Influence of High Hemoglobin-Oxygen Affinity on Humans During Hypoxia

Humans elicit a robust series of physiological responses to maintain adequate oxygen delivery during hypoxia, including a transient reduction in hemoglobin-oxygen (Hb-O2) affinity. However, high Hb-O2 affinity has been identified as a beneficial adaptation in several species that have been exposed to high altitude for generations. The observed differences in Hb-O2 affinity between humans and species adapted to high altitude pose a central question: is higher or lower Hb-O2 affinity in humans more advantageous when O2 availability is limited? Humans with genetic mutations in hemoglobin structure resulting in high Hb-O2 affinity have shown attenuated cardiorespiratory adjustments during hypoxia both at rest and during exercise, providing unique insight into this central question. Therefore, the purpose of this review is to examine the influence of high Hb-O2 affinity during hypoxia through comparison of cardiovascular and respiratory adjustments elicited by humans with high Hb-O2 affinity compared to those with normal Hb-O2 affinity.

Real-time whole-brain imaging of hemodynamics and oxygenation at micro-vessel resolution with ultrafast wide-field photoacoustic microscopy

High-speed high-resolution imaging of the whole-brain hemodynamics is urgently needed to facilitate the next level of neurovascular research. Image acquisition speed and image quality are crucial to visualizing real-time hemodynamics in complex brain vascular networks, and displaying fast pathophysiological dynamics on a micro and macro-level, enabling advances in current queries in neurovascular and brain metabolism research, including stroke, dementia and acute brain injury. Further, real-time oxygen saturation of hemoglobin (sO2) imaging to differentiate arteries from veins and capture fast-paced oxygen delivery dynamics is needed to solve pertinent questions in these fields and beyond. Here, we present a novel ultrafast functional photoacoustic microscopy (UFF-PAM) to image the whole-brain hemodynamics and oxygen delivery. UFF-PAM takes advantage of several key engineering innovations, including Raman-shifter-based dual-wavelength laser excitation, water-immersible 12-facet-polygon scanner, high-sensitivity ultrasound transducer, and deep-learning-based image upsampling. A volumetric imaging rate of 2 Hz has been achieved over a field of view (FOV) of 11× 7.5 × 1.5 mm3 with a high spatial resolution of ~10 µm. Using the UFF-PAM system, we have demonstrated proof-of-concept functional studies on the mouse brains in response to systemic hypoxia, sodium nitroprusside, and stroke. We observed the mouse brain’s fast morphological and functional changes over the entire cortex, including vasoconstriction, vasodilation, and deoxygenation. More interestingly, for the first time, under the whole-brain FOV and micro-vessel resolution, we captured the vasoconstriction and oxygenation change simultaneously in the spreading depolarization (SD) wave. Our work provides a great potential for fundamental brain research under various pathological and physiological conditions.

Pathophysiology of Hemorrhage as It Relates to the Warfighter

Saving lives of wounded military Warfighters often depends on the ability to resolve or mitigate the pathophysiology of hemorrhage, specifically diminished oxygen delivery to vital organs that leads to multi-organ failure and death. However, caring for hemorrhaging patients on the battlefield presents unique challenges that extend beyond applying a tourniquet and giving a blood transfusion, especially when battlefield care must be provided for a prolonged period. This review will describe these challenges and potential strategies for treating hemorrhage on the battlefield in a prolonged casualty care situation.

Prostate-specific membrane antigen (PSMA) targeted singlet oxygen delivery via endoperoxide tethered ligands

A PSMA targeting ligand is functionalized with endoperoxides which thermally release singlet oxygen. The results show that this modular design results in significantly more cell death in PSMA-expressing prostate cancer cells.

An evidence-based approach in the management of fatigue due to heart failure: breathing exercises

Fatigue is one of the common symptoms that adversely affect the quality of life of patients with heart failure. It has been reported that fatigue seen in heart failure is caused by conditions such as deterioration of peripheral circulation due to decrease in oxygen delivery, autonomic nervous system abnormalities and deterioration in the strength of the respiratory muscles. Breathing exercises are one of the integrative applications that can increase oxygen delivery due to the functional connection of the heart and lungs providing relief from fatigue. In the literature, breathing exercises have a wide range of breathing techniques that create changes in breathing form and rate. Many studies have found that breathing exercises reduce fatigue, and can have significant effects on patient care and clinical outcomes. Nurses have a major impact on patient outcomes such as reducing fatigue in heart failure patients and improving health-related quality of life. For this reason, it is very important to include breathing exercises in nursing practices. In this regard, the importance of breathing exercises in the management of fatigue due to heart failure has been addressed in this review.

Reconciling Oxygen and Aerosol Delivery with a Hood on In Vitro Infant and Paediatric Models

This study aimed to evaluate optimal aerosol and oxygen delivery with a hood on an infant model and a paediatric model. A facemask and a hood with three inlets, with or without a front cover, were used. A small-volume nebuliser with a unit-dose of salbutamol was used for drug delivery and an air entrainment nebuliser was used to deliver oxygen at 35%. Infant and paediatric breathing patterns were mimicked; a bacterial filter was connected to the end of a manikin trachea for aerosol drug collection, and an oxygen analyser was used to measure the oxygen concentration. For the infant model, inhaled drug dose was significantly higher when the nebuliser was placed in the back of the hood and with a front cover. This was verified by complementary computational simulations in a comparable infant-hood model. For the paediatric model, the inhaled dose was greater with a facemask than with a hood. Oxygen delivery with a facemask and a hood with a front cover achieved a set concentration in both models, yet a hood without a front cover delivered oxygen at far lower concentrations than the set concentration.