, independently of the specific distribution of tissue optical properties. This finding enables the introduction of a previously undocumented concept termed eigenspectra Multispectral Optoacoustic Tomography (eMSOT) that can effectively account for wavelength dependent light attenuation without explicit knowledge of the tissue optical properties. We validate eMSOT in more than 2000 simulations and with phantom and animal measurements. We find that eMSOT can quantitatively image tissue sO2 reaching in many occasions a better than 10-fold improved accuracy over conventional spectral optoacoustic methods. Then, we show that eMSOT can spatially resolve sO2 in muscle and tumor; revealing so far unattainable tissue physiology patterns. Last, we related eMSOT readings to cancer hypoxia and found congruence between eMSOT tumor sO2 images and tissue perfusion and hypoxia maps obtained by correlative histological analysis